The required amount of waterproofing (it is made in 2 layers) therefore: 5 x 8 x 2 = 80 m² plus for an overlap 15 cm;
In the event that the frame is with 15 cm cells, then for one belt (transverse direction) it will be required (5: 0.15) + (8: 0.15) = 87 rods, and for the longitudinal direction, too, you need as much. For two belts you need 107 rods with a length of 8 m and 67 pcs. — 5m Prutiki;