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!

3 Answers

Airseal but still have a draft from basement

Since I found you guys Ive airsealed my attic and ducts.
I cheaped out our unfinished basement airseal/insulation with foam xps 1" foam sealed edges and r19 batt, the basement will be sealed with rigid foam and plywood eventually as we need the space.
Ive also chalked the baseplate perimeter to the foundation.
I have a Weil Gold cgi with some form of mechanical blower from the side of the boiler outside assuming the air draft is coming in from this as I dont think it opens or closes just starts when the furnace is on

In Green building techniques | Asked By Darren Finch | May 17 12
8 Answers

"Fooling" a tankless hot water heater

In reading the article about the Chautauqua cottage renovation, the author mentioned that low water volume fixtures can "fool" a tankless hot water heater. (presumably not to come on) The author mentioned using a booster tank to help with the problem. Could someone explain what type of a tank this is and how it works?

In Mechanicals | Asked By Joe Cooper | May 3 12
4 Answers

Can an air handler be placed in the garage without an enclosure?

In climate zone 3, under the 2012 Energy Code, can a residential air handler be placed inside of a garage attached to the dwelling?

In Building Code Questions | Asked By henry zuckerman | May 10 12
6 Answers

Split, Mini-split, or Air-Source Heat Pump?

I am leaning towards mini-splits for a 30 unit 3 story affordable apartment building in Chicago but have been told that the cost of electricity makes that a bad choice. I know air source heat pumps are also all electric but is that a better choice? Apartment sizes range from 300 to 500. For an identical building a few blocks away we installed a high efficency individual gas furnace with condensors on the roof. We have an opportunity to try (experiment) with this building with another system. If the upfront costs were the same what system should we install based on use of energy.

In Mechanicals | Asked By julie klump | Sep 9 11
11 Answers

Fiberglass insulation hangers for under roof deck

I'm having trouble finding fasteners for hanging fiberglass insulation from sprayed-on polyurethane foam in a conditioned attic conversion application.

The stack will look like:
roof sheathing
sprayed polyurethane foam
--------|----|----|----|----|----|----|----|---- <- fasteners pushed into foam
fiberglass insulation to cover foam to meet code and increase total insulation value
Attic conditioned air space

In Green building techniques | Asked By David Johnson | May 14 12
3 Answers

Will Delta-Dry provide any reduction in thermal bridging?

I like the concept of Delta Dry as a rain screen and am wondering if it will also help at all against thermal bridging, assuming that there is no additional rigid foam layer between rain screen and sheathing (only felt or building paper). My mind tells me that the presence of a positive air space between the Delta-dry and the felt/sheathing means that the sheathing suface will still experience the same temperature fluctuations and will therefore still be susceptible to thermal bridging.

In General questions | Asked By Shane Gagner | Apr 11 12
9 Answers

Minimum requirement for roofing nails sticking through sheathing?

Looking at a 2005 tile roof installation manual, it looks like the minimum penetration of a roofing nail into roof sheathing was 3/4". So If I assume 1/2" OSB sheathing, I should be able to cut the nails off with 1/4" still sticking through the sheathing into the attic. Is this correct, or am I missing something?


In Energy efficiency and durability | Asked By David Johnson | May 15 12
3 Answers

What can I add to my "green shopping cart"?

Howdy all! I live in Portland, ME (zone 6A). I was recently approved for an energy loan of $15,000. What prompted me to do this was my kitchen renovation. As with most people, money is tight, and I was looking for away to finance part of the renovation. This loan will cover the energy star appliances and some replacement windows.
House: 1960's cape with added on 1st floor 350 first floor bedroom.
Insulation: Fiberglass batts with vapor barrier, not too bad.

In Plans Review | Asked By Seth Fernald | May 16 12
22 Answers

What would you do? XPS or EPS or ISO?

I am building a 3000 sq foot home in northern ontario (zone 8 or 9) with about 9000 HHD.

I am weighing my options on this wall contruction type.
It will be a 2x6 frame with R24 blow in batt in wall cavity and exterior foam insualtion, 1x4 strapping and siding

After reading and calculating foam thicknesses(thanks Martin) I would like to get to R20 if possible for the foam giving me a total wall R40+ rating, will be detailing like a REMOTE wall (window bucks)

Assume all of these will be taped:
I have been able to find EPS 5" thick(R20) non faced - plain white stuff

In General questions | Asked By Brian Krmpotic | Mar 28 12
19 Answers

What is a cost-effective wall assembly?

it seems a variation of this building question gets asked a lot so forgive me... i am building a 600 sq. ft. home in the Rocky Mountains of British Columbia where the building code calls for poly on the warm side of the insulation.

i would like to get as close to R-40 for the walls as economically as possible. Seeing that the received opinion around the GBA is the tandem of polyethylene sheeting and exterior rigid foam is not ideal, what do the builders on this site recommend? Larsen truss seems fairly labour-intensive and rigid foam is expensive... Is a double stud wall the answer?

In General questions | Asked By erik olofsson | May 13 12
Register for a free account and join the conversation

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