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!


3 Answers

Final Countdown, will 2" Foam be worth it for me?

Hello all!

I have been asking questions and researching energy efficiency for the past two years. Finally I am getting around to building my own home and will be installing, or not installing, rigid foam in the next couple weeks!

My house build is financed mostly by a construction loan.

  • I have calculated $2,380 in the cost of rigid foam
  • $160 in material to bump out window and door openings 2"
  • $80-$160 in Aluminum
  • $300-$500 for labor to get Aluminum fabricated for the bottom
  • $40 in cap nails
Asked By Nicholas C | Jul 28 15
1 Answer

Feedback on 2 X 8 exterior walls w/2 X 4 studs in the bays to limit bridging. Cellulose ins.

I live in Eastern Washington, Zone 5 A. 100 degrees in the summer to zero in winter with 1-3 ft of snow. I will hopefully be building a home this summer, 2016. I originally looked at SIPs but am convinced that if they are not installed perfectly I may end up with moisture problems later on. My brother suggested 2 X 8 top and bottom plates with 2 X 4 studs, (1/2 inch gap between them to break the thermal bridging), and blown cellulose insulation. Then two separate pieces of 1 inch ridgid foam insulation on the outside.

Asked By Thomas Flanagan | Jul 28 15
0 Answers

Question about insulating foundation Superior Walls

Hello,
We are planning our new home in Illinois (border of Zone 4 and Zone 5). The entire exterior will be EIFS. The majority of the basement will be finished. The east wall of the basement will be a walkout, which we plan to have wood-framed. We plan to use the Xi Superior Insulation walls for our foundation, which adds 2.5" of Dow Styrofoam to the original Superior Walls for R-12.5. Here's a note from their website about the walls:

Asked By Kevin Hoene | Jul 28 15
4 Answers

Flogging the half dead vapor barrier horse…

At the risk of being heaped with much deserved abuse I have a yet more vapor barrier questions.

I am in the process of designing my new home and have settled on a double stud wall construction with a load bearing inner shear wall, a sheathed 2x3 framed outer wall and dense cellulose insulation.

Asked By L. M. | Jul 26 15
13 Answers

Insulating a wall that is exterior on 2nd floor, interior on 1st.

I hope the topic of this question is understandable. Imagine a floor plan that is a simple 2-story box (ie, 40x40) that has a single-story wing to one side. The common wall between the main structure and the wing will be both an interior (1st floor) and exterior wall (2nd).

Asked By Clay Whitenack | Jul 28 15
4 Answers

Pretty Good House in Iowa

I am planning on building a "pretty good house" in the MidWest (Des Moines). After throwing around ideas on different wall structures (double stud, 2x6 with wet blown cellulose and rigid foam exterior), I'm curious what the prevailing thoughts are on building a 2x4 wall (16" o.c.) with 1/2" exterior plywood sheathing. 2" rigid EPS would go exterior, with WRB being Tyvek, then furring strips and hardi-plank siding.

Asked By Thomas R | Jul 27 15
8 Answers

Insulation for 1:12 standing seam metal roof

Hello all,
Newbie to GBA but we are interested in building an efficient home. We live on the edge of zones 4 and 5 in Illinois. 100% of the exterior will be EIFS. The plan is for our exterior walls to be 2x6 with cellulose in the cavity and rigid foam over the sheathing.

My question is about how to ventilate our standing seam metal roof (1:12 pitch). Our architect didn't seem to have a good grasp on green building techniques.

My questions to architect:

Asked By Kevin Hoene | Jul 22 15
0 Answers

How much energy does the evaporator coil waste?

While working through Manual D calculations I was surprised at how much of the total static pressure from a blower motor is dropped through the air conditioning evaporator coil. In my case I had a drop of .3 iwc at the coil for a total external static pressure of .7 iwc at 990 cfm. That's almost half of the blower load being used to push air through a coil that in my climate (zone 5) is just in the way most of the year.

Asked By Jonathan Dalton | Jul 28 15
3 Answers

Insulate ducts in conditioned basement?

I have been air sealing my ducts as best I can with mastic. I now have the first 4 feet or so of supply duct from the furnace sweating pretty good whenever it's on. This is all in the basement, which we use as another family room like area, don't use it as much as the first and second floor, but a fair amount.

In the summer it's freezing with the air conditioning on and the ducts sweat for a few feet, as mentioned.

In the winter, however, it's still a little chilly, certainly not overly warm.

Asked By Jeremy M | Jul 27 15
6 Answers

Is a ductless minisplit appropriate for a house with primary wood heat?

Hello,
I am contemplating installing a ductless mini-split heater in our new build house in Southeast Alaska. The climate is of course very wet, with fairly cool summers and fairly mild winters with the occasional cold snap.
We heat primarily with wood. Is a mini-split heater an appropriate choice when the wood stove is expected to do 80% of the work of heating? We want an auxiliary heater that will simply limit how cold the house will get while we are away for a long day or a weekend (to 50 degrees or so), but will not run at all when the wood stove is going.

Asked By Justin Smith | Jul 23 15
Register for a free account and join the conversation


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