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

[Click map to enlarge]

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

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!


18 Answers

Closed crawlspace with dehumidifier and foundation insulation

I am still in the planning stages of building my new house. I would like a closed crawlspace (I'm in a mixed humid climate) with a dehumidifier and foundation wall insulation. See page 35 (which is actually page 41 on the pdf page counter) http://www.advancedenergy.org/portal/crawl_spaces/pdfs/Closed%20Crawl%20... for a sample design of what I'm going with. I have two main questions about this design choice:

Asked By Michael Geoghegan | Oct 27 14
3 Answers

Half insulating a stone basement?

It's been a long road and we are almost ready to move in to our project. I tackled the two part plaster myself with nice results but now it's getting cold. My basement is typical fieldstone 1880 style and the house is in Zone 6b. The foundation is about 4' underground and 2' exposed with a 10x10" fir sill plate beam. I have read the building science articles about completely modifying the basement but that's not in the cards and is another massively expensive project I cannot tackle at the moment.

Asked By Geoffrey Cook | Oct 31 14
4 Answers

Minimum R-values for exterior foam for 2x6 walls

I am building an Arctic entry with 2x6 walls, what is the minimum R-values for exterior foam over my OSB sheeting and house wrap to reduce the chance of moisture accumulation in the walls. I live in Wasilla Alaska, which is zone 7 with about 10,500 Annual Heating Days.

After completing the Arctic entry plan on removing siding and retrofitting all outside walls.

Thanks, all help/info will be appreciated

Craig Steinman

Asked By Craig Steinman | Oct 30 14
5 Answers

How to seal 4" EPS foam at slab edge (radon concerns)?

Basement concrete 4" slab to be poured on top of 10mil poly, 4" EPS (2 layers staggered seams), and gravel at bottom with perimeter drains connected to vertical radon vent pipe. Building in a high radon zone, will the poly be sufficient covering the 4"x4" foam perimeter strips not covered by concrete at the slab edge? Should I be tapering the foam edge instead of keeping the full width of 4"x4" strips?

Asked By e c | Oct 29 14
4 Answers

Pipe leak in basement

I am finishing my basement. So far i have installed on the floor a layer of plastic, 1" of XPS insulation taped at the seams, and then a floating subfloor. Yesterday one of my pipes sprung a pinhole leak. The water ran down the wall and got stuck between the plastic and the foam. It ran to the other corner of the basement where my sump pump is located. I can lift up a little bit of the subfloor and insulation in one corner to dry it out but most of it is impossible to move without tearing it out.

Asked By Andrew Sirianni | Oct 31 14
4 Answers

Foam insulation question for 100-year-old brick home

The attached illustration depicts the current condition of my wall. The plaster and the lathe is currently removed from the wall.

What I'm thinking of doing is spraying 1/2 to 1 inch of closed-cell foam along the inside of the stud and on top of the sheathing, which will serve as a vapor barrier. The remaining space will be filled with fiberglass insulation, and topped by 5/8-inch of drywall and latex paint.

Another option would be to spray low-density insulation between the brick and wood sheathing by drilling holes in the sheathing.

Asked By Wes Leland | Oct 30 14
8 Answers

PERSIST vs REMOTE vs SIP ?

We are building a new house in MN (6b), considering various wall systems, and trying to get a handle on the pros and cons of each. Thus far we have:

SIP Pros
- Better known construction method, easier to find carpenters, ...
- Well documented construction details

PERSIST Pros
- Seems like it would be easier construction than SIP.
- Easier to get all details correct.
- Provides significant interior space in attic for ducting, extra room, storage areas, etc.
- Chemical elements (foam, osb, etc) on outside of air/vapor barrier

REMOTE Pros

Asked By Walker Angell | Oct 21 14
10 Answers

Steel frame home insulation

Climate zone 2
Ventilated Attic
We plan to use 3" polyiso on exterior walls, taped, with an air gap and steel lap siding.
Plan is to use 6-8" of polyiso on attic floor, and also putting HVAC system in conditioned space.
Radiant barrier on purlins with metal roof.

I'm looking for comments, concerns and advice on whether this amount of insulation is adequate?

or any other thoughts on this approach or things to consider with steel construction.

Thanks

Asked By J B | Oct 28 14
9 Answers

A very low addition...

We've been contracted by a repeat client to build a small dining room addition (11' x 12') attached to a contemporary ranch in Maine. Due to very difficult access issues, the addition has to be supported on sonotubes. Bottom of joists (2x10 with fg batts) will only be 2-3 inches over grade.

Asked By ron letourneau | Oct 29 14
2 Answers

Paint exterior before rigid foam?

Zone 2...1962 block one story house...bare painted block is interior look. Installing 2" exterior ridged foam..
The question....since the foam is a vapor barrier do I need to seal the block prior to foam installation.
House has a couple coats of structurally sound paint...but could use a repaint.

Asked By Robert Brown | Oct 31 14
Register for a free account and join the conversation


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