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4 Answers

Insulation behind a gas fire place?

Have a client that has a high level of air infiltration from behind their gas fireplaces. The house is insulated but behind the fireplaces the brick is exposed and the area along the floor is unsealed.

Can I add ridged foam to the back wall of the fireplace, seal with foam around the edges and then cover with drywall?

Do I need to work about a vapor barrier in this space?

This area seemed to be missed during inspections when the house was renovated and the draft will extinguish a candle outside of the fireplace.


In General questions | Asked By Charles Juris | Oct 28 10
5 Answers

Insulation question: knee walls, roof, or attic floor?

Hello, I am working on a new construction Passive-Solar house in Northern VT. The house is under 2,000 SF, 2 floors with an additional unfinished (for now) walk-up Attic and full basement. I will be using the 10-20-40-60 rule for insulation (perhaps more). My question: should I insulate the roof of the attic and knee walls instead of the Attic floor since it eventually might be a finished space?

In Energy efficiency and durability | Asked By Daniel Morrison | Oct 29 10
5 Answers

Bonus room over garage

Other than the additional square footage, there is nothing "bonus" about this room. It is unusable in summer and winter. It is of typical design...small flat attic above 8' flat ceiling in center of room that contains R-30 batts; sloped ceilings following roof rafters that are only R-19 and do not have continuous air chutes (therefore the side attics are not connected to the upper attic for ventilation purposes); side attic areas with the knee walls being non-backed and insulated with R-13 batts. Knee walls are only 3' high, so the side attics are largely inaccessible due to ducts etc.

In General questions | Asked By Chris Brown | Oct 27 10
5 Answers

Are two layers of exterior foam better than one when the total thickness is the same?

I plan to install 2" of foam. I can get 1" tongue and groove XPS for about the half of the price as 2" flat edge XPS, so the cost for 2" thickness is about the same, except additional tape and my labor to install.

Are two layers better than one? If so, why and how significant is the difference?


In Green building techniques | Asked By Trying to Learn | Oct 27 10
10 Answers

Installing a roof over unvented attic/cathedral roof?

We are having a debate on best installation details for a nonvented roof assembly. CZ4b
1. One part is over a cathedral ceiling w/ 2x8 rafters and open cell foam and another part is attic space and open cell foam. Total insul: R38+
2. We agree on using 1" of rigid foam over the roof sheathing for thermal bridging.
3. We disagree in installing a second sheathing on top of the rigid bd.
4. We disagree on roofing material: shingles vs. metal or tile.
Are there any shingle manufacturers that allows shingle roofing installation over an unvented roof assembly?

In Green building techniques | Asked By Armando Cobo | Oct 27 10
50 Answers

Tankless Hot Water Heaters

OK, this one has me really scratching my head.

The big green selling point has always been saving storage tank losses....why heat water when you are at work or sleeping? Save energy by only heating the water on-demand.... instantaneously, when you need it. Wow, that make great sense. Sign me up.


In Green products and materials | Asked By Conrad Welch | Nov 4 09
9 Answers

Tight Home Problem

I am working on a retrofit of a 1400 sq ft home. We sealed the home pretty tight using a variety of typical weatherization measures. The home now measures 0.1 Natural ACH, 2.1 ACH50, or 732 CFM50.

In General questions | Asked By Ron Flax | Oct 25 10
14 Answers

Cellulose Hot roof application?

I am trying to build a super or well insulated workshop with upstairs room. The main story are walls made from ICF, the upper are trusses with "room in attic" setup. It has a steel roof on purlins. with the top chord of the trusses being 2by8 and 2by4 purlins (stood up) i think i have created a decent amount of space to insulate. i was hoping that this would mitigate issues with the sloped part of the wall ( this area in my house, a cape cod, seems to be problematic for heat loss)

In Green building techniques | Asked By Tyler H | Oct 21 10
11 Answers

How do I stop moisture between foundation and slab?

I have a homeowner who is having moisture issues in one of her bedrooms. Everything we build now has a capillary break and vapor barrier under the slab and a WRB on the exterior sheathing of the home, but this one, like hundreds we've built over the years and countless thousands in our market doesn't have either. This home has a pier and grade beam foundation with a floating slab on about 16 inches of fill sand.

In Green building techniques | Asked By James Fincher | Jul 20 10
6 Answers

to add or not to add, that is the question

I am finally getting around to making the attached garage of my house into a den. I knew it was 2x4 framing and assumed it was uninsulated. It had been my intention to remove the existing drywall and add 2" rippers to the studs and fill it with R-19 batts (properly installed). Imagine my surprise to to find R-19 batts already in the 2x4 cavity and properly installed to boot! With the paper stapled to the face of the studs! The question is whether consensus would say it is most cost effective to leave it alone or whether I should stick to my original plan and firr out the studs.

In GBA Pro help | Asked By kim shanahan | Oct 25 10
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