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5 Answers

Exterior rigid foam

I'm soon residing my house and plan to incorporate 2" of exterior rigid foam (EPS). Is it a no-no, or is it okay to adjust the typical order of things by having 1" of EPS, then strapping over that, and then a second layer of 1" EPS. This makes for a 3/4" space that is not typical. But is it a problem?

Thanks for any input/advice.

Asked By Howard Gentler | Jun 11 18
7 Answers

Vapor retarder/barrier in an insulated above-garage floor

CZ6A, Ottawa ON

Our build will have a bedroom that extends out above the un-insulated garage. The floor will be 14" deep I joists and will be dense packed with cellulose (R50-ish). I'm planning to use Intello on the interior walls as a vapor retarder.

Question: What should I do for a vapor retarder/barrier above the garage?

Do I use a vapor retarder on top (between the floor sheething and joists), underneath (between the joists and the garage ceiling drywall), or is a totally different approach necessary? Should I be using a vapor barrier instead, like 6 mil poly?

Asked By Lance Peters | May 10 18
6 Answers

Vented open-cell cathedral ceiling

Good afternoon - What are the draw backs to venting an open cell spray foam cathedral roof assembly?

To note - the original roof assembly was design was with R30c kraft face batt insulation. - The framing inspector is concerned that I have a double vapor barrier between the kraft face and rigid XPS.

Asked By Bob Harshman | Jun 11 18
3 Answers

Insulate stud cavities with the possibility to install exterior foam in the future


I am planning the remodel a 1920's craftsman and wanted to get feedback on how to install the insulate in stages.

The building is a 1.5 story craftsman with a basement. The basement has a 2' cripple wall. The wall framing is 2x4's. Exterior to interior the layers are hardiboard, 1x12" lapped plank sheathing, 2x4s 16" OC with empty cavities, and then lath and 1/4" plaster walls. The roof is an A frame with 2x8 rafters.

I live in climate zone 4C.

Asked By dgardner88 | Jun 11 18
2 Answers

Bonfiglioli strapping size

Does anyone know why Bonfiglioli uses 1x3 straping instead of instead of 1x2?

In addition to additional cost, it requires 2 different assemblies: 1 centered for wall studs and 1 offset for plates and corners. The only functional benefit seems to be having additional nailing surface, which might be necessary given need to accommodate 4 mechanical fasteners: insulation to strap, then assembled furring to studs, then drywall to furring, and then trim/cabinetry/pictures on drywall.

Any concern with ripping down Zip-R to strips versus site-assembled?

Asked By PJ Clem | Jun 9 18
2 Answers

What type of interior insulation with 1" exterior rigid foam?

I had a strong hand in the design of my new home. However, I was a newbie when detailing the exterior wall details and we only put on 1" of exterior rigid foam. I now wish we would have done 2", but it's too late to change. We are currently planning on installing closed cell foam as interior insulation, but I just heard Martin speak on the Fine Homebuilding podcast and he says that rigid foam on the exterior and closed cell foam on the interior is a dumb idea. We live on Cape Cod, have 2x6 exterior walls with plywood sheathing, a liquid WRB, the 1" XPS foam, a rainscreen and cedar shingles.

Asked By Holly Trick | Jun 8 18
6 Answers

Brick veneer soffit gap: block and drill weep holes?

Common scenario, but I searched the internet for hours and somehow couldn't find this answer. I'm very slowly working on insulating and sealing our 40s brick veneer house, Cape 2.5 story with slate roof and no overhangs.

Asked By BryanBL | Jun 7 18
7 Answers

Nits & grits redux

Climate zone 3A (Atlanta, GA)
3 levels with basement walk-out to rear
Bonfiglioli wall
2x6 studs
Batt insulation in 7.25" cavities, type TBD
Plywood sheathing
Seams taped, type TBD
Housewrap lapped, type TBD
No exterior insulation
Air gap to majority brick exterior wall veneer
Rainscreen to minority fiber cement siding
Fluffy insulation above upper ceiling, type TBD
Site-built roof frame, 5:12 hipped upper roof with some 3:12 lower level roofs
Plywood sheathing roof deck ***NO INSULATION***
Peel & stick lapped, type TBD

Asked By PJ Clem | Jun 8 18
17 Answers

Rigid foam for hot roof

I am interested in converting our bungalow attic to finished space, and it was not designed for venting. I've heard I can do a hot roof insulation method using spray foam. However, I am a DIY guy by nature, and was interested in methods I've seen using closed-cell polyiso rigid foam and spray foam cans to achieve the same result, at least in walls. I am curious about using this method on a hot roof. Surely it would cause head-scratching with code officers. Would it work, though?

Asked By Asa Bradford | Jul 13 14
33 Answers

Heat runs to unfinished basement? Pacific NW area

I realize the basement is considered part of the conditioned space, but I was a little startled at an HVAC guy proposing to cut heat runs into the basement (which we do not plan ever to finish). It's a 1901 basement with concrete walls to ground height and wood joists above that. Previous owners had put fiberglass insulation in the joists, which was a really bad idea as one can see from old water stains. That's long gone, but when we first lived in the house we used to get water coming up through the floor drain during storms (no leaks through the walls that I am aware of).

Asked By Irene3 | Apr 20 18
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