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!

17 Answers

Hello folks,

First, I'd just like to say how thankful I am for the invaluable resource that is GBA. I spend A LOT of time reading the blogs and Q&A and I find that pretty much any question I might have has been covered here already. Though sometimes my understanding gets a little vague regarding certain details so I am hoping for some input on a potential wall detail.

Asked By Noah Byler | Jul 23 14
3 Answers

Hello, I really appreciate this website.

I understand that powered attic ventilators have a lot of problems. But my contractor is suggesting adding one to support a whole-house fan, due to the limited attic ventilation. (I do have some passive ventilation but not quite enough, and the gables are maxed out because it's a flat roof.)

So as long as I always run both fans at the same time, and as long as the cfm of the whole house fan exceeds the cfm of the attic fan, is there still going to be a problem?

Thanks!

Asked By Robert Shelton | Jul 25 14
3 Answers

Investigation revealed 3 problems: 1) no soffit vent; 2) insulation extending beyond the end of plastic rafter vents closing off the air channel up to the ridge vent; 3) no blocking above the wall to seal up the fiberglass. I've corrected the first two and caulked the ridge on the inside, but am unable to fix the blocking. The odor persists and I fear the fiberglass is contaminated with mold that the revived air flow won't be able to dissipate. Would pulling out the fiberglass (through the soffit to avoid major deconstruction) and filling the bays with foam work?

Asked By Michael Roland | Jul 25 14
3 Answers

As a long time visitor and few years member, I have tried to absorb the lessons, opinions, science and conjecture presented here. However, I now find myself confronted with conflicting theory regarding unvented roof profiles.

For my own project, (high altitude, dry, -10 to 90 F) I have regarded the "top" layer of sheathing in an unvented assembly to be essentially in dead space - not exchanging air or moisture - the underside in contact or glued to impermeable insulation, the top side sealed off from all contact with the locally required ice and water shield over the entire roof.

Asked By Roger Berry | Jul 24 14
3 Answers

This is probably only a hypothetical question as I doubt I could talk my wife into a composting toilet but…If we have a tight home with balanced ventilation, and if we had a composting toilet that has a small 5W fan continuously exhausting air - how would we provide make-up air?

Asked By Scott Tenney | Jul 24 14
18 Answers

I am not in construction or an architect, just someone who would like to live in/build a small, comfortable, energy efficient home. I don’t need and could never afford a Passive House. Don’t even know if one would work where I live. I live in the low desert southwest near Phoenix. Living is very different here than in cold weather areas. And very different than Florida or humid areas of Texas. Outside temps over 100F in shade 5-6 months; highs 115F; nighttime lows 95F for at least 2-3 months. Low humidity 10 months. Little or no drought resistant shade trees.

Asked By Anneal G | Jun 27 14
5 Answers

We are in the planning phase of a passive house near Louisville, Ky. The site is a South facing hill with a great view of fields, trees and a creek. We plan on a walkout basement under a 2300 square foot home. I am concerned about moisture through the wall of the basement. Some precast concrete wall providers guarantee water tight walls with insulation on the inside. If they are used what precautions should be taken relative to the floors and vapor pressure to the inside?

Asked By Paul Nicholls | Jul 22 14
1 Answer

My wife and I recently bought an old (1880's) two-story duplex with separate apartments on each floor, each about 750 square feet and very poorly insulated. We have long-term renovation plans, but our primary near-term complaint is the inability of the apartments (especially upstairs) to cool down at night -- even with our quite cool summer nights here in Northern Colorado and all the windows open. We don't want air conditioning, but we would like to improve night-time ventilation.

Asked By Kevin Ummel | Jul 24 14
2 Answers

The question is when going with foam installation on the attic CEILING between the rafters only not on the attic floor, which is recommended for attic CEILING open or closed cell.

Asked By TERRY KELLEY | Jul 24 14
14 Answers

I put the cart before the horse, and selected the house depicted below to build in the Adirondacks, NY. After working out the design details inside the house, I moved to the outside. I questioned the building designer about the low profile 3/12 pitch roof and how it is vented on the high edge, and the reply was "this home uses water impenetrable closed cell urethane insulation, sprayed in to fill the cavity from below prior to drywalling, and it therefore unvented.

Asked By Don Moore | Jul 23 14
Register for a free account and join the conversation


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