Draughtproofing

If you draughtproof your building, be careful not to block up any intentional ventilation, because this could make it damp. It takes a careful professional assessment to understand whether and how intentional ventilation can be reduced.

On external doors or ones between rooms at very different temperatures, think about the gap at the bottom, any letterbox, the keyhole, and gaps around the door. You may not be able to draughtproof fire doors or some doors in listed buildings.

Chimneys can have their airflow reduced with a chimney balloon, chimney cap, or a board covering the hearth, but they do need some airflow to avoid damp.

Loft hatches, the locations of previous extractor fans, and gaps around pipework often get overlooked. Gaps in floorboards and under skirting boards can also be worth addressing.

Some professionals can identify the most important areas to draughtproof using thermal imaging, but this takes training to do well. Professionals also offer airtightness tests to find out whether your building in unexpectedly leaky, although this does not identify where the losses are. It’s possible to get a sense of the effects of obvious gaps by checking what they do to a smoke pen when the building is heated and there’s gentle air movement outside.

Some draughtproofing can be done as a DIY job, but professionals have access to better skills and materials. Window draughtproofing is particularly difficult, and expensive as a result. For both windows and some doors, really good curtains can really help with the draughts.

• Thermal curtains and blinds

• Draughtproofing advice (Energy Savings Trust)

• Draughtproof your property (from Historic Environment Scotland)

• How to draughtproof your chimney (Energy Savings Trust)

• Draughtproofing in churches (video, from 44:15, with some ingenious cheap tricks)

• Explanation of airtightness with a diagram of likely leaks (technical)

• Smoke pen