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!


1 Answer

Old brick with closed-cell foam on interior - Exterior paint?

I have read a considerable amount about the challenges of insulating brick homes. As I am in an historic district, interior insulation is my only option. From what I have read, closed cell foam is my best bet.

My question is how to best handle bulk water on the exterior of the home. It is a rowhouse with zero overhangs. Presently the front of the house is painted and the rear is exposed brick.

In Energy efficiency and durability | Asked By Wayne Weikel | Mar 28 14
11 Answers

Fireplace vs energy-efficiency

I'm striving for a net zero house in northern CA zone 11, which I think is a zone 3B on the US map. 6 inch blown cellulose walls with 1 " outside foam, R50 blown ceiling; mini-splits on each level. Here's the issue; my wife wants a fireplace for aesthetic reasons; I would prefer a wood stove with glass front as a supplemental heat source. . She's ok with an insert in the fireplace.
Is there technology that will make the insert a supplemental heater and not blow half my heat budget up the chimney when it's not on? Blowers to get more heat output? Your thoughts appreciated.

In Green building techniques | Asked By Michael McKinley | Jan 3 13
3 Answers

Improvement of older windows...

My son's home has a "great room" with lots of window area, including two double doors to a deck (one fixed glass panel and one door), rectangular windows above each door of nearly equal size (same width, slightly shorter), and two triangular windows at apex of ceiling/roof. These are 20+ year old standard thermopane wood windows of the time (seals appear to be intact).

In Energy efficiency and durability | Asked By Howard Gentler | Mar 24 14
3 Answers

Insulate knee walls

Situation: Currently have knee walls with no insulation behind them or the cathedral portion of the ceiling. The rafters are 2x6's. Ventilation is provided from vents installed between the exposed rafter tails. Blown in insulation is currently blocking off the top of the cathedral portion. I live in zone 5.

In Energy efficiency and durability | Asked By Jim Johnston | Mar 28 14
1 Answer

Efficient roof hatch?

In a flat roof row house, I have a hatch similar to a commercial building to access my roof. There is no ceiling to speak of, save for a small crawlspace in the front. I will be insulating on the underside of the roof deck, thereby making the roof hatch an integral part of the insulated ceiling.

I have been surprised to find very little on the market in the way of an energy efficient, well insulated roof hatch.

In Energy efficiency and durability | Asked By Wayne Weikel | Mar 28 14
6 Answers

Flip the blower door?

How often are home *pressurization* tests done? The usual
blower-door run seems to be the "suck" test, looking for cold
air coming in, but it may not tell the whole story. Turning the
fan around seems to be a logical part of a "fog test", but one
doesn't necessarily want to blast fog juice all over an occupied
dwelling as even the most benign water-based formulations still
leave behind *some* sort of residue.

I'd opt for simply using warm air as my indicator. Tonight
I ran a "blow" test on my place, using my window-fan lashup

In Green building techniques | Asked By Hobbit _ | Mar 24 14
2 Answers

Window incentives / rebates?

Anyone know of any federal rebates or incentives for changing out old leaky windows for some new energy efficient windows?

In Green products and materials | Asked By Peter L | Mar 28 14
4 Answers

Best way to air seal an attic?

Just had a BPI Energy Audit and was told that they would use 1 inch of CC spray foam to air seal the attic floors and then blow in 15 inches of cellulose. Is this the best way to air seal and attic floor? Is it the most cost effective? There are ducts and an air handler in one attic space and just ducts in the other. The house is in Zone 4. Thank you.

In Energy efficiency and durability | Asked By Woody McMahon | Mar 27 14
4 Answers

Can someone tell me a few minisplit models that work exceptionally well in the colder climates?

Climate zone 6.
Approximately 1000 square foot area. Will be very well insulated. R40 floor, R60 or better roof, R30 walls with well detailed air sealing. Approx 76 sf of triple glazed windows.

The floor plan is very open, so I'm hoping one unit will be sufficient, with some electric baseboard supplemental heat in strategic areas.

This winter was horribly cold, with many days below zero, but I wouldn't call that the norm. The coldest day was approx -18 below for the low, and approx -8 below for the high.

In Mechanicals | Asked By Rick Van Handel | Mar 26 14
9 Answers

How much electricity do residential oil/propane heating systems draw?

I am on the energy committee in my town. (It's a volunteer committee that reports to the town government, promoting energy goodness to the municipality and residents.) Our committee recently was contacted by a resident in a rental home with a question about a mysterious spike in electric use.

In Mechanicals | Asked By Jonathan Teller-Elsberg | Mar 26 14
Register for a free account and join the conversation


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