Q&A: A Forum for Green Building Experts and Beginners

Q & A Instructions

[Click map to enlarge]

The GBAGreenBuildingAdvisor.com web site has a wealth of articles on a wide variety of construction topics. Before posting your question, you may want to check out the articles on this page: How To Do Everything. You just might discover an article there that provides the information you seek.

Please register for a free account or sign in to ask and answer green building questions.

If you want to post a question, the usual rules of courtesy apply:
1. Be nice.
2. If you can't be nice, be polite.
3. If you can't be nice or polite — well, please be brief.

To attach a photo or illustration: Under the box labeled “More explanation,” look for the words “File attachments.” Click that, and you should be able to attach a photo.

Thanks for joining the conversation!


1 Answer

Attic open-cell foam: off-gasing / odor

We have a traditional 1966 two story home, dual-zoned home in Atlanta (zone 3A). On April 18th we had our existing inadequate fiberglass insulation removed and open cell foam installed in our 1200 sq ft attic. We have had odor / off-gasing problems since. On cool, cloudy days it’s not very noticeable but on hot, sunny days the odor is quite pronounced and our second floor A/C (handler in the attic) is not usable as it blows in the odor/gases. We’ve been living with open windows and fans upstairs since. The odor is closer to the paint-like I have read about, not the fish-like.

In Green products and materials | Asked By User-7075353 | May 22 18
12 Answers

Exterior Insulation on Cinder Block Walls

I have been through many articles talking about exterior insulation techniques, and insulating the exterior of foundations. My house is a little unique, and I'm hoping that someone can offer some insights/guidelines on how to handle things.

In Green building techniques | Asked By Jameson Taylor | May 18 18
11 Answers

Attic ventilation needed for a 100-year-old slate roof in a coldish climate?

Hi all,

First time owners looking at 100 year old house in NE US (climate zone 7).

Beautiful slate roof, very steep (making the attic much smaller than 1300 sq foot footprint of house).

Attic is totally not vented.

Inspector said to look into venting it to help roof last longer.

My question is, it’s lasted this long (I’m sure it’s had repairs along the way) is it safer to leave as is or look into venting?

In Energy efficiency and durability | Asked By slateandall | May 21 18
12 Answers

Water heater pad

My HPWH is going in a tall crawlspace and I want to protect the base. Since it is going in before the crawlspoace is conditioned, I was thinking about using a condenser pad, but most of those top out at less than 400 lbs or load and my water heated will weigh roughly twice that when filled.

I found the Insulfoam water heater pad, but it is not available online from what I can tell.

What alternatives are there?

In Energy efficiency and durability | Asked By Norman Bunn | May 17 18
10 Answers

Water Testing After Pex Repipe

I live in South Orange County, California, a repiping companies paradise. A massive amount of newer homes are being forced to repipe due to copper failing and slab leaks. The pinhole leaks begin developing between 8 to 15 years after the home is built and sometimes sooner. The theory according to most is that the builders went cheap and installed copper M in the homes, while the water company uses cholormine which the Copper M can’t handle. Most repiping companies will recommend PEX A, but also market USA made Copper L for the repipe.

In Green products and materials | Asked By JohnZ99 | May 16 18
4 Answers

Tyvek over foil-faced polyiso

I was looking a the spec sheets for foil faced polyisocyanurate and it gives an R value for the foam and then a R value of the foam with an air space. For example, the 3/4" foam has an R value of 5, but the R value of the foam with 3/4" reflective air space is 7.5. If I'm installing foam, covered in Tyvek then 3/4" furring strips with siding, do I have the reflective air space to get the R of 7.5 since the Tyvek is directly over the foil facing?

In General questions | Asked By E247 | May 19 18
4 Answers

Debating cavity insulation

I'm starting a house build in New Brunswick (Climate Zone 6A). My planned assembly has 3" of EPS foam on the exterior (3" Silverboard XS). I've already bought the Silverboard, so there's no going back now.

To please the local code officials, I will be installing Membrain on the interior.

In Energy efficiency and durability | Asked By Chris Burpee | May 18 18
2 Answers

Comfortbatt/Rockwool/Roxul and temporary compressibility

I have some framers coming tomorrow and have a basement wall being constructed inside the existing wall so as to insulate inside the stem wall. I'm planning on using rockwool comfortbatt at the bottom of the wall to allow for some breathability of the stem wall.

Will I be able to squeeze the 5.5" comfortbatt through a 3-3.5" wide opening (it will expand to full size, once in the wall)?

It hard to tell if it can compress that much, even intermittently, though I'm guessing so.

In Green products and materials | Asked By rossn1 | May 20 18
2 Answers

Over my head

I'm new to this forum, so I hope this is an appropriate question. I'm at the planning stage for a gut rehab of a ~2500 sq ft home in Boston, MA (which I think is zone 5). We're going to be completely rebuilding the envelope and replacing all the systems. We will have 14kW of solar on the roof.

In Mechanicals | Asked By Bradslees | May 19 18
1 Answer

Does the roof sheathing side in the attic space have to be insulated?

in some rooms in the upper levels there is attic space with an access door. I realize that the walls which are against the liveable space have to be insulated, but does the side with the roof sheathing have to be insulated? This is the side where the roof shingles are attached.

In Building Code Questions | Asked By C D | May 19 18
Register for a free account and join the conversation


Get a free account and join the conversation!
Become a GBA PRO!