The only doors you should worry about are external ones or those that connect with a cold, uninsulated space, such as a garage or utility room. There are heat losses through the fabric and frame of the door and draughts around the edges and through keyholes and letterboxes. A gap of 2-3mm around a door produces heat loss equivalent to a hole of 14 cm2 in your wall.
Thin plywood panels and single glazing are probably the two main areas of heat loss and in both cases installing a second layer of wood or glass respectively will be effective. The glazing could be in the surround to the door, as well as in the door itself. It is also possible to have a brand new, high-performance door, as explained by CSE. New doors have to meet a minimum energy efficiency standard (or Door Set Energy Rating – DSER).
Because of the amount of use and wear that many doors experience, there are frequently large air gaps at the bottom, as the threshold becomes worn. Other sources of cold draughts come from poorly fitting letterboxes and keyholes with no cover. Both of these latter problems can be solved easily: there are new, tightly-fitting internal letter-box covers from the usual hardware stores. These are functional rather than attractive, but they can be fitted with the existing traditional external part, so the door looks the same from the outside. With a keyhole cover, it is best fitted on the outside, so the wind cannot blow in, and because it remains easy to put the key in.
The photo below is a thermal image of a keyhole:
Other solutions for draughty front doors include ‘sausage dogs’ and thick curtains. A sausage dog is a long tube of material, stuffed with fabric or small beads, that can be pushed up against the door when it is shut, to restrict air movement. These can also be effective throughout the house. A thick curtain would extend beyond the area of the door, so that all the edges are covered. Often it hangs from a rail that opens with the door.
A final option is to build a porch. Surprisingly, this can be a very effective and useful solution. You might want to spend some time looking at what your neighbours have done, to help you make up your mind. Where you have the letterbox, the amount of glazing, whether you can still get the bike through are some of the issues to confront. Most porches probably have to be built in situ, so can be constructed to your individual design.
- There are some really simple DIY solutions for draughty doors such as sausage dogs and thick curtains.
- Porches are a very effective solution – have a look at what your neighbours have done.
Caroline (OX2): We found that we had a draught from our letter box, so after hearing about eco flap letter boxes, we purchased one from Nigel’s Eco Store (£24.95 + pp). Installation was just a short DIY job and its a really effective improvement and still easy to put post through.
One of the draught-proofing products Brenda Boardman particularly likes is V-seal from Stormguard. This is available from at least some of the local hardware chains, for wooden and metal hinged doors and windows. Only one half of one-side of the V is adhesive and this is stuck to the frame, so the V faces to the outside. When the wind blows the V is forced open and becomes more effective. It is reasonably durable.