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!

11 Answers

Insulation for vaulted ceiling

We re-roofed our house this summer and found a lot of damage over our family room with a vaulted ceiling. We replaced the plywood and are now redoing the underside. The roof has a roof ridge vent and ventilation holes in the soffits. We are creating on-site baffles with 1" rigid foam boards. We are planning to use R30C insulation which is denser for cathedral ceilings. The question is do we use faced or unfaced, and do we need to use plastic sheeting as a vapor barrier? We want to get it right this time!

In GBA Pro help | Asked By Kim Howard | Nov 22 16
3 Answers

Smoke odor

Hi, We are restoring a severely fire damaged home and while many components have been simply removed (down to the studs), the framing needs to be treated to eliminate the smoke odor. Our research has pointed us toward alcohol based shellacs. Some say first use an oil based primer and then the shellac. Can you advise?
Thanks, jk

In GBA Pro help | Asked By Joseph Klockner | Jan 23 17
1 Answer

Can Roxul Comfortboard 80 be installed on roof deck in non-vented assembly 70psf load requirement?

Passive house build in Northern California

In Green building techniques | Asked By Forrest Kerr | Jan 14 17
1 Answer

Cold access room - Air barrier gaps between roofline and exterior wall

Hi Everyone,

In General questions | Asked By Joe Duchek | Jan 13 17
1 Answer

Hydronic radiant heat over concrete slab

I'm building an addition that partly includes an extension for an existing room off one side of my house here in Connecticut. Existing floor is 2 1/4" x 3/4" oak strip hardwood floor. Addition floor will be slab-above-grade with poly and rigid foam underneath the slab. Need to "marry" the existing oak floor (conventional wood subfloor/structure) to new concrete slab using new oak strip flooring. Because I'm building this addition myself, there will be more than sufficient time for the slab to dry (perhaps a year or more) before new finish flooring needs to be installed.

In General questions | Asked By John Rooney | Jan 14 17
1 Answer

Insulating an historic house's attic

Hi all!

I live in Montgomery County, PA, which is at the northern edge of the 4-A climate zone according to the map on this site.

In Plans Review | Asked By Robin Klingsberg | Jan 15 17
9 Answers

Insulation retrofit

Looking for some advice on a smallish rehab project I am about to start. I've read many of the great articles and Q&A discussions here, so I think have bit of direction...but as I am novice, I am interested in some feedback before I moved forward.

In GBA Pro help | Asked By Jeremy Kachejian | Jan 12 17
2 Answers

Air sealing and insulating up to a chimney?

Hi guys!

I'm looking for some advice on insulating and air sealing near a fireplace and chimney in my house (zone 6a). The chimney is unlined and the furnace and water heater are vented up chimney. I'm not going to use the fireplace as is, but I'm planning to put in a wood burning stove insert at a later time. Looking at the attached pictures, do you have ideas on how to air seal the space between the right of the chimney and the framing. Can I fill this space with mineral wool insulation? For the rest of the house I used mineral wool with membrain. Thanks, I appreciate any help!

In General questions | Asked By Betina Chaon | Jan 16 17
10 Answers

Does anyone know if there is a manufacturer that makes an energy efficient, dual HVAC/ ventilation system that would satisfy both of my needs and eliminate the need for 2 duct systems?

I'm planning a moderate size home in SoCal in a semi-desert climate with adequate thermal mass. The home will have a tight envelope and my understanding is that some sort of ventilation system with separate duct work is required.

I was planning on an air-source heat pump to meet heating and cooling needs, but this will only be used in the summer and winter months mostly.

In Green products and materials | Asked By Paul Minotto | Jan 20 17
6 Answers

Florida Shed With A/C, Insulation, Vapor Barrier - Please help!

We are planning to buy a 12 x 24 pre-fab portable building like the Lofted Barn at Cookstuff.com.

We live in southwest Florida and need to air condition it 365/yr (pretty much). Going to use the building for our handmade soap workshop and humidity is very important to our soap curing process so we will be using a portable dehumidifier in the space in addition to a wall a/c.

In General questions | Asked By Ron Taylor | Jan 16 17
Register for a free account and join the conversation

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