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5 Answers

Owens-Corning mineral wool compared to Roxul Comfortboard?


I've noticed that our local building supply store carries Owens-Corning R-16.8 "Safing Fire-Stopping Mineral Wool Insulation". At a 4" thickness, that's something like R-4.2/inch.

In comparison, Roxul Comfortboard 80 R-6 48-sq ft Unfaced Rock Wool Batt Insulation with Sound Barrier (24-in W x 48-in L) (This is their 1.5" thick Comfortboard) is R-4 per inch.

In Green products and materials | Asked By Matt Gauger | Jan 7 17
2 Answers

Spray foam and abating moisture issues in Zone 4

I am remodeling a home outside of Seattle, WA. I plan on spray foaming the existing 2x4 exterior walls with closed cell spray foam (looking for R-24) and plan to frame out a new interior wall (probably 2x3).

I'd like to install a 2" polyisocyanurate board in the gap between my existing exterior wall and new interior wall to add a continuous R-13 across the faces of my exterior wall studs. The polyisocyanurate will be caulked to the studs, to each other, and joints will be taped.

In PassivHaus | Asked By Matthew Wahlrab | Jan 7 17
1 Answer

Temperature difference between full basement and daylight basement

Temp in my full basement after 10 days of single-digit outside temperatures is 45°F. That's the coolest it's been in 20 winters.

What's the expected temperature difference between full and a daylight basement with southern exposure and large windows?


In General questions | Asked By clyde farquhar | Jan 7 17
16 Answers

Solar hot air preheat for HRV/ERV

Has anyone seen a successful approach to using a solar hot air collector to preheat the intake air for an HRV / ERV?

It would be fairly simple to bypass the collector when preheat wasn't desirable.

One major concern is regulating temperature so excessive heat doesn't compromise the HRV / ERV.

It seems like it could be an ideal way to temper incoming air on cold, clear Colorado days (climate zone 6B), and get a little extra solar gain.

In Mechanicals | Asked By Pat Kiernan | Aug 17 16
5 Answers

Building a "pretty good house" in Southwest Michigan

My husband and I are in the blueprint & planning process of our post-frame barn home build; we are building in Southwest Michigan (zone 5A). While we are not a financed build and are not going all out Passivhaus or net-zero energy, we are planning on doing what we can afford using green and passive solar concepts for heating, air exchange units and to use Roxul insulation and Prosoco weather barrier. All of which my husband could describe in grander detail...think Martin Holladay's "pretty good house" concepts :-)

In Energy efficiency and durability | Asked By Brant Quinn | Jan 6 17
20 Answers

Housewrap under Roxul Comfortboard IS?

We are designing our new house in the PNW in a Marine 4 zone. The walls will be 2x6 with Rock wool batt insulation. We are planning to use plywood CDX sheathing taped or otherwise sealed as the air barrier. 2" Comfortboard IS would go on the outside of the CDX with furring strips for a rain screen under the siding. Siding will either be clapboard or cedar shingles if I can figure out how to do the attachment efficiently to the furring strips (may have to have horizontal over vertical furring strips).

In Green building techniques | Asked By Kevin Camfield | Dec 23 16
15 Answers

Is it poor ventilation or heat getting into attic causing mold in attic?


In GBA Pro help | Asked By annette finkelstine | Jan 1 17
4 Answers

Plywood window boxes


I am currently building my first passive house in Nova Scotia Canada.

(Trying at least)

The wall construction, is a larsen truss system (2x6 structure, 1/2" OSB taped seams on exterior, 11-7/8" TJIs, plywood sheathing, typar, wood siding).

For my window rough openings, I have created 1/2" plywood 4-ply window boxes. I taped/sealed the interfacing joint with the OSB sheathing around the perimeter, and all exterior window box corner edges.

In Energy efficiency and durability | Asked By Phil Dennis | Jan 6 17
8 Answers

Basement – Best way to eliminate musty smell / mildew/ mold etc

I am new to the forum. Thank you for your suggestions.
Purchased a lake house last year. The basement (see attached picture) is musty.
Looking for suggestions / products to redesign the room and clear the air.

My thoughts were to:
Purchase a dehumidifier
Purchase fan(s) to circulate air internally
Install a fan with a timer in the back wall between the 2 room to circulate air

Do I need:
a dehumidifier
a combination of fans to circulate the air
to exhaust bad air to the outside / bring fresh air inside

Here are some facts:
Total SF = 682

In Green building techniques | Asked By D Moye | Sep 30 16
17 Answers

Damp between insulation and exterior wall

I've been trying to upgrade the insulation in our 1950's family home in Southern-Ontario and have been following some of the advice I found on this site. I have air sealed as many leaks as I could around ceiling fixtures, interior wall top plates, and the gap between the ceiling drywall the top plate of the exterior wall. I used acoustic sealant and expanding foam where applicable. I have also added some new fiberglass batts and made sure to fit them over the top plate, around studs, etc.

In General questions | Asked By Andrew Ross | Dec 14 16
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