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

DensArmor Plus

anyone know what tape to use for DensArmor Plus in a bathroom? the bathroom has a shower. i swear i read somewhere not to use regular fibatape but the only other non-paper tape i can find is alkali-resistant cement board tape. it looks like regular fibreglass tape but is grey jn colour...

In General questions | Asked By erik olofsson | Mar 12 13
4 Answers

Bathroom moisture control in HRV defrost mode

Planning new residential construction in moist and winter cold zone 5A.  Basement/walls/roof are R20/40/60, triple-pane, super-tight, well-drying, direct-vent, and mechanicals all in conditioned space.  I feel like I have covered most angles, and am looking for extra insurance against mold.
I'm planning for 2 mini-splits to handle 3000sf plus another mini-split for a 600sf in-law, and an HRV to not only provide exhaust/fresh air, but with the help of a few transfer grills, to also distribute heat & cooling throughout the fairly open layout.

In General questions | Asked By Bill Littlewood | Mar 11 13
3 Answers

Is anyone familiar with reflective insulation, specifically Think Smart?

I was introduced to it a a home show. The cost is about $2.75 per square foot. It seems high, but could get a 4-5 year payback. Comments please.

In Energy efficiency and durability | Asked By Tom Swanson | Mar 11 13
15 Answers

Mineral Wool Exterior Insulation, Humidity and Windwashing

Every time I think I have my insulation strategy set, I learn something new that makes me question it. That's what you get for reading the internet.

Anyway, I am planning on 2 x 6 walls with dense pack cellulose with a smart vapor membrane like Intello Plus, an insulated 2" service chase. Outside of the cellulose would be plywood, housewrap, then probably 2 inches of mineral wool exterior insulation (Roxul Comfortboard is my plan) then strapping, then Hardiboard. I am in zone 3 mixed-humid in the Piedmont of the Carolinas.

In Green building techniques | Asked By Lucy Foxworth | Mar 8 13
18 Answers

Greenest EVER insulation! (It's also very cheap!)

- 0 carbon/embodied energy
- easiest installation of all
- comes when most required
- very very DIY friendly
- can be moved around

u guessed it ?

water ....ergg SNOW of course :)

I join a picture view from my first floor patio door taken on feb 28 2013 for your enjoyment
( for those southerns that think we don't have snow in Canada ...wait everybody thinks we have tons of it ?? damn .. )

On a more serious note,
i've designed my flat roof terrace on my own house to take advantage of the snow we have each year during the coldest phase of our winter in Quebec.

In Green products and materials | Asked By Jin Kazama | Mar 7 13
6 Answers

Tape test results

The results of my test of eleven air sealing tapes on six materials has been published.

Anyone interested in reading the results can find them here: Backyard Tape Test.


In Energy efficiency and durability | Asked By Martin Holladay | Mar 8 13
18 Answers

What kind of chimney for an energy-efficient home?

The recent discussion on masonry heaters in super-insulated homes is great, and Martin's "farewell to the chimney" post is a classic, but I have a question that I don't think has yet been covered here.

I am designing a well-insulated home that will require a modest amount of Btu input that I want to provide with a modest woodstove. What is the best type of chimney to use, masonry or insulated stovepipe? (Or some other option I'm not specifying.)

In Mechanicals | Asked By Tristan Roberts | Jan 29 11
3 Answers

How to hit studs with 4.5 inches of interior polyiso?

I am starting to install my polyiso on the interior of my slanted cathedral roof assembly and am having trouble finding the studs through the 4.5" of polyiso that I have.

Things working against me:

1. not all studs are perfectly 16" OC.
2. The ceiling deck is at an angle.
3. When I place the screws in it's hard to get them into the studs or even find the studs with the angle of the ceiling.

Are there any videos or techniques that can help me find the studs...I'm at a loss here!


In General questions | Asked By Kevin Lauscher | Mar 11 13
4 Answers

Kitchen vent fan options to control cooking odors

I'm building a 2200 sq ft ranch with six inch thick combo foam/blown fiberglass walls,triple pane windows and HRV. I would like to avoid the additional exterior wall penetration and cold air infiltration when a traditional kitchen exhaust fan is operating. I was leaning towards a Broan QS1 series recirculating fan to difuse kitchen cooking odors (onions and garlic..no grease). My wife, the cook, says outdoor venting would be best. I'm more concerned with cold air infiltration when the fan is not in operation. My gratitude for any insights or suggestions. Sincerely, Dick

In Energy efficiency and durability | Asked By Dick Reznik | Mar 11 13
4 Answers

Siga Corvum tape

hi all, i would like to trim the foam and apply corvum for additional airtightness. i got a little overzealous when flashing the window r.o.. should i cut the tyvek back to the same depth as the window so that the corvum would adhere directly to the window and osb? i realize if i do not cut the tyvek back i will be relying on the bond of the tyvek tape bonding the tyvek to the osb...

In General questions | Asked By erik olofsson | Mar 10 13
Register for a free account and join the conversation

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