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| Searching for weak spots. |
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| Found a cold spot! |
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| Cold spot behind some I-joist blocking. |
We finished the poly vapour barrier installation- just after the blower door tester walked into the house today. Overall, it seems like the house is fairly tight. And very well insulated. When the house was de-pressurized by the activated blower installed in the door, the "certified energy evaluator" walked around with a thermal camera to show any weak spots. We found a bunch. The windows- and poly seal with tuck tape around them was the biggest culprit. So were the places were we used scrap pieces of insulation- rather than fresh/perfectly cut pieces. The blower door seemed to suck air right through the pieces of insulation. Wiring and pipe penetration were also obvious week spots, as were the I-joists and blocking that sit on top of the foundation wall. So, we went around with a red pen and marked all the locations that we need to re-visit. *Sigh* More work to do with that red sticky tape and acoustic sealant.
Hi Shafraaz,
ReplyDeleteYou mentioned leaks at the windows. Is this because you tried to seal the vapour barrier at the openings with foam?
At the locations where you used scraps of insulation, could you seal the joints with low expansion spray foam?
Jim
No, the weakness is in the tuck tape and the drywall fin of the windows. Some of the tape didn't stick or wasn't pressed down hard to seal it to the window drywall fin.
ReplyDeleteThe weakness where we used scrap insulation was observed really because of the blower door creating a large pressure differential through the exterior wall. I imagine we'll just leave it as it, as the insulation will still be effective in place- and the drywall will not allow the infiltration / air movement through those locations provided the vapour barrier is sealed well.
so, what's the lesson here? tuck tape is good if you ensure that it has been adhered well - or, would windows benefit from acoustiseal? I still have to tie-in my windows to the poly and I've been debating this
ReplyDeleteThis Fine Homebuilding website gives examples of using peel and stick membrane to complete the vapour barrier wrap and to protect the window opening framing from moisture.
ReplyDeletehttp://www.finehomebuilding.com/how-to/install-replacement-windows-and-flashing-correctly.aspx
A few years ago, when renovating my house, I used this method. The peel and stick is attached to the interior vapour barrier.
Jim
The lesson is you must perfect the technique of slipping the poly into the expanding foam around the window just in time to get it at it's stickiest and then tape another layer on the drywall fin and poly for good measure...
ReplyDeleteThanks for the link Jim~ that is a great article!
ReplyDelete