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!

6 Answers

I have a crawl space with cold joints that are inadequately sealed and ooze water. How can I seal them?

I would like to do it healthfully and effectively so I don't have to be concerned about water intrusion in the future.

In Green building techniques | Asked By Kevin Krafft | Feb 7 16
1 Answer

Zip panels as a WRB for SIPs?

We are building our home with 8.25" SIPs made from OSB and EPS foam. I have been considering using a fluid applied WRB like one from Prosoco, Stoguard, Tremco, or the fluid applied Tyvek brand. I'm reading varying reports of their durability and have been turned off by their steep prices. For instance, based on estimated coverage, the Prosoco Cat 5 would run me around $1.44 per sq ft. Surprisingly, sheathing over the Sips with Zip system panels would be around $0.62 per sq ft.

In Energy efficiency and durability | Asked By Brian W | Feb 10 16
2 Answers

Venting in open-face cladding

We are completing the exterior cladding for the house, in climate zone 5, Pittsburgh, PA. The cladding is high density fiber cement panel, over 3x1 wood rainscreen, and per manufacture's instructions, we left 3/8'' gaps between panels, in both horizontal and vertical directions. Rainscreen wood is covered with EPDM rubber prior to installing the panels. The instructions also call for leaving 13/16'' (2 cm) ventilation gap below the roof, but spot-check inspection shows that some of these gaps were really closer to 1/4'' or even less.

In General questions | Asked By Lucyna de Barbaro | Feb 10 16
7 Answers

HVAC question

So, I am admittedly not an expert, thats why Im here :) And I know there are a ton of variables but I hope to sum this up as clearly as possible. This is all relating to heating.

In General questions | Asked By rob elzey | Feb 10 16
6 Answers

Another “rigid-foam attached to the underside of rafters” plan

This is new construction with an all hip roof with a very short ridge located in the northern part of zone 3. I’ve ended up with a large cathedral ceiling area which opens to additional living space tucked under the roof resulting in an unvented attic. Is my insulation plan workable? Might I have future water issues? Will my stack-up breathe and dry sufficiently? What issues will the trades find with the plan? is there a better plan?

In General questions | Asked By Richard | Dec 28 15
2 Answers

Can I put up 2 kraft-faced batts in a shed roof?

I have a room with a new roof and rafters, and want to install R-30 worth of insulation by installing 2 R-15 3 1/2 inch batts, is it kosher to put one kraft-faced batt on top of another? My buddy John says that is a risk for moisture buildup between the batts but I argue that the kraft paper is not a moisture barrier, There will be a baffle above the batts to allow an air channel from the front (bottom) of the shed roof (with a soffit vent) to the top (also soffit vented)


Tom in Westford, MA

In Green building techniques | Asked By Thomas Ennis | Feb 10 16
12 Answers

Basement insulation / wall framing with limited space

Hi. I'm working on a basement in a 1960s ranch in Minneapolis, all below grade, with a concrete block foundation. I've read pretty much all of the articles here about basement insulation, and I was set on doing the following: 2 inches of XPS glued to the block, then a 2x4 framed wall, and then either XPS or spray foam in the stud bays. HOWEVER...

In General questions | Asked By Jay | Jan 20 16
2 Answers

Farley Windows

I recently received a quote for double pane Farley Windows from Home Depot. There price was good, and the warranty excellent. My housing situation is I'm located on a large acreage of trees (with a lifetime supply of firewood available. I'm looking at a low SHGC window, even though I'm in Prince Edward Island, Canada, since my heat is free, but I'd have to pay for AC. I'm not looking for the world's most efficient window. I just want to get good value for my money, good warranty and be comfortable in either a hot or cold windy day sitting beside the window.

In General questions | Asked By Mitch MacLean | Feb 10 16
5 Answers

Add insulation to this cathedral ceiling?

We recently purchased a log home with a built up, vented cathedral ceiling. From the plans (left behind by original owner) and what I can tell from poking around the assembly from the inside is... open rafters - tongue and grove pine ceiling - 4 inches foil face rigid foam (foil towards TG pine) -- 1 inch airspace via prefabbed baffle -- plywood, felt, shingles. In our up stairs bedrooms there is additional TG pine on the bottom of the rafters (presumably to match the TG pine on the dormers where they are no exposed beams). See attached sketch.

In Energy efficiency and durability | Asked By John Carr | Feb 10 16
1 Answer

Drywall above stud wall framing good for fireblock?

First off, the website has been a wealth of information and a great help so thank you. I'm in the process of finishing my basement and have put 2" XPS in the rim joist section and plan to follow-up with 1" XPS on the interior walls followed by the framing in-front of that. For a fireblock, is 1/2" drywall safe in the basement to attach to the joists and then butting the top of the XPS against along with the top plate of the stud wall? I assume this would be an acceptable fireblock but not sure if the drywall would be a safe bet.

In Building Code Questions | Asked By Jason M | Feb 10 16
Register for a free account and join the conversation

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