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

Vent separations and strategies

I'm building a home where I'm venting a high efficiency propane forced air furnace, a HRV (stale indoor/fresh outdoor), an on demand water heater, and a propane dryer from a mechanical room in about 8 feet of horizontal wall area. Additionally, I'm spot ventilating a range hood and bathroom fan on adjacent walls. My biggest concern is that I have dry fresh air for the HRV. There aren't any windows to really worry about and the mechanical room is on the first floor of a two story home so I can go up with some of the vents.

Asked By Jack Nichols | Nov 20 14
64 Answers

Do I really need 4 minisplits?

My wife and I own a lot in a development in the Pacific NW (Zone 4c), and we are planning to build our retirement house on it. We have never built a house before. Our projected house (which we designed ourselves) is 1,833 sq. ft. on one story, a modified California-style bungalow, as simple in geometry as we could make it.

Asked By Gordon Taylor | Jan 23 12
54 Answers

Dealing with mold on the inside of OSB sheathing

Zip code 53951, south central WI, zone 6a.

Working in non-perfect situation - occupying unfinished house and can't afford to finish it up in timely manner. Heated by central air furnace with supplemental wood burning stove heat. Plan is to finish walls first and after we can afford to do the infloor heat, finish ceilings (2 stories to do)

Moved in early October, found mold about week ago (late February), when moved some fiberglass for new electrical box. Still recovering from the shock...

Here is wall profile, all new materials:
- (no siding yet)

Asked By Nick Zees | Mar 3 13
2 Answers

Insulating a crawl space

Situation: Existing uninsulated very shallow crawl space with a concrete floor that doesn't have insulation or vapor barrier under the slab located in climate zone 6 just a few miles south of the "border" for climate zone 7.

My plan is to insulate the space with 4" on the walls and 2" on the slab of type 1 EPS and then cover that with about as much blown cellulose as I can fit in the space (about 2' high). It is empty space - no mechanicals of any sort in there.

Asked By Greg Smith | Oct 4 13
4 Answers

Dryer vent in air-tight Passive House

I am building a house in the Seattle area to Passive House standards. After spending countless hours sealing every crack, seam and penetration to achieve under 0.6 ACH, creating a 4 inch diameter hole in my air barrier pains me. I've looked into condensing dryers that are used in some European Passive Houses, but they seam to take much longer to dry and use lots of water. Since I will be installing a vented dryer (unless someone can come up with another solution), are there ways to make the dryer wall vent more air-tight when the dryer is not in use?

Asked By Gerald Blycker | Nov 21 14
29 Answers

Trusting a heat load calculation & downsizing...

I'm replacing my furnace & had a Manual J-based heat load calculation done by a reputable person using the Rhvac software. I paid a sizable amount of money for this heat load to be done - but I was tired of going to contractors who relied on rules of thumb & made educated guesses based on experience. I just want the concrete numbers to back up any claims.

Asked By Jeff Watson | Nov 15 14
2 Answers

Is this a sufficient wall system for my basement?

Zone 6a. One inch foundation plus type two eps foam adhered directly to concrete with PL. Seams taped and corners spray foamed. 24 oc studs with r20 fibreglass Batts. Should I include a poly vapor barrier before drywall? I've been told to omit this as the foundation plus should be sufficient enough for a vapour barrier. Also should I spray foam the small portion of exposed concrete at the top of the wall between the type two foam and the Sill plate? I should also mention it's an eight foot foundation with about six and a half feet below grade.

Asked By Mark McKenzie | Nov 20 14
5 Answers

We ran into a few deep uninsulated roof channels

Too little to have a cellulose sub. Are you better off packing them full with pieces of fiberglass batts, or risking air movement by sliding a loose batt down? What is the R factor of hand-packed fiberglass? Thanks.

Asked By Robert Mason | Nov 20 14
3 Answers

Dense pack cellulose rig rental in Philadelphia area

I've decided to make a DIY attempt at installing dense-pack cellulose to a fairly small section of the thermal envelope in my home (which happens to live under a floor, well above grade). I'm looking for the highest-power cellulose blower I can rent, preferably an Intec Force 2 or better, plus a kit for reducing tube diameter to the appropriate level and providing whatever stiffness/bendiness is needed for the circumstance. Anybody know where I can rent such equipment in the Philadelphia area, preferably less than 1 hour drive?

Asked By Andrew Levitt | Nov 19 14
19 Answers

Is 1" enough?

We are constructing a home in far western SD (Climate Zone 6b)....There is a lot of bedrock here so we have opted to build a post frame (pole barn) style structure. From the outside in, our wall 'sandwich' will be
1-pole barn style tin wall covering
2-Tyvek
3- 1" Tongue and Groove XPS foam
4-Half inch OSB attached to the girts
5- 7" of cellulose filling the curtain walls
6- OSB on the shop walls and Drywall in the house.

Asked By daryl stisser | Nov 16 14
Register for a free account and join the conversation


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