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!


10 Answers

Water Testing After Pex Repipe

I live in South Orange County, California, a repiping companies paradise. A massive amount of newer homes are being forced to repipe due to copper failing and slab leaks. The pinhole leaks begin developing between 8 to 15 years after the home is built and sometimes sooner. The theory according to most is that the builders went cheap and installed copper M in the homes, while the water company uses cholormine which the Copper M can’t handle. Most repiping companies will recommend PEX A, but also market USA made Copper L for the repipe.

Asked By JohnZ99 | May 16 18
13 Answers

Water cooled refrigerator coils

This may seem weird, but I’m curious...

We just bought acreage in west central Florida and we’re planning our home. We plan on making everything as energy efficient as we possibly can, and I ve been researching geothermal ground loop heat pumps.

As I’m grabbing some leftovers out of the fridge, I feel hot air being blown on my feet from the condenser coils underneath. At the same time I hear the AC kick on outside. The lightbulb flickers on above my head... I’m running the AC to cool the room that is being warmed by the fridge...

Asked By LT.Son | May 19 18
4 Answers

Tyvek over foil-faced polyiso

I was looking a the spec sheets for foil faced polyisocyanurate and it gives an R value for the foam and then a R value of the foam with an air space. For example, the 3/4" foam has an R value of 5, but the R value of the foam with 3/4" reflective air space is 7.5. If I'm installing foam, covered in Tyvek then 3/4" furring strips with siding, do I have the reflective air space to get the R of 7.5 since the Tyvek is directly over the foil facing?

Asked By E247 | May 19 18
4 Answers

Debating cavity insulation

I'm starting a house build in New Brunswick (Climate Zone 6A). My planned assembly has 3" of EPS foam on the exterior (3" Silverboard XS). I've already bought the Silverboard, so there's no going back now.

To please the local code officials, I will be installing Membrain on the interior.

Asked By Chris Burpee | May 18 18
38 Answers

Please critique my floor plans (first draft)

This house build is in rural Southwestern New Hampshire. 1500sq ft ish. 2 story, 2 bedroom, no basement. Site is south-facing Hillside. House will be on the north edge of a 2 acre clearing. Site has really good exposure for PV panels.

Details:
Shooting for Net Zero with PV Solar array on garage (11kw ish)
Double stud wall construction
ZIP system sheathing
Very tight air sealing details (with a blower door test)
variable permeance interior vapor retarder--- Pro Clima Intello Plus
R20 floor, R40 wall, R60 ceiling
dense pack cellulose insulation (walls, roof)

Asked By Tech1234 | May 17 18
2 Answers

Comfortbatt/Rockwool/Roxul and temporary compressibility

I have some framers coming tomorrow and have a basement wall being constructed inside the existing wall so as to insulate inside the stem wall. I'm planning on using rockwool comfortbatt at the bottom of the wall to allow for some breathability of the stem wall.

Will I be able to squeeze the 5.5" comfortbatt through a 3-3.5" wide opening (it will expand to full size, once in the wall)?

It hard to tell if it can compress that much, even intermittently, though I'm guessing so.

Asked By rossn1 | May 20 18
2 Answers

Over my head

I'm new to this forum, so I hope this is an appropriate question. I'm at the planning stage for a gut rehab of a ~2500 sq ft home in Boston, MA (which I think is zone 5). We're going to be completely rebuilding the envelope and replacing all the systems. We will have 14kW of solar on the roof.

Asked By Bradslees | May 19 18
1 Answer

Does the roof sheathing side in the attic space have to be insulated?

in some rooms in the upper levels there is attic space with an access door. I realize that the walls which are against the liveable space have to be insulated, but does the side with the roof sheathing have to be insulated? This is the side where the roof shingles are attached.

Asked By C D | May 19 18
7 Answers

Sound transmission and ventilation

From a practical perspective the ideal ventilation system might be a fan (or HRV) connected by several very short runs to the rooms it serves.

Is there a point where the runs are too short and form a path for sound transmission between the rooms? Do the small ducts used by systems such as the Zender work better at preserving acoustical privacy? should the ducts be configured so they all enter the fan or core so that there is no shortcut for sound transmission?

Asked By Malcolm Taylor | May 18 18
7 Answers

Cathedral ceiling and lights

We're building an ICF home with an unvented attic (rigid insulation over sheathing) and metal roof. The living room and kitchen will have a cathedral ceiling (roof 4:12 pitch). Living room will have a combination of sconces, pendants, LED strip lighting (indirect), and floor lamps.

The kitchen is another issue. The south wall will have two levels of windows with a counter and no overhead cabinets. We will have an island and plan to place pendants over the island. The north wall will have overhead cabinets with under-mount LED lights and LED strips for indirect lighting on top.

Asked By User-7022224 | May 18 18
Register for a free account and join the conversation


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