One of the most important components of an external door is the weather-stripping which surrounds it. This (usually rubber) seal surrounds the door, preventing air from penetrating the gap and entering the house. But over the years, as the door is repeatedly opened and closed, this seal will deteriorate – as will its performance. What this means is that eventually, cold air will be able to get into the house far more easily, and the building’s thermal efficiency will suffer. To prevent this from happening, you’ll need to occasionally replace your weather stripping. Exactly how this should be done will depend on the age of the door. You’ll find that newer doors often come with a special groove set into the casing, into which the weather-stripping will be set. To replace yours, the best approach is to simply pull out the old weather stripping and take it down to your local DIY shop in search of a like-for-like replacement. You find a match in the form of a rolled-up length of foam or rubber, or a more rigid length of stripping that must be nailed into place around the door. More likely than not, you’ll be replacing the rubber sort. One of the big advantages of this material is that it can be installed and removed without the need for adhesive – just wedge the thin strip into the groove, and the rubber cushion should face outward ready to absorb the impact of the door. Once you’ve gotten a little bit of the rubber into (or out of) the groove, the rest of the seal should follow without much difficulty.