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9 Answers

2-inch foam on the interior face of the wall: What are my electrical box options?

Due to a foundation snaffu, it looks like I will have to move my 2in. EPS foam to the inside of the wall assembly. Although that seems feasible, it will add some labour and material cost (3/4" strapping everywhere, 3/4" plywood for the kitchen/cabinet area etc.)

I was specifically looking at the extra pain involved in installing electrical boxes. It seems most of the box extension rings I could find are limited to 1.5", which is a bit shy of the 2in. I would require.

Asked By Mai Tai | Dec 2 17
5 Answers

How important when insulating with foam board is it to be for the joints be overlapped, or pieces be foamed in place?

My project is a retrofit of foam over the sheathing of a geodesic dome. Every triangle has a gentle angle, which will interrupt the five inches of XPS foam that's being added. The sheathing below the foam will be primed with an acrylic sealer and taped. Over the insulation will be a water barrier, and strapping, 2 3/8 inch vent space, sheathing - with Densdeck Prime (sealed and taped) and a single ply adhered roofing of TPO.

Asked By Christopher Glasspool | Nov 27 17
5 Answers

Tape seams of exterior sheathing on double-stud walls or not?

Logging in--for the first time--from Schenectady, NY (5A)

Asked By User-6865122 | Nov 27 17
6 Answers

Chimney chase condensation

Hello All,
Classic problem I believe.

I have a wood framed chimney chase which houses two 8" insulated, stainless steel metalbestos wood stove pipes and my main DWV stack. On certain days, when the inside/ outside temps, and the relative humidity are just right, I have condensation build-up and dripping from the underside of my chimney chase roof.
Construction detail:

6x10 timber rafters 36" (on center)
2 x 6 rough sawn decking (not T&G)
Grace Tri-Flex
3 layers of 3" Polyiso foam board
2x6 Sleepers 36" (on center, screwed to rafters below)
3/4" T&G OSB decking

Asked By Dave Cummings | Feb 16 12
2 Answers

In Md. I have a vapor barrier and I want to insulate and finish basement

What is the best way to finish the basement. I already paid for drainage system; vapor barrier is up on walls. What is the best type of installation...? Basement is framed 24' vs 16. This is so frustrating for me, my brother gave me R19 that he had left over but I don't think I can use it. Someone told me not to use paperback fiberglass near vapor barrier...Help!

Asked By blgoodw | Nov 20 17
4 Answers

I want to build a wall in front of a masonry wall that emits moisture.

Dear GBA folks,

This fieldstone carriage house, built in 1910, has 22" thick stone walls (see picture). Inside on the second floor, 2x4 stud walls built about 2" away from the stone are covered with 1" plaster.

Asked By Robert Cramer | Nov 13 17
4 Answers

Why caulk between studs, etc?

I understand that a small amount of air can pass through the gap between two or more side-by-side framing members, but so what? Then that air hits the drywall, which is an air barrier. In the middle of a stud bay, that same air is passing through fiberglass batt insulation (not an air barrier) and hitting the drywall. What's the difference? For that matter, why caulk the drywall to the top plate? Isn't the intersection of the wall and ceiling drywall taped and mudded? Isn't that an air barrier?

Asked By JeffSch1 | Nov 8 17
3 Answers

Will radiant heat system PEX tubing melt polyethylene vapor barrier?

The heating contractor we hired to install a hydronic radiant heat system for our backyard cottage project did not put a polyethylene vapor barrier on top of the gravel, under the 2" rigid foam insulation. The rigid foam insulation panels he installed have a mylar-like film on the under side, which he thinks is sufficient. We live in VERY wet Western Washington so I'm wondering if this will in fact be enough.

Asked By Mightorta | Nov 12 17
5 Answers

Why does insulation have to contact six sides?

On the internet I've read about 15 years worth of claims that insulation must contact all six sides for it to be effective, but haven't seen an explanation why. Yes, I've read many times that a building's insulation and air barrier must completely surround the conditioned space and be in contact with each other, but can't find the science behind it explained. I would sure appreciate a scientific explanation from anybody. Thanks very sincerely.

Asked By JeffSch1 | Nov 8 17
4 Answers

Air barrier

I live in zone 3 central west virginia, and designed my own home,construction of which is currently under way.

Asked By ryoung26554 | Nov 7 17
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