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!


6 Answers

High humidity in spray foam attic

Hello all,

Last fall I had my attic spray foamed. Warm temperatures have arrived and I am experiencing higher than anticipated temperatures and humidity in my attic.

I have 3 main questions (pertinent details follow):

1. Is a semi-conditioned attic RH in the 60 - 70% range cause for concern?
2. Should my attic be 10+ degrees warmer than the interior? It will get much warmer here in the coming months and I am worried that the attic temperature difference will grow.

Asked By Nic Smith | Apr 30 16
2 Answers

Integrating rainwater collection system into house water faucets?

Hi all,

Building a new house and at some point I would like to have a rainwater collection system. This system would route the gutter downspouts into an underground tank and then have a pump to distribute the water around the yard.

Thinking about how to distribute the water around the yard, I had the idea to connect the tank to my house water hydrants (house bibs, outdoor water hydrants, etc.).

Asked By Clay Whitenack | May 2 16
10 Answers

Exterior finish on 1850s farmhouse

I've got an 1850s farm house I'm in the process of renovating. The house needs considerable exterior painting.

Do you all have recommendations on the best exterior finishes for an old house like this? I could shingle instead of painting, for example, or strip and stain.

I'm hoping to create the most energy efficient old house possible with minimal future upkeep. Paint seems to need redoing quite frequently, and other possibilities would be welcome.

Thanks,

Ilmari

Asked By DJ Polojarvi | Apr 30 16
5 Answers

Re-roofing low-slope roof, unvented insulation techniques

Shed dormer on back of 1.5 story cape cod.. 20ft X 20ft roof. Low-slope, 1.5 in 12.

Little or no access to interior "attic".

2X6 rafters. "Vented" at soffit. Insulated with 4" to 10" of fiberglass batts as room allowed (done before ceiling drywall was installed.)

Re-roofing dormer. Will replace roof sheathing. Considering un-vented roof for this shed dormer. No room to add rigid foam on top of sheathing

Asked By David Heinicke | May 1 16
2 Answers

Ventilation

I am rehabilitating a 1950's shop/garage building. It has a gable roof and has a 1 foot overhang on the gable ends. The overhang was constructed with 2x4's that were toe nailed to the gable wall. On the underside of the 2x4's, a thin (1/4 inch) plywood application was mounted. I am removing all of the existing exterior wood, facia and rake boards, siding, etc, and installing new materials. My question is, do I need to be concerned about ventilating this 1 foot overhang and, if so, what is the best way to accomplish that? Thanks.

Asked By Peter Liberatore | May 2 16
1 Answer

Cellulose comparisons

My new construction will be getting dense pack in the walls. I've been looking at National Fiber's

Asked By daniel f. vellone | Apr 30 16
9 Answers

Why are these wires putting burn marks on paper-backed batts?

I've seen two houses in the past couple of weeks where wiring is leaving burn marks on paper-backed batts (see pics). I found these because I was snooping around looking for air leaks. I've always been told that insulating around wiring is fine if it's modern Romex type wiring, and that knob and tube is the only thing to watch out for. So finding these two examples is pretty terrifying.

Asked By Peter Rogers | Mar 15 15
1 Answer

Is there a code requirement for residential boiler piping insulation?

Is there a code requirement for residential boiler piping insulation?

If so, what is the R-value for pipes in conditioned space? And unconditioned space?

We live near Baltimore, MD.

Asked By Brantley Gent | Apr 30 16
10 Answers

Best wall system for Vermont?

I am building a modular home in Chittenden County Vermont and have been debating what type of wall system and insulation combination will be best. There are three wall systems under consideration, but I am open to alternatives.

1) 2x8 framing 16" on center with Roxul cavity insulation (R30) and Thermalstar sheathing w/1.5" EPS foam (R7.5) for total R-value of 37.5.

2) 2x6 framing 16" on center with Roxul cavity insulation (R24) and 2" polyiso rigid foam (R13) for a total R-value of 37.

3) 10" double stud 2x4 wall, BIBS cavity insulation and Zip sheathing for total R-value of 39.

Asked By Craig A | Apr 29 16
12 Answers

Best furring strip over exterior foam to hold Hardie siding?

Ok, this has come up before and I want to get final recommendations from those who have done the work in the field as my foam board is almost finished.

I have attached 2.5" of recycled EPS to the exterior over my drain wrap. Windows are INNIES and are flashed well. As a point of fact, the Tyvek brand tape worked and adheres excellent to the EPS. I have some 3M all weather tape but the Tyvek tape works great and is easier to work with.

Asked By Joe Suhrada | Apr 26 16
Register for a free account and join the conversation


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