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!

10 Answers

Feedback on this sill insulation overlay detail

So I'm considering changing using this detail instead where the insulation covers the sill and comes down to the top of granite veneer, while inside the foundation the interior insulation comes up between the joists. It sounds like a typical basement detail - but it's fairly unique because of the granite veneer and the way I insulated in front of the joists, by using a shelf on the inside....it's decision time reaaaaal soon - so thoughts - criticisms - whatever!

In General questions | Asked By Brad Hardie | Jun 21 15
2 Answers

Why my hall is so hot?

My house is double floor house.. our 2nd floor hall is soo hot but other rooms are quite cool.. the length of the hall is kind of less to rooftop
The sunlight hit the rooftop n makes our hall soo hot than outside temperature.
Is there any way tu cool down the hall without any reconstruction?

In General questions | Asked By Shahir Ahmed | Jun 22 15
4 Answers

Spray foam advice

Hi All,

In Energy efficiency and durability | Asked By Joe Pavia | Jun 18 15
2 Answers

REMOTE house construction technique

The REMOTE house construction technique outlined here,


brought to mind a question:

In Energy efficiency and durability | Asked By Brian W | Jun 21 15
1 Answer

Another "How to insulate this old house" question

I am in Louisville, Ky; climate zone 4A. I have a 115 year old 1.5 story house with gambrel roof and have obtained a ton of detail from this site on how to insulate behind and under knee walls, etc. while maintaining a ventilation channel.

In Energy efficiency and durability | Asked By Jason Hartlage | Jun 22 15
4 Answers

Insulating the Interior of Poured Basement Walls

This picture is from building science.com and shows an ICF foundation with insulation under the slab. My question relates to the interior wall plane where the floor slab meets it. Does the code require that the slab make physical contact with the concrete wall? If it does, how do code officials deal with situations like this one with ICF foundations? I wanted to have a similar insulation setup on the interior with poured walls. Prior to pouring the floor I would lay rigid foam along the ground and up the wall - thermally isolating the slab.

In Building Code Questions | Asked By Brian W | Jun 21 15
17 Answers

Distance of exhaust fan wall cap from windows and soffit intake vent?

How close can a wall cap for a bathroom exhaust fan be from a soffit intake vent?
I'm trying to efficiently vent a 2nd story bathroom without sending the moist air right back into the attic and I don't have a lot of options as far as placement is concerned.

In General questions | Asked By Joseph Moore | Jun 1 15
2 Answers

Trade offs of closed-cell foam between roof rafters

Hi All,

In Green building techniques | Asked By William Duerr | Jun 20 15
8 Answers

Use PERSIST and put the WRB inboard of the sheathing OR use PUR nailbase panels and put the WRB outboard?

I'm insulating my house on the exterior - the design currently call for 9" of Neopor with the WRB against (Prosoco - spray/roll-on ) the sheathing. The Neopor is outboard of the sheathing. 9" is a lot - but gives me the R-40, without having to use any insulation on the interior. I'm getting a great price on the Neopor.

Just yesterday someone suggested PUR Nailbase panels instead of Neopor. PUR is a (polyurethane) panel, and would reduce the size of the overall wall thickness, is vapor impermeable, and fire resistant -higher embodied energy though .

In General questions | Asked By brad hardie | Jun 19 15
36 Answers

Wet basement OSB sheathing

I want to do my walk out basement over, but the area sitting on top of my foundation which is 6" studs with OSB sheathing gets cold. If I use batting insulation it drips wet, even with humidity at about 50.

It's new construction, I should mention.

In Energy efficiency and durability | Asked By Neil Cicciu | Feb 6 15
Register for a free account and join the conversation

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