The reliability of the building and the comfort of living in it depend on the quality of roof construction. Its design is selected optimal for local operating conditions. Special significance has such a parameter as the slope of the roof, which will be discussed further.

The angle of the roof slope depends not only on its design and the features of the facade of the house, on the selected roofing material, but also on other factors. It is necessary, first of all, to take into account the climatic conditions of the area where the building is being erected. Where the number of drops in winter time precipitation is high, a large roof angle is preferable (within 45-60 degrees): this contributes to better snow melting, which means reducing the load on the roof. It also becomes less likely that the surface of the floor will freeze due to compaction of the snow cover.

If a building is being erected where weather with strong winds prevails, it is advisable to choose a minimum roof slope angle to reduce the windage of the structure. Otherwise, the structure is in danger of rapid destruction. Most often the tilt range is in in this case– 9-20 degrees.

The greater the slope of the roof slope, the easier the snow cover comes off it.

But basically, the optimal roof slope angle is selected in average values, that is, from 20 to 45 degrees. It is suitable for almost any type of roofing material, for example, corrugated sheeting or metal tiles, which are very popular today.

In areas with a warm climate, where there are much more sunny days than cloudy ones, flat roofs will be more acceptable: their area is smaller than that of other types of structures, which means heating from sun rays will occur to a lesser extent. But such a structure should not be absolutely horizontal: the slope of a flat roof should be at least within 3-5 degrees. The minimum slope of the flat roof will ensure normal drainage of rain and melt moisture.

Types of roofing structures

Utility and utility buildings are often built with a pitched roof: it is easy to install and does not require large expenses. In fact, such a building has walls of different heights with a ceiling laid on them. The slope of the ceiling is selected within the range of 9-25 degrees, which is well suited for corrugated sheets and metal tiles. This design requires ventilation of the under-roof space.

But the most popular is the gable one: two planes located at an angle are connected along the line of the ridge. Other (end) planes are vertical and are called pediments. They may have doors to access a balcony or external staircase.

There are many options for roofing structures

Hip ceilings, the most popular representatives of which are hipped ones, are aesthetically very attractive. In such cases, especially in more complex structures, the slopes can be any: it depends on the chosen design and personal preferences of the developers. The advantage of hip roofs is that there are no restrictions on the use of roofing material.

Option hip design– attic: the attic space is used as a living space, so the requirements for insulation are very high. Free space under the ceiling is formed due to the high angle of inclination of all slopes, in which the presence of dormer windows should be provided.

Dependence of roof structure on floor material

Before choosing a roofing material, you should study it technical specifications: this will help you optimally approach the issue and choose the most reliable one. In addition, there is a rule that determines the dependence of the slope angle on the roofing material used.

We list the main ones:

When choosing the slope value, you should take into account the strength characteristics of the roofing structure: the safety margin should be enough not only to withstand its own weight and the weight of the roofing material, but also for external loads (gusts of wind, snow). Also, the type of sheathing for laying most materials also depends on the slope of the slope: for small values ​​of this parameter, either a continuous sheathing is installed or with a small pitch (350-450 mm). When erecting any roof, especially a flat one, it is necessary to install a system of slopes and drainage. If the area is particularly large, additional drainage will be required.

Calculation of the angle of inclination

The design must meet the following requirements: be strong enough, provide reliable protection from precipitation, and have good thermal and sound insulation. It is also important that there is access for repairs and maintenance. How to calculate the angle of the roof so that all these conditions are met? Experts recommend using simple options its devices, which include single-pitch, gable, hip (and half-hip), and attic.

Roofs can have a design of any complexity, with different angles slope

Single-pitch ones are most convenient for verandas, extensions and utility buildings. The principle of creating a lean-to roof is the same as other types: rafters and sheathing are installed, after which the roofing material is laid. The latter plays a decisive role: for corrugated sheeting an angle of 8-11 degrees is required (it is better to do 20), for metal tiles - at least 25, for slate and seam roofing - 35 degrees.

If climatic conditions allow, it is better to make a roof with a slope of 45 degrees: this will allow you to neglect calculations related to the mass of snow. It's practically perfect pitched roof: the angle of inclination will not complicate its installation and will facilitate maintenance (snow will not accumulate on its surface). But in this case, it will be necessary to strengthen the rafters and sheathing, since the wind pressure on the structure increases 5 times. It should also be taken into account that this will require high costs for materials - approximately 1.5 times.

Roofing material must be selected depending on the roof slope

As can be seen from the graph, each slope corresponds to a certain group of roofing waterproofing materials. There are 11 of them in total, with the inclined lines corresponding to the angle of inclination of the slope. The thick line indicates how the height of the ridge relates to ½ of its depth. It can be seen that the segment h is equal to half of the horizontal segment, designated by the fraction ½. The numbers at the tops of the semicircular scales correspond to the angle of inclination (in degrees), the vertical scale also indicates in percentage. When choosing any roof configuration, you should adhere to these recommendations and purchase roofing materials suitable for your chosen option.

In order to make it clear how the roof slope angle is calculated, we will give an example of calculating the smallest slope angle of a roof with tile waterproofing. On the graph we find a semicircular curve corresponding to a given coverage: this will be the curve indicated by the number 2. Tracing it to the point of intersection with the vertical scale, we find that minimum slope such a roof is equal to 50%.

Taking into account the fact that the slope of the slope is the ratio of the height of the ridge to ½ of its depth, we calculate the slope. That is, with a ridge height h = 4 m and a slope equal to L = 15 m, the slope will be determined as h: (L/2) = 4: (15/2) = 0.53. To display it as a percentage, multiply the result by 100 and get 53%. This value of this parameter guarantees good drainage of rainwater. The minimum slope in the valley is 1%.

Features of calculating a gable roof

Gable roof is the most successful and widespread design. There are several reasons for this: high reliability, relative simplicity, low cost design. When constructing a roof, not everyone correctly chooses the optimal angle of inclination of a gable roof.

In areas of strong winds, it is necessary to calculate the gable roof so that its slope does not cause too strong wind loads. The greater the angle of inclination of the structure, the higher its windage.

You cannot reduce it to values ​​less than 25 degrees: precipitation will be less easily removed from the roof, and dampness may appear in the under-roof space. Making it larger than 60 degrees is also not recommended: a strong impulse of faith can destroy the roof. The roof does not have to have symmetrical slopes: if you orient the building with a more gentle slope to the south, the roof will dry better after rain.

Conditions for using roofing materials depending on the slope angle

Useful attic area and drainage system

The usable area of ​​the attic space depends on the roof structure: the greater the slope angle, the larger the area and vice versa (this is clearly shown in Figure 2). When constructing an attic, you have to make a compromise between the area that can be easily used, the cost of building a roof and the strength of the structure.

The method of removing precipitation can also be different. There are external or internal organized and unorganized - only external. The latter involves installation drainpipes and gutters, while wall and suspended systems are mounted on roofs with a slope greater than 15%. The gutters are attached with a minimum slope of 3 degrees, their sides are made with a height of about 120 mm.

The usable area of ​​the attic depends on the angle of the roof.

The distance between the pipes should be no more than 23 m. The cross-section of the pipe should ensure normal drainage of water and is selected depending on the area of ​​the slope. External drains of an organized type are more suitable for areas with a warm climate. Internal gutters are used for cold climates. Such systems consist of a funnel for receiving water, a riser, an outlet and a discharge pipe. The main condition is that water drainage must be ensured at any air temperature.

Installing a roof is a very important task that requires the participation of highly qualified workers. Installation errors can cost home owners dearly. To avoid troubles, roofing work should be entrusted to specialists with sufficient experience: this will guarantee the reliability of the building and the comfort in it.

A properly equipped roof is the key to the reliability and comfort of the entire building. Of particular importance is the slope angle of the roof slopes, the calculation of which is carried out at the design stage. Let's look at how to determine the angle of a roof in degrees without resorting to complex calculations and bulky instruments.

The influence of various factors on the choice of inclination angle

The degree of roof slope is influenced by the design of the entire house. In addition, it also depends on the roofing material. The climatic conditions of a given region are also of some importance. For example, if construction is carried out in an area with frequent rain and snowfall, the minimum roof slope is recommended as 45-60 degrees. In this way, the load of snow cover on the roof structure is reduced: snow masses simply cannot accumulate there, sliding down under their own weight.

If the area is characterized by strong winds, then the best option in this case would be a low-slope roof with a low windage. Usually we are talking about angles of 9-20 degrees. As for the universal indicator, it is somewhere between the two indicated parameters, and corresponds to 20-45 degrees. This slope angle allows for a wide selection of roofing materials.

What types of roofing are there?

Outbuildings and ancillary buildings are most often equipped with a pitched roof. It does not carry any special design originality, captivating with its cheapness and speed of installation. All that is required is to build two walls of different heights and cover them with a roof. The slope angle of such structures is generally in the range of 9-25 degrees, and corrugated sheeting is often used for covering. Since there is no attic here, a minimal roof slope can be selected. However, do not forget about the need for ventilation under the roof space.

The most popular gable roofs, consisting of a pair of planes (slopes) connected along one line. Pediments (ends of the structure) can be decorated with doors to enter the attic or carry out repairs. Ventilation holes (vents) may also be located there. Currently, hip roofs are gaining popularity because they have significant aesthetic potential. Roof slope indicators here can be very diverse: it all depends on personal taste and the chosen project.

More often than others, a four-slope type of hip structure is used, where two slopes have a triangular shape. When constructing hip roofs, the use of almost any roofing material is allowed. Although we have to deal with a highly complex structure, the effort spent is more than repaid in beauty and effectiveness.

The mansard roof is a complicated version of the hip roof: in this case, the goal is to create optimal conditions for use attic space for furnishing a living room. This involves carrying out work on reliable insulation and vapor barrier. Attic room is formed by a system of broken slopes, with quite significant angles of inclination. Most often there are dormer windows, carrying both practical and aesthetic functions. IN mandatory the space is insolated.

Climatic factor

When choosing the optimal slope angle, you need to take into account the climatic features of the area. If the region experiences frequent strong winds, then it is best to use a roof with a slight slope. If this is not done, then due to the increased windage, the structure may be damaged and even collapse. As for the possibility of strengthening a roof with steep slopes, this is usually accompanied by significant financial investments.

If the region experiences heavy snowfall, a roof with a low slope will not be effective. The slope of the slopes should be increased, which will ensure that the snow masses quickly slide down under its own weight. In this way, it is possible to avoid a significant increase in loads on the roof structure.

For areas with abundant sunny periods, a minimum slope of slate roofing is recommended, which will minimize the heated surface. Often in such cases, to protect against overheating, dark roll materials a layer of gravel is poured onto the flat slopes. It is best for such a roof to choose a slope angle of no more than 5 degrees, carefully positioning the drainage holes.

Minimum slope for some roofing materials

When choosing a roofing material, you should carefully read it performance characteristics and recommendations for use.

• Piece materials (slate, tiles). Minimum slope slate roofing- 22 degrees. In this case, moisture will not be able to accumulate in the joint area, which threatens subsequent seepage inside.
• Roll materials. Here great value has the number of laying layers. If three layers are used, the slope is selected within 2-5 degrees. Two-layer installation will require an increase in angle to 15 degrees.
• Profiled sheeting. Slope metal roofing should be no less than 12 degrees. Small angles require additional sealing of the joining areas.
• Metal tiles. The slope of the slopes is at least 14 degrees.
• Ondulin. From 6 degrees.
• Soft tiles. From 11 degrees, in which case the installation of a continuous sheathing is mandatory.
• Membranes. A universal coating used on a wide variety of roofs. The minimum roof slope is 2 degrees.

When determining what the minimum roof slope should be, the load-bearing capacity of the roof structure should be taken into account. It is important that it can effectively withstand all external loads characteristic of a given region. There are permanent (weight of the roof and its equipment) and temporary (atmospheric influences) loads.

The slope angle has a direct impact on the construction of the sheathing. It is recommended to equip minimally inclined slopes with continuous sheathing, or use a pitch of 350-450 mm. In addition, a flat roof will require additional time to arrange water drainage from its surface. For these purposes, a slope system is used. On large rooftops, an emergency water drainage system is often installed in case water flows exceed the capacity of the main drains.

Since roofing materials are quite expensive, you need to choose them very carefully, taking into account all the advantages and disadvantages. It is important to choose the most optimal coating for your home from the variety of options available for sale. The process of constructing a roof should also be organized as responsibly as possible, since even minimal errors in the process of calculating the angle of inclination can have the most disastrous consequences. It's good if you can get away with it minor repairs or rework. It often happens that an incorrectly designed roof undergoes significant damage and destruction during strong winds or snow. This can lead not only to serious financial losses, but also to injuries to the people living in such a house.

Example of roof slope calculation

When starting to calculate the slope of roof slopes, you should carefully study the climatic features of the area where you plan to build a house. When collecting information, you can turn to the experience of your neighbors, taking into account their constructive research. The more precipitation there is in the region, the larger the slope angle is; the stronger the winds, the smaller. If we talk about economic considerations, the lowest material consumption is observed when constructing roofs with a slope of 10-60 degrees.

To determine the height of the roof ridge and the location of the rafters, use either a square or a special calculation formula. Here, a value equal to half the span width should be multiplied by a special coefficient. For example, if a house has a width of 10 m and the angle of inclination of its roof is 25 degrees, to calculate the height of the rafters, half the width (5) is multiplied by the corresponding coefficient (0.47). The result is 2.35: this is the recommended height for raising the rafters. The list of coefficients, depending on the angle of inclination, is contained in special literature.

The ancient saying “measure twice, cut once” is also quite true for roofing. Of particular importance is the correct calculation of the slope of its slopes. If the angle of the roof is calculated incorrectly, the consequences can be dire. The most common defect is roof leakage at joints. individual elements styling This usually happens during heavy rain and spring melting of snow accumulated on the roof. More serious consequences of errors in calculating the angle of inclination are damage or destruction of the roof under the influence of wind or snow load.

If you decide to build a house on your own, but you are not confident in making calculations for organizing the roof, it is best to turn to experienced specialists who can draw up an optimal project. In the future construction work can be done independently using accurate calculations.

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 is left in the attic, whether there will 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 sheets, 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 roofing pie- 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. The main advantages of building such a roof:

1. Less material consumption.
2. Easier and safer roofing work.
3. 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 roof slope 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 it will take more bars, but you will save a lot on roofing material. It will be possible to use corrugated sheeting that is cheaper, with a lower wave height, because now its load-bearing capacity will play a smaller role than with flat roofs

In addition, if the angle of inclination is insufficient, it is impossible to equip a residential attic, which reduces the heat loss of the house through the roof by up to 9%.

And finally, roofs with a small angle of inclination require much more complex construction. rafter system that could withstand heavy 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, these are the climatic features of 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 sometimes powerful ones torn off by the wind “walk” through the fields? polycarbonate greenhouses? 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. Do you remember what the main disadvantage of corrugated sheeting is? "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 made of this material run the 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 Novgorod region For example, the average value is 23 kg/m, where snow 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, so much snow can accumulate on a flat roof 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 it trigonometric function or arm yourself with an engineering calculator:

The second one is no less common and is like this the right way: 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 heat interior spaces, in the roofing pie provide 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 membrane 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.
• With a minimum angle of inclination of a metal profile roof of 8°, the joints between the sheets must be made double, carefully sealing them with sealant to prevent water from getting 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.

In addition, with minimum slopes between the rafter system and the corrugated sheeting, a ventilated gap is required - 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 detailed master class How to install corrugated sheeting on such a roof:

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

In civil low-rise construction, experienced builders call the most common, rational and economically feasible type of roof pitched structures. They can consist of one, two, three or even four slopes, planes that meet at one point, called the ridge. From flat roofs pitched roofs are distinguished by an angle of inclination, which, according to building codes, must exceed 2.5 degrees. Slope selection – important stage creating a project on which the strength, load-bearing capacity and durability of the structure depend. In this article we will tell you how to choose the right angle of inclination to make it easier for snow to melt in winter period.

The angle of inclination of the roof is a parameter for the engineering calculation of roofing structures, reflecting the ratio of the height of the ridge to the width of the base of the slope. Pitched roofs can have a slope of 2.5-80 degrees, however, the optimal range of slope angles is 20-450. The area of ​​the slopes, wind resistance and snow load depend on this parameter. The following terms are found in the specialized literature:

• Minimum slope. The minimum tilt angle in general is 2.5 degrees, but depending on the waterproofing material used, this parameter may increase. The minimum angle for roll bitumen and membrane coatings is the smallest; it is 2-4 degrees. The minimum permissible value for metal tiles and corrugated sheets is 11-12 0, for ceramic tiles - 22 0.
• Optimal. Optimal is the most suitable roof slope in given climatic conditions when using a certain waterproofing material. The optimal angle of inclination ensures that snow melts off independently, making roof maintenance easier.

Important! The slope of a roof can be expressed as degrees, as a percentage, or as an aspect ratio. To calculate this parameter of the roof structure, it is necessary to divide half the width of the facade by the height, and then multiply by 100 percent.

Selection criteria

The choice of slope is based on an engineering calculation that takes into account the climatic conditions of the area where construction is taking place, the characteristics of the roof covering and the load-bearing capacity of the rafter frame. To ensure a reliable design, the following criteria must be taken into account:

1. Wind load. The steeper the roof, the stronger its sailing ability. Therefore, in regions with strong, gusty winds, flatter roofing structures are preferable. Although, on the other hand, the wind can tear off waterproofing material from low-slope slopes.
2. Snow load. The greater the snow load, the more covered the slopes become. A roof inclination angle of 40-45 degrees ensures that snow will melt off the surface of the roofing material on its own.
3. Characteristics finishing coating. Each roofing covering has optimal slope, which must be taken into account when designing the structure.
4. Bearing capacity of the frame. The smaller the cross-section of the frame elements and the greater the distance between them, the higher the slope must be to withstand the snow load.

Optimal indicator for facilitating snow melting

The limiting factor when choosing the angle of inclination of roof slopes is middle lane Russia is characterized by a high snow load, characteristic of this area. Large quantity Snow falling in winter increases pressure on the rafter system, leading to deformations of the frame and roofing material of the structure. Experienced craftsmen believe that there is a strong correlation between slope and resistance to snow load:

1. If it is less than 30 degrees, then snow accumulates on the surface of the slopes. Snow drifts and ice have a significant mass, due to which the load on the rafter frame increases, reaching critical levels. However, some of the snow is blown away from the surface by the wind. If the angle of the roof is in this range, then snow guards are not installed on it, especially if the roofing material has a rough surface.
2. At a value of 0 degrees (i.e. for flat roofs), the snow load on the surface reaches its maximum values. Snow on such structures accumulates into large drifts, which lead to the collapse of the frame if the roof is not periodically cleaned.
3. If the roof is 45 degrees or higher, then in calculating the load on the rafter frame the weight of the snow can be neglected, since the snow slides off the slopes on its own without stopping on the slope. To ensure safe operation of a roof with a large angle of inclination, snow cutters are installed on it, cutting the layer of snow as it descends into thinner plates that have a lower speed and fall energy.

Please note! According to construction climatology, the territory of Russia is divided into 8 climatic zones, each of which has its own average annual snow load. This reference value is used to calculate the roof slope, the cross-sectional thickness of the rafter frame elements and the selection of roofing covering.

Impact on design

It is important that changing the slope to facilitate snow melting greatly affects the roof structure as a whole. An increase in slope has the following consequences:

• Increase in weight of the roofing pie. Weight 1 square meter a roofing pie with a slope of 50 degrees is 2-2.5 times higher than a roof with a slope of 2 degrees.
• Increasing the area of ​​the slopes. The steeper the roof, the larger area its slopes, the greater the consumption, and, consequently, the cost of the roofing material.
• Lightening the rafter frame. In the absence of a snow load, you can lighten the roof frame to save on wood.
• Inability to use roll materials. If the roof slope exceeds 40 degrees, it is not recommended to use bitumen and membrane roll materials, as they are subject to high temperature they can simply “slide” down.

Experienced craftsmen note that right choice helps to increase the service life of roofing structures, facilitate the operation and maintenance of the roof in snowy conditions Russian winters. Errors in the design associated with the incorrect choice of the optimal angle lead to deformation of the rafters, collapse of the sheathing, and the pouring of atmospheric moisture into the joint space during slanting rain or during thaws.

Video instructions

The reliability of any building, as well as the comfort of living in it, depend mainly on how well its roof is constructed.

And one of the criteria for the quality of a roof is its slope.

Since the amount of roofing material depends on its size, the choice of the angle of inclination and its preliminary calculations are carried out before the purchase of the selected roofing material begins.

What affects it

Depending on the slope of the roof slopes, the features of its operation depend.

It is customary to distinguish 4 types of roofs:

• high, with an angle of 45-60 degrees;
• pitched, with a slope of 30 to 45 degrees;
• flat, the slope angle is 10-30 degrees;
• flat. Slope of 10 degrees or less.

The choice of the value of this parameter is influenced, first of all, by natural factors that are characteristic of a given area.

Strong winds place the greatest pressure on high roofs.

Because such roofs, due to the large angle of inclination, have a very large area.

A large surface area has a very high windage.

Accordingly, the load on the entire structure of the rafter system is very high.

And if you decide to install a high roof with a very large slope, then you should take care of a very solid foundation.

However, in areas where strong winds prevail, it is unsafe to install flat roofs.

With this type of roof bottom part the stingray will turn out to be high blood pressure in strong winds.

And if the roof fastening is weakened, the entire structure may fail.

Therefore, in areas where strong winds often occur, it is recommended to arrange pitched roofs with an inclination of 25 - 30 degrees.

If the wind force is small, then the roof slope can be 30-45 degrees.

If in the area where the house is being built there is heavy snowfall during the cold season, then the roof should be built with a large slope angle.

In this case, the high roof is beyond competition.

On roofs with a large slope, snow does not linger.

It is for this reason that in all northern countries the roofs on buildings are very high (Sweden, Finland, Norway, etc.).

The smaller the roof slope, the longer the fallen snow will remain on the slopes.

The more weight will affect the entire structure.

If the design of the rafter system is made with a large margin of safety, then a certain layer of snow on the roof is not bad.

It provides a little extra insulation.

However, if the design of the structure's rafter system is not designed for heavy loads, then big problems can arise.

We choose the slope depending on the roofing material used

Gone are the days when only two types of roofing materials were used for roofing: tiles and slate.

Today there are a huge number of roofing materials!

Each material has its own individual technical characteristics and this should be taken into account when calculating the required inclination angle.

After all, it may happen that the material you like is simply not suitable according to its parameters.

Minimum tilt angle

There is a concept of a minimum value for this parameter.

This parameter is different for each material.

And if the angle of inclination obtained as a result of your calculations turns out to be less than the minimum value for the roofing material you have chosen, then you cannot use it for roofing.

A lot of problems can arise in the future if you break this rule:

• for any piece of inlaid roofing materials, such as tiles or slate, the minimum slope is 22 degrees. It is with this value that moisture does not accumulate at the joints and moisture does not leak into the roof;
• The angle of inclination for rolled materials (roofing felt, bicrost, etc.) depends on the number of layers you plan to lay. If there are three layers, then the slope can be 2-5 degrees. If there are two layers, then it needs to be increased to 15 degrees;
• Manufacturers of corrugated sheets recommend setting a slope angle of 12 degrees when installing a roof from this material. Corrugated sheeting can be used at lower values, but in this case it is necessary to glue the joints of the sheets with a sealant;
• For metal tiles the value of this parameter is 14;
• for ondulin it is a value of 6 degrees;
• minimum slope for soft tiles equals 11 degrees. But at the same time prerequisite- continuous sheathing;
• for membrane roofing coverings There are no strict requirements for the minimum value of this parameter.

This is about minimum values.

I'll give you some advice - stick to these rules.

So that in the middle of winter you don’t have to re-cover the entire roof.

Now about the optimal values

If rain and snow occur frequently in the region, then the optimal roof would be one whose slope angle would be 45 - 60 degrees.

After all, it is necessary to remove the load from water and snow from the roof as soon as possible.

Because the strength of the rafter system is not unlimited.

And thanks to the large slope of the roof, rain and snow will melt away as quickly as possible.

If there are constantly strong winds in the region where the house is built, then the roof is dealt with differently.

With a smaller inclination, its windage decreases.

And there are no excessive loads on the roofing material and rafters.

Also, the roof will not be torn off during sudden gusts of wind.

In this case, the optimal roof slope angle is 9 - 20 degrees.

Very often there is both snow and wind in the region.

For example, Orenburg region.

In this case, choose the average value of the inclination angle.

As a rule, its value is in the range of 20 - 45 degrees.

If you notice, most pitched roofs have exactly this meaning.

We calculate its value

For a single slope

Since a pitched roof rests on walls that have different heights, then the formation of a given angle of inclination is carried out by simply raising one of the walls.

We draw a perpendicular L d along the wall, originating at the point where the short wall ends and resting on the wall that has the maximum length.

The result is a right triangle.

If the length of the wall L сд is equal to 10 meters, then to obtain a slope angle of 45 degrees, the length of the wall L bc should be equal to 14.08 meters.

For gable

Calculation principle for gable roof similar to the previous principle.

Let's look at an example

Leg C is half the width of the building.

Leg a is the height from the ceiling to the ridge.

The hypotenuse is the length of the slope.

If we know any two parameters, then the angle of inclination can be easily calculated using a calculator.

If the width is 8 and the height is 10 meters, then you should use the formula:

cos A = c+b

Width c = 8/2 = 4 meters.

As a result, the formula looks like this:

cos A = 4/10 = 0.4

Using the Bradis tables, we find the value of the angle to which a given cosine value corresponds.

It is equal to 66 degrees.

For hipped

And again you can’t do without roulette and Bradis tables.

Knowing several parameters, you can easily calculate others.

Including the angle of inclination of the hipped roof.

It should be remembered that all dimensions must be taken as accurately as possible.

A special tool, an inclinometer, will help you measure the slope of an already constructed roof.

After all, if you make a mistake, then the angles of inclination, length and area may not be correct.

This means that you will make a mistake in the amount of material required or the strength of the roof will be lower than planned.

Watch a video about the slope of the ramps.

Sergey Novozhilov - expert on roofing materials with 9 years experience practical work in the field of engineering solutions in construction.