Check for air leaks Light a match or candle near any windows or doors where there may be potential air leaks. If the flame dances around, it means there is air flowing through the area. The movement of the flame should intensify - or the flame will blow out - as you move closer to the source of the leak.
Clean area to be sealed To ensure proper adhesion of the filler, remove any old caulk and paint before you start filling. Make sure the area is free from dust, grease and loose/flaking paint, by giving it a wipe.
Prep the caulking gun Cut the seal at the top of the No More Gaps cartridge using a knife or secateurs, at a 45° angle with an opening that is approximately the size of the hole being filled. Fit the nozzle to the top of the cartridge and insert it into the caulking gun by pushing the base of the canister into the gun.
Caulk the leak Apply steady pressure to the caulking gun trigger to force the gap filler into the area that causes the leak. Move the nozzle along the joint in one smooth action. At the end of each section wipe excess product away with a finger, spoon or spatula dipped in a 50/50 mix of water and detergent.
Finish Clean off any excess sealant with a damp cloth immediately. Allow the filler at least 30 minutes to cure if you are planning to paint over it.
For a neater finish and easier clean up, you can tape both sides of the gap before applying the product.