You can use expanding foam filler for insulating, stopping draughts, filling gaps and dampening sound. We have foam filler as hand held, gun grade, sticky and PU perfect as a gap filler foam or range of applications. Expanding PU foam needs moisture to expand and cure. If applying foam to dry areas, mist the area first as this will help it to cure faster. However, foam won't stick to a wet area. If you are filling a big hole, the best approach is to fill the perimeter first and let it cure, then add another layer to fill the hole. Once the foam has curred you will may wish to scrape or sand off an additional foam.