Creating an attic - a popular type of room - with your own hands today is not difficult. Let's look at all the stages of construction, as well as the pros and cons of this design.

Peculiarities

Home is a place where we would like to surround ourselves with comfort, have the opportunity to relax with our families and work. Sometimes this becomes impossible due to lack of square meters. How to make housing spacious and comfortable? Construction technologies have stepped far ahead - resources have appeared that allow you to expand the occupied space with your own hands through extensions. But if there is not enough land, then the attic will be the most successful option!

Currently, this is a fashionable design for private houses. Back in the 17th century, the attic was conceived as a way to expand housing for the poor. And thanks to the French architect Mansard (fr. Mansard), the conversion of roofs into residential apartments has become very popular among the rich. From here, by the way, the name came - attic.

Many people ask the question: "Attic or additional floor?". It is worth clarifying right away that these are two different things. Before choosing one or another option, weigh all the pros and cons, take into account the purpose of your home (dacha or permanent place of residence), your Family status as well as the budget. It will be much more economical to build an attic than a full-fledged second floor.

In this article, we will tell you how to significantly convert the usable area when minimum investment. And with the implementation of all the necessary activities, you can handle it on your own.

Installation and arrangement of the attic, the facade of which is completely or partially formed by the surface of a sloping roof, is a vast scope for imagination and creativity. So much space shouldn't be wasted! A great studio, office or storage space for unnecessary things will come out here. But isn't it too wasteful to turn precious square meters into a warehouse?

Typically, attic spaces are provided to children who like to be placed on high levels, and besides, low beams often cause some inconvenience to adults. This floor is the last one, and the higher, the better the view, no doubt. The presence of pipes, the proximity to the roof, a remote balcony, a sloping ceiling - all this will become a stylish help for creating an architectural design.

An objective assessment of the specifics and knowledge of the constructive qualities of this type of superstructure give a chance that everything will work out as well as possible, the load-bearing walls and foundation of the house will not be harmed, and the dwelling will last a long time. Believe me, the attic is very useful thing!

The most successful solution is a frame attic. Before you begin to develop a superstructure plan, you must make sure that the lower floor can withstand the additional load. After all, every person who encounters a building knows that the main building is located on load-bearing structure, which is calculated based on the entire mass of the structure. Therefore, at the beginning of construction, it is necessary to make the necessary calculations, as well as check the foundation for cracks or any damage on it. If necessary, the base will need to be strengthened. At this stage, it is best to turn to professionals.

Based on how the roof is constructed, the appearance of the attic can be different. As a rule, the attic occupies the entire top floor, although sometimes there are options located on one side of the longitudinal axis of the building. It is not often possible to see attics that extend beyond the lower structures.

Most often, the roof is gable or broken. More complex view gable configuration is popular: the roof consists of two planes, as it were. But we will discuss each of them in more detail a little later. Windows, large or small, located on the ceiling let in many times more light than ordinary windows in the rooms on the lower floors.

When choosing a roofing, observe harmony so as not to disturb the combination of form attic floor and roofs.

You can also immediately insulate the room with SIP panels. As a result, you will get a lightweight construction, which consists of more than 50% of lightweight polystyrene foam, therefore, it does not create a load on walls and ceilings.

There are several design features that cannot be ignored.

  • take seriously the thermal insulation, which should be strengthened, because it is the roof that often “suffers” from frequent and sometimes strong temperature changes;
  • it is important to make waterproofing conscientiously, so that over time the insulation does not get wet;
  • between the thermal insulation layer and the roof, ventilation must be done properly.

Options roof structure must be due to the further construction of thermal insulation, which is placed between the timber rafters and has a thickness of at least 20 cm. The rafters must be at least 25 by 25 cm.

The main indicators of wood that are important for the design of the system are flexural and compressive strength, the desired density and moisture content.

Wooden rafters, in turn, require treatment with antiseptics or fire and bioprotective structures and must have fire resistance limits.

Designers are advised to leave the attic space intact. Nevertheless, if it becomes necessary to separate rooms, then it is better to build partitions using drywall.

Consider also the disadvantages of this type of adjustment:

  • due to the sloping roof, unlike the usual floor, the size of the attic area will be smaller;
  • the height must be optimal, otherwise there will be problems with closing / opening the doors;
  • psychological factor: sometimes it seems to people that there is not enough air, every time you want to bend down, a person may feel discomfort;
  • regardless of the type of roofing and even correct installation soundproofing sounds from the rain will penetrate the room;
  • it is important to think over the heating system correctly;
  • the stairs leading to the attic may be too steep and therefore unsafe.

Design options and materials

Using the advice of experts, carefully develop a future attic project. After that, prepare the design of the attic, as this is not just a certain number of square meters, but the individuality of the facade - the pride of the building. The appearance and interior depends on the methods of coating and materials for the roof.

There are several types of roofing.

Shed

The simplest option, which is a sloping area fixed on load-bearing walls. Advantages: ease of calculation and installation work, due to its low weight, it is suitable for buildings on foundations of a simplified type. Disadvantages: not the most attractive appearance, sensitivity to loads (snow).

gable

One of the most common options. Such a structure consists of two opposite slopes, which lie on the walls of the building that serve as a support and are connected at the top with a ridge. Material investments in a gable roof are quite small, while it looks aesthetically attractive. The gable roof device includes: rafters, lathing, inclined planes, mauerlat, horizontal ribs, ridge, valleys, overhangs.

broken line

The broken roof structure is a subspecies of the gable roof, but with a more complex configuration. Because of the shape and the presence of broken lines, this name came about. Such a roof gives the house solidity and solidity.

Four-sided or hip

One of the strongest and most resistant to strong winds and leaks during rainfall roofing systems, where two triangular slopes are installed instead of gables. Complex installation - minus this design: requires accuracy in calculations truss system and frame installation. For this reason, designing is usually trusted to professionals.

Multi-forceps

Among all the designs, the most complex, but at the same time the most interesting is considered to be multi-forceps. It is characterized by the presence of several gables (from 3 or more). A big plus is the ability to cover several rooms with one level. But in general, this type of attic works mainly on the architectural style and design.

The attic part is divided into two types. She may be:

  • single-level- a fairly practical option in execution that does not require complex development and serious calculations;
  • two-level- This is a building that is difficult to erect, the project of which is created immediately together with the house.

Current building technologies make it possible to make different types of balconies in the attic. To select the desired design, you should consider the design features of the lower floor. And it doesn't matter if the balcony was already included in the plan, it can be done at the end of all stages of construction.

Most good option location - from the end. In this case, the balcony will resemble a loggia. It is erected together with the attic, which allows you to use part of the roof as a canopy, and the ceiling of the floor as a floor.

Another type of construction is the option when the balcony is located in the roof part. At the stage of roofing, part of the building is left uncovered so that a balcony can be equipped there.

Drawings and calculation

The main parameter when planning the attic floor is the ceiling level, the optimal height of which should be at least 2.5 m. Make a drawing before direct construction, evaluate everything and indicate accurate calculations so that everything can be built accurately. Most perfect option is a broken line pitched roof, but then as many bearing supports as possible should be installed for sufficient reliability, since this type of roof increases the pressure on the walls.

Do not forget to include the ventilation system, as well as windows and pipes in the calculations. furnace heating, if any are expected.

The height of the superstructure itself has no limit, but the lower ends must be at least 90 cm.

The plan should contain all the information about the shape features, geometric dimensions and slope angles of the slopes.

After the exact calculation of the mansard roof truss system is completed, all the necessary materials should be purchased and the roof should be prepared. Only after that, you can start building.

Do-it-yourself attic manufacturing steps

It is very important to choose the design and style of the interior at the initial stage, as well as decide on the materials for decoration. You should listen to the opinion of professional designers who advise using only high-quality raw materials. We will guide you step by step through all stages of construction.

Roof

So, the first stage is the development of a project for a new future roof in an old room. It does not matter whether it is single-pitched, double-pitched or broken, without a doubt, the appearance of the result will directly depend on the structural properties of the roof, as well as the raw materials used. Make a diagram in different perspectives to better understand how to place the elements of the truss system. The most important thing is to accurately calculate the height of the roof ridge, because the size of the area under it depends on it.

We take the height of the ridge about 3.5 m - with the independent construction of the frame, which allows you to straighten up to your full height.

It is important to remember that in order to build a frame with your own hands, you must be aware of the existence of two types of truss systems: inclined and hanging. They differ from each other by the method of attaching nodes to the walls.

In houses where there is no load-bearing wall, the mechanism of hanging rafters will be used, which will be held only on the walls of the house and connected to each other with nails or screws using corner plates. In this case, the width of a single-span building, where this particular type of rafters is assumed, cannot exceed 6 m. If the parameters of the house are larger, for example, when the span width exceeds 9 m, then more struts have to be done.

In two-span houses, where there is only an average supporting wall, layered rafters are made. In this case, the three base points (two on the outer walls of the house and one on the inside) depend on the width of the building: more than 10 m - one support, and with a width of about 15 m, two supports will be needed. The rafters are attached to each other with the help of corner plates. The crate itself is made of slats or boards.

Steam and thermal insulation are key steps in creating an attic. A membrane-type film is laid on top of the crate, which will protect against moisture penetration, and glass wool is laid on the inside for insulation.

The next stage is the installation of the roof, interior processing and design of walls and partitions, as well as the installation of windows.

As we have already mentioned above, the most successful will be the use of metal tiles or corrugated board as a material for roofing.

floors

First, take care of sound and thermal insulation from the floor below. This task can be accomplished in several ways: backfilling of expanded clay or laying mineral wool slabs. Both methods involve protection from moisture with hydrofilms. Also pay attention to the wooden floors. Here, the insulation is performed with dressing of the seams of the insulation and beams.

Choose the flooring of your choice. It can be ceramic, parquet or laminate.

Window

Loft windows are quite a labor intensive but worthwhile process, so consider if you can do it yourself. In fact, they do not differ much from facade ones, but there is one serious difference - a special type of opening. In addition, during installation, you will have to disassemble the metal tile, while trying to maintain waterproofing. But this is not scary, because it is thanks to the windows that the room becomes much lighter and more spacious!

It is very important to know that if snow and ice are not cleared regularly, the window may be subject to temperature changes, so it is important to select models in accordance with the climate in which you live.

Heating selection

For comfortable living and the use of the premises, you also need to take care of heating the attic. It should not only maintain and retain heat inside, but also be safe and economical.

All details must be taken into account early stages design. We bring to your attention several methods of heating the attic floor.

  • Fireplace. Efficient, comfortable and completely safe way.
  • If your house already has a heating system on the ground floor, then you only need to install additional pipes and batteries.

  • Installation of an independent heating system only for the attic - the most correct solution. It is possible to install absolutely any heating boilers, while observing the necessary safety measures. But more comfortable - turbocharged gas boilers that do not require a separate room. They are wall mounted and very easy to use.
  • "Warm floor". To create a comfortable microclimate in the room, you can install underfloor heating. This can be done both with your own hands and with the help of specialists. In any case, this is a fairly economical option.

An important point is the proper arrangement of ventilation. Only in this way will attic heating work well.

Warming and ventilation

Since the attic has the largest area of ​​​​contact with the street, compared to the lower floors, its insulation should be taken very carefully. Today the market offers a variety of insulating materials. However, when solving this problem regarding full-fledged thermal insulation and vapor barrier for the house, do not forget about the main conditions, and then this will not only reduce heat loss and heating costs at home, but also protect the ceiling and walls from dampness, rot and sputum, the formation of ice on the roof . The choice of materials for the "roofing pie" must be carried out in accordance with the requirements of SNiP.

When you choose a finish in a store, focus primarily on the characteristics of your home. For example, where it is hot in summer and frosty in winter, the insulation must be resistant to external circumstances. Therefore, one of the main conditions will be thickness. The colder, the denser it should be, and, conversely, if you live in the south, where the temperature practically does not drop below zero in winter, you can choose a thinner material.

The most versatile and most budgetary - based on mineral wool, polystyrene foam is used less often. Sometimes it is possible to use a heat-insulating layer consisting of modern filling agents or materials in the form of a liquid sprayed onto the walls and solidifying into a solid form. In all these cases, the roof will come out no less stable.

With the correct assembly of the “roofing pie”, the design of which consists of metal tiles or corrugated board, lathing, waterproofing membrane, truss system, properly equipped ventilation of the under-roof space is sure to extend the life of your roof. Never play the lottery "will carry it - will not carry it", but "wind it on your mustache" the advice of experts.

To create a beautiful and cozy living space, you can use wood as a finishing material from the inside, different kinds composite panels, HRL panels (or in Russian LVD - laminate high pressure). No less popular is the attic, decorated with your own hands using drywall sheets (gypsum plasterboard).

Roofing should be made of lightweight materials: corrugated board, metal tiles and similar materials that can lighten the weight of the mechanism, taking into account the load that will be transferred to an existing building.

To begin with - before altering the attic - you need to make drawings and draw up an estimate. This way you will see in advance what difficulties you will face.

It is not easy to develop a plan for a mansard roof alone: ​​certain knowledge and skills in designing and carrying out specific calculations are important here. You can’t make mistakes: then the structure of the building will be unreliable, and besides, it can damage the overall building. Although if the idea is not too complicated, then you can do it yourself.

Everything must be included in the estimate: from the beginning of construction to the design of the premises.

Partitions

One of the most simple tasks, which you can definitely handle with your own hands, is a device interior partitions. Usually, drywall and metal profiles are used for these purposes. Everything is done quickly and at minimal cost.

The design is simple: a frame, and gypsum boards are attached to it. At the end, the lining of the partition is made. To do this, you can use lining, block house, imitation timber or even plywood with wallpaper - a matter of taste.

Finishing work

After warming the attic, you should think about finishing. Of course, it all depends on how you will use this room. The peculiar geometry provides excellent prospects for creative design solutions. Immediately, we note that the finishing process is a complex of tasks, each of which has its own function. Let's take a closer look at finishing materials.

  • The most popular material plastic lining. Advantages: uniqueness, budget, environmental friendliness. The installation of the board can be different: diagonally or in a circle, horizontal or vertical. Of the minuses, it is worth noting fragility and, perhaps, weak resistance to negative factors.

  • Not the most expensive material plywood sheet. Covering the walls with them is quite easy. It also has excellent sound and heat insulating properties; no pre-leveling of the surface is required before installation.
  • Finishing the attic with drywall will allow you to embody the most original design solutions: with its help you can create dropped ceilings, arches and even columns. At the same time, this material easily absorbs moisture, which is its negative side. But if you choose a special type that is resistant to moisture, then this finish will last you a very long time.

So, let's sum up and summarize the above.

To design a beautiful and high-quality attic you will need:

  • careful design of the future extension;
  • strengthening load-bearing walls and foundations;
  • roof removal;
  • erection of the frame (it will be easy enough for you to assemble it with your own hands);
  • roof insulation, waterproofing;
  • window installation;
  • interior decoration and warming.

With excessive savings, as practice shows, the house can eventually turn out to be of poor quality and unattractive. Therefore, choose materials wisely, take into account the recommendations of experts, consult relatives and friends, as well as those who already have similar experience.

Modern people try to use the area of ​​their home as efficiently as possible. Therefore, the proposal to equip additional space under the roof is always met with enthusiasm. It is much easier to plan the construction of an attic at the stage of building a house, but you can make an additional superstructure above the old building.

How to make an attic on an old house

The presence of an attic not only increases the living space, but also gives the building a colorful look.

Attic turns Vacation home in a fabulous building

An old house can be updated by building a superstructure in accordance with existing standards.

The attic superstructure begins with calculations of the strength of the old house

First you need to decide whether the existing foundation and walls can withstand the load of the attic floor and the new roof. If they have a sufficient margin of safety, then you can start remodeling the house. Otherwise, they should be strengthened.

Old brick walls sometimes seem strong, but with additional stress, cracks may appear in the mortar over time. Therefore, it is necessary to immediately consider their condition, and, if necessary, tie them with a rigid belt. This is done as follows:

  • metal poles with a section of 10x10 cm are inserted into the foundation with the lower edge, and connected with the armored belt of the first floor with the upper edge. Installed around the perimeter of the house every 2 meters;
  • metal fittings with a cross section of 12 mm are placed in strakes and tie the house along the walls: from the bottom of the window every 2 meters up;
  • lays over the reinforcement metal grid with a cell size of 2x2 cm, which, after completion of all work, is covered with plaster.

Strengthening the foundation is carried out by tying with a reinforcing belt from all sides.

If the old foundation cannot withstand the attic, then it must be sheathed with reinforcement

Having decided on the strengthening of the building, you can proceed to the choice of the project of the future superstructure. It should look harmonious against the background of other buildings and match the style of the whole house.

The type of mansard roof will determine the calculation of the dimensions of the inner upper room and necessary materials for construction

There are several types of attics:

  • single-level with a gable roof - low ceilings with a small living space;

    A single-level attic with a gable roof is the simplest type of superstructure for small buildings

  • single-level with a sloping gable roof - increased interior space, but serious costs and time for construction;

    A single-level attic with a broken gable roof is usually built on a brick house

  • single-level with cantilever extensions - a complex structure that allows you to get even more area, since the attic frame extends beyond the building, and the windows are installed vertically;

    A single-level attic with cantilever extensions allows you to get a lot of internal space by increasing the upper structure

  • multi-level with mixed roof support - used in the construction of a new house, built only by specialists.

    A multi-level attic with a mixed roof support on old houses is usually not installed due to the complexity and large amount of work.

Video: converting half of the old roof into an attic - an easy way

Alteration of the roof under the attic - comparatively cheap way increase in living space. In a private house, a pitched roof is usually placed, so you can make an additional spacious and bright room with your own hands.

Internal wood paneling makes the attic warm and bright

And if the house is large enough in length, then the attic can turn into a real floor: with several rooms and even a balcony.

A large attic allows you to divide the area into different residential areas

Advantages of creating an attic:

  • the possibility of arranging one or more new living rooms;

    An attic with low ceilings under a gable roof is most conveniently furnished with low sunbeds

  • low costs compared to the construction of a full-fledged floor or a side extension to the house;
  • renovation of the exterior of the building;

    A house with an attic under construction always attracts the eyes of passers-by and is interested in the final result.

  • opportunity to observe beautiful view from the attic window.

    A lot of sunlight comes through the windows in the attic, illuminating the room all day

However, this solution also has certain disadvantages that must also be taken into account:

  • the need for insulation and soundproofing of the ceiling and a new roof, the installation of several double-glazed windows;
  • the difficulty of conducting additional heating and lighting in the upper part of the old house - you will have to combine it with home wiring or use an autonomous connection;

    To heat the attic with access to the balcony, you can use a potbelly stove

  • layout of a part of the home space under the stairs leading to the attic;

    The stairs leading to the attic must be fenced for safety.

  • the need to purchase special furniture for a sloping roof or purchase squat models: low cabinets, sofas and tables.

    Low furniture is best suited for attic interiors

The presence of sloping walls makes the room unusual and romantic, but with this decision you will have to take a more responsible approach to design development. You can make furniture for an inclined superstructure yourself or assemble a single complex from existing multi-level models, painting everything in one color.

Furniture that repeats the slope of the attic can be made independently

So, the main disadvantage of converting an attic into an attic is the need to invest, but it's worth it.

Building an attic will cost much less than creating an additional floor, regardless of what materials will be used to build the walls. Indeed, to create them, you will need the main material, insulation and decoration, while for attic superstructure all you need is a roof insulation and a new truss system.

The superstructure is made in a symmetrical or asymmetrical shape. Internal walls are designed both inclined and vertical.

Having studied the schemes of single-level attics with different types roofs, it is easier to make a choice when planning

Alteration of the attic into an attic does not require the dismantling of all existing structures. But you need to make sure that ceiling: check its condition, reinforce it with wooden or metal beams, sheathe with a new board. Then it will be able to withstand the weight of furniture and people.

For frequent climbing to the attic, you will need to do comfortable stairs, provide for the installation of ventilation, natural and artificial lighting, perform interior decoration - all this will create a cozy and comfortable room.

The sloping roof superstructure, decorated in light colors, visually enlarges the space, while splashes of color add brightness to the interior.

When building an attic floor, the following conditions must be met:

  • rafters are made of glued timber with a thickness of at least 250 mm so that the required amount of insulation can be laid;
  • foamed polystyrene is used for insulation due to its low weight and high thermal insulation characteristics;
  • a gap is left between the thermal insulation and the roofing material to provide natural ventilation;
  • a hydro- and sound-proof layer must be laid.

Alteration of the roof under the attic do it yourself

During the construction of a house, there is usually not enough money, so many refuse to build a second floor. Or another situation may arise when an old one-story house of a small area is purchased along with the site. In both cases there is affordable option increasing space for living - do-it-yourself restructuring of the attic space into an attic.

Create a project

Before starting work, you need to draw up a plan and develop a project with accurate drawings. Correct calculation will allow you to get a cozy, durable and reliable room. You can perform all the calculations yourself or entrust it to specialists.

You can draw a plan and develop a draft design yourself by studying different variants in the Internet

Reinforcement of walls and foundations may be necessary in case of complete replacement rafters. If the roof is partially redone, then reinforcement may be needed only for overlapping. You also need to immediately decide what types of windows will be used in the attic: the reinforcement in the truss system will depend on this.

The location of all windows in the attic roof must be thought out in advance and this data entered into the project plan

truss system

Rafters can be layered or hanging. The first is based on internal walls houses or additional supports, and the latter - on external walls.

In the attic, layered and hanging rafters are used.

Hanging rafters are best suited for the attic.

Attic with hanging rafters looks prettier and wins in the size of the internal area

The attic usually occupies the entire space of the attic, and its walls are combined with the outer ones.

The best option for creating an attic is a layered truss system.

The rafter system consists of different load-bearing bars. To understand the structure of the entire structure and build it correctly, you need to understand the purpose and operation of its individual elements.

Image individual elements truss system helps to understand the device of the whole structure

Refurbishment of the premises

With a sufficient height of the attic, the truss system does not need to be redone. It is enough to inspect the old rafters, identify possible flaws and eliminate them.

If the truss system is in good condition, you can proceed to the arrangement of the floor. Insulation is first laid between the lags, after which the surface is sheathed ordinary boards or sheets of OSB, chipboard.

The floor in the attic is insulated and covered with boards

Before laying the insulation, all necessary communications are mounted between the rafters, places are cut in the roof for installing windows. carried out before warming.

All wires and pipes of communications must be placed in special corrugations

Care must be taken to create natural ventilation of the under-roof space through the vents so that moisture does not accumulate inside the room.

Roof insulation

It is necessary to insulate the roof correctly and efficiently - the microclimate under the roof will depend on this. Typically, mineral wool, polystyrene foam or sprayed polyurethane foam is used as insulation.

A thick layer of heat insulator is tightly laid and fixed between the rafters so that there are no gaps or gaps anywhere. On the upper part of the roof - between the roof and the insulation - waterproofing is mounted, then heat-insulating material is laid from the side of the room. Then from the inside the insulation is covered with a vapor barrier film.

For better ventilation, a small distance is left between the roofing material and the insulation: this is how air circulates through the holes in the eaves and ridge. If the roof is covered with corrugated sheets, then the thickness of the gap should be 25 mm, if flat material, then it is necessary to bring it to 50 mm.

When creating attic thermal insulation, it is necessary to strictly observe the sequence of layers

When planning an ascent to the attic, you need to take care of the convenience and safety of movement. Therefore, the ladder is usually mounted inside the house. It is constructed from wood or metal: it can be either a screw or a marching structure.

The stairs to the attic can be different kind and design, which allows it to fit into any interior

An opening is cut in the ceiling of the first floor, which is reinforced along the perimeter with metal or wooden strapping.

The design of the stairs to the attic must be durable, reliable, safe and beautiful.

Interior decoration

For wall cladding, in most cases, gypsum boards are used, the seams between them are plastered. Wallpaper is glued on top or superimposed decorative plaster. Alternative option- lining or natural wood.

If some rafters protrude through the walls into the attic, then they can be designed as decorative elements and even used as a horizontal bar for hanging a hammock, swing, chandelier and other fixtures.

The design of the visible parts of the rafters in the interior of the attic is an interesting and creative business.

It is not recommended to use heavy finishing materials in the attic, as they increase the load on the walls, ceiling and foundation of the building.

There are many options for interior decoration of the attic, but it is advisable to use only light materials.

To cover the floor, you can use a laminate or linoleum, and it is better to refuse tiles or porcelain stoneware.

Roof of the attic floor

The roof of a residential superstructure should consist of the following layers (in order - from the street to the interior):


Video: why and how to properly lay layers on the roof of the attic

Mansard roof calculations for a house

Determination of the total weight of the roof

To calculate the total weight of roofing materials, it is necessary specific gravity multiply one square meter of coverage by the total area of ​​the mansard roof. To obtain the weight of one square meter, it is necessary to add up the specific gravity of all the materials that make up the roofing cake, and multiply it by the safety factor (1.1).

If the thickness of the crate is 25 mm, then its specific gravity is 15 kg / m 2, a 10 cm thick insulation has a specific gravity of 10 kg / m 2, and ondulin roofing material has a weight of 3 kg / m 2. It turns out: (15 + 10 + 3) x1.1 \u003d 30.8 kg / m 2.

According to existing standards, the load on the ceiling in a residential building should not exceed 50 kg / m 2.

Roof area determination

To calculate the surface of a sloping roof, you need to break it into simple shapes (square, rectangle, trapezium, etc.) and determine their area, and then add everything up. To determine the surface of a gable roof, it is necessary to multiply the length by the width, multiply the resulting value by two.

Table: determination of the attic roof area

When calculating the angle of inclination, the climatic zone in which the house is located is taken into account, and that it is convenient to move in the attic in full growth

It is also necessary to calculate the slope of the roof. Usually the angle is 45–60 degrees, but when determining it, one must take into account the climatic zone in which the house is located, the type of attic construction, snow, wind loads, and the architectural design of the house.

The greater the angle of inclination of the roof, the less will be the load on the truss system, but the consumption of materials will increase.

Calculation of the truss system

When choosing a truss system, you can stop at the following options:

  • hanging rafters;
  • oblique type;
  • skating run;
  • combined design.

If the length of the roof is more than 4.5 m, then support runs and struts can be used for reinforcement. With a length of more than 7 meters, a ridge beam is installed.

For wooden rafters, a bar with a thickness of at least 70 mm is used. The step of their installation should be 50 cm.

On a large area, it is better to fix a metal truss system: due to the increase in the distance between the rafters, the absence of spacers and struts, the weight of such a structure will be less than that of a wooden one, and the strength will increase significantly.

If the attic area is large, then it is better to install metal rafters

Calculation of the required amount of materials

To carry out the calculation, you need to know the following parameters:

  • width, thickness and pitch of the rafters;
  • distance from the edge of the roof to the rafters;
  • the size of the boards for the crate and the step between them;
  • size, type roofing material and overlap between its sheets;
  • type of steam, hydro and thermal insulation material.

The roof is divided into simple shapes and the required amount of each of the materials is determined. For this, simple mathematical formulas are used.

The results obtained are converted into standard values: for a tree - into Cubic Meters, for roofing materials, steam, hydro and thermal insulation - in square meters. And you can go to the store.

Common Mistakes

Most often, when calculating independently, errors are obtained during the determination required amount insulation. If climatic conditions severe, then its volume will have to be increased, otherwise it will not be possible to create comfortable living conditions in the attic. The insulation is laid on the floor of the house, the walls of the gable and the slopes of the roof. But everywhere the thickness of the insulation can be different.

Video: calculation of a mansard roof with diagrams and loads

The attic floor allows you to get additional living space and gives the private house a modern attractive appearance. It is not difficult to create an attic with your own hands, you just need to draw up a project correctly, perform calculations and carry out high-quality installation of all materials. And the result will please the owners for a long time.














Today we will talk about popular solutions for mansard roofs, their capabilities. After reviewing the illustrations, diagrams of the truss system, you will get a clear idea of ​​​​their device. And having studied the basics of calculation, you can optimize the cost of lumber. Get information about important points space layouts. Find out in what sequence the mansard roof truss system is mounted.

The mansard roof is a complex structure and requires careful calculations.

Drawings of the truss system

Any mention of an attic is associated with a voluminous "pentagonal" roof in which you can live, but there are other options.

Shed

Extremely simple, reliable shed mansard roof. Thanks to the rectilinear forms, it looks modest, but elegant. Large floor-to-ceiling panoramic windows add special respectability, because such a design not only allows, but provokes their installation.

House with pitched roof, with windows almost on the entire wall

The rafter system is very simple: the straight rafters of a single slope rest on the mauerlat of opposite walls of different heights, and, if necessary, on intermediate supports. The proportions of the walls are selected for a slope of 35-45 degrees, which guarantees stability to wind loads and normal snowfall.

The volume is used effectively - if desired, this is an additional full-fledged floor, since the usable area is equal to the area of ​​the previous floor.

gable

Relatively simple widespread roof. It looks unpretentious, but inspires confidence, as it maintains the traditions characteristic of the Russian style. As a result, it is rarely designed specifically for the attic, more often it is adapted in finished form.

The gable roof is traditional, and most often the choice falls on it.

Structurally simple - specifications and a truss system like a conventional gable roof. Straight rafters rest on the Mauerlat, angled into a ridge. Gables are triangular in shape, straight, sheer, almost always glazed, often with access to a balcony.

Most often, a similar scheme is used for arranging an attic in small house with gable roof

It is problematic to fully use the volume, but it is possible, even necessary. The useful area is relatively small, the ceiling is usually "broken". However, the skillful arrangement of furniture, bold design solutions disadvantages can be turned into advantages.

broken line

The most popular option is a sloping roof with an attic. Which is not at all surprising - despite the complexity, it is the most convenient and practical. Overall forms and broken lines symbolize solidity and professionalism. Appearance of this roof "by default" is associated with the "mansard". This is quite natural - it is purposefully designed for living quarters.

To add space on the attic floor, preference is given to a sloping roof

The rafter system is quite complicated, but its advantages are worth the money and effort spent. Characteristic pentagonal gables, with the functionality of a gable roof - the same opportunity to insert windows, arrange an exit to the balcony.

The circuit is more complex, but gives more space

Spacious attic roof of a private house. The volume is used to the maximum - at full height, the useful area of ​​\u200b\u200bthe room is equal to or slightly less than that of the previous floor.

Calculation basics

The purpose of the calculations is to find a compromise between aesthetics, reliability and cost.

aesthetic side. To begin with, a general sketch of the roof is being designed. The proportions are determined, compared with the size of the house.

Difference between broken roof and gable essential

After that, a constructive calculation is carried out, where factors are taken into account:

    Own weight structural elements of the roof. The load from it acts on each element of the truss system.

    Wind loads. They are variables and affect all elements.

    . It acts unevenly, it is transmitted from areas where mansard roof with a slope of less than 30°, snow does not linger on steeper sections. In this case, the load can be unevenly distributed over the left and right slopes. Affects beams and upper rafters.

    Weight people, interior elements and furniture. Loads only the floor.

Factors are processed, summarized. Based on the results, conclusions are drawn about the dimensions of the structural elements. For guaranteed strength, they are rounded up. But technological assembly is hampered by the individual width and thickness of each structural element rafter system, and their custom-made production is unprofitable. Therefore, the elements are combined into groups standard sizes lumber. A standard solutions significantly reduce the cost of the project - after all, to order is always more expensive.

If the project is individual and non-standard, it is better to order accurate calculations. Taking into account the number of factors, their specific impact on the truss system, the conclusion suggests itself - an accurate calculation is the business of specialists. It makes no sense to do calculations on your own - there is a high probability of error. For standard and standard solutions, a ready-made existing project can be adapted.

In addition to the main points, a few practical recommendations will come in handy:

    Rafter step corresponds to the dimensions of the heater.

    Rafter width corresponds to the thickness of the insulation.

layout

The stairs are key. Its position must be linked with future floor beams. If the pitch of the rafters allows, we simply orient it between the beams. Otherwise, we design a reliable convenient entrance to the attic.

At the planning stage, it is useful to think over the interior. At this stage, decisions are made about partitions and additional natural lighting - skylights. Of course, it's too early to think about decorating, but the engineering part should become clear - what functionality will be implemented.

In the attic you can equip an office with a corner for music lessons

After all, the features of such premises: broken-inclined ceilings, their reduced height, unusual walls and non-standard lighting.

Therefore, a specific layout of the premises is necessary, and in them, the distribution is correct - space zoning:

    For the main life activity, are allocated bright and well ventilated premises.

    Uncomfortable areas are equipped under the storage.

    "Unusual conditions" to give away at the disposal of children.

Interior design and ultimate comfort are created by the skillful use of potential finishing materials, furniture and accessories.

Assembly

In most cases, the construction of a mansard roof begins with a Mauerlat device. A strictly horizontal position, parallel, reliable fastening of its bars is important.

Mansard roof truss construction

For the installation of the rafter system, two options are practiced: the elements of the truss system on the ground are assembled into trusses, lifted and installed ready-made. Or everything is collected separately at the top - "in place", observing procedure:

    Roof beams are laid. This takes into account the step of the truss system and the possibility for arranging stairs.

    Straightaway laying a rough ceiling, or temporary flooring for safe work.

    Racks are mounted. Temporary braces are arranged to keep them in a vertical position. Runs are laid on the racks.

    Over runs stacked puffs.

    Mounted lower rafters.

    Temporary braces change to permanent wind connections in the longitudinal position.

    Installed top rafters.

    exhibited pediment frame, taking into account the design, openings are organized for: windows, balconies, other options are provided.

    Further down the rafters roofing membrane is laid, and is pressed against them with a counter-lattice - bars with a section of 50x50 mm. To organize the ventilation gap. This preparations for warming. They need to be carried out at this stage. Missing is a huge omission.

    On the counter-lattice crate stuffed, with a step corresponding to the roofing.

    mounted roofing, its additional elements: wind boards, ridge.

The same house can look different and have different usable area.

Video description

About the features of the calculation of the mansard roof in the video:

Exactly according to the same principle, an attic floor with a gable roof is mounted. Moreover, its device is even simpler - all the rafters are solid.

The next step is to insulate the roof. Of course, it can be done from the outside, before the installation of the membrane, battens and roofing. But it is safer from the inside - there will be no threat of precipitation and work will be carried out more carefully, because successful operation depends on it.

The insulation from the inside of the room is protected by a vapor barrier film. And between it and the interior trim, a mandatory ventilation gap device - the interior trim is not mounted directly on the rafters. For her, specially, as well as outside for the crate, a counter-rail is stuffed, or a frame is arranged.

On our website you can find contacts of construction companies that offer a turnkey roof calculation and repair service. You can directly communicate with representatives by visiting the exhibition of houses "Low-Rise Country".

Conclusion

Mansard roof is perfect solution, allowing you to increase the usable area of ​​\u200b\u200bthe house without a significant increase in the cost of its construction. There are a lot of solutions for the construction of the attic floor - they can be both standard and designed for a particular house. But in any case, the installation of the attic requires specialized knowledge and this work should be done by professionals.

It is difficult to imagine a building without a reliable roof over it. Any roof is the basis, the main guarantor of the inviolability of things in the house, the safety of property. She is the main protector from rain and snow, wind. After its construction, you can proceed to the next stage, which implies interior work. Having made this part unreliable, one cannot speak of a full-fledged dwelling. A do-it-yourself gable roof is the simplest and most functional option among other types of roofing.

There are several options for roofs, one of which is gable. The construction does not require a lot of talent, since this type of roof is the simplest. The housing element consists of the parts shown in the figure:

The design consists of the following parts:
Skate. The upper part that will connect the 2 slopes.
Rack. An installation that serves to redistribute weight from the top to the bottom of the roof. It must be done from quality materials.
Sill. Bar located horizontally. Connects the rack and bearing wall.



Struts. These boards are fixed at a slight angle. They serve to redistribute the weight from the rafters to the supporting elements below.


Rafter leg. These elements form a visible outline in the shape of a triangle. They serve to hold the roofing. The heavier it is, the more often it is necessary to lay the rafters.
Filly. Boards that extend the rafters. Necessary to create an overhang from a gable roof, according to building codes, which should be at least 0.5 m.



Difference between rafters
gable roof and the drawing is quite realistic to do on your own. There are several ways to construct all elements. The difference is the truss system used for construction. There are the following types of rafters:


The systems are used in many dwellings, the quality of both is sufficient for comfortable use. When building a mansard roof, they are used together. In this case, the hanging and inclined type of rafters are combined. It is worth creating drawings of rafters that will show the location of each element of the roof, erected by oneself, so that there are no incomprehensible moments. It will help to calculate the amount of materials needed.
Any element of the house must be created, understanding how all this will look like as a result. For clarity, a drawing is created, and so that everything fits perfectly, it is calculated in advance. The plan takes into account the length of the roof along the ridge, the length of the slopes, and the length of the plumb lines is shown separately. The angle of inclination of the roof is determined. The angle is determined taking into account the following points:

  • With strong winds in the construction area, the angle is made around 10-12o so that the roof is not torn off.
  • With significant winter precipitation, the slope is within 30-40o. snow will slide off easily. There are no difficulties in the calculations, but if the roof is made with a complex shape, this will make it difficult to calculate the required values.

Roof construction

After making the calculations and acquiring the necessary parts, the Mauerlat is installed. After that, a crate is created. The element is the basis for a do-it-yourself roof, made of pine or other coniferous wood. The material is strong and light, capable of spreading the weight of all elements over the entire plane. It is placed along the roof slopes, between the rafter legs, the top of the walls.

In order for the element to last longer, an insulating layer is needed between the wall and it. Suitable for this ruberoid. Mauerlat can be fixed using any fasteners that are convenient.
For the construction of the roof, you must follow the plan:

  • Fixing rafters. If hanging ones are used, they must be assembled in advance, using fasteners to stiffen this part. First, the extreme elements are made, after the internal ones. With a layered system, a bed is first created, where the supports will be installed. If the length of the elements is insufficient, you can add it using the installation of filly.

Lathing installation. Any materials can be used for construction, but it is important to get rid of the bark from the boards in order to increase the service life of the elements. If you plan to use soft roof, the crate is made continuous. It requires a rigid base so that there is no deformation during operation. Lattice system

Roof laying. There are many coating materials, each of them involves the use different methods coatings. Do not neglect the recommendations of the manufacturer of the material. It is important to make a small overlap between the elements. The structure must not be broken so that there are no leaks.
Don't forget that reliable roof, built with your own hands - a guarantee of the safety of property in the house. Do not neglect its construction, so that later you do not have to make complex repairs.

Use the entire possible area, give the house originality and significantly reduce heat loss through the roof - these are the tasks that the attic solves. If there is a certain margin of safety at the foundation, in this way it is possible to turn a one-story house into a two-level one. It is also attractive that a do-it-yourself mansard roof can be built even without special building skills. It is important not to make a mistake with the choice of materials and do everything according to the rules.

Windows in the usual floor are located in the walls. There are no or almost no walls in the attics. Roofing replaces them. That is why windows are made special: they not only have to let in enough light, but also withstand wind and snow loads, which are much more on the roof than on the walls.

Skylights

When planning an attic, it is worth considering the recommendations of SNiP. They recommend that the window area be at least 10% of the floor area. So if the attic is divided into several rooms, each should have a window.

Of all the methods shown in the photo for arranging skylights with an attic, the inclined installation is the easiest to implement. At the same time, it is necessary to ensure the proper degree of waterproofing of the junction, as well as to use special models with a reinforced frame and reinforced glass - the load on the surface can be significant.

Benefits of a sloped roof window:

  • more light, not so sharp borders of light and shadow;
  • the roof surface remains flat, its relief is not complicated;
  • relatively easy installation.

When planning such a window, it must be remembered that its area increases with an increase in the angle of inclination. At what height is it more convenient to install such a window and how its height in centimeters increases depending on the slope, see the photo.

The steeper the slope relative to the floor, the lower the height of the window should be.

The width of the window frame should be 4-6 cm less than the pitch between the rafters. Then it can be easily installed without disturbing the structure of the frame. If the window is wider, it is necessary to make a reinforced beam above it, calculate the load.

If you need to have a larger window, it is easier to put two narrow ones side by side. They look no worse than one big one, and there will be fewer problems.

When installing a dormer window, the geometry of the roof becomes more complicated: a valley appears on top and on the sides. Because of this, the truss system becomes more complex in both planning and assembly. The complexity of laying roofing also increases. All valleys are the places where leaks are most likely to occur. That is why it is necessary to do everything very carefully. In regions with a lot of snow, it is advisable to install snow retainers above such windows: so that they are not blown away during a sharp descent.

The device of a vertical window-dormer in the mansard roof

The advantage of such a window: near it you can stand in full growth. But they let in less light, the terrain becomes more difficult and the roof becomes more problematic.

A recessed window is usually used if an exit to a balcony is made through it. In other cases, this method of device is not the best option: little light enters, the shadows are very deep, which is tiring for the eye, the geometry also becomes more complicated, although not to the same extent as in the previous version.

The easiest way is to make a window in the end part of the attic. In this case, a reinforced frame or reinforced glass is not needed. Quite simply high-quality glasses are enough. This option is most often seen on country mansards: this is the most inexpensive option, which is easily implemented with your own hands.

truss system

At self construction private houses with an attic usually choose a sloping roof. It allows you to get a room of a significant area, larger than under the gable.

With an equal width of the base (house), the attic room under a sloping roof is larger than under a conventional gable. The truss system becomes more complicated, but gable roof with an attic under a sloping roof is still more popular

The design of the sloping mansard roof is such that the overhangs can be lowered quite low, giving the house an interesting look. But the long overhang of the roof is not only a decorative role. They also cover the upper part of the wall from precipitation and divert the bulk of the water away from the foundation. Although when planning, you need to keep in mind that in strong winds they increase the windage. Because of this, it is necessary to use more powerful boards and beams. Therefore, the size of the roof overhang is chosen based on several considerations, the main of which is weather conditions.

Tilt angle

It depends on the roofing material, but most of all - on the region and weather conditions. The classic version is shown in the figure: the lower slopes in relation to the plane of the attic floor are inclined by 60 °, the upper ones by 30 °. Based on these data and the parameters of your building, all lengths can be calculated. Just keep in mind that according to SNiP, the ceiling height in the attic cannot be less than 2 m. Then, by definition, this is an attic. A person will feel comfortable if the ceiling is raised to a height of at least 2.2-2.3 m. Based on this, according to the rules of geometry, calculate the required lengths.

In the classic version, the load from precipitation on the side surfaces may not be taken into account. Precipitation can only be held on the upper part, the angle of inclination of which is less than 45 °.

In general, the slope of the side surfaces usually ranges between 45° and up to 80°. The steeper the slope, the greater the windage it has, this must be taken into account: in regions with strong winds it is better to make more gentle roofs. Then the wind loads will be perceived much better.

Types of rafter systems of broken roofs

The design of a broken mansard roof is one of the options for the truss system (the most common)

For the manufacture of a sloping roof frame with their own hands, pine lumber is most often used, the grade is not lower than 2. The choice of the section of timber and boards depends on the size of the roof, the selected roofing (its weight), wind and snow load in the region, the installation step of the rafters. All these parameters are taken into account in the calculation. The technique is prescribed in SNiP 2.08.01-89 and TCP 45-5.05-146-2009.

One of the options for building a frame with hanging rafters

Above in the figure is a drawing of a frame with hanging rafters. It can only be implemented if the base of the upper triangle is no more than 4.5 meters (in this case, this is the width of the attic room). If more, you will have to make layered rafters, which should rest on the load-bearing wall in the middle (the attic will turn out to be divided into two parts by a row of beams).

Another version of the upper part is shown in the photo below (the picture is clickable). In this case, the side rafters are reinforced with struts. They significantly increase the rigidity of the system.

There is a second way to achieve a similar effect - to set contractions - in the figure they are only outlined with barely visible lines. The length of the side rafter leg is divided into three, contractions are set in these places. They will be needed if the roofing will have a solid weight.

A variant of the rafter system of a sloping roof - with struts that increase the rigidity of the system

For a building that is small in size, the roof frame can be generally simple: at the top there are two hanging rafter legs, a puff, floor beams, racks and side rafters (pictured below).

The device of the truss system of a broken mansard roof for a small house

How to calculate a sloping roof

The mansard sloping roof of a small house (width no more than 6-7 meters) has been built so many times that, based on experience, we can say what materials should be used. Many parameters are dependent on other materials. For example, the installation step of the rafters is tied to the parameters of the insulation. To ensure that there is as little waste as possible during insulation, installation is easier, it is necessary that the distance from one rack to another is slightly less than the width of the insulation (by 20-30 mm). So, if you are going to use mineral wool, its width is 60 cm. Then the racks must be installed so that the clearance between two adjacent ones is 57-58 cm and no more.

The width of the board for the rafter leg is again determined based on the insulation. For the central zone of Russia, the required thickness of basalt wool is 200-250 mm. That's not all. In order for the thermal insulation to dry out, a ventilation gap of 20-30 mm is required (without it, the condensate will gradually rot the wood and render the mineral wool unusable). In total, it turns out that at a minimum the width of the rafter leg should be 230 mm. The thickness of the board is at least 50 mm. This is in regions with mild winds and not very heavy snowfalls. Summing up, for all rafters - ridge and side - a board of 230 * 50 mm is required.

If lumber with such characteristics turns out to be too expensive, it will be possible to make insulation in two directions: part along the rafters, part, stuffing the crate, across. You can lay a minimum of 100 mm of basalt wool, therefore, you can take a standard board 50 * 150 mm and leave it on the ventilation gap of 50 mm, or order a non-standard 130 * 50 mm. See what is more profitable in terms of money.

For racks and beams, it is better to take a beam of at least 80 * 80 mm, better - 100 * 100 mm. Especially in areas with difficult weather conditions - with heavy snowfalls or strong winds.

For a more accurate estimate, ask the experts. This is a long process, consisting of the collection of loads from the roofing material, the structural elements themselves, wind and snow loads. After that, according to a certain formula, the elements are selected. For more information on how the calculation is carried out, see the following video.

Do-it-yourself mansard roof: installation procedure

The Mauerlat device on mansard roofs is no different from the standard version. If or logs, you can use the upper crown as a Mauerlat. It is only pre-treated with impregnation with high protective properties.

If the wall is made of foam blocks, a reinforced monolithic belt is arranged on top of it. On brick wall or folded from shell rock, other similar materials, the device of such a belt is optional. Waterproofing is laid on the wall in two layers, and on top - a timber treated with an antiseptic - 150 * 150 mm or a log. It is fixed with embedded studs.

When assembling all elements, long nails are used - at least 150 mm long. In the most critical places, it is better to connect three or more elements with bolts or studs with double-sided threads. It is desirable to strengthen all joints with steel plates or corners.

First way

The installation of mansard roof rafters is done in two ways. First: parts are assembled on the ground, then they are lifted up in finished form. There, the first to expose the extreme structures that will become the gables. They are placed vertically, fixed. It is often more convenient to fix them with long bars nailed to the wall (temporary). The following are inserted into the prepared recesses in the Mauerlat (they are made with the required step) assembled structures. They are set strictly vertically, carefully fixed. If necessary, install additional temporary spacers that fix them in the desired position. Side rails are installed.

How to build a sloping roof in this way, collect nodes, see the video below.


Second way

The second method - the construction of a sloping roof is carried out by sequentially collecting elements right on the spot. This method is more convenient if the structure is large and when assembled it can only be lifted using special equipment (crane).

First, floor beams are laid. Racks and puffs are attached to them, temporary struts are placed to hold them in the vertical direction. Next, the rafters of the upper and side legs are assembled, puffs and jibs are installed.

During installation, the following sequence of actions is observed: first, the extreme elements are installed and set in the desired position, securely fixed. If necessary, use temporary spacers. Between them, a fishing line, rope, lace is stretched, which will serve as a guide for the installation of all subsequent elements. This simple move allows you to get the perfect geometry (do not forget to check the slope angle, verticality or horizontality).

Puffs are attached over the racks - bars, to which the side rafters are then fixed and on which the puff of the upper triangle is installed. Puffs are attached with metal corners. Since the beams are long, they sag. This is further eliminated - after installing the upper rafter legs- using vertical beams of fixed or adjustable height. And temporarily they can be propped up with racks (so as not to pull the entire system).

To make it easier to maintain the desired angle when installing the side rafter legs, templates are made according to which the cuts are made. But since the geometry of DIY buildings is rarely perfect, adjustments may be needed. To check the resulting angle of inclination from several boards, another template is knocked down, which checks the correct installation.

If the standard length of lumber - 6 meters - is not enough, either order the required length (expensive) or increase it. When building up, two boards with a size of at least 0.6 meters (30 cm on each side of the junction) are nailed to the junction. They are nailed on both sides or bolts are used.

A reliable way to build rafters. The length of the "patch" - at least 60 cm

After installing the side rafters, it remains to install the top ones. A template is also made for them, it is first sawn on the ground, and installed at the top.

The top part can be done in different ways. Its structure depends on the width of the base. See the photo below for how to make it.

Since the device of the mansard sloping roof does not provide for the presence of a ridge, a beam is stuffed in the middle, to which the slopes are attached, fixing the triangle in the required position.

Nodes and their drawings

When installing the truss system, questions may arise regarding the assembly of nodes - the intersection and connection of several structural elements. In the photo you see drawings of key connections.

The second option is to connect the side rafters and the upper triangle. Bolts are used for more secure fastening.

How to make a do-it-yourself fastening of the upper triangle and rafter leg on a mansard roof

The methods for attaching the rafter legs to the Mauerlat or, as in this case, to the side beam are shown in the figure below. To make it easier to mount a heavy element, a stop board (bar) is nailed to the rafter from below, which limits its movement: the board rests against the edge and prevents it from falling lower.


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