Waterproof floor with gravel ballast
- Corrugated metal sheet substrate
- Insulation panel, mechanically fixed to the substrate.
- Double layer waterproofing system, made of:
a) first layer: FLEXGUM-P 4 mm applied by torching, semi bonded on the horizontal area and totally bonded on the perimeter;
b) second layer: FLEXGUM-P MINERAL 4,5 Kg/sqm, applied by torching in total adherence to the first one and on the verticals, up to a height of 20 cm above the level of the water.
For double layer systems, it is always advisable to lay the cap sheet in longitudinal direction respect to the base sheet, arranging the overlaps by having the ones of the upper layer in the middle of the first layer sheets. The sheets must be laid as well in such way that head overlap are staggered in longitudinal direction by at least 100 cm.The joints must be made by torching, overlapping the membranes (laid as “tiles”, in the direction of the slope, to favour the down flow of the water), for at least 8 cm in the case of the side and 12 cm for the head. Vertical walls and other protruding structures must be waterproofed with the same type of membrane, possibly mineralised.
- Layer of gravel, washed, with 15·30 mm granulometry, 5·7 cm thickness, according to the thickness of the insulation.