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!


68 Answers

Why haven't steel-framed homes become more popular?

I am in the planning phase of building a home in the NJ-NY area, Climate zone 5. As I investigate my options; SIPS, double wall stick 2x4 wood, 2x6 wood, ICFs, CMU, Larsen trusses, etc.. and the myriad of permutations to insulate each one (spray foam, cellulose, hybrid batt & flash, exterior rigid foam/iso panels, etc....) I came across STEEL. My goal is as high R-value as I can get within reason $$, with hope of upwards of R-30 final values. That said, I need some objective input.

Asked By Sal Lombardo | Dec 27 12
9 Answers

Insulation options?

Zone 3 remodel (gutted)

Please help decide how to finish off the insulation on the inside.

from the outside
zip r6 sheathing
1" xps
block wall

essentially r11 on the outside of the block.

I have started to put 1" xps on the interior of the block wall and 1" furring strips... I am realizing that this is taking up 2" of space... and I have the ability instead (and probably a lot easier) to just frame a 2x4 wall on the inside instead.

I am spray foaming the roof deck with 8" of open cell.

Asked By Dean Sandbo | Jun 22 16
12 Answers

Eastern Canada 'pretty good house' Insulation strategies

I've read so many articles my head is spinning. I'm building in New Brunswick Canada which appears to be equivalent to your climate zone 7. I'm endeavouring to build a pretty good house meaning efficiency to the point of diminishing returns aka maximum value. One of the major challenges I have here is reconciling good building practices I'm reading about here with the capabilities of local contractors. With that said, I have a few questions.

Asked By Barry Reicker | Jun 14 16
11 Answers

Mini split advice

Climate Zone 5, Oakland County Michigan, building starting in July
2357 sq ft ranch, 2357 sq ft walkout basement.
2x6 walls dense pack cellulose, 3 inches exterior mineral wool
R60 ceiling insulation
Superior wall foundation for backfilled walls
R 7 Windows from Klearwall
Have access to natural gas but prefer to go electric if possible.

Thought I'd try and get your thoughts Dana and others on our Heating and Cooling plan. We just had a Manual J calculation done:

Total heating required including ventilation air: 37,561 Btuh

Asked By Brian W | Jun 22 16
2 Answers

Crawl space drainage

The best I can tell there is a spring (seep) under my house.

This is not an uncommon is our area. Most everybody has a spring or seep in their yard or around the foundation or both.

Asked By Eric Dolly | Jun 23 16
3 Answers

How to calculate soil heating storage capacity?

I need to know how much heat in BTU can I store in a specific volume of a soil. I am using the underground soil of greenhouse as thermal mass storage. Right now I just know the volumetric heat capacity. But I want actual number of BTUs that I can store inside the soil. Do I need to measure the temperature variation through out the soil and then calculate the heat storage capacity?

Asked By Siddharth Patil | Jun 23 16
5 Answers

Insulate on top of rigid foam?

We insulated the concrete walls of our basement with 2" rigid foam XPS insulation. We taped and caulked seams. Our insulation contractor says it meets code as is (R-10) and we studded it out and plan to drywall it. Some of the space is finished but most of it isn't. One wall is partially exposed to air on the exterior. Should we add in some mineral wool or dense packed cellulose between the studs? We have mainly dense pack netted cellulose and mineral wool throughout the rest of the home. Thank you!

Asked By Kara English | Jun 22 16
12 Answers

Does anyone have experience with Zehnder ComfoFlex?

We are building a new house and in the final stages of design. The design includes an HRV and Zehnder ComfoTube looked great until I discovered that it is not UL listed. So, I'm curious if anyone can provide feedback on ComfoFlex. There isn't much on the intertubes...

Asked By Trevor Fontaine | Feb 9 16
11 Answers

Sizing a whole-house fan for a larger house?

Hi All,

Considering a whole house fan for our soon-to-be-built "Pretty Good House" in Central KY, zone 4A.

The house is on the larger size, and the calculations for the type of WHF I need are off the charts in terms of what is available in the marketplace (I assume), what I have attic venting for, etc.

So, keeping in mind that the fans in the marketplace are about, say, one third or one half the size it needs to be sized correctly, is there still a benefit to including one in our build?

Asked By Clay Whitenack | Jun 21 16
3 Answers

Notched I-joist fix

We had a plumber notch our new home's engineered i-joist when installing a tub drain. We were furious but that is besides the point at this time. We are attempting to get it repaired.

Per the building inspector's recommendations, we contacted the joist company. They suggested cutting a 13" section of the damaged part of the joist and heading it off with smaller i-joist sections attached perpendicularly onto the two adjacent i-joists.

Asked By Kara English | Jun 22 16
Register for a free account and join the conversation


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