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3 Answers

Vapor barrier on the inside against sheet rock or outside against sheathing or both sides of rock wool?

I'm doing a rehab remodel on a house I recently bought and have the exterior walls exposed on the house. I'm trying to upgrade the existing insulation since I had to replace quite a lot of the framing to repair dry rot. I'm trying to minimize moisture buildup in the wall spaces from both directions as well as effectively insulate the house. Plus, I've been getting clobbered on utilities.

In Energy efficiency and durability | Asked By Ken Swartz | Oct 12 15
0 Answers

Recommendations for a small HRV

Hi everyone
I'm looking to buy an HRV for our small (1000 sqft) ranch home.

I already installed all the dedicated ductwork last year and had been using a home-made HRV that worked very well, but I don't have the time to keep tinkering with it to get it to work just right. The cabinet was made of plywood and I kept having problems with the air streams crossing and causing condensation and mold in the cabinet.
Anyway as a result I'm going to hook up a new HRV to my ductwork.

I'd like a small unit - I will be installing it in a closet
Quiet would be good
Also with ports on top

In Mechanicals | Asked By Carlo Giombi | Oct 12 15
1 Answer


Does anyone know of a SIP manufacturer using a low GWP blowing agent, like Honeywell's Solstice blowing agents?

In Green products and materials | Asked By Steven Gubkin | Oct 11 15
6 Answers

Easiest concealed-fastener metal roofing

Working alone, I will be covering the simple gable roof of my new house with steel panels attached to purlins 2' oc without decking. I would like to use a concealed-fastener system. The Vertical Seam panels made by Metal Sales are approved for open framing, but after reading the installation manual, I have the impression they will be a pain to install, using tons of butyl tape and tube sealant in addition to quite a wide assortment of steel parts, including z-closures that have to be cut and bent on each end by hand for each of the 78 panels I will install.

In Green building techniques | Asked By Jeff Cooper | Oct 11 15
5 Answers

Gree Mini-split heat pumps

I'm hoping Dana will weigh in on this question given his expertise with specifying and analyzing mini-split heat pumps.

There are some new heat pumps on the market from Gree that appear to approach the performance of the best units from Mitsubishi and Fujitsu. It appears to me that the cooling efficiency is right up there with Mitsubishi and Fujitsu, though the heating efficiency isn't as good. They do however specify heating capacity down to -20 degrees F.


In Mechanicals | Asked By Joshua van Tol | Oct 9 15
6 Answers

Dense pack cellulose in sloped ceilings -- need vent chutes?

I have an 1800's story and a half log home. There are knee walls on the 2nd story which have been insulated in a variety of different ways -- but most knee walls are treated as unconditioned space.

An insulation contractor proposed bringing the knee wall floors and the upper attic floors up to R50 by adding more blown in cellulose.

He proposed stuffing the rafter bays in the knee walls and dense packing the sloped bedroom ceilings (connecting the knee wall to the upper attic) with dense pack cellulose.

In Energy efficiency and durability | Asked By Andrew S | Oct 10 15
4 Answers

Insulating a crawlspace

Hi, I have a 70 yr old home built on a post and pad foundation. It is quite leaky and I'm in the earlier stages of fixing it up. I'm currently in the process of removing and replacing the skirting that runs the perimeter as it is unisulated and has enough rot to warrant its replacement. We live in southern coastal British Columbia. Winters here are rainy and only drop below freezing for short periods of time. My plan is to frame between the posts and fill with sheets of 2" xps topped with a rainscreen and cedar siding. The idea is to trap the heated air that escapes under the house.

In Green building techniques | Asked By Michael Blake | Oct 10 15
11 Answers

Moving a gas water heater into the envelope of the home...or switch to electric?

I just acquired a early 90's home and it turns out we can't get our minivans into the garage! On one side we have the HVAC equipment and on the other the water heater (both are gas). The HVAC I think we can relocate to an area of the bonus room directly over the garage so there will be minimal adjustment needed to the duct work. The logical place to relocate the water heater will be just inside on the same wall it is now which is currently a laundry room. I have never had a house with gas units inside the envelope of the home. So....

In Mechanicals | Asked By Andrew Bennett | Oct 9 15
4 Answers

Using nailbase panels as wall sheathing

I'm considering framing a large addition with 2x4 studs (actually, engineered studs) 24" OC with open cell spray foam in the cavity, with a exterior application of 2" nailbase (1 1/2" foam with OSB sheathing attached). My question is whether the nailbase will serve the lateral bracing function of typical sheathing, given that it will be separated by the 1 1/2" of foam to the studs. In other words, can I just use nailbase without adding a redundant layer of sheathing directly applied to the studs?

In General questions | Asked By David Hornsteing | Oct 9 15
12 Answers

Below grade XPS placement, protection, and detailing

I'm pouring a traditional 8" concrete foundation for a client this week. They planned to have us place 2" of XPS foam on the outside of the walls for insulation. Once they can afford to finish the basement, they would place another 2" of foam on the inside of the walls between treated 2x2s and sheetrock over it for the finished assembly.

I've attached a rough sketch of the various components.

In Plans Review | Asked By Nethaniel Ealy | Sep 16 15
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