I have a finished attic which gets hot very quickly, requiring running the central AC excessively and due to the imbalance, the downstairs tends to get too cold while the finished attic is still too warm. (Don't worry, I am addressing the HVAC imbalance separately from this post.)

I've gone through and sealed around outlets and other visible cracks and gaps but I believe I still have significant leaks somewhere. Is there a trick I can use to discover where the air or heat is passing through?

  • 1
    A smoke grenade may show lots of holes... but perhaps those smoke sticks or matches might be better.
    – Solar Mike
    Apr 9, 2021 at 19:04
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    I am not understanding the correlation between it being too hot and having leaks.
    – Alaska Man
    Apr 9, 2021 at 19:13
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    Hot air rises, so might come from floor. Do you have windows where sun shines though, that can also raise temperature fast? Do you have vents to let hot escape?
    – crip659
    Apr 9, 2021 at 19:15
  • @AlaskaMan In places other than Alaska, it is hot outside and cool inside in the summer. :D Apr 9, 2021 at 19:17
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    @jay613 Ok. It's central air from the crawl space that has a duct that goes through a shaft to the attic, through the unconditioned space, into two finished attic rooms. No zoning. The attic is vented but does not have soffits. I'm halfway through the process of installing a return from the attic. Doors can be open or closed. Apr 10, 2021 at 13:50

1 Answer 1


Two separate issues here:

Attics Get Hot!

This is a fact of life. Attics heat up from the sun all day long. Color and type of roof can make some difference (reflection vs. absorption), but it is quite normal for an attic to get really hot. The usual solution is an attic fan. This can be thermostatically controlled so it only runs when hot. For an attic fan to work, you need to have the fan on one end and air coming in from elsewhere (but not from your house below).

If your attic is really getting hot from your house, or if your attic gets hot and the hot air goes down into your house, then you get to checking for leaks:

Thermal Imaging

There are thermal (infrared) cameras available as standalone devices, and also as add-ons for handheld computers (aka smart phones):

FLIR camera

You can either buy something (if you like gadgets and can justify it to yourself) or borrow or rent one.

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