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

Insulating a wall

Hi, I live in Toronto.Canada
Situation: I have a garage attached to my house. The wall that separates the garage to the living room, I removed the drywall and all the kraft faced insulation between the studs. The drywall on the living room side I don't want to remove because I installed laminate on the wall with a fireplace. How would I insulate this wall from the garage side? I was thinking of installing 3.5" of rigid xps inbetween the studs then re drywalling. Thank you

In General questions | Asked By Vernon Mcconnell | Oct 16 17
5 Answers

Mini-split for Phoenix, AZ Duplex?

Hello everybody,

I'm Ben and I'm new to GBA. Well, I've been reading lots of articles here and searching the Q&A, but this is my first post.

I recently purchased a duplex in downtown Phoenix, Arizona. It needs pretty much a total rehab. Most of the flooring needs to be replaced due to water and/or termite damage. This gives me the opportunity to seal the crawlspace if I want. Luckily, the exterior walls are all concrete block, so no terminte damage there.

In Mechanicals | Asked By Ben | Oct 7 17
5 Answers

Capillary break sprayed on to footer

We are pouring footers next week and have to make a decision on how to provide a capillary break between footer and foundation wall. Specs in our contract builder call for a liquid applied product to be used, with a $250 allowance for that. The idea was to apply it before drilling in the rebar, then to patch as necessary after rebar is in place.

Now my builder is suggesting that we could instead have the waterproofing contractor spray Tremco Tuff n Dri on the footer after the rebar is in place. He would do this for $250, so it's within budget.

In Green building techniques | Asked By William Costello | Oct 14 17
7 Answers

Radon fan causing increased humidity

Thanks everyone on the feedback concerning humidity and attic insulation. I have discovered the problem. After documenting the temp and RH in both the house and crawl space, I have discovered the Radon Fan is somehow bringing humidity ( outdoor air) into the building envelope. i noted the RH and temp in both the crawl and home with the radon fan running-and I did it in the evening hours so the HVAC or outdoor temps would not alter the findings- but the dedicated dehumidifier in the crawl continued to run. So here we go:

In General questions | Asked By Hotandhumid | Oct 11 17
6 Answers

I have some questions regarding insulating the roof of a detached garage

It is fairly recent construction and currently not insulated. Truss roof with 2x6 top chords 24" o.c. First floor will be used as a workshop and second floor for storage.

Planning on conditioning the space with a heat pump for heating and cooling. Located in upstate New York.

Would like to insulate the ceiling using a "cut and cobble" approach. Have done a good amount of research here and elsewhere and think I have a strategy that I'm comfortable with but would like to get some input as I haven't seen my specific scenario discussed.

In Energy efficiency and durability | Asked By Theodore Shaw | Oct 10 17
12 Answers

2,700 sq/ft house climate zone 6 R20-R27-R40-R70 7,300 HDD -1 Design temp...minisplit sizing and zones?

First of all thank you all of have contributed to this website. I've researched a lot and it's provided valuable insight. I'm designing my house right now. 2x6 framing with zip sheathing as the primary air barrier and 4" exterior polyiso R42. Basement walls will be 2" polyiso with 3.5" roxul R27 (should I increase this?. Slab 4" XPS R20, and attic R70-blown in with poly as the air barrier. The plans show sliding windows and sliding doors but everything will be single doors and awning/casement/fixed.

In Mechanicals | Asked By user-6925805 | Sep 27 17
11 Answers

Passive open-concept family home in Climate Zone 8 - Ontario

Hi All

I just finished binge listening to some finehomebuilding podcasts and heard the 2 with Martin in and thoroughly enjoyed listening. We would live in US Zone 8 being 45 minutes north of Grand Portage, MN.
Degree Day Rating (18C / 64F) 5673

In Plans Review | Asked By Kiefk | Oct 14 17
7 Answers

Help with a new home and Isokern fireplaces

We live in a new home in Mansfield, Texas. Inside, we have 2 Isokern fireplaces with Eiklor Ultimate 5 log sets. When we run the fireplaces, they do seem to generate a strong smell we are concerned about. The smell in the master is worse than the living room. The home is air tight, energy efficient, and 1 story. The 3 ac units/furnaces do have Honeywell Fresh Air intakes. The fireplaces also have fresh air intakes. The logset installer says there are no gas leaks.

In Energy efficiency and durability | Asked By Austinl | Oct 15 17
6 Answers

Ducted heat-pump water heater

CZ 3A - Greenville, SC - mixed humid

I have been reviewing some studies online regarding ducting a heat pump water heater and think it might make sense in my new house. Here are the results from the study above, which assumes a garage located heat pump WH in central Florida:

Cooling Season Savings
Indoor to Indoor 3.8%
Outdoor to Indoor --1.2%

Heating Season Savings
Indoor to Indoor -5.9%
Outdoor to Indoor -17.5%

In Mechanicals | Asked By Norman Bunn | Oct 13 17
3 Answers

Seal foam attic baffles at kneewall

I am installing the foam version of the attic ventilation baffle at my kneewalls so that I can blow in a good amount of cellulose. The online video from the manufacturer shows them simply hammer-stapling these along the trusses. Two things I notice, 1.) These things rattle like nothing else when air is coming from my vented soffit at the right speed/angle because there is nothing pinning these tight to the underside of my roof's OSB (ideally I'll have enough insulation to keep them somewhat tight) but I don't think it'll be *that* deep.

In Green products and materials | Asked By Nicholas C | Oct 13 17
Register for a free account and join the conversation


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