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!

8 Answers

ZIP Window Detail with Exterior Insulation

On ZIP's website, they have window details which appear to combine the flashing/window buck of an outie window, but it is shown flashing into a WRB (in this case the ZIP sheathing) located behind the exterior insulation.

In Green building techniques | Asked By Derrick Krienert | Jan 15 17
7 Answers

Radiant bathroom floor and auxiliary heat in the master of our PGH

Hi all--I've got a couple of questions regarding HVAC in my Pretty Good House (PGH). As you may recall, I built a PGH a little over a year ago and many of you contributed wonderful advice to my queries. We had a nice discussion on how best to heat my house and I decided to go with a single minisplit and a natural gas, heater rated fireplace. This system has worked well for most of the house, save the master bedroom.

In Mechanicals | Asked By Matt Mesa | Jan 16 17
9 Answers

Exterior wall polyiso worth it?

I live in central Texas and I'm debating whether adding 3/4" Polyiso to the outside of my exterior walls. would be worth the cost. I originally planned on it, but since my wife and I are doing the majority of the work, it has come down to just not having the time (we both work full time jobs, plus a bit more), and the initial cost of it.

In Green building techniques | Asked By Jacob Cox | Jan 17 17
10 Answers

Solar powered crawl-space dehumidifier?

I live in Texas where the humidity in the summer can be quite high and where the use of crawl space vents can be counter-productive. I have installed a vapor barrier over the crawl-space soil and have blocked all the crawl space vents.

I have been exploring the possibility of of using hot attic air in conjunction with a silica-gel based dehumidifier to lower the humidity in the crawl space. The idea is to circulate the crawl space air over thin beds of silica-gel during the evening to absorb excess moisture.

In General questions | Asked By James Houston | Nov 8 16
1 Answer

Fujitsu Duct type halcyon inverter

Recently I had a duct type halcyon inverter installed. One unit is in the attic and the other in the basement. As I have read, you already addressed the issue of the indoor units set at the factory to read the temperature instead of the thermostats. This may have been a good idea with split units, but the attic unit was working too hard and the basement unit not hard enough. That was fixed when myself, and later the installer, found out that the thermostats are set at the factory to allow the ducted units to determine the temperature. After a few calls we were able to change that.

In General questions | Asked By Peter Sampieri | Jan 19 17
13 Answers

Exterior Rigid Foam Under Sheathing?

In my local area there is a green building consultant that recommends a CI panel which is basically EPS foam glued to OSB. The way this is installed would be the OSB to the exterior. Almost every house I see with exterior rigid foam in my online wonderings is covered with blue and pink XPS, the OSB sheathing is nailed directly to the studs and is completely covered with the rigid foam. This leads me to the following questions:

- Is anyone familiar with these kind of CI panels?

In Green building techniques | Asked By Joshua Greisen | Dec 8 16
1 Answer

Help identifying roof shingles

Hi - Can anyone provide insight into what type of roof shingles are used in the two attached pictures? I like how they present thick horizontal lines, but I can't find any shingle manufacturer websites with similar looks.  I think both of these houses were in Europe somewhere.


In Green products and materials | Asked By Brad White | Jan 19 17
6 Answers

Thermal breaks for window bucks in double stud walls

We'll be buliding double stud walls for a new house, with the inner wall being structural (the outer wall will consist of modified Larsen trusses). Total wall thickness will be around 16" and windows will be "in-betweenies". This will be my first double-stud wall house and I'm working in the wall details trying to minimze thermal bridging.

In Energy efficiency and durability | Asked By Chris Chenier | Jan 18 17
3 Answers

How thick a layer of closed cell spray foam under roof deck?

Our roof has 4" of rigid board closed cell foam with OSB (Atlas Nailbase) installed above the roof deck, but the seams between the sheets of foam were not sealed, as one can see in the attached picture. For those areas I can access, I started spraying closed cell foam on the underside of the roof deck - how thick a layer of spray foam under the roof deck do I need to have for reasonable insurance against moisture condensation at the seams of the Atlas OSB??

In Energy efficiency and durability | Asked By Jim Berry | Jan 18 17
7 Answers

Could you moderate first posts to stop the flood of spam?

Recently, I haven't been reading the Q&A on GBA, because it's always full of spam. Could I suggest that you moderate the first several posts by any non GBA Pro user who hasn't posted before? The idea being that you either have to pay for a subscription or post three moderated and approved posts before you get unfettered access to the forums.

In General questions | Asked By John Ranson | Jan 19 17
Register for a free account and join the conversation

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