Even if you use material with poor heat production, such as, for example, ceramic tiles, or ondulin, and other poorly holding the heat of the coating, just like in the case of metal roofs, condensation is still formed on the roof. This condensate will fall on a waterproofing layer, or with the help of air will easily fall under the roof into the space of the room. That is why it is necessary to mount waterproofing on the rafters on the rafters. Waterproofing is needed in order to stop the wetting with condensate or stooped moisture from the slings. Keep in mind that even such heater known in the market as isover and Ursa will lose their properties at the first getting wet, and will mechanically deform with any contact with moisture. As a result, a gap is formed between the insulation and rafters, along which it is warm and goes out into the street. But if we consider more expensive heater, such as a steam or rockwall, then, of course, they behave much better. The fact is that such heater is afraid of less water, but they will be much more expensive at a price. There should be a double crate between the roof and waterproofing. Chatter is a bar of 30 by 50 mm, which is laid along the rafters. The crate with the step of the material itself needs to be laid across the counter. Thus, the help of the counter-rein is ventilated by the entire roofing space.