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!


3 Answers

Straw bale retrofit?

Hello, I would like to insulate the exterior of my 1940's prefab with straw bales. Has anyone done this? If you have, could you advise me of the best way to tackle it?

Thank you.

In General questions | Asked By David Flint | Mar 23 13
8 Answers

Coastal considerations

Looking to build a small, age-in-place cottage down in Rhode Island. It's across the street from a bay and faces west. I'm thinking the west side will have a good ammt of windows and will be the gable end. Solar opportunities on the south facing side.

It gets really windy there, so I'm wondering what type of insulation scheme we should persue. Or if the wind factor changes your approach at all. I'm also wondering if we should build on piers.

If there are any green builder architects in RI coastal work you can recommend, it would be appreciated.

In Green building techniques | Asked By stephen edge | Mar 29 13
1 Answer

Wedi replaces green board and cement backer?

http://us.wedi.de/_shared/_pdf/infomaterial/zum_herunterladen/wedi_techn...

Any thoughts on the use of the Wedi or Fundo systems? Looks like puting it over drywall will make a bathroom stand up better to bulk water, spray, and condensation. Also seems a better substrate for tiles than green board, cement backer, etc. My thinking is to use it on the walls and celing of a mechanically vented bathroom.

In General questions | Asked By Oak Orchard | Apr 2 13
4 Answers

Support slab or not support slab?

I have designed an ICF wall with an insulated slab supported on one edge as described on this site and also Building Science's paper "Slab Happy". See drawing below.

My builder doesn't like this because of the extra labor and material costs and concerns about the slab on the edge of the stem wall, possibly leading to cracking

He prefers to not support the slab and let it float within the stem wall as per drawing two. I am concerned that this is more prone to movement and cracking if there is any settling.

Both would have compacted soil and some sand or gravel underneath the slab.

In Green building techniques | Asked By Stephen Carlton | Apr 1 13
2 Answers

Snow load on PV panels

Where I'm planning on building the code requires design for 75 PSF snow load.
The best rating for load that I've found in PV panels is 40 PSF. In the unlikely event that an actual maximum snow load were to occur some of the panels may fail but no other structural damage would occur. Could such a situation be approved?

In Building Code Questions | Asked By Jerry Liebler | Mar 28 13
11 Answers

Icynene & moisture

OK some of you may remember my previous question/story about Icynene, we now have more data and more questions;-)

Here's the beef:
I am removing Icynene OC foam from under the roof because it still stinks but here's something that's very odd.
It's a 1920s house with wood planks all over, a new metal roof installed right over 3 layers of self adhering premium underlayment.
Icynene was sprayed 6 in underneath deck to fill the rafter space about 1.5 years ago.
Now, here's what I measured.

In General questions | Asked By Don J. | Apr 1 13
15 Answers

Issues or success with rigid insulation under strip footing

I wonder what experience anyone has had with installing rigid insulation under continuous strip footings supporting a standard concrete foundation wall.

In Green building techniques | Asked By Kim Kornylo Walton | Mar 26 13
2 Answers

XPS interior closed cell roof insulation (DIY)

Quick question for you building experts!

It's a 1920s house with wood planks all over, no vents no plywood, a new metal roof installed right over 3 layers of self adhering premium underlayment. No gaps no venting.

I bought 2 in XPS from HD, cut it and placed under roof deck between rafters. Left 1/2 in gap around and used Great Stuff to spray around it and sealed it.
Actually this method appeared quite easy and it's much quicker to do than I thought once I figured out how to do it efficiently. It takes me about 20 minutes per rafter. Should have done this long time ago....

In General questions | Asked By Don J. | Apr 1 13
2 Answers

Crawlspace foam board and fire code?

When installing rigid foam in an unfinished crawlspace, what is needed to have it comply with the fire code? Foam board to be installed on inside of foundation wall and on the underside of joists?

In Building Code Questions | Asked By Dennis Dipswitch | Mar 31 13
22 Answers

How can I insulate an exposed flooring system properly?

hi,. i have an addition on my house thats aproximately 11x14 on piers and 5 ft off the ground over sandy soil and exposed on all sides.It has a 2x8 ,16" on center floor system framed lengthwise over 2 , triple 2x10 beams, one for each set of piers.The subfloor is 3/4 tongue and groove plywood and i will be installing prefinished 3/4 x 2-1/4 tongue and groove strip oak flooring.

In General questions | Asked By mr. mike | Mar 24 13
Register for a free account and join the conversation


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