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15 Answers

How to tell if I need a HRV?

So at the conclusion of my home energy audit, it was recommended that a heat recovery ventilator be installed because my house (built in 2002) is already too tight.

I always though excessive wintertime moisture was a good indication that a HRV was needed. However, the humidity level in my home drops to about 17% in the dead of winter. Isn't this an indication that I already have a ton of air infiltration?

I'm very confused and wonder if the auditor performed the blower door test incorrectly. Could the forced air system be the culprit for the dry air?

Thanks in advance!

Asked By BuildingNewb | Dec 10 17
6 Answers

Zip System vs. OSB

I am in the process of choosing between zip system and osb sheathing for the exterior of a new home project. I have read through a lot of articles on this site though I am still trying to decide on if it is worth the added cost if OSB is installed cautiously. I would still use a high quality tape on all seams. I intend to use a high quality sealant inside at the plates and blocking to sheathing joints. I also intend to install Tyvek on the exterior since the home will have vinyl siding and I don't want to rely on the tape alone at sheathing joints (if using zip).

Asked By Brian Ducharme | Dec 10 17
1 Answer

Does traditional plaster serve as a sufficient air seal between living space and attic in an older home?

We're restoring an older balloon-frame structure (1890s) in a northern Gulf Coast climate (extreme humidity, some heating load, large cooling load). Fortunately, we've been able to design the house's first ever HVAC system so that all the ductwork and mechanicals are located in a fairly short run down the long central hall -- within the conditioned space, and just beneath the existing ceiling plane (a false drywall ceiling will sit a foot or so below the old ceiling). The existing ceiling over most of the house is a rather thick plaster (with surprisingly few visible cracks).

Asked By user-6970120 | Dec 9 17
19 Answers

Insulating Basement - Southern Part of Climate Zone 4

I live in Northwest Arkansas, Climate Zone 4 not far from the climate Zone 3 border. Most people don't have basements around here, so no one seems to know what's best for this climate.

Asked By Arkansas67 | Dec 4 17
10 Answers

Does sealing rim joists slow the flow of air into attic?

Will sealing the rim joists in my basement significantly slow the stack effect or will the house just begin to pull its makeup air from other areas in the house instead?

Similarly, would sealing gaps from inside the house also slow the stack effect such as around hvac registers, ceiling fixtures, outlet boxes etc?

Due to the difficult layout of my attic with ductwork everywhere, I'm trying to do as much as I can from the accessible portions of my home.

Asked By BuildingNewb | Dec 6 17
5 Answers

Retrofit flood-resistant wall assembly

Proposed Wall Details:
- 2x4 treated bottom plate, untreated 2x4 framing, 1/2" exterior plywood sheathing covered with building paper and Hardi Plank siding on the exterior (No rain screed).
- Bottom of stud cavity (First 12" to 18") insulated with closed cell spay foam, the balance of the wall insulated with fiberglass of rock wool.
- Bottom ( First 12" to 18") of interior finished with PVC wainscoting or other waterproof material. the balance of the interior wall finished with 1/2" drywall..

Asked By Anthony Swoope | Dec 8 17
4 Answers

Recommended sheathing tape width?

How wide should sheathing tape be to provide a quality air seal on OSB in CZ 3A? I am looking at 3M 8067, but am open to other options.


Asked By Norman Bunn | Dec 5 17
3 Answers

Replacing double-paned window glass

Old window is Willmar Window uPVC, 70/32, installed horizontally in 2001. The seal failed in 2016 on the lower left hand side.

We replaced only the window glass in the summer of 2017. Synergy Solarban 70XL

After a recent winter storm, the frame of the Willmar seems not to support the new window glass.

Asked By Carolelm | Dec 5 17
1 Answer

Unvented roof assemblies without spray foam

I am planning an addition on my home in Seattle with an unvented roof assembly. I have looked at the costs and I am not considering using spray foam of any kind.

For an unvented, cathedral ceiling, the local code calls for R-38.

Asked By User-6965270 | Dec 7 17
4 Answers

Adding to existing blown-in fiberglass insulation


I am located in climate zone 5, bordering 6. I have remedied sealing and kneewall issues in my attic. I am ready to add additional blown-in insulation to the existing blown in fiberglass (R-38). My plan is to bring the final R value to R-60. If I currently have blown-in fiberglass, is there any benefit to adding cellulose over the top or just top it off with additional blown fiberglass?

Many Thanks,

Asked By Mg6467 | Dec 4 17
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