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!

7 Answers

Adding more insulation to damp-spray cellulose?

I've got an old pier and beam house with stucco skirting and about 1-2" of damp spray cellulose over the subfloor and joists. I was thinking that rather than deal with the complexity of keeping the closed crawlspace and conditioning or dehumidifying, that I'd take it off and add more insulation. I can't figure whether I can spray more (damp) cellulose, or whether I should just put foil afced foam over the bottom of the joists, or remove (?) the cellulose and replace with closed cell spray foam. I'm in Austin, TX - hot & humid, zone 2A

In Energy efficiency and durability | Asked By Matt Desloge | Jun 1 14
4 Answers

HVAC help!

I am a homeowner with a 3500 sq ft. home in New York. 10 years ago I purchased an American Standard 16 seer ducted HVAC system. When temperatures go below freezing I have to back up this system with baseboard heaters. Some of my baseboard heaters are newer and some are very old (and probably extremely inefficient). I would love to have a net zero house but I’m not sure if this is possible. Last year I added insulation to the basement and attic. I have solar water heater which is fantastic. I also have sunpower solar panels and wood burning stove that can heat 3000 sq.

In Mechanicals | Asked By Randi Gustafsson | Jun 9 14
3 Answers

Installing and sealing windows without a flange

Does anyone have any suggestions on how to re-install and seal windows without a flange?

These were replacement windows that were installed 10 years ago and the flange had been removed to facilitate installation into the existing opening.

We are redoing the siding and would like to re flash the windows.


In Green building techniques | Asked By Aaron Gatzke | Jun 5 14
1 Answer

Spacing and attachment of rain screen materials (specifically Sturdi-Strips)

Our wall system is double stud, the outer wall is 2x4s 16" OC with 1/2" Advantech sheathing. Siding is quarter sawn spruce clapboards (longest pieces are 6').

We are planning (and have purchased) to use Cor-A-Vent Sturdi-Strips and the SV-3 vents, this is a 3/8" rain screen gap.

My assumption is that best practice would be to:
-staple (about 1-1.5" length staples) the Sturdi-Strips in line with our 16" OC studs?
-then the clapboards would get nailed along this same interval?

In Green building techniques | Asked By Brian Post | Jun 9 14
12 Answers

Sheathing under metal roof

I Goggled this question, what lead me to this website. I read about this same topic here, I believe it was from 2012, however, the same question but for a house not a shed.

In Building Code Questions | Asked By Philip Taylor | May 29 14
4 Answers

What is the best way to weather wood artificially?

We are finishing the south side of this barn with red cedar planks reclaimed from a house where they have been in use for close to 50 years. We are using the back side of the 5.5" T&G boards (running the T&G sides~ mostly mashed from removing the boards through the table saw) ~ the unfinished boards look raw compared to the aged fir boards on the other three sides (see image) I have been looking at artificial (instant) weathering. I have come across the Vinegar+Steel wool and the Ferrous Sulphate solutions to at least get the wood looking gray and then allowing it to age naturally.

In General questions | Asked By Caroline Di Diego | Jun 8 14
15 Answers

I'm building an off the grid house with double wall construction and I'm concerned about condensation on the sheathing

My plan right now is to use double wall construction and have a catherdral roof. I'm looking for a R-60 on the walls and a R-100 for the roof. A little overkill but when you're off the grid in zone 6 too much is never enough. The wall construction I'm looking to use is from outside to in Betflex siding, 2x4 batten to create an air space, house wrap, 1/2" ply sheathing, 2x4 stud, 2" of spray-on closed cell foam, 15" of dense packed celulose, 2x4 stud, gyps (no vapour barrier).

In Green building techniques | Asked By Geoff Frood | May 18 14
11 Answers

Website repairs and the "Access Denied" glitch

Taunton's tech team has been working to address GBA's bedeviling glitches, including its defective spam filter and the dreaded "Access denied" glitch.

We are hoping that the maintenance work performed this week will reduce or (dare we hope?) eliminate the "Access denied" glitch. GBA readers who experience the "Access denied" problem are urged to report it. Your reports will help us improve this site.

Feel free to contact Taunton customer service:
or me:
martin [at] greenbuildingadvisor [dot] com

In General questions | Asked By Martin Holladay | Jun 5 14
2 Answers

Is it possible to insulate an exterior wall masonry chimney with Roxul?

I'm considering buying a small house which has an exterior masonry chimney. Would it be possible to insulate the chimney from the exterior with Roxul to reduce the tremendous thermal bridging through the uninsulated stone? I'm not particularly worried about the aesthetic downsides.

In Green building techniques | Asked By Elliot Firestone | Jun 7 14
1 Answer

Basement slab insulation

I am working on insulating my basement from the interior. I would like to install a 1" layer of EPS as shown in the Fine Homebuilding "The Stay-Dry, No-Mold Finished basement". At this point we are about to pour concrete around the perimeter of the basement where we installed a drain tile, as well as a new 10x10 slab in one corner of the basement. Is there a certain amount of time I need to let the new concrete cure before covering it with the EPS? If I have access to commercial polysio, is that ok for use over a basement slab?

Thanks for any feedback

In Energy efficiency and durability | Asked By Charles Chiampou | Jun 6 14
Register for a free account and join the conversation

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