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Is it cost-effective to retrofit an air barrier to a kneewall that is fiberglassed?

How much does the existing fiberglass's R-value increase too with the added exterior air barrier. Does the cost of adding this air barrier pay for itself?

Asked by user-7049627
Posted Jul 11, 2018 2:57 PM ET
Edited Jul 12, 2018 6:57 AM ET

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2 Answers

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1.

Both questions are impossible to answer without more information.

If you use sheets of 0.05" platinum for the exterior air barrier it's unlikely to "pay for itself".

If using housewrap stapled to the studs caulked & stapled to the framing at the edges and seams, and discount your labor to $0 as a DIY it almost certainly does "pay for itself", assuming you are paying to heat & cool that space.

If you're hiring somebody at $50/hr to install the housewrap, maybe not- it depends.

The performance question depends on the density & thickness of the fiberglass, the average temperature difference across the layer, the air tightness of the conditioned space side of the wall, and how well vented the micro-attic space on the exterior side of the kneewall is.

Answered by Dana Dorsett
Posted Jul 11, 2018 3:17 PM ET
Edited Jul 11, 2018 3:17 PM ET.

2.

User-7049627,
First of all, can you tell us your name? (I'm Martin.)

It looks like you posted this question in two locations. My answer is on the other page where you posted the same question. Here is the link: "Is it cost-effective to retrofit an air barrier to a kneewall that is fiberglassed?"

Answered by Martin Holladay
Posted Jul 12, 2018 7:00 AM ET
Edited Jul 12, 2018 7:22 AM ET.

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