damp

can anyone tell why my grow room has dampness and mould spots.seems to be worst around about my window which is sealed with black/white.cheers

Condensation. The amount of water that the air can hold decreases with temperature. When the air gets close enough to a cold object to become cold itself, the water it can no longer hold at that cooler temp falls out and collects on the cold surface. To prevent this, you have to either lower the humidity or isolate the cold surfaces from the air.