Why is dampness dangerous ?
Water is an enemy of all adhesives and makes them totally useless. If the relative humidity level is very high when the strips are being laid, a film of water may condense on the strip treated with adhesive, because of the local cooling effect caused by the evaporation of the solvents, and this will prevent the glue from sticking. If the dampness is actually in the paving itself, the heat from the sun will cause it to rise to the surface after the strip has been laid, and if it has no other means of escape, it tends to detach the sheet from underneath. This can be observed by putting a layer of transparent polyethylene on the ground and sticking the edges down with adhesive tape. With the sun’s warmth the inside will steam up in a short while and this condensation is a result of the dampness rising up from the paving.
