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!

5 Answers

Ice & water UNDER or OVER the drip edge?

I did a little searching before asking this, thinking that the topic
*must* have come up in the past, but didn't find anything coherent.
We're having this bit of disagreement between a GC and a roofer as
to whether ice & water shield over decking should flash over or
under the drip-edge piece at the connection to the fascia. The
roofer's claiming that putting the drip-edge metal over the I&W
isn't a reverse flash because water in an ice-dam situation would
flow upward, and the GC [who I'm tending to agree with] points out

In Energy efficiency and durability | Asked By Hobbit _ | Oct 26 12
4 Answers

100 year old house--insulation for exterior walls/ceiling

We're gutting a 6x15 area, originally a pantry, to add a tiny powder room and walk thru pantry. The exterior sidewalls are 3/4" pine boards with redwood clapboards. About 15 years ago we stripped the claps, used oil based primer and 2 coats of high quality latex paint. There is no housewrap, but some red rosin paper under the claps. The roof is sound with no leaks.

In Energy efficiency and durability | Asked By Jo Swearingen | Oct 29 12
2 Answers

Should Mastic Be Applied inside Ducts?

We hired a contractor to clean our crawl and seal our ductwork. The company used Hardcast 321 mastic. We are concerned becasue they smeared into the floor vents from above and all around the cold air return. I have attached a couple of pictures. Should mastic be applied inside the ducts like this, is it harmful/toxic?

Thank you for any info/advice.

In General questions | Asked By K. L | Oct 29 12
22 Answers

Fear of cold plywood sheathing in a cold climate


A while back I asked about the wall system I am planning (drywall, taped smart membrain, 2x3 framing, 12" cellulose, 2x6 structural framing, taped plywood sheating, tyvek, strapping, siding). In your opinion it should perform well and with an adequate rain screen the plywood sheating would be fine. Given the mantra "sheating should not be cold", I am wondering what your reasoning is? Is it that with an adeqauate rainscreen the sheating will stay dry and therefore mold free? And when you say rainscreen, I am thinking simple strapping, albeit thicker (1 1/2"??)

In Energy efficiency and durability | Asked By jessie pratt | Oct 25 12
0 Answers

Mathews Brother's Windows

I'm looking for a review from fellow New Englanders on Mathew's Brothers triple pane vinyl windows? They are manufactured in Belfast, Maine. They seem to be very reasonably priced. Does anyone have any experience with their energy performance and quality? My biggest concern is that their SHGC and visible light is lower than I'd like (0.25, 0.4 respectively with a U = 0.19.) My window budget is tight so my options are limited to get a low cost tri-pane with reasonable performance.

In Energy efficiency and durability | Asked By Brian Beaulieu | Oct 27 12
2 Answers

Would someone be kind enough to review my floor plan?

I am doing a major remodel and addition to my house. Here's the proposed floor plan.

In Plans Review | Asked By Edward Yeh | Oct 26 12
51 Answers

? for Martin regarding his report on the BSC whole wall assembly R-value testing results.

Did the Building Science Corporations report on their whole wall performance r-value tests quantify the decrease in R-value below 50 degrees that they found happening with Poly-Iso insulation? What is the R-value curve for Poly-Iso?

In Energy efficiency and durability | Asked By Spencer Burnfield | Oct 20 12
1 Answer

Stucco for your home's exterior - saves energy?

Hi there,

Our new home has just been constructed, but its exterior is still pretty bare. So, our local contractors suggested that we cover the walls with stucco. I am pretty eco conscious and I would like our home to be warm so we don't use much energy to heat it.

Is stucco good at keeping the energy bills low? Should we use their stucco service, or we are better off with using some other type of construction technology and if so, what type? Any word on stucco vs siding vs Hardie board? Many thanks for any piece of advice.

In Energy efficiency and durability | Asked By James Paterson | Oct 25 12
7 Answers

Best way to retrofit / insulate a 1883 house

I am considering ways to insulate a home with balloon framing, 4 1/8" X 3" studs, lath and plaster, 7/8-inch horizontal plank sheathing and clapboards. The clapboards come off easily and many have to come off anyway for a major multi-level porch project on the west, weather facing wall.

The thermal bridging is worse than most as the studs are 3 inches wide and every 16 inches as well accounting for almost 20% of the wall (probably more including windows doors etc.).

In Energy efficiency and durability | Asked By Rob Crampton | Oct 24 12
9 Answers

Air barrier on top of Roxul insulation

From everything I read, I need an air barrier on top of the roxul insulation we have in a vented attic space we are renovating. I put the roxul down and am struggling to find a cheap, easy way to create an air barrier without causing moisture issues.

I'd love to buy some rigid foam to help the Rvalue, but am worried about creating a moisture issue.
Tyvek is expensive

Are any of these cheap ideas viable?

I had been thinking of going to an appliance store and begging for free sheets of cardboard, but never got around to it.

In General questions | Asked By Nick H | Oct 23 12
Register for a free account and join the conversation

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