The optimal angle of inclination of the gable roof. Roof slope What should be the minimum slope of a tiled roof

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The foundation and the roof are two of the most important and complex architectural elements of any building. Roof bearing elements - rafter system, and its performance largely depends on the angle of inclination of the slopes. Ordinary developers choose the optimal angle of inclination of the roof, based on different criteria than the designers.

They are not entirely interested in the strength calculations of the bearing nodes, they are not very interested in the influence of the angle of inclination of two pitched roof on the cost and complexity of the rafter system, etc.

What do ordinary developers pay attention to?

Roof angle selection options	Short description
	Every owner wants to have beautiful house with their own individual differences. The angle of inclination of the slopes has a great influence on the appearance of the house. Architects have their own requirements for buildings; houses must organically fit into the style of existing buildings. This parameter is especially strict when the house is located within the city. Quite often, local governments make decisions prohibiting the violation of the traditional architectural appearance. You cannot, for example, build a house with a roof angle of 45 ° if all buildings on this street have a slope of no more than 20 °.
	This factor has very little effect on the optimum angle. Roofing materials have only general recommendations for installation on flat and sloped roofs. Flat roofs have a slope angle of less than 10 °, all structures with a slope angle exceeding these values \u200b\u200bare considered sloped. The technology of installing roofing materials with an angle of inclination of 15 ° is no different from technology roofing works on slopes with a slope of 45 °. There is, however, a limitation for piece shingles; they can be installed on roofs with an angle of inclination of at least 22 °.
	The greater the angle of inclination of the slopes, the higher the attic. Such roofs are built for buildings with mansards. Developers pay great attention to this factor, but not everything is as simple as it might seem at first glance.

These wishes are taken into account by architects during the design and calculation of the elements of the truss systems. But a rather large number of purely engineering factors are added to them, which have a decisive influence during the calculation of the parameters of the rafter system. And the angle of inclination of the slopes is not the only one among them, all values \u200b\u200bdepend on each other and cannot be taken into account when developing the project.

How do designers choose the optimal angle

Calculations are made on the basis of SNiP 2.01.07-85. The posted norms are used during calculations taking into account permanent, temporary and special loads and their various combinations.

SNiP 2.01.07-85. The PDF file will open in a new tab

What loads are taken into account when determining the angle of inclination of the roof

Loads are divided into several categories depending on the duration of their exposure: long-term, short-term and special.

Long-term (constant) loads on the rafter system... These include the weight of roofing materials, insulation, wooden elements of the truss structure. This category should include the loads arising from thermal expansion and changes in linear dimensions due to changes in the relative humidity of sawn timber. Normative temperature changes are determined by formulas separately for heated and unheated rooms. The weight of the snow cover is also considered a long-term load on the rafter system and must be taken into account when determining the optimal angle of inclination of the rafter legs.
Short-term... The rafter system is influenced by the weight of the workers, the stored building materials, the weight of special equipment and tools used during construction, and wind loads.
Special loads... Efforts arising during natural disasters, earthquakes, explosions, with a sharp loss of the bearing capacity of one or more loaded nodes of the rafter system.
Among the special loads are earthquakes and natural disasters

When determining the angle of inclination of the roof, the maximum possible load combination is taken into account. Both of these parameters affect the thickness and length of the rafter legs. The calculation of the rafter system and the angle of inclination of the slopes is done according to limiting states, taking into account all unfavorable factors.

The maximum deflections and movement of the rafter legs are regulated without dependence on their linear dimensions and should not lead to partial depressurization of the roof. For all types of roofs, regardless of the angle of inclination, the following conditions are put forward:

the safe operation of buildings must be guaranteed;
the integrity of the structure cannot be violated even during short-term peak loads;
the appearance of the roof should not change during the entire period of operation.

Moreover, each requirement must be fulfilled regardless of the others. The limiting values \u200b\u200bof the deflection of the rafters are limited taking into account the performance characteristics of the roofing materials. If the standard values \u200b\u200bdo not have a noticeable effect on the appearance, then they are not adjusted.

Practical advice. It is much easier to ensure the integrity of the roofing pie of the roof not by increasing the strength of the rafter system, but by using special structural expansion joints.

The comfort of operation and the reliability of the building mainly depend on how well and competently the construction of the roof is, and also on how correct the slope of the roof is. About him will be discussed further.

The slope of the roof of the house mainly depends on the design of the facade and roof of the building, also an important feature is the material chosen for the covering. The slope is taken into account depending on climatic conditions the region in which the new building is being built. For example, in areas where there is heavy rainfall, and in winter period very heavy snowfalls, the slope is chosen from 45 to 60 degrees. Such an angle of inclination is specially designed, as it allows to reduce the load, especially in winter, on the roofing system, since the snow simply will not accumulate on the roof, but will slide down due to its own weight.

And if a roof is designed for a region where strong and constant winds are characteristic, then the minimum is chosen, since this reduces the so-called "windage" of the roofing. Basically, the angle is chosen from 9 to 20 degrees. Therefore, the most universal solution is a value chosen between the two above ranges, i.e. it is best to make an angle of 20-45 degrees. A slope of 20 to 45 degrees has another advantage - it is the ability to use most of the roofing materials purchased in modern markets.

Varieties of roofs of houses

Types of roofs: a - flat gable, b - steep gable, c - hip hip, d - single-slope (in the form of a desk), d - broken (attic) gable, e - hip hip, w, h, and - half-hip (attic) hipped.

The most common for ancillary or outbuildings is the lean-to roof of a house, which does not offer an original design, but at the same time attracts with its simplicity of construction and its low cost. The structure of such a roof consists of walls and roofing material laid on them.

The slope in this case should be from 9 to 25 degrees, since most often it is these roofs that are subsequently covered with corrugated board. Such a rather small angle of inclination is formed due to the lack of an attic area.

Another fairly common type is the gable roof of the house. Its design consists of two slopes (two planes), connected by a ridge (one line). The walls are the ends of the building and are called gables. They often provide for doors that will allow the attic to be used as an additional room, moreover, these doors act as air vents (ventilation holes). Making such roofs is easier than everyone else.

Modern designers and just builders often make hip roofs. They allow you to make a unique design of the facade and the roof of a broken shape. In such structures, the slope angle can be absolutely any, depending on the imagination and taste of the person who designs the roof structure. There are practically no restrictions on the use of roofing material in the construction of such roofs. The complex structure is compensated by the spectacular appearance of the roof of the house, and the more complex the overall plan, the more original the design hip roof can work out.

A more complex type of hip roof is mansard roof a broken shape, the purpose of the construction of which is to use the attic space in a living room, while insulation and vapor barrier are mandatory.

Due to the rather high angles of inclination and slopes of a broken shape, a space is formed from which the entire attic floor consists. In addition, it will be appropriate to make the so-called "dormer" windows, which will serve as an additional decoration of the facade. And you just need to perform insolation (lighting the room with sunlight).

You should also familiarize yourself with the data on the smallest angle for various materials:

For piece materials such as roof tiles and slate, the smallest angle is 22 degrees. This prevents moisture from accumulating at the joints and seeping into the building.
For roll materials, the minimum angle of inclination will be selected depending on the number of layers laid. With a three-layer coating, the angle will be from 2 to 5 degrees, with a two-layer coating - 15 degrees.
A small angle of inclination of the roof made of corrugated board is considered to be 12 degrees. At small angles, according to the recommendations of the manufacturers, the joints should be additionally glued with sealants.
For roofs covered with metal tiles, the minimum angle is 14 degrees.
For roofs covered with ondulin, the minimum angle is 6 degrees.
For soft tiles a small angle is considered 11 degrees, while regardless of the selected angle, there is required condition - installation of solid lathing.
Membrane coatings have a minimum angle of 2 degrees.

Roof slope calculation example

The angle of inclination of the roof is calculated, as we have already said, taking into account the climate of the area and the selected material for the covering. The height of the ridge and the value of raising the rafters is determined with a square or the width of the span is calculated, divided in half and multiplied by the appropriate coefficient from the table.

For example, if the width of the house is 10 m, and is equal to 25 degrees, then the height to which the rafters should rise is calculated by multiplying 5 m (half the width of the house) by the coefficient from the table (0.47) and we get 2.35. It is to a height of 2.35 that the rafters should rise.

The question of how to calculate the angle of inclination of a roof with a shed structure is a difficult task for those craftsmen who are just beginning to master the basics of roofing skills. This is due to the selection of parameters that determine the difference in the roof structure. Let's consider its main components:

rafter system and additional accessories;
lathing;
roofing threshold made of layers of thermal insulation, waterproofing and vapor barrier;
roofing material.

It should be borne in mind that a large angle of inclination will require the use of significantly more building materials, thereby increasing the cost of roofing up to 20%. When building in regions with a high wind load, use the structure shed roof with a slight angle of inclination, which in most cases is located to the windward side. This provides significant resistance to wind loads. For this reason, a competent calculation of the angle of inclination contributes to a high level of savings in roofing materials, while observing all building codes and regulations. The determining factors are:

climatic features of the area in which construction is carried out;
roofing material;
purpose of the building.

Dependence of the angle of inclination on the type of roofing material

When choosing a roofing material, it should be borne in mind that it has a direct impact on the structure being erected and its cost. The calculation of the angle of inclination of the slopes should be carried out taking into account the type of roofing material. We recommend using the table below for this.

The table shows that the roofing material is the determining factor in the implementation of calculations.

Using soft roof, the angle of inclination is much smaller compared to slate.

The calculation should also take into account the atmospheric features of the area where the construction is taking place. One of the features of roofs with a slope of 300 is the accumulation of snow on the leeward side and an increase in the load on roofing materials, and the rafter system.

Formula for the correct calculation of the required parameters

Since the pitched roof rests on walls with different heights, the angle of inclination is formed when building walls with different heights. In construction documentation, it is allowed to take an angle of inclination in the range from 5 to 60 °. For areas with an increased level of precipitation in the winter season, the calculated value is in the range from 45 to 60 °. When calculating the angle of inclination of the slopes, the load of atmospheric precipitation is taken into account, which is associated with the design features of single-pitched roofs and the mechanical strength of roofing materials. In general, the formula has the following form:

where L walls is the height of the wall gable;

L length - the length of the house wall;

A is the angle of inclination.

For the construction of a pitched roof, the length of the rafters should be calculated, which is determined by the following formula:

To find sinA and tgA, use the special tables below:

Calculation example

House wall length: L length \u003d 5 meters;

Roof inclination angle: A \u003d 25 °;

Determine the height of the wall: L wall \u003d 5 × tg25 ° \u003d 5 × 0.47 \u003d 2.35 meters;

Determine the length of the rafters: L rafters \u003d 2.35 ÷ sin25 ° \u003d 2.35 ÷ 0.42 \u003d 5.6 meters.

To obtain reliable calculation results, add the length of the front and rear overhangs to the length of the rafter leg. They will serve as optimal protection of the house from atmospheric precipitation.

Competent calculation of the roof is associated with the aesthetic appearance that it will have as a result of the completion of construction. Most modern home owners prefer high roofs, which give the building a slender classic look. Another advantage is the possibility of arranging a spacious attic. But, from a financial point of view, the construction of a flat roof is much cheaper than its peaked counterparts.

Advantages of a pitched roof

A pitched roof has many advantages that make it the most popular option when arranging premises and structures for domestic purposes. Its main advantages include:

simple design;
the construction of a gable roof requires significantly less building materials than its other varieties;
simple and easy installation;
low construction costs;
high resistance to wind loads;
short construction time.

Disadvantages of a pitched roof structure

In addition to the advantages, the pitched roof has the following disadvantages:

during its construction, there is no opportunity to equip a comfortable attic; it's connected with design features roofs;
reduced level of thermal insulation, which is due to the minimum volume of free space under the roof.

Calculation of the slope angle of the roof allows for a preliminary preparatory stage obtain reliable data on the amount of materials required for the construction of a pitched roof. Applying the correct calculation methodology ensures the optimal balance between the cost of building the roof and its performance. To save financial resources during construction, it is not at all necessary to reduce the reliability of the roof or refuse to use high-quality materials. It is important to carry out a competent and correct calculation in a timely manner, which will reflect the true cost of construction.

Calculation of the angle of inclination of a shed roof. Learn to Find the Slope of a Shed Roof Using the Slope Formula

Determine the optimal and minimum slope of a pitched roof

Single slope roofs are coming into vogue. There are many reasons for this, including their practicality, low cost and characteristic appearance. The slope of single-pitched roofs in most cases differs from gable and hip roofs: it is less. Consider what determines the optimal and what the minimum slope of a shed roof is limited by.

What the norms say: we study SNiP "Roofs"

In the updated version of SNiP II-26-76 "Roofs", updated within the framework of SP 17.13330.2011, it is indicated that the slope of a flat roof should be from 2 ° to 12 °. It is logical to assume that the norms assume a value for a pitched roof over 12 °. However, SNiP does not contain any information about the slope of the pitched roof. A value of 12 degrees is optional. In fact, the border between a flat and a pitched roof is not fixed in a normative way and is more often determined by eye.

One of the factors indicating that the roof is single-pitched is the use of roofing material on it intended for pitched roofs (all types of tiles, sheet materials, corrugated board, etc.). Flat roofs on average have a slope of 3 ° and are covered, with rare exceptions, with rolled bituminous materials. Rolled bitumen roofing can be successfully installed on pitched roofs.

Determine the optimal slope angle

The optimal slope of a pitched roof is dictated by the architectural and planning features of the building. With the same slope as a gable roof, the skate ridge will turn out to be twice as high, therefore, gable roofs are flatter. For a shed, garage, veranda, in most cases, 10-15 ° will be enough. A pitched roof is economical, especially for small buildings. As a rule, a slope of 10-15 ° is sufficient.

A pitched roof is of little use for organizing an attic in a classic form: one part of the room will turn out to be too low, the other too high, such a volume is difficult to use rationally. Even with the construction of the attic floor, it is hardly worth making a slope over 30 °. An attic shed roof, relatively flat (10-20 °), allows you to equip rooms with different ceiling heights on the floor. Living rooms are taken out to the higher part, to the lower part - toilets, utility rooms, stairs.

If the layout provides for floor levels shifted along the elevations, a steep pitched roof with a slope of 20-35 ° will be rational.

We calculate the minimum slope

The limiting factor for the minimum and maximum slope is the manufacturer's recommendations for specific types of roofing materials. Shed roofs are rather flat, we will be more interested in the minimum values.

Rolled fusion-bonded bitumen roofing allows covering any roofs, including flat ones. Only the maximum angle of 25 ° is limited, although it is better not to go beyond 15 ° so as not to complicate the installation. The most durable and reliable bitumen-polymer materials, the top layer is sprinkled with stone chips. Roll materials are hot glued onto bitumen mastic.

Asbestos-cement corrugated sheets (slate) require a fairly large slope. For sheets of a reinforced profile, it must be at least 25 °, normal - 35 °. It should be noted that the amount of overlap of the sheets of the upper row is taken depending on this value. The higher it is, the more overlap.

The so-called "euro slate" is less demanding on the steepness of the surface, a minimum of 6 ° is allowed. When installing bituminous corrugated sheets, not only the size of the overlap depends on the slope, but also the design of the lathing: at 6-10 ° it should be solid, at 10-15 ° the pitch of the bars or boards is taken as 45 cm along the axes, with a larger value 60 cm is enough.

The metal tile can theoretically be laid with a slope of 10 °. But with a parameter of 10-20 °, all the joints of the sheets will have to be sealed, and this is not an easy matter. A rational decision the use of metal tiles for roofs with a slope of over 20 ° without additional sealing.

The corrugated board can serve as a roof covering for roofs with a slope of 5 °. At 10 °, the overlap is increased, a sealing tape is laid in the joints.

Seam roofing, both from standard elements with a factory seam, and in the manufacture of seam on galvanized steel sheets directly on the construction site, is used for foundations with a slope of 8 °. Provided that the seam joints are sealed, the value can be reduced to 3 °.

Bituminous shingles are used with slopes of at least 11 °. With a value of up to 18 °, the lining layer should be continuous, with a larger one, it is enough to roll out the rolls only along the outer contours of each of the roof planes and additionally isolate the holes.

Ceramic and concrete tiles require a slope of 22 °. It can be reduced to 10 ° by installing an additional waterproofing layer under the tiles. The shingles are quite heavy and are not often used for pitched roofs.

The data provided are not entirely accurate. Each manufacturer of roofing materials sets its own requirements, they may differ slightly. In addition, the slope is highly dependent on the snow load for a particular area. The less snow, the flatter the roof can be. There are territorial standards that establish the minimum, depending on the climatic features of the area.

We found that the slope of a pitched roof is determined by the architecture of the building and is limited by technical requirements. The calculation of the rafter system to ensure the necessary strength with a rational consumption of materials should be entrusted to specialists.

We calculate the minimum angle of inclination of a shed roof for optimal results

The angle of inclination of a gable roof is much lower than that of a gable. What factors are decisive in the design, what limits the minimum slope

Features of calculating the angle of inclination of a pitched roof

The pitched roof has gained considerable popularity due to the relative ease of installation and financial benefits. This type of roof is becoming a common choice when building country houses. With the help of a pitched roof, you can reliably protect the building from wind and the negative influence of other weather phenomena, if the angle of inclination of the pitched roof in relation to the windy side is correctly calculated.

A single-pitched roof will last longer and will more reliably protect the building from the effects of weather conditions if its rafters are supported by walls of different heights, and they will be less affected by gusts of wind.

According to experts, even a person without special skills can install a pitched roof. They argue that it is enough to observe all the necessary safety measures and theoretically get acquainted with the specifics of the work progress. This ease of installation and the minimum amount of materials used are the primary advantages that attract many consumers who are building country houses today.

For maximum safety when installing a pitched roof, use the most reliable ladders and remember to wear a rescue harness.

The design features of a single-pitched roof allow one hundred percent to avoid

An example of calculating the angle of inclination of a pitched roof

irrational use of space in the room. A pitched roof does not provide for an attic and few comfortable attics.

In addition to summer cottages, garages, sheds, outbuildings for various purposes and quite often residential buildings are equipped with pitched roofs. In residential buildings, a roof of this type helps to create a more unique design of the premises. Also, the equipment of a pitched roof in a residential building often requires terrain characteristics. So, you can minimize the amount of rainwater and melted snow flowing down the road.

Varieties of pitched roofs

Depending on whether the room has roof ventilation, two types of pitched roofs are distinguished:

Ventilated. They are usually used in the construction of closed buildings. In this case, the angle of inclination of a pitched roof ranges from 5 to 20%. Ventilation is a void specially designated for the passage of air between the waterproofing and heat-insulating layer of the roof. This significantly increases the service life of the building roof.

When installing a pitched roof with the provided ventilation system, it is necessary to make holes on the sides of the building at the roof level. This will ensure constant air exchange regardless of wind direction.

Not ventilated. Most often used in the construction of terraces. The tilt angle in this case is within 3-6%. The open type of premises requires special care, especially in winter.

There is also a combined version of pitched roofs with and without ventilation. In this case, a slight slope of the pitched roof is provided by thermal insulation. At the same time, significant savings are observed in creating a structure, but they create certain inconveniences during operation. So, in winter, with a large amount of snowfall, it is necessary to constantly clean the roof, reducing the load on it.

What are the advantages of pitched roofs?

In addition to the minimum volume of materials used and ease of installation, as mentioned earlier, a number of other advantages can be distinguished, due to which a shed roof is chosen when building buildings for various purposes.

If wood is a scarce material in the region where the building is planned to be erected, a pitched roof will be the most profitable option from a financial point of view for the developer. Its installation involves the use of a minimum of wood.
The minimum slope of the pitched roof significantly reduces the windage indicator. Thus, the space under the roof will be used in the most rational way, you will not have to equip the least comfortable and less functional attic.
This type of roof can be easily used in household buildings with walls of different heights.
If there is a carriageway on one side of the building, a pitched roof will avoid the discharge of large amounts of snow and rainwater onto the road.

To eliminate the possibility of damage to the roof by gusts of strong wind, it is necessary to install a special curb on the drain side, reinforced with galvanized iron or tiles.

Roof rafter system for pitched roofs

The roof rafter system is, in fact, its skeleton. That is why its primary task is to evenly distribute the mass of the material of the roof itself on the supports on which it is attached. Also, when forming a rafter system, one should take into account the strength of the effect of winds and precipitation in a given area.

It is imperative to increase the indicator of the estimated load on the rafter system, calculating it, as they say, with a margin.

When developing a pitched roof, one should take into account the plan of the walls that act as a support, the characteristics of the overlap of the attic and interior partitions, the external parameters of the building, as well as the distance of the largest span.

The angle of the roof and the ease of its installation depends on the type of connection of the rafter system to the supports. So, there are three types of mounts:

Hanging rafters are used if it is not possible to provide support for the rafters in the distance between the side supports. In this case, the assembly of the trusses takes place on the ground, and then the finished structures are carefully transferred to the extreme supports. This process takes the most time and effort. It is complicated by the presence of large spans. The load-bearing elements of the roof are usually made of softwood, metal and reinforced concrete. The most suitable rafter section is 5 * 15 centimeters. Bars for lathing should be characterized by a section of 5 * 5 sentiments.

Inclined rafters assume support on the outer walls of the leading elements at an angle. In the upper part of this type, the rafters rest on a beam, secured with struts and racks. The partitions act as a support for the struts. Also external load-bearing walls... The length of the distance between the rafter systems can vary between 60 and 140 centimeters. This distance depends on the thickness of the tree and the parameters of the material used for the roof. The structure is supported by walls of different heights. Most often, inclined rafters are chosen when arranging the roof of household buildings.

Do not forget about the rotation of the roof slope relative to the windy side.

Sliding rafters use a log in a ridge as a support. When connecting the rafters to the walls, in this case, special elements are used, called "slides". Sliding rafters are most often used when arranging the roof in log buildings. Thanks to the use of this type of rafters, it is possible to compensate for the rather large shrinkage of the log house, preventing damage to the building at the junctions of its main elements.

Materials used in the formation of pitched roofs

Asking the question of how to determine the angle of inclination of the roof, first of all it is necessary to take into account the material from which the roof is planned to be created. So, there are certain limits of the permissible slope for different types roof material:

The slope of the corrugated roof can vary from 8 to 20 degrees.
If a metal tile is selected as a material for the roof, its minimum slope can be 25 degrees.
For slate roofs, the minimum angle of inclination increases to 35 degrees.
The folded roof can be at an angle in the range of 18-35 degrees.

Do not try to make the angle of inclination less than eight degrees, as such a roof can fall through even under the weight of snow in high rainfall.

After the most suitable roof angle for a particular building has been determined, it will be necessary to raise the facade wall of the building so that its height in relation to the rear wall forms the specified slope. With such calculations, it is simply impossible to do without the use of certain trigonometric formulas, therefore, for correct calculations, you should often contact experienced specialists in drawing up projects of such a plan.

Slope angle of a pitched roof: the minimum and optimal roof slope - how to calculate?

The article slope angle of a pitched roof will tell you how to calculate the slope angle of the roof, which slope angles are the minimum and optimal for different types roofing, as well as calculation examples and factors influencing the selection and calculation of the roof angle.

How to correctly calculate the angle of inclination and height of a pitched roof

Across the globe, there are thousands upon thousands of architectural traditions in plan appearance roofs. But modern architects have completely changed the idea of \u200b\u200bculture. suburban constructionby introducing single-pitched roof shapes as ideally combined with landscape design and diverse in performance. Of course, the inhabitants of Australia set this new fashionable tone, where the absence of snow in general as a natural phenomenon allows them to create with the architecture of residential buildings whatever their fantasy dictates. But in the snowy regions of Russia, such a roof can be built, but with an appropriate slope and in the right direction. In a word, the main parameter of functionality is the slope angle of a pitched roof, which we will now teach you to calculate.

Step 1. Calculate permanent and dynamic loads

The first step is to calculate the load on the pitched roof. They are usually divided into permanent and dynamic. The first is the weight of the roof covering, which is always on the roof, such installations as antennas and dishes, a chimney, and so on. Those. everything that will be on the roof both day and night.

And dynamic loads, or, as they are also called, variable, are those that happen from time to time: snow, hail, people, repair materials and tools. And also the wind, which, well, loves to tear off lean-to roofs due to their windage.

Snow loads

So, if you make a slope of a pitched roof at 30 °, in winter the snow will press on it with a force of 50 kg for each square meter... Just imagine that on your roof there will be one person for every meter! This is the load.

And if you raise the roof to above 45 °, the snow will most likely not be able to linger at all (it also depends on the roughness of the roofing). But for middle band In Russia, where snowfalls are moderate, it is enough to make a pitched roof within 35-30 °:

The minimum angle that must be in order for the snow to be able to come off the pitched roof itself is 10 °. And the maximum is 60 °, because it makes no sense to make the roof steeper. The same goes for snow, which clings even more to such a roof.

That is why the owners of lean-to outbuildings in winter often take up a shovel. Only the coverage area saves: the smaller it is, the less likely it is that snow can bend the material.

Wind loads

But in windy regions, it is impossible to build roofs with steep slopes at all. By comparison, an 11 ° slope of a pitched roof experiences exactly 5 times more wind force than a 45 ° slope. In view of this, keep in mind that a pitched roof is always made low to the leeward side.

Combined loads

And also be sure to calculate such a value for a pitched roof as a combination of the most unfavorable permanent and temporary loads. Those. that critical point that the rafter system must be able to withstand. By the way, this is often forgotten! They think that the roof will withstand the snow, the wind too ...

What if you and your friend have to climb onto the roof in a strong storm and snow? Is the structure designed for snow, wind, and the legs of at least two people at the same time? That's how trouble happens.

Step 2. Select the roof slope

The slope of a pitched roof is in a fairly wide range: from 6 ° to 60 °. It all depends on the area in which you are going to build: if you need to successfully dump tons of snow every winter, then make the slope steeper, if you plan to protect yourself from the wind, then flatter. And also from many other factors, including aesthetic ones.

Steep pitched roofs

The greater the angle of such a roof, the faster the water flows down it into the gutters. Neither leaves nor dirt will linger here, and therefore the roofing itself will last much longer. In addition, on such a roof, the visual aesthetics of the selected flexible tile or metal profile is more visible, which often plays an important role for the owners.

Low slope pitched roofs

The speed of rain and melt water flowing down on low-slope slopes is much lower, and therefore there is a risk of water stagnation, collecting dirt and ice getting stuck. Moss quickly develops on such roofs and foliage sticks. Especially if the roofing is rough.

As for rainwater, the main requirement for the roof is that the water on it, when snow melts or after rain, does not remain on the surface of the roofing material, and easily rolls off. If it has too low a slope (for a certain area), then the liquid will stand for a long time in all irregularities and seams. And the longer, the more chances it has to get inside and create many problems in the form of dampness, deteriorated insulation and corrosion of metal roof elements:

But, if a large roof of a house rises above such a building, then it's okay:

But here it still has its own plus: the smaller the angle of inclination of the pitched roof, the closer the geometry indoor spaces to the traditional cube. And, therefore, it is perceived more easily and used with greater benefit.

Therefore, the lower the angle of inclination of such a roof, the more you need to take care of its waterproofing so that melt and rainwater cannot penetrate into the rafter system. Therefore, such roofing coverings as membranes, roll insulation or solid sheets are already needed here.

With a standard slope angle, a single-pitched roof is built as follows:

The minimum angle of a pitched roof

A pitched roof, the angle of which is only 3-5%, is often made inversion. Those. subject it to certain additional loads: walk on it, grow a garden on it, or even use it as an open terrace. Like here:

In addition, at a certain angle, a pitched roof directs the air flow in the desired direction, capturing precipitation and diverting it. Remember this!

Step 3. Determine the requirements for the slope

In functional terms, pitched roofs are divided into three main types: ventilated, non-ventilated and combined. Let's consider each option in more detail.

Ventilated design

These are equipped in closed-type buildings. Air vents and special voids between the insulating layers serve as ventilation, through which the air, passing, captures droplets of moisture from the insulation and carries them out.

If such ventilation is not provided, then moisture will remain inside the insulation (and it still gets into it, albeit a little), and the insulation will begin to dampen and deteriorate. And as a result, the entire roofing pie will gradually collapse.

But a ventilated pitched roof has its limitations. So, the angle of inclination can only be in the range from 5% to 20%, otherwise the air will not be able to effectively pass through the vents.

Non-ventilated design

This type of pitched roof is advantageously built on terraces and outbuildings. Usually the angle of such a roof is in the range of only 3-6%, although there are no restrictions to it.

Ventilation in such roofs is not needed because the air in a room without walls or with wide doors often open (as in the case of a garage) is well ventilated by itself, carrying any water vapor into the street. Which, by the way, by themselves, are not particularly formed in such buildings:

Combined design

Such roofs combine the device of both previous types. Here, the desired roof slope is provided by thermal insulation. It turns out economically, but in winter you have to constantly clean off the snow.

But the device of such a pitched roof is already different, because dynamic and dynamic loads are now added to the variable and static loads. And usually everything looks like this: the bottom is corrugated, on it there are two layers of insulation and good waterproofing.

The angle of a shed roof also depends on parameters such as the type of connection of rafters to the Mauerlat or walls. Let's take a closer look.

Step 4. Calculate the exact slope angle

The angle at which the rafters and the roof slope are inclined to the horizontal plane of the ceiling is called the angle of a pitched roof. And take this scheme seriously if you want to provide your roof with the correct mechanical strength:

The angle of inclination of the slopes is measured in percentages and degrees. But, if it is even more or less clear with degrees (thanks to the school geometry course), then what are percentages? Percentage is the ratio of the height difference between the ridge and the eaves to the horizontal of the ramp, multiplied by 100.

There is another interesting point: many architects specially calculate the angle of the pitched roof so that it is equal to the angle of the sun in a given area in mid-spring. Then you can calculate up to a millimeter when and what kind of shadow will be, which is important for planning terraces in front of the house and other recreation areas.

Step 5. Limiting the range of choice of roofing

Modern roofing materials have their own requirements for the minimum and maximum angle of inclination of a pitched roof:

Decking: min 8 ° - max 20 °.
Seam roofing: min 18 ° - max 30 °.
Slate: min 20 ° - max 50 °.
Soft roof: min 5 ° - max 20 °.
Metal tiles: min 30 ° - max 35 °.

Of course, the smaller the angle, the cheaper materials you can use: roofing material, corrugated board and the like.

You will be surprised, but today, especially for low-slope roofs, the same types of roofing are being developed that are usually used with a slope of at least 30 °. What for? This is the fashion in Germany, which has come down to us: the lean-to roof is almost flat, and the roof is stylish. But how? It's just that manufacturers improve the quality of the locks, make the overlap area larger and carefully consider the protection from dirt. That's all the tricks.

Step 6. We decide on the rafter system

And from the chosen angle of inclination of the roof and the planned loads on it, we determine the type of fastening of the rafters to the walls. So, there are three such types in total: hanging rafters, layered and sliding.

Hanging rafters

Hanging rafters are the only option where the connection must be rigid, but for the rafters between the side supports there is no way to support.

Simply put, you only have external load-bearing walls, and no partitions inside. Let's say that this is a rather complex rafter system, and its construction must be approached with responsibility. The whole problem is in large spans and in the pressure that is applied to the walls:

Or like in this project:

Rafters

Here, the entire roof presses on at least three supports: two outer walls and one inner one. And the rafters themselves are used here dense, with a section of at least 5x5 cm of bars and 5x15 cm of rafter legs.

Sliding rafters

In this rafter system, a log in the ridge serves as one of the supports. And to connect the rafters with it, such special elements as "sliders" are used. These are metal elements that help the rafter to move forward slightly when the walls are shrinking to avoid cracks. Very little! And thanks to this device, the roof easily tolerates even a rather noticeable shrinkage of the log house, without any damage.

The bottom line is simple: the more knots in the rafter system, the more flexible and durable it is. The more a pitched roof is able to withstand the pressure of the weight of the roof covering and snow, and at the same time not break. But there are rafter systems where the connection is generally static:

Step 7. Calculate the height of the pitched roof

Here are the three most popular ways to accurately calculate the correct height for your future roof.

Method number 1. Geometric

A pitched roof looks like a right-angled triangle. The length of the rafter leg in this triangle is the hypotenuse. And, as you remember from school course geometry, the length of the hypotenuse is equal to the root of the sum of the squares of the legs.

Method number 2. Trigometric

Another option for calculating the length of the rafter legs is as follows:

Let us denote A the length of the rafter beams.
Let's denote by B the length of the rafters from the wall to the ridge, or the length of the part of the wall in this area (if the walls of your building are of different heights).
Let's denote by X the length of the rafters from the ridge to the edge of the opposite wall.

In this case, B \u003d A * tgY, where Y is the angle of inclination of the roof, and the length of the slope is calculated as follows:

In fact, all this is not difficult - just substitute the necessary values, and you will get all the parameters of the future roof.

Method number 3. Online calculators

By the way, modern online calculators will also help to calculate the desired angle of a pitched roof. Usually they are adjusted to the current SNiPs - "Load and Impact" TKP 45-5.05. But this method can only be used as an additional one.

Calculated? Now let's move on to building the roof itself:

We hope you figure it out easily!

Slope angle, height and slope of a pitched roof: how to calculate

Simple step-by-step instructions, convenient tables and clear calculation schemes. Step-by-step guide to calculating the angle of inclination of a pitched roof.

Roofing is one of the most important stages of construction. The roof protects the home and performs an aesthetic function, completing the design of the building. Choice suitable material Is not the only significant nuance. It is also necessary to correctly calculate the roof slope. This article will tell you how to do this.

Features:

IN modern projects country mansions take into account a large number of requirements. Performers are forced not only to comply with the norms, but also to implement the wishes and whims of customers. However, regulatory requirements are still in the foreground, because the roof, first of all, must be reliable. Therefore, architectural delights often fade into the background.

The roof covering must fulfill its intended purpose - to protect against moisture.In some cases, thermal and sound insulation is required. This is sometimes necessary to increase the functionality of the premises under the roof. Therefore, designing a roof cannot be called a simple matter. This work requires extreme responsibility, especially if the customer insists on a complex configuration. IN different situations professionals use a variety of techniques. Calculations are performed using the appropriate software.

The theory of calculations can be of interest to the owner of the house. For example, such knowledge makes it possible to check whether the correct technique was applied by professionals. They also help to competently present their author's ideas. In addition, the calculated parameters allow you to determine the required amount of building materials for both the rafter system and the roofing.

The peculiarities of the calculations are that professionals use different quantities for measurements. For example, not everyone measures the slope angle in degrees. In the everyday life of some masters, there are concepts such as percentage or relative aspect ratio. You also need to know what is taken as the angle of inclination of the roof.

The roof slope is formed by the intersection of two parameters:

one horizontal plane;
one plane of the roof slope.

This parameter is measured from the top edge to the base of the rafter system. When calculating, only acute angles are taken into account, since obtuse slopes do not exist by definition. Steep slopes are rare. As a rule, they are used for decorative purposes (for example, when they build turrets in the Gothic style).

Roofs can be steep attic view... In this case, the lower rafters are positioned at a very large angle. On ordinary roofs, slopes up to 45 degrees are mounted.

For a better idea of \u200b\u200bwhat it should look like, you can take a protractor and look at the divisions with degrees.

The value of the inclined angle is calculated as the ratio of the parameters of the ridge to half the width of the structure, multiplied by 100. Most professional builders use the so-called tabular charts. Depending on the indicators, it is customary to subdivide roofs by type.

Views

Experts identify several main types of roofs.

Shed roof. In this case, the roof looks like a flat plane. It has distinctive height parameters.

Gable roof.It is a reliable, easy-to-install option. The roof includes two slopes connected at right angles.

Hip roof.It is supplied with four slopes, two of which are triangles, and two more are trapezoids. The top of such a roof looks cut off. Despite the complexity of the structure, such roofs are very economical in terms of material consumption.

Vaulted roof type.It is rare as it involves a limited selection of materials. Such options are erected only from brick or stone. The rarity of the choice in favor of such roofs is also due to their heaviness. In small private construction, this type is practically not used.

Multi-gable roof type.It is complex in configuration, but very beautiful. Such a roof is difficult to install due to the many abutments and lintels.

Also, experts identify types of roofs that can be subsequently operated., and options that are not exploitable. If professionals classify the roof as an unexploited type, this means that there is practically no space between the roof itself and the upper floor. This territory can be used, but only as a technical one. For example, such is a low-slope single-pitched roof.

Shed roofs are the most profitable for construction. They require a minimum of material costs, but the work can be done independently. If the roof has a slight slope, then a resting place can be realized on its surface without the construction of a complex attic.

The space under the roof can be used if the roof type is pitched.The attic area can be used for household needs. Also, due to it, you can expand the living space.

The choice of this or that type of roof is associated with many nuances. One of the main factors is the climatic factor.

Climate influence

For example, a huge load on the rafter structure can be caused by wind.Even a slight increase in the inclined angle increases the wind load. For example, if the angle of inclination of the roof is 30 degrees greater than the standard values, the wind load becomes five times greater. Therefore, even a slight increase in indicators can play a cruel joke with the owner of the house in case of a natural disaster.

Precipitation is no less destructive to the quality of the roof. At the same time, a well-chosen slightly higher slope will avoid the accumulation of snow on the surface. Snow will not melt at all with a roof slope of 30 degrees. And with a slope of 45 degrees, the normative indicators for the snow load on the roof will be observed.

In northern countries (Sweden, Finland, Norway, etc.), it is customary to make very high pitched roofs. It is obvious that snow does not linger on high slopes. However, it is generally accepted that some layer of snow on the roof plays the role of additional thermal insulation.

To eliminate the risk of breaking the roofing material, a strong rafter system is made, because a large weight will affect the entire structure.

It is worth remembering that the larger the slope of the roof, the more funds will have to be spent on construction. Also, the costs are associated with the choice of the roof covering option (not all materials can be laid on high pitched roofs).

For different materials

Before choosing a roofing material, you should carefully consider technical features cover. This will help to accept optimal solution and choose the most reliable option. There are rules that determine the relationship between the angle of inclination of the roof and the applied roof structure.

Slate or shingles can be installed on roofs with a minimum slope of 22 degrees. On roofs with a smaller slope, moisture will accumulate and seep inside at the joints of the parts. If the roof has slopes with a lower degree, roofing felt and other bituminous materials can be used, which are mounted with a solid sheet.

Profiled sheet manufacturers claim that this material can be laid at a minimum angle of 12 degrees. Moreover, if the slope angle is minimal, then the joints between the sheets must be glued with a sealant.

For metal shingles, the minimum possible slope is 14 degrees. At the same time, there are rules for arranging floors. For example, if the angle is more than 45 degrees, then the installation location of the ridge board changes. The method of mounting the ridge itself also changes. At small values \u200b\u200bof the value, an aero roller is attached between the ridge strip and the tile. It prevents snow from penetrating under the roof.

For a roof covered with ondulin, the minimum possible slope is 6 degrees. For soft tiles, the optimum surface slope is 11 degrees. Although a larger bias is acceptable for this material. In this case, the crate must be continuous.

Membrane-type coatings are more versatile. PVC membrane, EPDM membrane, TPO membrane - this is modern materialssuitable for roofs of any shape. The versatility of materials is due to the excellent technical characteristics and long service life.

When choosing a particular coating material, one should take into account not only the features of the slopes, but also the strength values \u200b\u200bof the roof. Structures must support not only their own weight, but also the mass of the roofing material. In addition, the entire roofing system must successfully withstand external loads.

The slope of the slopes is often associated not only with the choice of materials, but also with the choice of the type of crate. If the angle of the slope is of little value, then a solid crate is mounted. Also, when installing a flat roof, a drainage system must be installed. There are standard parameters for any roofing option. They should be kept in mind, even if the simplest flat option is chosen.

Guideline values

Arrangement of a flat roof is a simple undertaking. The main thing is to use properly selected high quality material. The slope of the flat roof is also important.

In fact, a flat roof is not completely horizontal. On such a roof, a slope equal to 15 degrees is constructed. Slopes must be present, since only in this case will water flow into the drains. If the slope is not done in accordance with the established norms, stagnant water will form on the roof surface.

When choosing certain bases, the type of construction should be taken into account. For example, if the floors are wooden, then the additional weight for the roof is contraindicated.

Today on sale you can find special plates that are distinguished by high thermal insulation qualities. Such slabs are wedge-shaped. It is enough to lay the material on a flat surface. The result is a bias corresponding to the standard indicators. The only drawback of the material is the rather high cost.

When using other materials, first you need to make sure that the surface is completely flat. Then beacons are installed on it. The slope must be directed into the gutters.

When creating a slope, it is worth considering the roof area. For a garage roof, for example, it is worth considering one slope, which will be directed into the drain funnel. Slope for a standard house of 80 sq. m will be 2-4 slopes. Moreover, all of them must be directed to the drainage system in order to freely deliver water into it.

How to calculate?

If there are usually no difficulties with arranging a flat roof, then engineering calculations are necessary for installing a roof with several slopes. The easiest way is to calculate and determine the values \u200b\u200bin degrees. For example, you can use a mathematical method to equip a roof with a sloped angle of 30 degrees.

This requires two measurements.

Vertical height (H).The value is measured from the top of the inclined plane to the bottom of the rafter system (from the ridge to the eaves).
Laying (L).This is the horizontal length from the midpoint of the bottom of the ramp to the eaves.

Mathematical calculation is performed using the formula. You can calculate the required parameter as follows: I \u003d H: L. For example, the length of the laying is 5 m, and the height is 3 m. In this case, the slope will be 0.6 (when calculating I \u003d 3: 5). This value must be multiplied by 100. It turns out 60 percent.

To convert the value to degrees, you can use a special ratio table. It can be found in specialized textbooks. Sometimes such a table can be found on sale in construction hypermarkets. It is not necessary to translate relative values. With the values \u200b\u200bfrom the above example, the tilt angle will be 30 degrees.

Experts do not always use a conversion table in their measurements. The percentage factor can be applied in the same way as the degree factor. In general, professionals use special tools in their calculations. For example, you can measure the area parameter using a special inclinometer.

The tool is a ruler with a staff. One axis contains the familiar scale in centimeters, the other a pendulum. If the bar with divisions is horizontal, the pendulum will show zero. When measuring the slope, the rail is installed perpendicular to the ridge. In this case, the scale shows the result for a specific value immediately in degrees.

Currently on the market you can find a variety of tools that can measure slopes. Levels can be either drip-type devices or electronic devices... In this regard, the mathematical method of measurement cannot be considered relevant. Modern appliances allow for more accurate calculations.

The content of the article

Several factors affect the minimum roof slope, not the least of which is the climate of a particular region. The roof, in addition to protecting the interior of the house from the effects of the external environment, also experiences stress from them. Snow cover, summer rains, wind - all these factors affect the choice of both the shape of the roof and its slope.

What affects the slope of the roof slope?

In areas where strong wind loads prevail, it is customary to make a slight roof slope. In such areas, a high roof creates additional windage, which can lead to its failure. In order to minimize these risks, you need to make a reinforced rafter system, which leads to a significant increase in the cost of the entire construction.
In areas with heavy snow loads, roofs are erected with a slope of up to 45 degrees or more. Snow will not linger on such a roof, therefore, the rafter system does not need to be reinforced. For roofs with such a slope, the load from the snow cover is no longer taken into account.

Low-slope roofing is carried out in regions with low precipitation and an abundance of sunny days. In this case, the roofs are built more flat. For roofs with a minimum slope, it is recommended to use membrane roofing materials that reliably protect the roof from leaks.

The abundance of the sun gives a strong heating of the roofing material, which, as a rule, for flat roofs is selected from roll or piece materials on a bitumen basis. Often, to protect the roof from overheating, pebble sprinkles are arranged on their surfaces, sod or green coverings are made.

But even in this case, the minimum slope of a flat roof must be supported by a water system so that even a meager amount of precipitation does not linger on the surface of the roofing.

The drainage system on flat roofs can be both external and internal. Internal drain arrange in areas with harsh winters. In this case, the drainage system will not be exposed to the destructive effect of low negative temperatures. In any case, the slope of the roof is made towards the water intake funnels so that water can flow by gravity into them.

Pitch angle and roofing material

The choice of roofing material also influences the slope angle of the roof slopes. Materials with a smooth surface will help drain water off the roof more quickly. Conversely, materials with a rough surface will inhibit the rapid outflow of water.

Roof slope angle , in turn, dictates the conditions for the selection of the rafter system and all the components of the roof - rafters, lathing step, roofing material. Naturally, the steeper the roof slope, the better and faster the outflow of water. In addition, a high roof looks better and the choice of roofing for it is greater.

As for roofing materials, each of them has its own recommended roof slope.

minimum roof slope and covering

The minimum slope of the roof from corrugated board make it equal to 12 degrees, for a roof covered with metal tiles, the slope increases to 15 degrees. But with such a small roof slope angle, all joints between individual sheets or other elements must be treated with a water- and frost-resistant sealant. In addition, if the slope angle of the roof is 15 degrees or more, the profiled sheet is laid with an overlap equal to 200 mm, with a smaller slope angle, the overlap increases by the value of two waves. The step of the lathing under the corrugated sheet also depends on the angle of the roof slope. The greater the slope, the wider the sheathing step becomes. With a minimum slope angle, the lathing can be solid.

Roll or piece roofing materials based on bitumen, as well as membrane coatings, ondulin, can be laid on the roof with a minimum slope of only two degrees or more. When choosing roll materials, the angle of inclination is affected by the number of layers of soft roofing. The more layers there are, the lower the slope angle of the roof, as its waterproofing capacity increases. If the soft roof is made from 1 or two layers of roll material, then the roof slope angle can reach 15 degrees.

Soft tiles (ondulin) can be laid on a roof with a slope angle of 11 degrees, but the lathing in this case must be solid.

The minimum slope of the pitched roof covered with asbestos-cement sheets or ceramic tiles, the slope angle of the roof slope must be at least 22 degrees. Do not forget that the smaller the slope angle of the pitched roof covered with slate or natural tiles, the greater the loads are created on the rafter system along the entire plane of the slope. Therefore, the rafter system must be calculated taking into account the slope of the roof.

How and how is the slope angle of the roof measured?

The slope angle of any roof can be calculated using geometric functions or a device called an inclinometer. The slope of the roof can be measured in degrees, percent or their ratio

The mathematical approach to calculation is to first find out the length of the legs or hypotenuse. The hypotenuse will be the straight line represented by the roof slope. The opposite leg will be the distance from the overlap to the ridge, the length of the adjacent leg is the distance from the middle of the slab to the eaves overhang of one of the roof slopes.

Knowing two of the three values, using trigonometric functions, you can easily calculate the minimum slope of a soft roof. The resulting value of the sine, cosine or tangent, depending on which dimensions of which constituents of the right-angled triangle were used, use the engineering calculator to find the percentage of the roof slope angle.

Another way to determine the angle of the roof slope is to determine the ratio between the height from floor to ridge and half the width of the floor. The height is divided by ½ the width of the building and multiplied by 100. Further determination is made using a special table.

Roofs made with a minimum slope must be equipped with the correct drainage system... The slope of the roof is made towards the water intake funnels, if provided internal system the catchment area, and towards the gutters if an external catchment is arranged.