Is it possible to put a ruberoid under profiled -

Starting the construction of a new roofing, you can choose any roofing material. However, when it comes to reconstruction of the old roof, you have to work with what is. Professional roofing masters note that a significant part of underused, economic and seasonal constructions in Russia during the last 50 years has covered roofing material, which has a short service life. During operation, cracks, bubbles and holes appear on this roofing material, then the landlord understands that you need to re-roof. Many masters in order to save time and money recommend leaving old roofing felt under corrugated flooring as a lining. In this article we will tell whether it is possible to do so.

"Diseases" of a ruberoid roof

Roofing material - roofing roll material, which is made of cardboard with a density of 200-420 g / m2, depending on the type of material. The cardboard is impregnated with low-melting petroleum bitumen, and then sprinkled with reservation dressing in the form of stone or granite chips, talc, chalk or quartz sand. In accordance with the density and type of dressing, ruberoid is divided into two types: lining and roofing. According to the reviews of experienced craftsmen, there are 3 “chronic diseases” in the ruberoid roofing:

1. Low mechanical strength. Due to the low mechanical strength, the ruberoid during operation is often damaged by strong gusts of wind, hail, and falling branches.
2. Cracking. Getting under the reservation dressing, atmospheric moisture when the temperature drops below 0 degrees causes cracking.
3. Bloating. Under the influence of ultraviolet rays and atmospheric moisture, blisters and blisters often form on the surface of the ruberoid roof, reducing the waterproofing properties of the coating.
4. Condensate accumulation. Roofing material does not allow steam, therefore moisture is condensed abundantly on the rafters, which leads to wood rotting.

Important! The lifetime of the roofing material in the composition of a multilayer roof is 7-10 years, after which the roof requires replacement or reconstruction. In such cases, some masters recommend laying decking without dismantling the old coating. They claim that the damaged roofing material can be used as a waterproofing layer of the roofing pie.

Laying a profile sheet on a ruberoid

According to professional builders, the dismantling of the old coating often takes up most of the time and amounts to more than one third of the cost of roof reconstruction. Roofing material begins to melt at a temperature of 60 degrees, so for several years of operation, it sticks to wooden rafters and crate so much that it is almost impossible to remove it. Therefore, many masters recommend laying a professional flooring without dismantling the damaged coating. However, this technology can not be used in all situations:

• If the structure to be overlapped is of an economic or industrial type, is used seasonally or is not heated, decking can be put directly on the old ruberoid coating, because in such a room there is no difference between outside and inside temperature, leading to the formation of condensate.
• If the structure to be covered is used as a residential building all the time, it is heated, professional craftsmen do not recommend laying a professional sheet on roofing material, since it does not allow steam that is abundantly formed in such structures. Steam condenses on the underside of this material, causing the roof frame to rot.

Note! If the old roofing material is retained during the installation of a new covering made of corrugated flooring, they are nailed to the battens of the counterbathing and a new crate from a bar impregnated with an antiseptic composition to create a ventilation gap preventing condensation.

Roofing material waterproofing layer

From the point of view of building codes, roofing material is not an optimal material for lining waterproofing, although it can still be used. It is laid on the rafters, fixed with oil nails, and the joints between the strips are soldered to obtain a hermetic coating. This almost monolithic layer does not allow moisture and steam, which leads to condensation in the roof truss system.  Mounting decking on roofing material, you must consider the following factors:

1. Profiled steel sheets have a high thermal conductivity, and therefore are very hot in the sun. The melting point of the ruberoid is only 60 degrees, so the corrugated flooring, laid without a counter-grille and crates, can penetrate the hole in it.
2. Due to the difference between the internal and external temperature, steam is condensed on the inner surface of the ruberoid, which penetrates inside the wooden elements of the truss frame and leads to rotting.
3. When heated, the bituminous material used as a lining waterproofing in the thickness of the roofing pie of a corrugated roof, bitumen fumes are formed, which are considered harmful to human health.

Professional roofing masters believe that during the reconstruction of the old roof, you can leave the roofing felt for waterproofing, after removing the bubbles and moisture accumulated inside the coating. However, when creating a new roof, it is better to use special diffuse membranes that let in steam.

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