Minimum roof slope. The angle of the roof is the optimal slope and snow loads. The relationship between degrees and percentages in roof slope

In everything globe there are thousands and thousands of architectural traditions in terms of appearance roofs But modern architects completely changed the idea of ​​culture suburban construction by entering single-pitched forms roofs 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 with architecture residential buildings everything that fantasy dictates.

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, main parameter functionality - one tilt angle 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 weight. roofing, which are always located on the roof, installations such as antennas and dishes, 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 likes 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's why owners of lean-to outbuildings In winter they often take up a shovel. 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, build roofs with steep slopes not possible at all. For comparison: a pitched roof slope of 11° is experienced exactly 5 times more force wind 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 must be able to withstand rafter system. 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 such a building rises big roof at home, 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 of the interior is 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 thawed and rainwater could not penetrate the rafter system. Therefore, roofing coverings such as membranes are already needed here, roll insulation or whole sheets.

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:

Moreover, at a certain angle pitched roof directs the air flow in the desired direction, capturing precipitation and removing 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 one has one 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 frequently open wide doors(as in the case of a garage) and 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 design 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 one more interesting point: many architects specifically calculate the angle pitched roof so that he was equal to angle the elevation 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 ones also have their own requirements for the minimum and maximum angle of inclination of a pitched roof. roofing materials:

• 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 is already pressing 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. This metal elements, which 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

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

Method number 2. Trigometric

Another option for calculating the length of the rafter legs is 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 required values, and you will receive 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!

The slope of the roof slopes - what it depends on and how it is measured.

Such an important fact for the roof is its slope. Roof slope- this is the angle of inclination of the roof relative to the horizontal level. According to the angle of inclination of roof slopes there are low slope(sloping), average inclination And roofs with steep(highly inclined) stingrays.

Low slope roof that roof, the installation of which is carried out based on the smallest recommended angle of inclination of the slopes. So, each roofing has its own recommended minimum slope.

What does the slope of the roof depend on?

• The ability of the roof to protect the building from external factors and impacts.
• From the wind- the greater the roof slope, the more value incident wind loads. With steep slopes, wind resistance decreases and windage increases. In regions and places with strong winds It is recommended to use a minimum roof slope to reduce the load on bearing structures roofs.
• From roofing covering (material) - For each roofing material there is a minimum angle of inclination at which this material can be used.
• From architectural ideas, solutions, local traditions- so in different regions preference is given for one or another roof structure.
• From precipitation: snow loads and rainfall in the region. On roofs with a large slope, snow, dirt and leaves will not accumulate in large quantities.

What is the roof pitch angle measured in?

The designation of the roof slope on the drawings can be either in degrees or as a percentage. The roof slope is indicated by the Latin letter i.

In SNiP II-26-76, this value is indicated as a percentage (%). IN this moment does not exist strict rules by designating the size of the roof slope.

The unit of measurement for roof slope is degrees or percentages (%). Their ratios are shown in the table below.

Roof slope degree-percentage ratio

degrees	%		degrees	%		degrees	%
1°	1,75%		16°	28,68%		31°	60,09%
2°	3,50%		17°	30,58%		32°	62,48%
3°	5,24%		18°	32,50%		33°	64,93%
4°	7,00%		19°	34,43%		34°	67,45%
5°	8,75%		20°	36,39%		35°	70,01%
6°	10,51%		21°	38,38%		36°	72,65%
7°	12,28%		22°	40,40%		37°	75,35%
8°	14,05%		23°	42,45%		38°	78,13%
9°	15,84%		24°	44,52%		39°	80,98%
10°	17,64%		25°	46,64%		40°	83,90%
11°	19,44%		26°	48,78%		41°	86,92%
12°	21,25%		27°	50,95%		42°	90,04%
13°	23,09%		28°	53,18%		43°	93,25%
14°	24,94%		29°	55,42%		44°	96,58%
15°	26,80%		30°	57,73%		45°	100%

You can convert the slope from percent to degrees and vice versa from degrees to percent using an online converter:

Roof slope measurement

The slope angle is measured using an inclinometer or mathematically.

Inclinometer- this is a rail with a frame, between the slats of which there is an axis, a division scale and to which the pendulum is attached. When the staff is in a horizontal position, the scale shows zero degrees. To measure the slope of the roof slope, the inclinometer rod is held perpendicular to the ridge, that is, at a vertical level. On the inclinometer scale, the pendulum indicates the slope of a given roof slope in degrees. This method of measuring slope has become less relevant, since now various geodetic instruments have appeared for measuring slopes, as well as drip and electronic levels with inclinometers.

Mathematical calculation of slope

• Vertical height (H) from the top point of the slope (usually the ridge) to the level of the bottom (eaves)
• Laying ( L ) - horizontal distance from the bottom point of the slope to the top

Using mathematical calculation, the roof slope is found as follows:

Slope angle i equal to the ratio roof height H to laying L

i = Н : L

In order to express the value of the slope as a percentage, this ratio is multiplied by 100. Next, to find out the value of the slope in degrees, we translate using the table of ratios located above.

To make it clearer, let's look at an example:

Let it be:

Laying length 4.5 m, roof height 2.0 m.

The slope is: i = 2.0: 4.5 = 0.44 now multiply by × 100 = 44%. We translate this value according to the table into degrees and get - 24°.

Minimum slope for roofing materials (coatings)

Roof type	Minimum roof slope
	in degrees	V %	in the ratio of the height of the slope to the foundation
Roll roofs bituminous materials: 3 and 4 layers (fused roofing)	0-3°	up to 5%	until 1:20
Roofs made of rolled bitumen materials: 2-layer (fused roofing)	from	15
Seam roofing	from 4°
Ondulin	5°		1:11
Wavy asbestos cement sheets(slate)	9°	16	1:6
Ceramic tiles	11°		1:6
Bituminous shingles	11°		1:5
Metal tiles	14°
Cement-sand tiles	34°	67%
Wooden roof	39°	80%	1:1.125

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 in cross section isosceles triangle, and different, having different angles of inclination and area.

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

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, facilitating maximum period roof services.

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

During its service life, the roof is constantly experiences stress 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- weight roofing pie and the roofs themselves, 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 be combated only by 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.

Choice correct angle tilting 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,.

the angle of inclination of the slopes should be minimal

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

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 the percentages are obtained from the ratio of the height of the ridge above the ceiling top 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 load-bearing elements, and calculation required quantity material.

How to measure an angle gable roof

Minimum slope angle of a gable roof

It is necessary to immediately determine the correct understanding of the term “minimal”. This means the least permissible value 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.

Considering these circumstances, the minimum angle can be defined as smallest value, declared 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

Any house is crowned with a roof - one of the main structures of the building that protects it interior spaces from rain and snow. One of the main criteria for any roof is the steepness of the slopes. Since flat roofs are mainly common only in multi-storey residential and industrial construction, this issue is especially relevant for owners of private houses and cottages.

The amount of roofing material depends on the slope of the roof, so the choice of the slope angle and its preliminary calculations should be done before purchasing roofing material.

Let's consider how to determine the angle of inclination of a pitched roof and its connection with the design of the entire roofing structure.

In this article

What determines the steepness of a roof?

The angle of the roof directly affects its performance characteristics. In construction, there are 4 types of roofing structures:

• Steep with a slope of 45-60°;
• Sloping – 30-45°;
• Flat – 10-30°;
• Flat with a slope of less than 10°.

Determining this value depends on a number of factors:

• Exposure to wind. The wind exerts the greatest pressure on steep roofs, since they have the greatest windage due to their large area surfaces. When settling in similar design important Special attention pay attention to the strength of the rafter system.

In areas with high wind loads, it is also dangerous to install flat and flat roofs: if the structure is weakly fastened, it may collapse. Thus, in areas with strong winds, the recommended roof pitch is in the range of 25-30°.

In areas where a significant amount of snow falls during the cold season, a steep roof, on the contrary, has advantages. Snow does not accumulate on it. At a lower angle, the snow will lie on the roof longer, creating additional load on the rafter system.

It is not necessary to arrange steep roof: a certain amount of snow lingering on the roof in winter period, It has useful property keep warm. However, it is important to calculate the load exerted by the snow cap on the structure in order to prevent it from collapsing.

• Roofing material. Each type of roof has its own limitations on the angle of inclination of the slopes. If you plan to use a specific roofing material, then it is important at the design stage to correlate the desired slope of the roof with its technical characteristics.
• Attic size. The angle of the roof directly affects the size of the room below it. The steeper the roof and the higher the ridge, the more spacious the attic and vice versa. When planning a room under the roof, we must not forget about the risks inevitably associated with a steep structure and its high cost compared to the construction of flatter roofs. A broken type can come to the rescue in this situation, which allows you to save the maximum volume for arranging the room, saving on the height of the ridge.

Minimum tilt angle

Such a concept as the minimum angle of roof inclination is related to the roofing material used. All roofs are provided with technical specifications, which, among other things, clearly indicate the slope limits for use. These rules cannot be violated, since in this case the roofing material will not retain its original functions and advantages.

Let's consider the main roofing coverings and the minimum angles for them:

• Piece roofing materials (slate, tiles) are laid on roofs with a slope of 22°. This indicator is due to the fact that in this case water does not accumulate at the joints of the roofing elements and, accordingly, cannot seep under them;
• When working with rolled materials such as roofing felt, it is important to determine in advance the number of layers. If you plan to lay 2 layers, then the roof angle should be at least 15°; when laying 3 layers, this value can be reduced to 2-5°;
• The corrugated sheet is installed at a slope of 12°. A lower value will require treating all joints with sealant;
• Metal tiles spread at a value of 14°;
• Ondulin – from 6°;
• Soft tiles can be laid on a roof with a slope of 11° if there is a continuous sheathing;
• Membrane roofing materials are the only ones for which there is no minimum threshold. They can be successfully used on flat roofs Oh.

Following the above rules is extremely important, since even a slight violation of them will result in the destruction of the roof and, possibly, damage to the rafter system.

Calculation of the angle of inclination

In addition to the minimum angle, there is such a thing as optimal angle tilt With it, the roof is subjected to the minimum possible loads from wind, snow, etc. Let us give examples of such optimal values:

• In areas with frequent precipitation in the form of rain and snow, it is optimal to build a roof with a slope of 45-60°, as it gets rid of precipitation faster, which minimizes the load on the rafter system;
• If the roof is being erected in a windy region, then it would be good to place its angle of inclination in the range of 9-20°. It will not play the role of a sail, catching the passing wind, but it will not capsize due to its sharp gusts;
• In areas where both wind and snow occur regularly, average values ​​of 20-45° are used. This range can be called universal for pitched structures.

Independently calculating the angle of the slopes comes down to a simple geometric process, which is based on a triangle. Its legs are the height of the ridge and half the width of the house, the hypotenuse is one of the slopes. And the angle between the hypotenuse and the leg is the desired value of steepness.

The angle of the roof is directly related to the height of the ridge. There are two options for calculating these values:

• Known roof height. If you want to arrange a spacious area under the roof living room with an acceptable ceiling height, the ridge height can be determined in advance. Having known two legs, it is easy to find out the size of the desired angle.

Let us accept the following notation:

• H – ridge height;
• L – width of half of the house;
• α is the desired angle.

Find the tangent of the desired angle using the formula:

tg α =H/L

We find out the magnitude of the angle from the obtained value from a specialized table of tangents.

• Pre-determined inclination angle. If you want to use a certain roofing material or due to weather conditions in the region, the roof slope can be determined in advance. Based on its value, you can determine the height of the ridge of the house and check whether it is possible to create a living room under this roof. To arrange the premises, the height of the ridge must be at least 2.5 m.

We leave symbols from the previous example and substitute the known quantities into the following equation:

H = L * tan α

Thus, the process of calculating the angle of inclination is much simpler and faster than analyzing all the populations to determine it optimal value for a specific region and building.

Due to the fact that the pitched roof rests on walls that have different heights, then the calculation of the given angle of inclination is carried out by simply raising one of the walls of the house.

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

If the length of the wall of the house L сд is equal to 10 meters, then in order to obtain an angle of inclination of 45 degrees, the length of the wall L bc should be equal to 14.08 meters.

Conclusion

In roof design, finding the optimal angle of inclination has important. This parameter depends on the correct estimate weather conditions, choice of roofing material, desire to create a living space. Its correct definition is the key to long and successful roof service in all weather conditions.

The content of the article

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

What affects the slope of a roof slope?

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

Low-slope roofing is performed in regions with low rainfall and abundance sunny days. In this case, roofs are built more flat. For roofs with minimum slope It is recommended to use membrane roofing materials that reliably protect the roof from leaks.

The abundance of sun gives strong heating to the roofing material, which, as a rule, for flat roofs is selected from rolled or piece materials on a bitumen basis. Often, in order to protect the roof from overheating, pebbles are placed on their surfaces, or turf or green coverings are made.

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

Drainage system on flat roofs can be both external and internal. Internal drain arranged in areas with harsh winters. In this case, the drainage system will not be subject to the destructive effects of low temperatures. negative temperatures. In any case, the slope of the roof is made towards the water intake funnels in such a way that water can flow into them by gravity.

Slope angle and roofing material

The slope of the roof slopes is also influenced by the choice of roofing material. Materials with smooth surface will contribute to faster drainage of water from the roof. Conversely, materials with rough surface will prevent the rapid outflow of water.

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

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

minimum roof slope and covering

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

Roll or piece roofing materials bitumen-based, as well as membrane coatings, ondulin, can be laid on the roof with a minimum slope of only two degrees or more. When choosing roll materials, the number of layers affects the angle of inclination soft roof. The more layers, the slope angle of the roof decreases, as its waterproofing ability increases. If the soft roof is made of 1 or two layers roll material, then the angle of the roof slope can reach up to 15 degrees.

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

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

How and with what is the roof slope angle measured?

The slope angle of any roof can be calculated using geometric functions or an instrument called an inclinometer. The roof pitch angle can be measured in degrees, percentages or their ratios

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

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

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

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