Community: GBA Pro help

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Anyone may ask a question and anyone may answer. Sometimes one of our 15 Advisors may chime in; in other cases, you'll get the wisdom of some of our members who have some experience in this area. We encourage everyone to give us the benefit of both their questions and answers. The usual rules of courtesy apply.

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19 Answers
Urethane spray foam on exterior above grade block walls?

I was talking with a urethane spray foam installer this morning who stated numerous concerns about all other spray foam products but his - more notably open cell products. He says they do not perform in areas such as rim joists, etc. They don't belong anywhere but in stud cavities on sidewalls. Go figure. He is currently spraying my neighbors' exterior above grade block wall foundation(in addition to 4-6" below grade) wall with a closed cell spray foam. He said there was a study that indicated this is as efficient as spraying the main floor 8' exterior walls.

Asked By Mark Miller | Aug 20 10
8 Answers
Insulation of Floor above damp basement

I have a cement floored basement with some humidity in summer which I control with a dehumidifier. I am having the sills and bays air sealed with foam and am planning to add insulation to the ceiling (of the cellar" with R-19 fiberglass. THe contractor is offering 3 choices, but no advice. 1. Place batts up against the floor with vapor barrier against the floor; 2. place unfaced batts up against the floor with poly ethylene barrier stapled to the bottom of the joists; 3.

Asked By Jack | Aug 12 10
34 Answers
Spray Foam and Batt Insulation

I thought I recently read an article on the Building Science website talking about problems installing batt insulation over spray foam - moving the dewpoint to the spray foam layer and causing the batt to get moist where it meets the foam. Now I can't find it anywhere and am wondering if I understood it correctly.
Can anyone explain this to me better or point me to more information. Thank you so much.

Asked By Amanda Evans | Jun 23 09
4 Answers
What's the best way to ventilate a flat roof with an EPDM membrane?

I often design houses with low slope roofs, ranging from 1/4" per foot to 1" per foot. EPDM has been a reliable roofing material, but because of its lack of any permeability, the potential for condensation in the roof assembly is increased. One option to address this in the Colorado Front Range, seems to be to apply 2" of closed cell polyurethane to the underside of the roof sheathing and then fill the rest of the roof cavity with blown-in cellulose. This results in an unventilated roof cavity.

Asked By Steven Dodd | Apr 8 09
3 Answers
Unvented roof deck

I am finishing an existing work shop with a low pitch vaulted ceiling. There is no practical way to vent the ridge. Since it is a shop, no code applies to r -values, but we want the most we can achieve.
Here is what I am working with:
Mixed climate ( Central Virginia)
2 x 12 rafters 24" o.c. 5/8 osb roof deck, full coverage ice shield and 50yr shingles 2 1/2 / 12 pitch
~ 685 sq. ft. ceiling area
2 x 4 sidewalls 16" o.c.
Concrete slab floor ( vapor barrier or insulation under is unknown)
Sheetrock is proposed for the final wall covering
Tight budget

Asked By JTN | Jul 27 10
1 Answer
Ventilating An Underground Chamber

Given the following:

1. Location of the underground chamber is in a humid tropical location.

2. Facility is off-the-grid.

3. Chamber size is 20' x 30' x 10' (height = 10' ).

4. Sources of electricity are roof-mounted solar panels.

5. Chambers meant to shelter 6 people.

How will be the essentials of a design for a good ventilation system be like for such a facility?

Asked By Boniface Willy | Jul 23 10
2 Answers
Where does one recycle vinyl siding and other PVC waste in Connecticut?

Are there any vinyl siding and PVC recycling companies or centers located in Connecticut? Is there a source for this information because the DEP in Connecticut has absolutely no information as to where or what to do. They only list PVC as a potential recyclable material. This information would be beneficial to many builders and remodelers throughout our state and throughout New England. It should be posted at the State of Connecticut site also. Thanks for your help.
Ed Palma

Asked By Edward Palma | Apr 8 09
3 Answers
How to waterproof and insulate old foundation walls from the outside?

Is 2" XPS over dimpled membrane over blue skin a good idea? Should the foam go up all the way from footing to the rim joist which is 3' to 4' above grade? Or is it better to stop the foam at grade level? If going up is better choice, how to protect and finish the above grade portion of the foam? The foundation is 8" concrete block which is flush with brick veneer of exterior walls. Location - Ontario, Canada. Your input will be very much appreciated.

Asked By Andrei Sosnovsky | Jul 5 10
5 Answers
Permability of building materials and good data on embodied energy

Wondering whether any of you could turn me on to good sources (books or websites) for finding out the permeability of building materials....and also a good site that discusses the embodied energy of building materials...for instance, the embodied energy of different types of spray foam insulation, which I hear has huge embodied energy. Thanks.

Asked By Conrad Welch | Nov 11 09
16 Answers
Best detail for EPDM on SIP roof? Second Try

I'm surprised I didn't get no even one taker on my question. Perhaps it's because I posted it under the wrong Q&A Category (Energy Efficiency and Durability), so I'll try again here.

I will be self-contracting my own residence. SIP walls and 1/4:12 slope roof, EPDM roofing material.

Unfortunately, when I have to explain to local builder/suppliers what a SIP is, any answer I might get locally does not seem reliable to me.

So I have searched the web to find how the best approach, is but no luck yet.

Asked By Robert Car | Jun 24 10