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!

1 Answer

We are in the process of retrofitting a 1949 house with a full basement in Cottage Grove, OR. We insulated the ceiling of the basement (floor of main dwelling space) with R-30 fiberglass batts. We are planning to install a hardwood floor on top of the existing doug fir subfloor, and are wondering about the best way to proceed with sealing the unheated basement space from the heated main floor. We will likely never finish the basement to be heated, as it will be used for root cellar/cheese cave. Should we put a plastic barrier under the batts? Under the new floor? Both? Or another material?

Asked By Abel Kloster | Oct 27 11
4 Answers

Do I need to tape seams in the vapor barrier and xps that will be under my slab-on-grade house foundation? I read Joseph Lstiburek's article on concrete floor problems and his assertions regarding air movement and vapor diffusion lead me to assume that overlapping the barrier would be effective since there won't be much air movement at all under the slab.

Also, tape the xps? I haven't found much in the way of tape that sticks well to it, particularly if it's cool and damp out - which is the dominant weather here now.

Asked By daniel f. vellone | Oct 26 11
9 Answers

I'm located in Portland, Maine. These questions concern a Cape Cod with a shed dormer running across the back side of the home -- 2x10 rafters, 4/12 roof pitch, with 3 feet of original 10/12 pitch left on either side of the dormer roof. The opposing side of the roof has 2x6 rafters with 10/12 pitch in full.

My plan is to apply Dow-R 2" rigid foam on the interior over the studs and rafters - 2x4 walls. I will be meticulous about air sealing seams etc.

Asked By dean manoogian | Oct 21 11
1 Answer

I am planning on using this type of rigid foam on the exterior of my house, specifically RMax Rmatte Plus 3. It says that when using under cement siding which is what I will be doing, that the white (non-reflective) side face-out. This will be applied to OSB/Plywood without housewrap. I know there is some controversy here, but I don't feel housewrap will perform properly in my remodel since I am doing it sort of piece by piece, so overlapping some areas would be difficult.

Asked By Adam Croft | Oct 27 11
6 Answers

This is in an older condo complex located in a ski resort. I have no way to add insulation on the roof.

Could one add rigid Polyisocyanurate (ISO) panels on the inside. In between the exposed trusses. Is that realistic? I don't know how to attached them to the ceiling. Quite sure glue wouldn't be strong enough.

Click to see ceiling:
http://inc.mlxchange.com/INCimages/160/940192_G01_22.jpg

Any suggestions?

Asked By pete rosegardner | Oct 25 11
3 Answers

Those who have been following the stories about smelly spray foam may be interested in reading an interesting post on the Up Hill House blog maintained by Larry Burks and Jill Burks of Cambridge, N.Y.

In their latest post, "Friend or Foam," they write about problems encountered with a DIY two-component spray foam kit they used to insulate their rim joist.

Asked By Martin Holladay | Oct 26 11
5 Answers

I want to insulate the attic of a house that currently has one layer of fiberglas batts installed. The attic isn't easy to navigate, since the roof is held up by numerous trusses. Would it be permissible to have a contractor blow in cellulose insulation over the fiberglas batts? Or does this create problems? Could spray foam be installed over the batts?

Many thanks.

Regards,
Bob Kozma

Asked By Bob Kozma | Oct 26 11
8 Answers

Foam insulation was the miracle insulation for green builders.
Now it has a bad rap because of the amount of oil used to manufacture foam.
Does anyone know how much oil is used to produce the varios types of foam?

Would like to put in perspective what the foam really costs.

Asked By Richard Patterman | Oct 25 11
6 Answers

We are planning to upgrade the insulation in only the renovated areas of the house, with either foam or dense-packed cellulose. Will the increased air-tightness in those areas force warm/moist interior air to seek equilibrium by moving through exterior walls that have not been upgraded, dramatically increasing the amount of air moving through the poorly-insulated walls and causing cavity condensation?

Asked By todd Stanley | Oct 21 11
3 Answers

Guys

Can someone educate me on typical heating costs for a semi-detached vs completely detached home? I'm considering two homes and both are about 2000 sq feet. I've heard the average in this area in NYC during cold months is about $500/month for detached homes but can't get a number for the semi-detached. The broker told me it will be 1/2 or 1/3rd of a completely detached home but that seems hard to believe

Does anybody know if having a shared wall saves you that much in electricity costs?

Thanks

Asked By sam dhak | Oct 25 11
Register for a free account and join the conversation


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