Waterproofing of roofs with roof-tiles fixed with nails
DELTA-FOL PVG Waterproofing roof membrane
DELTA-FOL PVE Waterproofing roof membrane
DELTA-VENT S Waterproofing roof membrane
DRAGOFOL White waterproofing roof membrane
DELTA-FOL LP Transparent waterproofing roof membrane
I. NATURE OF THE PROBLEM – REQUIREMENTS
Waterproofing a tiled roof is necessary, since the layer of roof tiles is not completely water impermeable: water may penetrate either through cracks or imperfections in the roof tiles construction or under the appropriate combination of rain and wind. Waterproofing is carried out under the roof tiles by using special sealing membranes.
Beyond effective waterproofing, these membranes should have the following properties:
They must be vapor-permeable, in order to avoid condensation of water vapor, which leads to damage (distortion, rotting, etc.) of the roof beams and to moisture in the area below (unpleasant living conditions).
They must be resistant and long lasting, because their position (high up and nailed below the roof tiles) makes any future intervention difficult.
They must have sufficient strength in order not to tear during their application.
They must be lightweight and in general easy to apply, since the position where they are placed creates by its own nature difficulties in the application of membranes (due to height, roof inclination, etc.)
Waterproofing roof membranes DELTA-VENT S, DELTA-FOL PVG, DELTA-FOL PVE, DRAGOFOL and DELTA-FOL LP successfully cover the above requirements. In particular they possess:
- Complete waterproofing, even in roofs of small inclination .
- Light weight, so to be easily applied .
- Vapour-permeability, so to avoid condensation of vapour on roof’s elements.
- High tensile strength, in order to resist tearing.
- Flexibility and adjustability, so to facilitate the formation and treatment of their ends in rain gutters, roof windows etc.
- High fire resistance, so in case of fire, they burn out by their own minimizing the spreading of fire.
Concerning the vapour-permeability of the waterproofing membranes, it is generally achieved by two ways: DELTA-VENT S, DELTA-FOL PVG, DELTA-FOL PVE are vapour permeable from their construction by vapour-permeable polymer layers. On the other hand the vapour-permeability of DRAGOFOL and DELTA-FOL LP is achieved by being perforated with micro-sized holes witch allow vapour but not water to pass through. The last two membranes are not recommended if they are going to be laid on top of the sheathing, because in that case it is possible that water could pass through the micro-sized holes due to cohesion forces.
The roof’s waterproofing is applied under the roof tiles.
The sheets of the waterproofing membrane are laid crosswise to the roof’s inclines, and are wedged in between the wooden beams supporting the tiles, and the rafters or planking, if any.
The membrane sheets should be laid starting from the lowest parts of the roof (along its perimeter), in order not to have joints where successive sheets overlap each other facing the opposite direction of the water flow.
Each successive series of sheets should overlap the entire length of the sheets of the previous layer, at least by 10 cm. If the roof’s incline is less than 22ο, the overlap should be approx. 20 cm wide.
During placing of the membranes, it is recommended to have the membranes form a slight sag between the rafters, in order to avoid creation of water flow near the areas where the rafters have been nailed.