Q&A: A Forum for Green Building Experts and Beginners

[Click map to enlarge]

Please register for a free account or sign in to ask and answer green building questions.

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!


7 Answers

Is a LP hot water tank enough to heat my renovated house?

I'm doing a deep energy retrofit on a 2000 sf ranch in Connecticut. I've having trouble getting a HVAC company interested. The first wanted to put a hi efficiency air to air heat exchanger in the attic and use the 40 year old ducts. Another said it needs a 4 ton system and he'd only consider it in the attic....on and on.... I finally got a guy who said he'd put in a 2 ton system if that is what I wanted. None of these guys care to do any calculations I guess. My calcs show a 2 ton cooling load and a 54k btu/hr heating load.

In Mechanicals | Asked By Walter Gayeski | Jul 21 12
1 Answer

Level of damp proofing for perimeter foundation under slab?

I am curious how much damp proofing is recommended for a perimeter foundation around a slab that is poured about 20 inches above pre-existing grade. I am building in an area with a high water table (12" down) so we excavated down about 20 inches to sand across the whole building site and beyond the foundation by 2-3 meters and then levelled out the hole with 10 - 16" of 3" rock. The footings were placed on top of the rock and then 20" foundation walls.

In Green building techniques | Asked By Patrick Walshe | Sep 30 12
7 Answers

Skylights

Is there an energy efficient skylight? I was thinking about a unidirectional skylight (e.g. lean-to, sawtooth) that only faces one direction for whichever use I want to use it for whether it be daylighting or passive solar. However, no one makes these that I can find in the U.S. The skylights would of course have glass only on one side or in one direction. Most companies that say they do custom are B.S. ers. Most of them can't conceive of puttling glass on only one surface and blocking off the other. Anyway, I am no expert either so ...........???anyone? Thanks

In Green products and materials | Asked By Lisa Young | Sep 15 12
1 Answer

Does a dehumidifier alone use less energy than an air conditioner?

I live in South Florida (very humid) in a small apartment that has an air conditioner with a dehumidifier. The "Mode" control has four positions: fan, cool, energy saver, and dehumidifier. The brand is LG. Will I save any energy by using the dehumidifier mode instead of the air conditioner mode? If so, how much energy, roughly, will I save? Thanks.

In Energy efficiency and durability | Asked By Bill Yribia | Sep 30 12
3 Answers

Insulating basement without foam

Can a basement, that is free of bulk moisture problems, be safely and reliably be insulated from the inside without using plastic foam? My thought is: 3" mineral wool (8#/sq ft rigid) against the concrete. Inside the mineral wool, a 2x4 stud wall with exterior face covered by ThermoPly, with seams tapped and corners caulked. The ThermoPly serves as an air and moisture barrier which prevents interior moist air reaching the cold concrete. The stud bays can optionally hold additional bats of mineral wool.

In Energy efficiency and durability | Asked By Jerry Liebler | Sep 29 12
5 Answers

Alphabet soup: ACH, CFM, ELA, MLR, SF

[You'll find a duplicate of this as a comment on an old blog thread
about "how much ventilation", but obviously that's not the way to
get it actually seen and commented on.]

Before my retrofit I did a quick-n-dirty volume and surface area
calculation on my relatively simple Cape, and have just redone it
a bit more accurately. I'm now reading up on blower-door testing
because I expect that eventually the place will get one, and the
confusion over which numbers are which, better, meaningful, BS,
etc is *profoundly* irritating. Anybody who comes along talking

In Energy efficiency and durability | Asked By Hobbit _ | Sep 27 12
3 Answers

Has anyone ever tied a radon vent stack into the plumbing vent stack to avoid extra roof penetrations?

Assuming our new construction waste pipes are all trapped properly there shouldn't be a chance of sub-slab gasses getting into the house. We're on a septic system. We're not really concerned about radon but installed the sub slab perf. pipe as a precaution and currently have the stack capped off in the attic adjacent the plumbing vent stack.

In Mechanicals | Asked By Dan Clere | Sep 28 12
0 Answers

Ceramic tile flooring double layer?

My bathroom ceramic tile flooring just has been tiled and i don"t like it. When I expressed my disappointment my tile layer said, no problem -- I can choose another tile and he will put it on top of the floor he just did. Is this wise to deal with 2 layers?

In Green products and materials | Asked By Jesse Conant | Sep 29 12
3 Answers

Air barrier on floors?

I am currently renovating a 1960's ranch home, adding two additions. The house has been fully gutted. I intend to cover the existing sub-floor ( pine boards on 45 degree angle) with 3/4" Advantek, and screwing the floor in place. The foundation consists of a partial basement and crawl spaces (which I intend to seal and condition). Is there any value to putting down an air barrier before the new sub-floor, and if so, what would be recommended?

Thanks

Bill

In Green building techniques | Asked By Bill Savoie | Sep 25 12
6 Answers

Neat silicone caulk

I have been looking to start making my timber windows internal beaded. i have had a look at some imported windows and have been very impressed at the quality of the silicone applyed to the external face of the window/unit ,no matter how i try i can not get the look i am after .Is there a tool i can use or are the eastern europeans bloody good at tooling of silicone .Any one help .
Cheers

In GBA Pro help | Asked By graham Cuckson | Sep 18 12
Register for a free account and join the conversation


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