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

Cathedral ceiling R-value boost

Zone 6. Layers from the outside in:
Galvalume steel roof
Grace advantec
Plywood deck
1 inch air space
1 inch foil faced tuff r
5.5 inch roxul
Rafters are filled at 7.5 inches.. 24oc

Question; what can I put under the roxul and rafters to get r38?

In General questions | Asked By stephen edge | May 17 12
3 Answers

Spray foam in walls

Katrin Klingenberg of PHIUS gave a talk called "Balancing the Investment: Enclosures, Mechanicals, and Renewables" which is available on demand from the Energy Center of Wisconsin.(1) At 25:00, she makes this comment on many houses with spray foam wall insulation applying for Passive House certification: "We have seen applications that are horrendous. The walls are going to be full of water in two years."

In Green products and materials | Asked By David Martin | May 17 12
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?

Dave

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
Register for a free account and join the conversation


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