To determine which seal to buy, close the door or window and, from the outside, check the size of the gap between it and the jamb (the part of the frame that stops the door or window from opening). From the inside, measure the width of the jamb and around the inside. We used a 9mm-wide brown seal to match the timber jamb, with a thickness of 8mm, which will seal gaps from 5mm to 8mm. A five-metre roll was just enough to seal around a standard large front door.
Clean around the jamb with a warm damp cloth to remove dust and grease, then leave the surface to dry thoroughly, so that the seal adheres.
Position the sticky side of the seal to run it along the top of the jamb, trim the end with a utility knife, run a finger lightly along the seal, then remove the paper. Avoid stretching or pulling the seal as this will affect the stickiness.
Position the seal at the top corner to run it down the side of the jamb, trimming at the base with a utility knife and removing the paper. Repeat with the other side.
Tip: Check the window or door closes properly. If it sticks to the non-adhesive side of the new seal and pulls it from the jamb, simply reposition the seal and dust along the outside with talcum powder to prevent sticking.