Concrete surface must be sound, free from dust, loose particles, and any deleterious matter. If the concrete surface is defective or has laitance, it must be cut back to a sound base. Excess laitance deposits are best removed by light mechanical scrabbling, grinding or grit/captive blasting followed by vacuum cleaning to remove dust debris.
The concrete surface should be allowed to cure for at least 28 days before applying the spray polyurethane foam and must be dry on the surface, with a moisture content less than 19%. An adhesion test should be conducted if necessary.
Joint openings above 6mm must be grouted prior to application of Vetotherm PU SF. Existing joints must be checked and repaired if necessary.
Remove or refasten all loose base flashing, counter flashing and gravel stops as required. Sprayed polyurethane foam is not recommended for lightweight or insulating concretes unless tests have been made to determine that adequate adhesion can be obtained or unless an overlay is installed.
Electrical and mechanical conduits should be transferred or raised above the finished roof surface. Lightning rods must be covered prior to foaming. Lightning rod cables shall not be embedded in the polyurethane foam and should be removed prior to foaming.
