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!

9 Answers

Brick house insulation


My situation: I have a brick house, that initially had plaster and lathe walls. With the floor joists supported by inner wythe, and the joist ends embedded in the brick. I removed the plaster and restudded the walls with 2x4s.

My concern: On the lower floor, I insulated the stud bays with batt insulation. I thought this was a good thing, however, after reading your article I think I may have been mistaken.  I am beginning work on the second story and don't want to make matters worse.

Asked By 3rd Little Pig | Dec 9 17
0 Answers

Best strategy to re-hang the ceiling drywall..?

Our basement (ground level) room suffers tremendously from the noise in the upper level where the kitchen and dining table are. Walking and moving chairs noise is very pronounced downstairs. I'd like to improve on it. We should have used resilient channel before hanging that ceiling drywall, but we did not. There are also 16'' tall floor joists - maybe the cavity even amplifies the noise? First floor is just the hardwood floor with a minimal (very thin) cork layer below it.

Asked By Lucyna de Barbaro | Dec 13 17
0 Answers

Registry of net-zero homes?

Is there a database or registry for net zero energy homes in US? I tried to ask the question of our HERS rating provider, Resnet, but so far have not heard anything back. HERS index for our home is 35 before PV, and -8 after PV. While we did not live in the house for the whole year yet, it looks like we will likely meet 12 month zero energy balance. I would be glad to call our house net-zero, and be registered/recorded somewhere as such.
On the web, I find the following:
Several organizations offer formal net zero energy certification programs:

Asked By Lucyna de Barbaro | Dec 13 17
15 Answers

1952 Cape Cod


First-time poster. In the past 2 months, I’ve read a hundred or so GBA articles and comment threads; I’ve been amazed by the expertise and generosity of the community. I’ve also read extensively at buildingscience and finehomebuilding -- I’m new to but very interested in building science. Here’s why:


Asked By Emerson W | Dec 11 17
4 Answers

Air sealing the cap of a double stud wall

I am currently building a double stud home in NH and am in the process of air sealing all exterior cracks with siga tapes. Since my builder decided to build the interior portion of the double wall after the exterior, we were left with a 4 inch gap between the two walls at the cap. We will be filling the 12 inch cavity with dense pack cellulose, so this gap at the ceiling needs to be blocked off. We decided to fill the gap with strips of plywood which has resulted in cracks on either side of the plywood filler that I'm worried may leak air.

Asked By Chris Roche | Dec 13 17
5 Answers

Workshop with dwelling above: Heating advice?


Asked By User-6964558 | Dec 12 17
3 Answers

Making sense of the first month of minisplit heating data

I have 4 Fujitsu mini splits (non xlth) hooked up to (2) 24k condensers. They were primarily for AC but I'm trying to reduce usage of my aging 199k/152k steam boiler while the temps are relatively mild (Boston). Right now I'm using a 12K head per condenser, per floor, so 2 total. Dana had some good advice as the min modulation range was about 6200 BTU/hr per unit, and to run both units, so this weather seems to be the sweet spot for efficiency and load.

Asked By Kjmass1 | Dec 12 17
16 Answers

Help selecting a heat pump

Hi Guys,

I'm going to be meeting with my builder this week, and he wants to show off the furnace of his choice, which is a Dettson Chinook. It's a small modulating natural gas unit, that can be paired with their Alize heat pump.

It's a pretty neat unit, designed to allow for very long cycle times, often measured in hours. The problem I have is that the heat pump portion kind of sucks in cold weather, it uses proprietary small high velocity ductwork, and a proprietary thermostat to control it all. It also has a short~ish warranty.

Asked By Stephen G | Dec 11 17
4 Answers

Ductless minisplit heat pump in a poorly insulated home?

Good morning,

I’m trying to find some information on the pros and cons of Ductless mini split heat pumps. (Mostly if one could work in my situation.)

My home is a 1930’s Cape Cod style home (Climate zone 4) with a full shed dormer on the front. The home is roughly 1100 sq feet. The first floor approx. 780 sq feet has an open floorplan that connects living/dining and kitchen with a sectioned off bathroom and guest bedroom. The 2nd floor approx. 275 sq feet serves as a master suite that has a sectioned off bedroom and bath.

Asked By Andy Pappas | Dec 13 17
10 Answers

Drain Water Heat Recovery

I plan to install a drain water heat recovery unit in my new home. Does anyone know of any guidelines on sizing? For example,there will normally be 2 people in the house, but on occasion that could easily double or more as we have extended stay guests (a week or even more). And we will have a 65 gallon heat pump water heater.

As the DWHR units tend to get pricey due to the copper involved, I want to make sure I get the most bang for the buck.

Asked By Norman Bunn | Dec 11 17
Register for a free account and join the conversation

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