The angle of slope of the roof for various conditions and roofing materials

By Admin | Roof And Roofing Materials
10 April 2016

roof of the house may have a different shape and a different slant of the roof.Moreover, the angle of slope of the roof is most often caused not by aesthetic considerations and the practical side and the specific requirements.Because of how a sharp and flat roof, and its strength is dependent on the proper functioning.Therefore, the slope is calculated, taking into account all the necessary parameters.

The minimum angle for various roofing materials


  1. Three major factors affecting the roof slope
  2. minimum allowable slope of the roof for various materials
  3. How to calculate the slope of the roof: some recommendations

Three major factors affecting the roof slope

builders have adopted this value (the angle of the roof slope is relative to the horizon) measured in degrees or as a percentage.To obtain accurate results are surveying instruments.To be clear, it is 0 degrees corresponds to a completely flat roof and large values ​​of the angle - acute ro

of.For pitched roofs it usually ranges from 0 to 45 11 0 During the construction it is necessary to calculate what should be the corner.And for this it is necessary to pay attention to these things.

Wind loads

If your area is dominated by a strong wind, it is not necessary to think about the project with peaked roof.Due to the high sail roof with a steep slope, it is more susceptible to the damaging effects of wind.In this case it is better to make more flat roof (the smaller the slope of the ramp, the safer) and rafters under it to build a strong, heavy-duty.Although much more expensive than the construction cost, but the roof will be much better protected from the wind.However, during the construction of the roof, not only the strength of the wind, but also its direction.Thus, it is desirable for the metal to the wind blowing directly into the plane of the sheets.If the gusts will drop from the ends, the roofing sheets are more likely to bend and break away.Therefore, depending on the prevailing wind direction must be correspondingly rotated eaves.

Wind loads

Rainfall and snow loads

If you live in a climate where winter snow is solid enough, the roof made with a minimum roof pitch of 45 degrees (can be more, but not less).It is necessary for the snow sliding down, otherwise it will follow on the roof, forming a too large layer that can push coat.But if the roof is large enough angle (about 45 degrees), it is possible and to strengthen the rafters do not worry.As, however, and the system of detention of snow.However, the wind loads for a reinforced roof.Therefore, the final choice is made, taking into account all climatic conditions.

It should be noted that not only snow but rain, and hail, and the scorching rays of the sun will be periodically testing the strength of your roof.If the terrain is sunny, but rain falls in the year a little bit, it can be limited, and a flat roof with a slope close to the minimum.

important: despite the fact that it is called a flat roof flat, slope it is still needed.Minimum slope for flat roofs is 1 degree or 1.7%.

roofing material

material which Croutes roof can be smooth or rough.In the latter case, the water draining from the roof will be worse, lingering on its surface (like snow).But with gladenkie cover all the moisture will flow down immediately.There are other structural parameters that determine the minimum and maximum slope.

The choice of design, depending on the slope of the roof

minimum allowable slope of the roof for various materials Metal

The smallest angle of the rays of the metal roof is 15 degrees (according to some manufacturers of metal - 14 degrees).For small slopes, some manufacturers recommend fluff each joint sheets sealed and water resistant, not afraid of frost composition.However, empirically it found that most likes to lie around in the snow metallocherepichnoy roofs with a slope of 20 to 35 degrees.Too small bias and bad - does not have time to drain the water from the roof, crushing the roof and drips at the joints for excessive showers.Several correct the situation only a choice of tiles with increased wave height.

Profiled (corrugated)

Well, the minimum roof pitch of the profiled sheet has a somewhat smaller value of - 12 degrees.Small angles require two-wavelength overlapping, and the angles of 15 degrees - 20 cm overlap.Step crates increases with increasing bias.Nearly flat roofs make continuous crate, t. To. In case of heavy snow may occur trough the roof.

Shingles (soft roof)

Crate under the shingles a solid base made of sheets of plywood or OSB.The minimum allowable slope of ramps for the roof covering is not less than 11 degrees.

bitumen-based materials

For such soft coatings is at least nothing - about two degrees.Very small tilt angle requires increasing the number of layers of the roof (because the flat roof is very important good moisture protection).If we provide only 1 or 2 layers of coating, will have to make the slope of the ramp at least 15 degrees.

Euroslate (Onduline)

For this material, the minimum pitch pitched roof is small, it is 11 degrees.But when working with Onduline roofs with a slight slope, there is one condition: the need lathing continuous type.

clay tile and asbestos slate

For these roofing materials required slope ramps is 22 degrees.It should be closely related to the calculation of the rafters, as the load of the heavy material will be considerable.And if you add to them a layer of snow or strong wind, if not get higher demands on the supporting system of the roof.And it should be noted that the decrease in slope entails an increase in load on the rafters.

How to calculate the slope of the roof: some recommendations

Now consider how to calculate the angle of the roof.To begin with, the slope, as mentioned above, can be measured in degrees and percentage.Sometimes inexperienced developers confuse them, which leads to errors in the calculations.But these values ​​are not equal.However, being careful and using special tables can produce a quick convert.

Value degrees and percent slope roof

Degrees, 0 Interest,% Degrees, 0 Interest,% Degrees, 0 Interest,%
1 1,7 16 28,7 31 60,0
2 3,5 17 30,5 32 62,4
3 5,2 18 32,5 33 64,9
4 7,0 19 34,4 34 67,4
5 8,7 20 36,4 35 70,0
6 10,5 21 38,4 36 72,6
7 12,3 22 40,4 37 75,4
8 14,1 23 42,4 38 789
9 15,8 24 44,5 39 80,9
10 17,6 25 46,6 40 83,9
11 19,3 26 48,7 41 86,0
12 21,1 27 50,9 42 90,0
13 23,0 28 53,1 43 93,0
14 24,9 29 55,4 44 96,5
15 26,8 30 57,7 45 100

# 1. slope measured in degrees, is the real angle between the ceiling and rafters.It can be calculated by dividing the height of the ridge (above the plane of the overlap) by half the width of the roof.If the roof has a broken shape, we take the width of the house, which is under the data portion of the roof.For example, the house has a simple roof 10 meters wide.The ridge has a height of 2 meters.We are making calculations.Divide 2 to 5, received 0.4.The percentages translate simple: multiply the number by 100. Will 40 percent.

# 2. can go even simpler way.Go online to find an online service with a calculator for calculating the roof slope (plenty of them on the Web).Enter the required values.This is the width of the building and the height of the ridge.In parallel, the length of the rafters and you instantly counted.The principle of operation of these calculators is based on the fact that, in fact, all the roofs are made of bi, which are calculated as a regular triangle.

# 3. another way - it is suitable for those who will believe his hands and eyes than estimated.You just have to take and measure the slope, using a simple device - inclinometer (otherwise, a protractor).Today there are many variants of this product, both analog and digital.

electronic inclinometer, which can measure the angle of the slope of the roof.

# 4. Since the width of the house can not be changed, then vary the inclination of the plane of the roof, you can change the height of the ridge.Naturally, only when both the wall of the house and its foundation are reliable, and has a margin of strength.After selecting the optimum slope for themselves the developer can determine what height he needed a horse.To help him, there are special tables with coefficients, which should be multiplied by one-half the width of the slab (slope specified).

# 5. In practice, the height of the ridge can be determined simply.Take the mark up, and the two outer walls of the house (which is located along our ramp).Cord rub chalk and stretch the tight between these tags.Measure out from the center of the cord, and at this point we put the bar.It should be exactly perpendicular to the plane of the overlap (check it for accuracy by a polygon).

changing the relative position of the twine plate (moving it up), we try to achieve the desired slope.To do this, periodically check the angle of the wall.Once the desired result has been achieved, we put a mark on the bar.Sawed off this piece, do a template for the ridge poles.If the support is not necessary, at each end of the roof determines the height of the docking of two rafters, fixing rails with taut cord.

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