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!

0 Answers

What is the best way to reduce heat gain in South facing garages?

This forum has had a lot to say about how foil bubble radiant heat barriers are silly and a waste of money.

I'm interested in reducing the heat gain in my South facing garages from the intense high desert sun. My garage bakes, and my neighbors is quite cool and comfortable, for a garage. I know he has done attic ventilation above the garage, and installed a radiant heat barriers on the door.

Asked By pshyvers | Jul 22 17
1 Answer

Foil faced rigid insulation

I am in mixed-humid (Zone 3A).

I plan to use foil faced roof sheathing in my vented attic as a radiant barrier and was wondering about the efficacy of foil faced rigid insulation on my exterior walls facing the air gap to the siding (brick, stone and plank). Given my climate, any wall moisture will typically dry to the interior, so it would seem the reduced permeability of the foil facing would not be an issue.

From inside out:
• Latex paint
• Drywall

Asked By pnjfksx | Jul 22 17
0 Answers

Main stack venting

I'm finishing tying in an addition to my existing slab on grade home and found the main stack vent on the existing house is about 6" into what will be a hallway.

The original house had a 3" main stack vent off the master bath, near where the drain exits the house to the septic. There is also a 2" vent on the other side of the house connected to the kitchen and another full bath. There is a 3rd full bath in the middle of these two vents. The original master bathroom piping has been capped and covered with concrete, except the main stack vent.

Asked By Mike M | Jul 22 17
0 Answers

Accessing a concealed duct unit

My HVAC contractor will be installing a Fujitsu 9RLFCD and a 12RLFCD. Each of the slim duct units will share space in closets and hang vertically. I don't have a utility room for them to be exposed in.
Now I need an idea on how to conceal the slim ducts but still make them accessible.
Do they need ready access like a breaker panel or can all the seasonal coats be hung in front of them? Are there pre-made access panels for sale?
What is a "good practice" for finishing these off? Any pictures?

Asked By Mark Walker | Jul 22 17
2 Answers

Naive question on LEED certification


Asked By Brian Gray | Jul 21 17
15 Answers

Insulation question and new construction.... thoughts?

New construction, we are doing a non-vented attic to keep our HVAC ductwork in a conditioned space with foam on the roof deck. Come to find out, we can put foam in all the walls vs using bibs for the same price which surprised me. This will make for a tight house and this brings the question in my mind "what type of mechanical ventilation"? House needs to breath and have a good exchange of air.

House is a 2 story and about 2700 sq ft. 2 HVAC units will be installed. Biggest concern is a good ventilation system..

Asked By Thomas Roberts | Jul 20 17
3 Answers

Energy efficient dryer vent

I was looking for a suggestion on a through-wall dryer vent for 8" thick wall that's energy efficient?

Asked By Michael Brackett | Jul 22 17
7 Answers

1870s rowhouse rehab energy efficiency - radiators and radiant heat?

I'm looking for feedback on heating and cooling (and energy efficiency) for a large, three story brick, italianate 1870's row house (with low-sloping flat roof) - it's attached to the neighboring brick house on the south, with a few feet between houses with the neighbor to the north). This is a big (4000 sq. ft), brick, main street structure with massive walls and many average sized (15' x 15') rooms that can't be opened-up too much because of the existing structure.

Asked By humbleadobe | Jul 21 17
0 Answers

One more PEX (safety) question!


I've been reading over information regarding the safety of PEX for the last few days. It's safe to say, there is a lot of uncertainty and varied opinions on which type of PEX to use.

I have read over some of the posts here on GBA but am still not sure which to go with.

Several users have mentioned a weird taste in their water when using PEX A and that PEX B is the safest in regards to chemical leaching. One reviewer stated: "A-type PEX leaches 50-200% more chemicals into the water".

Asked By Tommy87 | Jul 22 17
3 Answers

My double stud wall assembly

We are in Minnesota (Zone 6a). 2200 sq/ft single level, slab on grade.

Finalizing my 10" double stud wall assembly details and want to get your suggestions and recommendations for improving the assembly without increasing significantly increasing costs.

-Certainteed Membrane 1-10 perm
-Dense pack cellulose
-1/2" plywood
-Tyvek 58 perm
-furring strips on the (north and east sides of the house)
-LP smartside lap, b&b, & shakes (north and east sides of the house)
-No furring strips, just vinyl siding (south and west sides of the house)

Asked By Scott K | Jul 22 17
Register for a free account and join the conversation

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