When arranging the roofs of industrial buildings and outbuildings, at least a minimum slope of a flat roof is required. This is explained by the fact that perfectly smooth and flat roof ineffective from the point of view of drainage: on such a roof, the water that has become after precipitation behaves unpredictably. And sooner or later, on a perfectly flat roof, so-called stagnation zones appear - puddles, and eventually swamps, which dry up only during extreme heat.
Why do you need a slope for flat roofs?
What is fraught with such zones of stagnation on flat roofs?
The formation of stagnant zones on flat roofs is by no means beneficial to the roofing material and damages many components of a flat roof.
First of all, it must be taken into account that the water remaining on the roof during the cold season is subjected to repeated freezing-freezing cycles. As a result, the top layer of the roofing material is destroyed, and conditions are created that promote the development of corrosion processes.
Also, in the stagnation zone, a certain analogue of the soil is formed, in which plant seeds brought by the wind take root. And if you do not deal with the occurrence of puddles on the roof, there is a risk of one day finding a small tree on the roof of the barn that has sprouted roots through the roof.
To avoid this, a flat configuration roofing device provides for the product of a ramp. Razuklonka is a set of measures that is carried out at the stage of erecting a flat roof, and is aimed at giving it a certain slope.
In most cases, the minimum slope of a flat roof, sufficient to ensure effective drainage of melt and rainwater from the roof through spillway systems, is 1 - 4.
This angle, at which the roof plane is inclined to the horizontal, is called the roof slope, and all work to ensure this slope is called slope.
Roofing methods
Flat roofing can be done in several ways:
- With the use of backfill insulation (perlite, expanded clay)
- Using lightweight concrete mixes based on the same heaters
- With the use of lightweight concrete mixtures based on fillers from polymeric materials
- With the use of insulating materials
Alas, the widely used bulk insulation as a material for arranging a ramp has a number of disadvantages.
First, the backfill material shifts over time, which can disrupt the slope configuration and nullify all your efforts. And secondly, the significant size of expanded clay granules (about 20 mm) does not allow creating a sufficiently smooth slope.
Deprived of these shortcomings, demolitions made of lightweight concrete, alas, are not always applicable.
Despite the filler, this design still has a significant mass - and therefore, creates an additional load on the nodes of a flat roof.
That is why sloping using concrete is possible only at the stage of building the building itself or overhauling the roof.
If only a small re-equipment is planned, then special polymeric materials can be used to flatten the roof. Most often, extruded polystyrene is used for this, but other materials can also be used.
Flat roof structure
Before proceeding with the formation of the slope of a flat roof, it is necessary to understand its structure for yourself. Unlike pitched roofs, a flat roof is a completely different, multi-layer structure.
The structural features of a flat roof are primarily related to its waterproofing characteristics - after all, even if the roof is sloping correctly, water drains from it much more slowly than from the flattest gable roof.
Consequently, the requirements for waterproofing flat roofs are immeasurably higher.
Most often, a flat-shaped roof covering consists of the following layers:
- Supporting structure (the base is most often reinforced concrete slabs or profiled metal sheet flooring)
- Leveling cement-sand screed (laid on top of a reinforced concrete base) (
- A layer of vapor barrier materials that prevents excessive condensation
- Layer of thermal insulation materials (rigid fibrous materials, extruded polystyrene foam mentioned above, foam glass, etc.)
- Waterproofing from rolled roofing material
In the case where the base is a profiled metal sheet, a profiled steel sheet structure can also be used as a waterproofing.
In other cases (for example, when flat roofs are made from built-up materials), the “roofing cake” may have a slightly different structure, but in most cases its principal diagram remains unchanged.
Below we will consider how to carry out the slope of such a roof in several ways.
Razklonka roofing materials
The slope of the roof using inexpensive backfill materials is carried out according to the following scheme:
- A layer of glass isol is laid on top of the reinforced concrete base - a material that provides waterproofing and is characterized by a long (up to 30-35 years) service life.
- We pour expanded clay on the glass isol along the slope laid down in the project.
Note! Large granules of expanded clay do not allow to accurately maintain the angle, therefore, for small angles, filling is done almost “by eye” - as long as there is a slope in the right direction.
- Expanded clay is covered with overlapped polyethylene film.
- On top of the film we equip a leveling screed from a cement-sand mixture.
Further, the roofing cake is formed according to the project - while laying each next layer, it is necessary to control the preservation of the slope angle.
The main drawback of this method has already been voiced: to accurately withstand roof pitch almost impossible, and even expanded clay begins to shift already when pouring the screed.
This can be avoided by pouring expanded clay with cement milk, however, this increases the drying time of the entire structure, as well as the load on the roofing units - a flat roof becomes much heavier.
Razklonka with the use of foam concrete
Instead of expanded clay with cement mortar, experts have recently recommended using foam concrete. On the base we pour a layer of foam concrete along the slope, then - a foam fiber concrete screed, on top of which we fuse waterproofing.
The resulting roof is characterized by high mechanical and thermal insulation characteristics. However, it is not without drawbacks, the main of which is the high cost.
This is due to the fact that it is almost impossible to perform foam concrete screeding on your own in an artisanal way - so you will inevitably have to involve highly paid specialists in the work.
Razklonka with heat-insulating materials
Well, and finally - the third way: ramping with the use of heat-insulating materials.This method of demolition is quite economical, relatively uncomplicated and can be performed both during the construction of the roof and on top of the already finished roofing during repairs.
The most advantageous in terms of thermal insulation and optimization of financial costs is a slope with the use of mineral wool and polystyrene plates (foam materials, teplex, etc.).
An additional advantage is the low specific gravity of such materials. When arranging the slope in this way, strengthening the roof is not required.
To carry out the most effective ramping, we fasten the insulating boards to the roofing base using dowels or self-tapping screws.
It is also possible that the heat-insulating boards are glued to a previously cleaned base - but in this case, the bonding strength must exceed the tensile strength of the heat-insulating board itself. roof material.
To form the required angle of the roof, we use either insulation panels already made with a certain slope (for example, the Roof Slope system from Rockwool, or plastic adjustable supports.
When using plastic supports, the heat-insulating material feathers are attached to each other with the help of special parts. The insulation layer in this case is a single unit and does not require fixing to the base.
As a result, we can summarize: no matter what your flat roof is, a slope on it is necessary, and you can achieve it in several different ways.
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