Experts know that the choice of roofing material is affected by the angle of the roof. Roof slope - how to count, our article is devoted to this issue. We hope you will find answers to your questions in it.
In order for water to drain faster from the roofs, its slopes are installed at an angle. Express the slope of the roof as a percentage (slopes with a small angle) or degrees.
The larger these values, the steeper the roof. You can measure them using a geodetic instrument (inclinometer). What is a roof pitch anyway? This is the angle of the slope of the roof to the horizon.
Usually there are 4 types of roof structures:
- Flat.
- pitched.
- Gentle.
- High.
Of course, as such, flat roofs do not exist, otherwise the water would constantly stagnate on them. The angle of inclination of the roof must not be less than 3.
As mentioned above, the slope value can be measured in degrees and percentages. Below we give a table of the ratios of these quantities.
Before proceeding to consider the influence of the angle of inclination of the roof on the choice of roofing, we propose to find out what factors affect this value.
What affects the angle of the roof?
The tightness, reliability and durability of the roof depends on the choice of the correct angle of inclination of the slopes. But this value is not taken "from the ceiling."
To begin with, you should pay attention to the following factors:
- Wind. The higher the angle of inclination, the more resistance the roof provides to it. But if the angle of inclination is small, the wind can rip off the roofing. That is, it is dangerous to make very steep roofs, but even without a slope is also bad. Therefore, experts recommend: for areas with weak winds, choose the angle of inclination of the roof from 35 to 40 degrees, for areas with strong gusts of wind from 15 to 25 degrees.
- Precipitation. Even a non-specialist understands that the greater the slope, the faster water and snow leave the roof without flowing under the joints of the coating. That is, the roof is more airtight. This should also be taken into account.
From all of the above, we can conclude that the climatic conditions at the construction site of the roof significantly affect the angle of its inclination.
The choice of coverage depending on the slope of the roof
When choosing roof coverings, it is imperative to take into account the angle of the roof.Not only the choice of material will depend on this value, but also the number of layers that will have to be laid (roll materials).
In Figure 2, you can see the minimum and maximum slope angle at which one or another type of roofing is used.
The vertical scale shows the slope of the roof in percent, and the semicircular (in the center of the diagram) in degrees. Looking at the table, we find that:
- Welded roll materials can be used for roofs with an inclination angle of 0 to 25%. With a slope of 0-10%, laying is carried out in three layers. If this value is 10-25%, it can be laid in one layer (material with sprinkles).
- Asbestos-cement corrugated sheets (slate) are used on roofs with a slope of up to 28%.
- Tiles are used for roofs with a slope of at least 33%.
- Steel coating is used at an angle of inclination up to 29%.
For your information! The greater the slope of the roof, the more material will have to be spent on its covering. Therefore, a flat roof is less expensive than a 45-degree roof.
Knowing the slope of the roof, you can easily calculate how much material you need and what the height of the roof will be.
Skate Height Calculation
After you have decided on the roof structure, decided what material will be used, took into account all climatic conditions and decided on the slope of the roof, it's time to find out how to calculate the height of the ridge.
This can be done using a square or a mathematical method. For the second option, the width of the span of the house (h) is divided by 2. The resulting number is multiplied by the relative value.
To find it, use the table below (Fig. 4). As you can see, the values are painted for each angle of inclination. To make it clearer, let's take an example. The width of the building is 6m, the slope of the roof is 20 degrees. We get:
6:2=3m 3x0.36=1.08m
The height of the skate is 1.08 meters. Using this formula, you can find out the slope of the roof (this may be necessary when repairing an already finished roof). How to count? In reverse order.
The roof pitch is the ratio between the height of the roof ridge and half the pitch.
What we get: 1.08:3=0.36 multiply this value by 100 and get the roof slope as a percentage: 0.36x100=36%, look at the table and see: 36%=20 degrees, which was required to prove.
We learned how to calculate the angle of the roof slope, and how to determine this value using an inclinometer, what is this tool?
This is a rail with a frame attached to it. Between the bars there is an axis to which the pendulum is attached (two rings, a plate, a weight and a pointer).
Inside the cutout is a scale with divisions. When the rail is in a horizontal position, the pointer coincides with zero on the scale.
To determine roof pitch angle, the inclinometer rail is held perpendicular to the ridge (at an angle of 90 degrees). The pendulum pointer will show the desired value in degrees. To convert to percentages, use the above table (Fig. 3).
Very often, during the construction of roofs, you can hear the phrase "roofing". What it is?
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Roof slope is a set of activities that are performed to create a slope of a flat roof, create skates and valleys on it. This event helps to solve the problem of stagnant water.
For flat roofs, the minimum allowable slope is 1.5 degrees (preferably more) and it must be made so that the water from the roof flows into special water inlets. For this, cement screeds or expanded clay are usually used.
If we are talking about the slope of the roof during the repair, and not the construction of the building, then it is better to use other materials (foam concrete, polyurethane foam, slab materials), since the screed will significantly increase the load on the roof. And this is already fraught with unpredictable consequences.
What else you need to know when choosing the angle of the roof:
- The slope in the valley must be at least 1%;
- At roof slope less than 10%, if rolled bituminous materials are used, the top layer must be protected with gravel (10-15 mm) or stone chips (3-5 mm);
- When using slate or corrugated board as a roofing material, the joints between them must be sealed;
- The method of draining rain and melt water will depend on the choice of the angle of inclination of the roof.
As you already understood, a lot depends on the choice of the angle of the roof slope. Experts say that the optimal roof slope is calculated for each building individually.
Many factors must be taken into account: climatic conditions, building design, what roofing material will be used, etc. So there is no universal answer.
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