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!


5 Answers

PEX heat transfer plates - extruded or sheet aluminum?

We're retrofitting an existing house with under-floor radiant heat. From my research, it seems clear that we should install aluminum heat transfer plates, but I haven't been able to determine whether it's worth investing in the extruded aluminum C-shaped heat transfer plates over the sheet metal (omega or U-shaped). Even when buying in large quantities, the extruded plates are about 3x more expensive than the sheet metal plates.

In Energy efficiency and durability | Asked By Alison N | May 10 17
3 Answers

Perimeter slab insulation floor coverings

We are looking at installing a gypcrete slab over 1.5" XPS to be finished with a tile covering in a laundry room and engineered wood in the adjacent rec room. The rooms are below grade in a basement with no water intrusion issues (new foundation with excellent drainage). We are very wary of heat transfer around the perimeter as there is a wine cellar in an unconditioned room adjacent to the laundry room. We have been advised to put a perimeter of 2-3"+ of XPS around the perimeter of the gypcrete slab to prevent heat transfer.

In General questions | Asked By User-6828204 | May 10 17
16 Answers

Insulating an old non-supporting brick wall

I am currently restoring a home from the late 1800s. The front brick wall is not load bearing, but given it's age it's also not built to current standards. There is the brick veneer, and then the interior framing (with a fair bit of gap between the two).

I read the articles on insulating load bearing brick walls and the article discussing Zarring homes bankruptcy, but neither article really hits on my specific situation (non-load bearing, old wall assembly).

In Energy efficiency and durability | Asked By Matthew Hicks | May 8 17
6 Answers

Ducted mini split sweating

Hello, I'm in zone 2A and recently had a 2 zone ducted Midea minisplit installed. The system is running well except for some sweating issues on hot/humid days.

I have 4 registers where airflow must go through a 14x5.5" joist space, 6" flex duct is joined to the end of custom made metal boxes insulated with R4 on the inside, R6 flex duct is joined via a metal collar on the end of the box, the end is insulation only (no metal).

In Mechanicals | Asked By Jimmy Black | May 9 17
1 Answer

Do I need a product like Hydrogap between the basement wall and the foam board insulation?

Mystic CT NZE house. I am applying a foil faced polyiso board (2.5") on concrete basement walls. Do I need a product like Obdyke Hydrogap between the basement wall and the foam board insulation?

In Energy efficiency and durability | Asked By Courtney McCracken | May 11 17
20 Answers

Properly installed can light vs. surface mount

I am doing more research in lighting after an earlier question and reading other articles. The general consensus I am seeing is: Can lights are evil. The logic? Because of air leakage.

In General questions | Asked By Nicholas C | May 1 17
8 Answers

How to spec high performance windows?

So I've done quite a bit of reading on windows. I'm finishing up the details of a high performance home build in Ottawa, Ontario (Zone 6a/7a equivalent), and need to get my window performance nailed down before I can have a Manual J completed.

In General questions | Asked By Lance Peters | May 9 17
2 Answers

Horizontal steel siding on house

We are going to be applying 6" of polyiso foam to the outside of our house. It will likely be 3 layers of 2" material. I have concerns related to the potential waviness of the siding plane. The steel siding, applied horizontally, seems to be very unforgiving. Has anyone tried this? And with what success?

In Green building techniques | Asked By Steve Young | May 10 17
14 Answers

Hot water tank under basement floor?

I have been planning on putting a water tank under the basement of a construction house in Zone 6B. The purpose is to give me a versatile way to store heat.

The heat could come from many sources including capturing the heat from waste water, active, or batch solar hot water, or a heat exchanger on the Masonry wood stove.

The heat could be used to temper the cold water before it enters the hot water heater, heat floors, or preheat EVR air.

All of this is for future use. I just think it makes sense to put it under the floor since it is doable.

In General questions | Asked By Jim Sweazey | May 9 17
1 Answer

What is a good and resilient approach to weatherizing a log home?

I recently audited a log home in central Vermont (climate zone 6). Unsurprisingly, it was really very leaky (19ACH50). The client is willing to go fairly deep with regards to weatherizing the home, and we both agreed that a reasonable approach seemed to be building a 2x wall inboard of the existing logs and filling the stud bays, including a varied amount of space behind the new stud wall. I would prefer to hold the new stud wall at least an inch off the logs, if the lose of interior space would be acceptable.

In Energy efficiency and durability | Asked By David Bailey | May 9 17
Register for a free account and join the conversation


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