Community: GBA Pro help

Q & A Instructions

[Click map to enlarge]

The 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!

5 Answers

OK to put rigid foam between rafters to convert a vented attic to unvented, for storage?

To all,

We live near Chicago and have a split level house built in 1959. I would like to use rigid foam to convert our two vented attics to unvented so that we can use them for storage. The rafters are 2x6, so there is 5.5" of depth under the roof deck to put layers of rigid foam into as a "stack of pancakes" between the rafters. I would also like to attach 4'x8' sheets of rigid foam (at least 1/2 inch thick) to the lower edge of the rafters to prevent thermal bridging.

Asked By Rebekah Haworth | Nov 9 16
11 Answers

I have an A-frame roof (scissor truss)

I am using 2" EPS as a baffle with 2" of vent space (I am using 2"x2" sticks of EPS glued to the underside of the roof deck for spacers). I am using "Great Stuff" to seal all the joints (where the baffle contacts the...)

I read somewhere to only put the "spacers" in the corners of the rafter space. I started this project before I read that, and I have some of the spacers more or less in the middle of the rafter space (not to one side or the other).

Any suggestions or concerns?

Please educate me.

Thank you

Asked By Jason Fuhrman | Nov 1 16
2 Answers

How do I ventilate a basement?

I live in a 1967 house in zone 6. I need suggestions on how to best ventilate our basement as we're finishing it. We want to ensure there's good air quality year round. We have central air and baseboard heat throughout the house, except the basement. The temperature is generally comfortable down there w/o AC or heat.

We've had a musty smell down there despite having no water issues, french drains, sump pump, downspouts extended from house and a 70-pint Frigidaire dehumidifier.

Asked By Masb Hroncich | Nov 3 16
4 Answers

Vapor barrier?

I have read your articles on vapor barriers and retarders and have a question about my cottage.
The basement is block wall construction (9' high) and is below grade for most of it (on 3 sides - walkout on one side which is wood frame construction on that side).
The floor is poured concrete.
We are in the 5A or 6A area of Ontario Canada.
The cottage is not air conditioned in the summer.
The block walls are spray foamed with 3" of closed cell foam.

Asked By D B | Oct 10 16
11 Answers

Retrofitting an apartment in an existing metal-sided building

Greetings and thank you in advance! I've been an avid reader of many articles on this site, and now it's finally time to put them to practical use...

I will be constructing a 700 sq. ft. apartment with a loft area in an existing wooden pole barn structure with metal siding. I have some questions on the best way to insulate the retrofitted space. Here are as many pertinent details as I can think of without burdening you with unnecessary details:

Climate Zone 3
The building is framed with 6x6" wooden posts spaced 10' apart.

Asked By John Peeper | Nov 2 16
9 Answers

Ground source cooling — no heat pump ?

I've been reading a lot of the questions and comments on different variations of ground source heat pumps, I've been kicking around an idea for while that may be unconventional because I haven't seen it mentioned yet.

My requirements may be unconventional as well, as I am interested in comfort, more that cooling, and a solution I am interested in needs to minimize its affect on the original fabric of our 1928 brick Colonial. Which I will explain.

Asked By Kurt Kiley | Oct 28 16
9 Answers

Cardboard insulation baffles

Wondering if there are any drawbacks/issues with using cardboard ventilation baffles? We made our own baffles out of foam sheathing for the last two homes we built to create an air tight insulation cavity between rafters. Needless to say it is a very time consuming and costly process, especially with a few volume ceilings.

We just experimented making baffles out of a sheet of cardboard and we think we could create, install, and seal these cardboard baffles in a fraction of the time it would take with other materials.

Asked By Bruce Miller | Mar 31 13
17 Answers

Is it possible to repair a SIP roof that is rotting?

We built an SIP home using panels from ACH Foam Technologies. The roof was installed according to manufacturers specks. The panels were OSB on both sides of expanded polystyrene insulation, about 7" thick. Block splines were installed with the prescribed Do All Ply sealant. This design had space between the lines of calk for air to move vertically. The OSB has begun to de-laminate at the seams visibly under the shingles.

Asked By Allan Poole | Sep 6 15
2 Answers

We're preparing to begin an extensive green remodel of our home

We would like assistance in locating a contractor in our area (South Florida). Please share any contacts you may have.

As a new "student" of Green Building/Remodeling, I'm invested in the success of this project for professional experience that I can use in the future.

Asked By Chanda Levy | Oct 25 16
1 Answer

Can 1.5" and 2.0" unfaced XPS be used as a continuous rafter baffle?

I am considering using either 2.0 or 1.5 XPS as a continuous rafter baffle (from soffit to ridge vent) using a 2" vent between the XPS and the the roof deck. The rafters are nominal 2x10s and the underside of the rafter will be insulated with Roxul and then covered with finished plywood with a high quality latex paint (Class II or preferably Class III vapour retarder). I have only seen 1" XPS recommended by GBA. Can a thicker board be used or is there concern re: drying to the exterior given the relative impermeance of the thicker board?

Asked By Andreas Seibert | Oct 18 16
Register for a free account and join the conversation

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