The pitch angle of the roof depends on. How to calculate the angle of a roof

It has a number of advantages, such as: its installation will require less materials, ease and simplicity of installation and additional usable territory.

Many people do not associate the phrase flat roof with a slope. Although this is far from true. Even the smoothest roof has its own slope, even if it is minimal.

At a minimum, this is necessary so that melt water and water after rain can easily flow into the installed funnels, which are part of the internal drainage system, or into the gutter of the external system.

In addition, on such a roof it is easy and simple to install additional, necessary equipment. To date, There are several types of flat roofs:

• Operated roof;
• Unused roof;
• Traditional roofs;
• Inversion roofs.

The slope that should be on this type of roof is is approximately 1-5 degrees, if you neglect this, then water, both rain and melt, will accumulate, which in turn will damage the roof.

In summer you may not encounter such a problem, since under the rays of the sun rainwater dries out. In winter and autumn, such water can freeze at night and melt during the day.

Puddles form, which ultimately leads to moisture gradually penetrates into the insulation. The essence of the mechanism is that moisture penetrates into the layer, which means that inevitable leaks occur.

But this is not the only problem. In addition, puddles on the roof can contain dust, which eventually settles to the bottom. Seeds of various herbs and plants can fall into this puddle and germinate there.

Often on the streets you can find houses with grass or thin trees on their roofs. It is logical that this spoils the roof and also spoils the aesthetic appearance of the entire building.

To avoid such a nuisance, and thereby extend the life of your roof, it is necessary to carry out the roof tilting procedure. Such complex manipulation is carried out at the time of construction itself.

The process itself is quite complex and includes many different structured activities. The purpose of this procedure is to ensure that the roof itself acquires the required slope.

But before you start pitching the roof, you need to find out what a flat roof consists of.

Flat roof

In essence, it is a cake made of several layers:

• Direct basis, which is reinforced concrete slabs that have a certain wave height;
• , which can be made from different materials, such as bitumen, or rolled materials;
• Next layer -, which can be made of mineral wool or other durable material.

The components of such a pie can be changed if the builder wants to make the entire roof using new building materials. It is worth understanding that such a procedure as slope, carried out immediately at the time of laying the insulation.

It is important that in addition to these main layers of the roof, there must also be water intake funnels or gutters.

The angle of the roof slope is very important, and it depends on many parameters. The first thing you should pay attention to is the wind exposure. If you live in an area where there are frequent strong winds, then it’s worth making a small angle of inclination.

CAREFULLY!

If you make a strong slope of a flat roof, then the wind can tear out roofing sheets. It is important to note that the angle of the roof dictates the necessary conditions For rafter system, as well as for all components of the roof, namely: rafters, sheathing pitch.

Obviously, the steeper the slope of the roof itself, the faster the outflow of water.

Slope in percent

Minimum angle and calculation of roof slope

The minimum slope angle can be determined based on the materials of the roof itself:

• If the roof is made of , then its minimum inclination must be at least 12 degrees(according to SNiP). If the roof is made of, the angle increases to 15 degrees. It is important to understand that the cracks in the material and other joints must be treated with a special sealant - frost-resistant/water-resistant. If the angle of inclination is 15 degrees, then the sheets of material should be overlapped by about 200mm, if the angle is smaller, then the overlap should increase;
• The minimum slope angle may be in cases where if the roof of your house is made of artificial materials. These, in turn, include membrane coatings and bitumen-based materials. It is logical that by the magnitude of the slope angle, The number of layers of the roof also affects. If, for example, the roofing is carried out in two layers. then a tilt angle of 15 degrees is quite sufficient;
• Having covered the roof, it is worth understanding that 11 degrees of inclination angle is quite enough, but in this case you need to make a continuous type of sheathing.

Such a process as the slope of a flat roof, made from such materials:

• Extruded polystyrene (technoNIKOL);
• Wool, both mineral and glass/basalt based;
• Polyurethane foam;
• Foam concrete;
• Foam glass;
• Various types of backfill materials.

Each of the materials has its pros and cons. And before you start work, it is worth correctly calculating the angle of inclination. In fact, this calculation is quite easy to carry out; for this you need to use a protractor, or use fairly simple mathematical formulas.

Despite the fact that a flat roof is called flat, it still needs a slope. The minimum slope for a flat roof is 1 degree or 1.7%.

In the instructions for using bitumen and polymer coatings for tilting, it is indicated that the optimal tilt angle should be 1.5 degrees. A tilt of 1-2 degrees is acceptable.

Everything is very simple here. You need to know the height of the roof and its width. Next, simple trigonometric formulas will help you calculate the immediate angle (sine, cosine, tangent). And from the existing table, which was calculated earlier, you can find out the value as a percentage.

There is another way to calculate - the value of the roof height must be divided by half the width, and the result already obtained must be multiplied by one hundred, after which, in the table, you can find out the percentage value of the future angle of inclination. This option is faster, but in terms of accuracy they are both correct.

Minimum slope

Sloping a flat roof using bulk materials

If you decide that the tilting procedure will be carried out using bulk materials, then the first thing worth noting is the diagram according to which such a procedure must be carried out:

1. First of all, on the concrete base itself, it is necessary to lay a layer of glass insulation. This material not only has a long service life (30-35 years), but also has high waterproofing performance;
2. Further, it is necessary to pour the main material on it - expanded clay. But at the same time, everyone needs to create the right bias;
3. Necessarily you need to cover a layer of expanded clay with a special plastic film. It is important to note that it must be overlapped;
4. Further, it is necessary to apply the prepared sand-cement screed, doing it smoothly, slowly. Its essence is to level the layer of expanded expanded clay;
5. After these events you can begin shape the roofing “pie”, according to the developed .

Remember that when laying each layer, you need to ensure that the previously prepared angle of inclination is maintained.

ATTENTION!

If you are worried that the expanded clay will move when you start laying sand-cement screed on top of it, you can fill it with cement laitance. But it is worth understanding that because of it, the structure becomes heavier.

If you want to create a minimum angle of inclination, and the roof area is not particularly large, then a sand-cement mortar will be enough.

Bulk material

Thermal insulation materials

One more good material, for roof slope are thermal insulation materials. Experts say that this is the most affordable option.

Its advantage is that it is quite light and quite cheap, which plays a very important role in construction. Mineral wool, the most best material. The process diagram is quite simple.

It is necessary to attach the material to the base itself, using self-tapping screws or dowels. Some people prefer to glue sheets of such cotton wool onto a previously cleaned base using special glue. This process can be performed both during and during roof installation.

Thermal insulation material

Foam concrete

A good material that can be used to slope a flat roof is foam concrete. It is immediately worth noting that this procedure must be carried out using special equipment.

A layer of foam concrete is poured onto the base itself, but at the same time the angle of inclination is noted, and only after make a special screed from foam fiber concrete. Next, it is important to apply waterproofing material.

A huge advantage of this tilt option is high thermal insulation rate, as well as other mechanical characteristics . For example, strength and durability.

Speaking of minuses, there are some here too, or rather one. This is the price. She's tall enough. And again, it will not be possible to carry out such a procedure on your own. Therefore, in this case it is worth turning to professionals.

• If the roof has a minimum slope, then it is important to note that in this case, proper drainage systems must be installed. The slope itself is done exclusively to the side (funnel, gutter);
• If your roof is bitumen, you should make the slope angle less than 6 degrees, while The bottom layer of waterproofing must be made of membrane materials;
• It is important to know that with small slope angles, it is necessary to ventilate the under-roof space itself, what does all the stingrays have to do with it. The thickness of the gap also depends on the value of the angle (the larger the angle, the smaller the thickness and vice versa).
In contact with

a - one of most commonly used roof structures that have two inclined planes separated by an edge - a ridge.

The slopes can be either identical, creating an isosceles triangle in cross section, or different, having different angles slope and area.

In addition, it is common attic structure gable roof, when the slopes consist of two planes with different angles of inclination.

This design allows more effective use the attic space for commercial or residential purposes.

The main advantage of gable roofs is considered simplicity of construction and reliability in operation, absence or small number of valleys or grooves that facilitate the accumulation of water or snow.

The design as a whole ensures optimal distribution of the weight of the rafters and roofing on the walls, contributing to the maximum service life of the roof.

Read in detail about how to make a gable roof yourself.

During its service life, the roof is constantly experiences stress of various kinds. The problem is not their availability - this issue is easily solved strengthening. The point is the diversity and unevenness of these loads.

Constant and unchanging- the weight of the roofing pie and the roof itself, they create continuous pressure on elements due to its weight. Additional factors include wind load and the weight of precipitation.

NOTE!

These factors dangerous for their unpredictability and a large spread of values.

If moderate winds of a certain direction prevail in the region, then a single gust of hurricane force can cause significant damage or completely tear off the roof. IN winter time with abnormal large quantities snowfall, the load on the roof can exceed permissible values, which is fraught with deformation or violation of the integrity of the coating and the formation of leaks.

Such natural manifestations can only be combated with preventive measures:

• Creating a safety margin in calculations.
• Taking into account the prevailing winds in the region, their strength and direction.
• Taking into account the average annual precipitation, its composition and quality indicators.
• Correct choice of slope angle.

Choosing the correct angle of inclination of the slopes is one of the most effective methods of neutralizing harmful effects on the rafter system.

It allows you to reduce snow pressure by preventing its accumulation, adjust the wind load by reducing the roof windage and ensure the drainage of rainwater, preventing it from freezing at night in the autumn.

Wind loads on rafter systems

Dependence of the angle of inclination on the choice of roofing material From the point of view of saving material and reducing the roof windage,.

At the same time, a roof that is too low will retain large masses of snow or prevent the effective outflow of water.

But most main criterion the choice of inclination angle is .

Its characteristics determine the optimum based on the following indicators:

• Rigidity. A value that determines the permissible weight or pressure on a surface without causing deformation.
• Plastic. The ability of a material to change shape under load without destruction.
• Waterproof. Absorption of water promotes rapid destruction material.
• Surface quality. Snow masses easily slide off smooth surfaces, relieving the roof of pressure. At the same time, the collapse of large volumes can cause certain harm people or property caught in the falling snow zone.

Based on these parameters, each type of roofing material has its own ramp slope limits. Simplifying somewhat, we can say that materials with a smoother and waterproof surface allow the smallest angle of inclination, while materials that are rougher and absorb water require a steeper inclination. Basically, they predominate values ​​from 20° to 45°.



Dependence of angle on angle and roofing material

How to measure the slope of a gable roof

First of all, you need to decide what an angle of inclination is. This is the angle between the slope plane and the horizontal.

The slope of the slopes is usually measured in degrees or percentage. If everything is clear with degrees, then percentages are obtained from the ratio of the height of the ridge above the ceiling of the upper floor to half the width of the building.

The use of percentages is introduced for simplicity - complex trigonometric calculations fraught with errors, and dividing one quantity by another is easier and more accurate. However, they often resort to help Bradis tables, to find out the exact value in degrees.

When calculating the angle of inclination of a broken slope, values ​​related to the areas being determined are used. This applies both to the width - the part that is covered by the roof section is taken into account - and to the height above the ceiling.

All subsequent calculations are made for each section separately; output and use some the average value is not possible.

This applies to both the determination of loads and power of load-bearing elements, and the calculation required quantity material.



How to measure the angle of a gable roof

Minimum slope angle of a gable roof

It is necessary to immediately determine the correct understanding of the term “minimal”. This refers to the smallest permissible value of the roof inclination angle, taking into account wind and snow loads.

It is at this point that many difficulties lie. : the indicated values ​​​​in different regions differ greatly from each other, therefore you need to know the average annual precipitation, volumes of snow and its high-quality composition(wet snow is much heavier than dry snow and may cause destruction incorrectly calculated roof).

In addition, you should be aware of the prevailing winds, their strength and direction and, most importantly, the presence of periodic hurricane-force wind gusts in the region.

CAREFULLY!

Ignore such extreme weather events for reasons of “maybe it will blow over” under no circumstances is it possible, since one single case is capable destroy the entire roof.

Taking these circumstances into account, the minimum angle can be defined as the smallest value stated in SNIPs, adjusted for climatic conditions. Experts definitely consider for pitched roofs at least 20°, which applies only to non-residential or unused attics.



Finding the minimum angle

The optimal angle of inclination of a gable roof

The angle of a regular gable roof lies within 20°-45°, which corresponds to the spread of values ​​of material properties and average climatic parameters.

The angle of inclination of a gable roof is important indicator, affecting the durability and integrity of the entire building, and cannot be treated as a secondary factor.

Taking into account all possible loads, both permanent and one-time extreme, will help ensure safety and comfort of your home.

More exact values are selected based on factors such as:

• Purpose of the attic.
• Roof covering used.
• Climatic conditions.



The optimal angle of inclination of a gable roof
































































Choosing the type of roof, determining the angle of inclination and other parameters of the roof is an important and responsible task that requires knowledge of standards and taking into account climatic features in the region. The article provides a description of a flat roof, its advantages and features. It explains in detail why a flat roof is needed and how it is sloped. The information will be useful to all owners of plots planning to build a residential building, auxiliary or outbuildings.



Source horoshidom.ru

Flat roof structure

A flat roof is a single sheet, not divided into separate sections, and has a certain slope to organize water flow. There are buildings of complex architecture, consisting of several departments with different levels of height. Each part usually has its own roof, but general rules for each individual section are saved.

Flat roofs are traditional for the architecture of southern countries, but in the northern regions they are used mainly for non-residential buildings - utility or auxiliary. The reason for this attitude is the abundance of precipitation, which does not occur in such quantities in regions close to the equator.



Source folksland.net

The traditional design of flat roofs consists of a support system (rafters) forming an inclined plane with selected parameters. A deck of boards is created on top of the rafter system, on which the roofing sheet is attached. This design is simple, erected quickly enough and allows for the removal of moisture from the under-roof space.

The disadvantage is the use of wood, which is prone to warping, rotting and represents fire danger. In addition, wooden rafters have limited load-bearing capacity, requiring careful calculation to comply with snow loads. A significant danger is posed by the influence of wind, strong gusts of which can rip off the roof, causing significant damage.



Source odome.kz

In order to increase the strength and load-bearing capacity of flat roofs, a construction technique has been developed in which the construction of the rafter system is abandoned, replacing it with a dense bulk layer - a slope. it is laid at a certain angle to the horizon, forming an inclined plane on which the roofing covering is laid. As a result, the roof of the upper floor becomes the supporting system, and the slope of the flat roof strengthens it and forms the required angle of inclination, optimal for the given conditions and materials.



Source krovlikom.ru

Advantages of flat roofs

The main advantage of a flat roof is its simplicity and cost-effectiveness of construction. Such a surface is convenient and safe, allowing for maintenance or renovation work V optimal conditions. The surface area of ​​such a roof is significantly smaller than that of pitched structures, which allows significant savings on roofing material.

An additional advantage of flat roofs is the convenience and ease of installation of various technical devices and equipment on them - satellite dishes, solar panels, etc. simplifies the repair and maintenance of equipment, which can be carried out at any time of the year.



Source ivd.ru

There are flat roofs, the surface of which is equipped for lawns, swimming pools, recreation areas and other areas. In these cases, the use of the surface is most effective, although it requires significant costs for the design and maintenance of the sites.



Source archilovers.com

Slope for a flat roof: whim or technical necessity

Slope is a necessity caused by the abundance of rainfall. Rain or melt water must be able to be removed from the surface, otherwise the roofing will quickly deteriorate and fail. In summer, stagnation of rainwater will provoke aggressive effects chemical elements and oxygen dissolved in the mass of sediments. In winter, the presence of moisture is even more dangerous - when the temperature drops, it will freeze and begin to expand. The smallest cracks in the surface where moisture penetrates will begin to increase.



Source blues-dev.ru

On our website you can get acquainted with the most . In the filters you can set the desired direction, the presence of gas, water, electricity and other communications.

To organize efficient water drainage, at least a minimum slope of the flat roof is required, allowing water to be removed from the roof by gravity. The optimal solution to the problem for roofs of a large area is to slope the flat roof with bulk materials, forming a plane with the right angle and at the same time performing the functions of insulation and sound insulation.

Minimum and maximum slope of flat roofs according to SNiP

The angle of inclination of the roof is a value regulated by technical standards. SNiP contains SP 17.13330.2011, or, more simply, in the Code of Roofing Rules. It defines the standard values ​​of the angle of inclination roofing covering depending on the roof structure, as well as the materials used. SNiP determines the values ​​​​that the slope of a flat roof has in accordance with the surface properties of various roofing coverings. The degree of roughness of the metal sheet is much less than that of soft or wavy surfaces.

The slope is measured in different units:

In percentages.

Height to length ratio.

In degrees.



Source kak-sdelat-kryshu.ru

This abundance of units of measurement is due to the specifics construction work– checking the angle using a protractor on the site is much more difficult than measuring linear dimensions.

The situation is somewhat more complicated when constructing a roof with a large area. It is not always rational to make a slope in such conditions. The solution to the problem is the slope of a flat roof with an internal drain, when the entire roof is divided into relatively small areas with drainage funnels. Water entering them is discharged through a pipeline system to storm drainage. This roof design is more complex and requires the creation of a system of drainage communications, but for large buildings this option is optimal.



Source blues-dev.ru

In practice, the angles of inclination are much smaller and largely depend on local climatic conditions. Main factors influencing the choice are:

Snow amount in winter.

The power of the winds prevailing in this region.

The weight of snow is a significant load. It can be determined from the tables in the appendices of SNiP, which indicate the average annual values ​​for different regions countries. The lower the angle, the less possibility of independent snow melting. At the same time, a large angle of inclination increases wind loads, which are dangerous because the roofing covering can be torn off the supporting surface. The destruction that occurs in this case can lead to casualties and threaten not only this building, but also all objects located nearby.

The choice of angle is based on the magnitude of the expected loads and is adopted in accordance with them. If the roof structure consists of durable materials that can withstand a static load from the weight of snow, then they usually try to minimize wind influences, which are dynamic in nature and unpredictable in direction.



Source architizer.com

How to calculate the slope of a flat roof

Specialized calculation of the angle of inclination is an extremely complex engineering task. The requirements of SNiP in this matter have advisory value and determine only permissible limits for each type of roofing. For an unprepared person, performing such a calculation is inaccessible and even dangerous. It is necessary that the design be carried out by competent and experienced specialists.

Alternatively, you can use an online calculator, which are abundantly available on the Internet. It is recommended to duplicate the resulting value on another resource in order to compare the data and balance the results. It must be taken into account that online calculations have only advisory value and should not be used in the construction of critical structures.



Source blues-dev.ru

Roofing materials for a flat roof depending on its slope angle

The choice of roofing material should primarily be determined by the angle of the roof. There are a lot options:

Roofs from piece materials and corrugated sheets

Metal roofing.

Soft roof.

You can create an angle of inclination by creating a supporting structure of the desired configuration or by filling the surface with an inclined layer of insulation. There are also specialized types of materials, for example, wedge-shaped insulation from the Technonikol company, the slope of the roof with which is created by laying slabs of a specific shape.



Source howbuilds.ru

Choice of the most suitable material is made by comparing local climatic conditions, construction parameters, capabilities and preferences of the owner. All these factors are equally important, but it is recommended to give priority in decision-making to representatives construction company with experience and specialized knowledge.

Video description

In the video you can see the construction of flat roofs:

Conclusion

In conclusion, it should be noted that the number of buildings with flat roofs has increased. The fashion for such architectural solutions, which came from Europe, requires the use of appropriate technologies and materials. Approaching construction using the usual standards common in Russia is irrational and impractical. For buildings with flat roofs, the creation of special project, taking into account the climate, properties of materials, hydrogeological conditions.

All over the globe there are thousands and thousands of architectural traditions in terms of appearance roofs But modern architects have completely changed the idea of ​​the culture of suburban construction, introducing pitched roof forms as ideally combined with landscape design and diverse in execution. Of course, this new fashionable tone was set by the residents of Australia, where the absence of snow at all is like natural phenomenon allows them to create whatever their imagination dictates with the architecture of residential buildings.

But in the snowy regions of Russia such a roof can be built, but with the appropriate slope and in the right direction. In a word, the main parameter of functionality is the angle of inclination pitched roof, which we will now teach you to calculate.

Step 1. Calculate permanent and dynamic loads

First of all, calculate the loads on a pitched roof. They are usually divided into constant and dynamic. The first is the weight of the roofing covering, which is always located on the roof, installations such as antennas and dishes, a chimney, etc. Those. everything that will be on the roof both day and night.

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

Snow loads

So, if you make a pitched roof slope of 30°, in winter the snow will press on it with a force of 50 kg per square meter. Just imagine having one person per meter sitting on your roof! This is the load.

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

The minimum angle that must be so that snow can slide off a pitched roof on its own is 10°. And the maximum is 60°, because there is no point in making the roof steeper. The same applies to snow, which clings even more to such a roof.

That is why owners of lean-to outbuildings often take up a shovel in winter. The only thing that saves is the coverage area: the smaller it is, the less likely it is that the snow will be able to bend the material.

Wind loads

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

Combined loads

And be sure to calculate for a pitched roof a value such as the 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 the roof can withstand the snow and the wind too...

What if you and a friend have to climb out onto the roof during a heavy storm and snowfall? Is the design designed to withstand snow, wind, and the legs of at least two people at the same time? This is 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 planning 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 make it flatter. And also from many other factors, including aesthetic ones.

Steep pitched roofs

The greater the angle of such a roof, the faster 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 chosen roof is more visible. flexible tiles or metal profiles, which often plays a big role for the owners.

Low-slope pitched roofs

The speed of flowing rain and melt water on low-slope slopes is much lower, and therefore there is a risk of water stagnation, dirt collecting and ice getting stuck. On such roofs, moss quickly develops and leaves stick to it. Especially if the roof covering is rough.

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



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



But there is still a plus here: the smaller the angle of inclination of the pitched roof, the closer the geometry interior spaces to a 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 rain water cannot penetrate into the rafter system. Therefore, roofing coverings such as membranes, roll insulation or solid sheets are already needed here.

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



Minimum pitched roof angle

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



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




Step 3. Determine the slope requirements

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 installed in buildings closed type. Ventilation is provided by vents and special voids between the insulating layers, through which air passes, capturing droplets of moisture from the insulation and carrying them outside.

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

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



Non-ventilated design

This type of pitched roof is advantageously built on terraces and outbuildings. Typically, the angle of such a roof is in the range of only 3-6%, although there are no restrictions on 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) itself ventilates well, carrying any water vapor outside. Which, by the way, are not particularly formed in such buildings:



Combined design

Such roofs combine the structure of both previous types. Here, the required roof slope is achieved through thermal insulation. It turns out to be economical, but in winter you will have to constantly clear off the snow.

But the design 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: there is corrugated board underneath, two layers of insulation on it and good waterproofing.

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

Step 4. Calculate the exact angle of the slope

The angle of a shed roof is usually called the angle at which the rafters and roof slope are inclined to the horizontal plane of the ceiling. Moreover, 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 degrees are more or less clear (thanks to the school geometry course), then what are percentages? Percentage is the ratio of the difference in the height of the ridge and cornice to the horizontal of the slope, multiplied by 100.

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

Step 5. Limiting the choice of roofing covering

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

• Profiled sheeting: 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 felt, corrugated sheets and the like.

You will be surprised, but today, especially for low-slope roofs, the same types of roofing coverings are being developed that are usually used with a slope of at least 30°. For what? This is the fashion in Germany, which has reached us: the pitched roof is almost flat, and the roof is stylish. But how? It’s just that manufacturers are improving the quality of locks, making the overlap area larger and thinking more carefully about protection from dirt. That's all the tricks.

Step 6. Deciding on the rafter system

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

Hanging rafters

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

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



Or like in this project:




Layered rafters

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

Sliding rafters

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

The point is simple: the more nodes there are in the rafter system, the more flexible and durable it is. The more a pitched roof can withstand the pressure of the weight of the roofing and snow without breaking. 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 desired height of a future roof.

Method number 1. Geometric

The pitched roof looks like right triangle. The length of the rafter leg in this triangle is the hypotenuse. And, as you remember from your school geometry course, 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 this:

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

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

X = A / sin Y

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

Method No. 3. Online calculators

Have you figured it out? Now let's move on to the construction of the roof itself:



We hope you figured it out easily!

One of the most painstaking tasks during the design of a corrugated roof is choosing its angle. No aesthetic considerations play a role here: the ratio of the height of the roof to its total area in the future will affect how much usable space remains in the attic, will there be problems with snow accumulation, and even whether the wind will blow your roof away in a strong storm.

But this is not uncommon! Shall we figure it out? So, what is the minimum slope of a corrugated sheet roof? And how to build a roof with a minimum slope - all the pros, cons, recommendations and subtleties of construction are here!

Let's look at the official data. So, according to SNiP, building regulations and rules, any roof can be covered with corrugated sheeting, the slope of which has a slope of at least 8°. This is the only way that precipitation will not be able to penetrate through joints and screws. The sheathing step in this situation should be 40 cm.

But 8° is the minimum angle of inclination for the roofs of utility and industrial buildings, and for residential buildings this threshold is 10°. And if the roof is laid in two or more layers, then the minimum threshold will be even higher. That's why modern construction companies They give guarantees for their work only on the condition that they cover a roof with a slope of at least 12° with corrugated sheeting. But the maximum angle for a roof made of corrugated sheets can be at least 70°, or even more.

Therefore, for profiled steel sheets as roofing material, SNiP recommends a 20° slope as the most best option. But what if you need to build an almost flat roof? For a garage, outbuilding or gazebo? Then just follow our advice - and no problems will arise!

Degrees, percentages and ratios

The roof slope is 8°, which corresponds to a value of 1:7 - this is the minimum value that can be when installing corrugated sheets. And after completing all the work, it is necessary to carefully check the roof for ventilation. But why do roofers, when determining the angle, talk not only about degrees, but also about percentages and even coefficients? All this is the same thing, the only difference is for design documents and when ordering materials. We have prepared a table for you that will help you figure out what's what:

Now let's understand the construction terms. So:

• Flat roofs are those whose slope angle does not exceed 5°.
• Sloping ones are those that are usually more than 20°. Naturally, pitched roofs are more waterproof, and therefore more popular in private construction.
• Roofs with a slight slope– up to 25°. Here you can already equip attic spaces, but without windows.
• Steep - those that have a slope of more than 40°. Steep ones allow you to arrange a good residential attic, which is never superfluous.
• Large is the roof slope that falls between 45-60°.
• But today the ideal roof slope angle is 38-45°.

So, the minimum angle of inclination of a corrugated roof is 8°. Here detailed video master class on how to build such roofs:

If you need to build a roof with an even smaller slope, then the profiled sheet should already be at the bottom of the roofing cake - like a ceiling. The design principle simply changes.

Pros and cons of a roof with a minimum slope

And now about what you will have to face during the construction of a minimum slope roof and what to expect from it in the future.

Advantages

Let's list the benefits first.

1. The main advantages of building such a roof:
2. Less material consumption.
3. Easier and safer roofing work.

No ridge or problems associated with its sealing.

Consider another point: the higher the ridge, i.e. The greater the angle of inclination of the roof, the heavier the roof itself will be. There will be more material available. And this is significant pressure on the house and foundation. In this case, the load will be insignificant.

Flaws And so we moved on to annoying disadvantages.

The minimum slope of the roof is bad because rainwater will drain much more slowly and will quickly find small cracks and joints to seep into the roofing pie. The threshold in this regard is considered to be an angle of 12°, at which it is still possible to do without additional sealing measures. Therefore, if you are building a flatter roof, the slope angle of which is less than 12°, the overlapping areas of the corrugated sheets will have to be sealed with special roofing sealants.

The chosen angle of inclination will determine what material you can use for the roof. So, for a flat roof and a roof with a slight slope, only durable load-bearing corrugated sheeting with high corrugation is suitable. But on roofs with a steep slope it is allowed to cover them with both a universal and a wall profile - because now the pressure on the sheets will be minimal. In other words, the same snow will easily slide off, and the water will not linger either.



Second point: material consumption will also increase, because The overlap of the sheets on each other will have to be made a little larger. So, if you are going to build a roof with an angle of 12° to 14°, you will need to increase the overlap of the sheets, but you can still do without sealant; if less, you will need both. This is why a slope of 15-30° is considered optimal for a corrugated roof. Here is a more detailed table of this data: Although to install steep roofs from corrugated sheets you will have to build quite long rafters, and more bars will be needed, but you will save a lot on roofing material. It will be possible to take corrugated sheeting that is cheaper, with a lower wave height, because now it load bearing capacity

will play a lesser role than with flat roofs

And finally, roofs with a slight angle of inclination require the construction of a much more complex rafter system that could withstand a lot of weight. The smaller the angle of inclination, the more additional support elements there are.

And now we will disappoint you a little: even after weighing all the advantages and disadvantages of a roof with a minimum angle, and giving our preference to the value of 8° as more suitable, it may not be possible to build just such an option. Or rather, it will not even be safe! Why? Read on!

Wind and snow loads

Determining the angle of inclination of a corrugated roof is actually influenced by many initial data. First of all, this is - climatic features the area where your house is located. Therefore, find out in advance what the usual depth of snow cover is on the winter days, how often it rains, how strong the wind is and what its predominant direction is:



After all, the slope of a roof made of a material such as corrugated sheets is calculated not for aesthetic reasons, but based on weather factors. Thus, the slope of the roofs of those houses that are located in areas with strong wind loads tends to a minimum value. In these areas, the so-called “roof windage” is dangerous. Have you heard or seen how powerful polycarbonate greenhouses, torn down by the wind, sometimes “walk” through the fields? But they were also not placed on the ground without fastening. And now imagine possible consequences, if part of your roof is already literally ripped off. Remember which one is the most main drawback corrugated sheets? "Sail"!

Here are the SNiP requirements in this regard. With an average wind load, the slope angle should be 35-45°, and with strong winds - 15-25°. In places where strong winds are the norm, make the roof angle made of corrugated sheets close to the minimum in order to minimize wind resistance. But almost flat roofs from this material there is a risk of being easily torn off, and therefore the complete lack of steepness in this case is also no better. Here is a rather impressive recording from a DVR, where the wind tears off a flat roof made of corrugated sheets:

Therefore, do not think that wind load is more harmless than snow load. In the Novgorod region, for example, the average value is 23 kg/m, where snow cover is about 75 kg/m.

Then shouldn't all roofs be flat? Not at all. In Russia, as everyone knows, there is snow up to the neck in winter. But snowflakes that seem so fragile at first glance actually weigh a lot. For example, in one unremarkable winter on flat roof so much snow can accumulate as if a whole company were standing closely on it. No rafters can withstand this, and therefore in areas with significant snow loads the roof slope has to be made up to 45° - so that the snow does not linger. Then there is no need to strengthen the rafters - precipitation on such a foundation will no longer be retained at all. After all, snow slides easily only from steep roofs.

Here's a map to help you find the parameters for your area:



Let's scare you: in Yakutsk, the snow load on the roof sometimes reaches 550 kg per square meter. And this is already half a ton! This is why the roofs of houses in this region are always so high and steep. But in southern countries They can even be covered with straw in a horizontal position.

Even a small layer of snow is much heavier in weight than you can even imagine. And, unlike rain, snow lingers on the roof, and in some regions of Russia its height on roofs sometimes exceeds more than a meter. And the worst thing in this regard is precisely the minimum slope.

Therefore, you need to make a decision about whether to make the roof angle of corrugated sheets so small.

How to calculate the angle of inclination yourself?

First of all, pay attention to what kind of roofs your neighbors have. We mean the place where you are going to build. Usually they have almost the same slope, the value of which has been hard-won over centuries and tested by hurricanes. And you can calculate the exact angle of inclination of the finished roof either using special graphs and matrices, or armed with a regular square.

Professional builders, for example, calculate the slope of a roof using a device such as an inclinometer, or using some geometric formulas. The result is written in degrees or ratio:



Or even simpler. As you probably remember from your school geometry course, the first thing you need to do is find out the length of the hypotenuse and leg. The hypotenuse is the straight line of the roof slope, and the distance from the ridge to the ceiling is the opposite leg. The distance from the middle of the ceiling to the eaves slope is the adjacent leg. Now let's use trigonometric function or arm ourselves engineering calculator:



The second no less common and reliable method: we determine the ratio between the height from the ridge to the ceiling and half the width of the ceiling. Divide the height by half the width of the building, and multiply by 100. Simple!

So decide what the slope of your roof will be based on four main factors:

1. Planned budget.
2. Estimated snow loads.
3. Average wind value.
4. The need for useful under-roof space.

And, if you finally come to the decision that you need a roof with a minimum angle, we will tell you how to avoid mistakes in construction and what you need to do.

Other important aspects of construction

Typically, minimum roof slopes with reinforced rafters are made in the roofs of those houses that are located in areas with frequent sunny days and little rainfall. To reduce heating of the interior, the roofing pie is provided with thermal insulation materials and a ventilated gap. Otherwise, all that remains to be taken care of is that no water gets into the house.

Leak protection

On flat roofs, when installing corrugated sheets, be sure to use sealing tapes and mastics for overlaps and joints of sheets. And such a roof is protected from leaks and damage by special membranes. waterproofing materials. Here is a standard pie of this design: corrugated board => rafters => insulation => waterproofing => sheathing.

There is still such a moment. If you are making a roof with a slope of less than 10°, use a modern three-layer membrane as waterproofing. Only this material can protect the roofing pie from moisture inside.

And finally, no matter how minimal the roof slope is, you will still have to build a drainage system for it. Moisture, like snow, lingers on such surfaces longer than many expect. Therefore, plan the slope so that it goes towards the water intake funnels, if the collection system is internal, or towards the gutters, if external.

Rafter system and sheathing

As in conventional projects, with a minimum slope, the corrugated sheeting is also laid on the sheathing and secured with self-tapping screws with rubber gaskets. But clamp the overlap, from 10 cm to 20 cm, with steel rivets. We recommend making an overlap of two waves.

There is such a dependence: the smaller the angle of inclination of the roof, the wider it is necessary to overlap the sheets. And the smaller the effective area of ​​the material:

• Within 15-30° of inclination, make an overlap of 15-20 cm.
• But when building a steeper roof, with an angle of 30°, the overlap should be from 10 to 15 cm.
• If the angle of inclination of the roof is already less than 14°, then the sheets must be laid horizontally with an overlap of 20 cm.
• At minimum angle 8° slope of the metal profile roof, the joints between the sheets must be made double, carefully sealing them with sealant so that water does not get inside.

The usual rafter system is installed in increments of 60 cm to 1 meter, but with a minimum roof slope it is better to reduce this increment to 40 cm. The base will be stronger and will more easily withstand the accumulation of snow on the roof.

Moreover, on slopes minimum value A ventilated gap is required between the rafter system and the corrugated sheeting - this is also a measure to reduce heat loss. More specifically: the smaller the angle of inclination, the wider you will have to make the gap for ventilation - and this is at least 50 mm.

Installation subtleties

Here is a detailed master class on how to install corrugated sheets on such a roof:



Follow the technology, follow our advice - and everything will work out!