In particular, I'm trying to insulate my loft. I'm not keen on the idea of taking a naked flame up there!

2 Answers 2


You can have a blower-door test done (or rent a blower and do it yourself). Basically you close all your doors/windows, and then stick a big fan in your doorway (sealed), then have it blow air outside. It creates negative pressure inside your house, amplifying any air leaks. I had this done as part of an energy audit (and when it was fairly cold outside), and just walked around using my hand to feel for any leaks (they are pretty obvious, because it is like a jet of cold air shooting in).

  • 2
    Using a feather during the test will help find drafts around windows and doors. Jul 30, 2010 at 3:57
  • 1
    If you get your fingers wet, you can feel the draft better as well.
    – Scott P
    Jul 31, 2010 at 16:06

An IR Thermometer could be useful, and they are getting rather cheap. A Thermal camera would be great, but they cost a couple thousand dollars.

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