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!


2 Answers

Air exchange / ventilation / dehumidifier options for a sealed, 640 s.f. structure

I am building a 640 s.f. structure and insulating i twith closed cell spray foam. Heat is provided by a fireplace with an outside air supply and baseboard heat.

I need an energy-efficient air conditioning / ventilation / dehmidifier / air exchange solution, mainly to keep it dry, but also to keep it cool.

It is located in a typical, four season climate where we get hot, humid summers and cold, snowy winters.

Asked By Nathan Hiscock | Feb 8 16
16 Answers

Geothermal and SDHV in new ICF home

We are in the process of building a new home in Climate Zone 5. It is an ICF [insulated concrete form] construction from basement foundation to gable.

I am intending to use a SDHV [small duct, high velocity] system for forced air and heating in conjunction with a closed loop ground source heat pump.

What I am trying to understand is the impact to efficiency caused by my desire for SDHV on the heat pump options side of life.

Asked By Esteban Carlos | Feb 4 16
0 Answers

perlite vs rigid foam insulation

Hello have a question that will probably generate many opinions, i am building a new house zone 5 , was planing on using rigid foam under slab , but some one recommended that i use Perlite in bags instead , says
1) easier to work with
2) easier to pour slab over as you can level things out with sand
3) cost about the same or cheaper then ridged Foam
4) has better R value

Asked By boris rubinstein | Feb 8 16
11 Answers

Best insulation for indoor air quality?

I cannot decide on a type of insulation for our new home. I want something that is the safest for indoor air quality. I am worried about the off gassing of spray foam, but am also worried about the borate used in blown in cellulose (mainly the reproductive effects of borate). Please help! I want energy efficiency, but indoor air quality is of primary concern. Thank you!

Asked By Carolyn Farrow | Feb 8 16
2 Answers

What makes ceiling fan remotes break?

About 10 years ago, somebody at the Florida Solar Energy Center was involved with the design of the Windward III ceiling fan, which at the time was the most efficient fan money could buy. Due I think to the variable blade pitch. I installed a couple of them and now one of their remotes no longer functions. What causes this and is it repairable?

Asked By Charles Campbell | Feb 3 16
6 Answers

Will this exterior wall system work for my tiny house?

I live in South Dakota in zone 6a (Sioux Falls). In a few months time I will be constructing a tiny house on wheels using 18 gauge structural studs. Starting in the wall cavity will be sprayed closed cell foam. On the exterior sides of the studs (and any other exposed metal areas- the steel trailer) I plan on using strips of 1 inch thick xps rigid foam with a compressive strength of 60 lbs/square inch. Also I will use steel strapping all around the outside to give it some shear strength and prevent racking.

Asked By Damon Beck | Feb 7 16
0 Answers

Using a second water heater as an indirect fired tank?

I have two water heaters. A 50 gallon HTP Phoenix Light Duty propane water heater, and a 50 gallon electric resistance water heater. The two heaters are plumbed in series, electric water heater first, then propane. To make a long story short, some things didn't work out as originally planned, and now I'm paying an extra $15-20/month (and wasting source energy) because I'm heating up a bunch of water with electric resistance right next to a high efficiency propane water heater.

I'd like to stop doing that. I have a couple of extra constraints:

Asked By Tim C | Feb 8 16
2 Answers

Basement remodel / Subfloor questions

I have a few questions about my plan to insulate a subfloor in the basement.

Let me provided the pertinent details and my purposed plan.

The brick ranch house located in zone 4a (Virginia) was built in 1965. It has both an above and below grade basement. The structure is concrete block. The front long wall and one short wall are completely below grade. The back wall and half of the other side wall are above grade. The basement is conditioned.

Asked By Steve Basic | Feb 3 16
1 Answer

Shingle roof over closed-cell foamed rafters

Martin - I'm the architect for a new house. The roof will be:

Wood shingles over
Horizontal strapping over
Vertical strapping over
Grace Ice and watershield over
Plywood sheathing over
Closed cell foam

Do you recommend this? Will there be trouble within the sheathing 'cause it's trapped between two non-breathing membranes: Grace Ice and Watershield (top) and closed cell foam (below)

Many thanks,

Louis Mackall
(you may remember me from Trident launchings in Groton!!)

Asked By Louis Mackall | Feb 8 16
6 Answers

Raised-heel trusses can be annoying

We installed raised-heel trusses with bottom chord overhangs on our house. The top of the top chord is 20" above our top plate. According to the 2012 International Residential Code for seismic zones or zones designated for winds of 100 mph, raised heel trusses more than 15.25" have to be blocked and braced.

Asked By Jimmy Nguyen | Feb 6 16
Register for a free account and join the conversation


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