Stop Attic Heat Leaks with Tape DYI (Thermal Test), by David M on YouTube. 2 min 54 s.
- Video length
- 2 min 54 s
- Time to do it
- 2 to 3 hours
- Difficulty
- Medium
- Steps
- 7
What you need
Steps
Go into the attic on a cold day and sweep the ceiling with the infrared thermal camera. Bright or dark streaks on the scan mark the spots where air is escaping, usually along joist seams and wall plates.
Mark each leak with a bit of tape or chalk so you can find it again. Work from one end of the attic to the other so you do not miss a section.
Press vapor barrier sealing tape firmly over the joist seams and gaps the camera showed. Overlap each strip by a couple of inches and smooth it down so no bubble or lifted edge is left.
Run the thermal camera over the taped seams again and compare with your first scan. Any spot still showing a temperature difference needs another layer of tape.
Measure each cavity between the joists and cut R-19 batts about an inch wider than the gap. Use a sharp utility knife on a board, not on the joist itself.
Push each batt into the cavity so it sits flush with the top of the joists. Do not squash or fold it, since compressed fiberglass insulates far less.
Frame out any remaining open cavities with lumber, then fill them the same way. Finish with a last thermal scan to confirm the hot or cold streaks are gone.
Tips and common mistakes
Seal the air leaks first, because insulation alone will not stop warm air pushing through a gap.
Only tape over clean, dry, dust-free wood, or the adhesive will let go within a season.
Wear a dust mask, gloves and glasses, and keep the knife blade away from your body when cutting batts.
Never cover vents, recessed lights or chimney gaps with tape or insulation.
Questions
Do I really need a thermal camera?
It makes finding leaks much faster, but on a cold day you can also feel for drafts with the back of your hand. A camera lets you compare before and after.
Can I use spray foam instead of tape?
Yes, foam works well for odd shapes and bigger holes. Tape is quicker and cleaner for straight joist seams, which is why it is used here.
How much insulation do I need?
Keep adding batts until the insulation sits level with or slightly above the joists. R-19 is a common choice for a first layer in many attics.
This guide was drafted from the video's details and general task knowledge. It has not been checked against the full video. Check the video and relevant product instructions before following a procedure. Report a correction.
