Q&A: A Forum for Green Building Experts and Beginners

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2 Answers

I'm going to insulate a small amount of attic floor with rigid foam. The joists are 2x6 @ 24" O.C. Plan is to install 5-1/2" between the joists and then another 2" over, followed by 3/4" plywood. The area is used for storage and the plywood surface will get occasional foot traffic. I want to use polyiso for this but I'm concerned about crushing at the joists. I could install a layer of plywood over the joists, then more foam, then more plywood. but would like to avoid that if I can. I've only installed polyiso in walls and have little sense of its crush resistance. Any comments?

In General questions | Asked By David Meiland | Dec 5 11
8 Answers
In Green building techniques | Asked By Chris Gregson | Nov 21 11
1 Answer

I am starting a new business and would like to make the edifice all solar. So my questions are 1. how much will it cost if the building size is 13 stories high and 3 city blocks wide? 2. how much time would it take to build. 3. are there any special permits needed. 4. how many people would be needed on a project such as this. Thanks for your time. I look forward to hearing from you.

In Energy efficiency and durability | Asked By Joanne Washington | Dec 5 11
1 Answer

Is this the most environmentally sound exterior finish for wood siding? This short video explains the process of finishing wood cladding with an all-solids (solvent-free) natural linseed oil paint. Linseed paint aficionados say this paint is more durable than any modern plastic resin paint, and a perfectly wholesome non-toxic substance. Here's a catch: this paint is very expensive and evidently only available as an export from Sweden.

Here are some things you might want to know (about paint):

In Green products and materials | Asked By TJ Elder | Dec 5 11
5 Answers

SETUP AS FOLLOWS: climate/region - Washington, DC, (More cooling days than heating) - Deep Remodel - R-45 roof - dense packed roof joists - with double roof for ventilation. R-36 wall values - 5.5" dense pack with 2 inches of rigid on exterior. Double glazed windows with proper solar shading. PROBLEM: I am struggling with mechanical sub about location of supply vents for three rooms on my second floor that have vaulted ceiling (2nd floor stairwell and landing zone with library and master bedroom - all on east side of house.

In Mechanicals | Asked By Patricia Shields | Dec 4 11
3 Answers

I’m planning an R-60 unvented cathedral roof assembly with 3” of rigid foam above the roof deck, dense pack cellulose in the rafter bays, and 5/8” drywall on the ceiling as the primary air barrier. What is the best installation practice for blowing dense pack cellulose in the rafter bays? The rafters will be 2x12 on 24” centers and will span 16 feet, ridge to eave. Would you advocate dense-packing through InsulWeb netting? Would 1x3 or 1x4 cross strapping be required or recommended with the netting for my assembly? Or would you blow the cellulose behind the installed drywall?

In Green building techniques | Asked By Jim Hinkle | Dec 3 11
11 Answers

An urban infill question.

Starting from scratch, if you had a lot across the street from a fire station--beyond (presumably) "windowless," how would you build your north house wall which faces that station?

Since the inverse square law is relevant: when the trucks pull into the street, that siren probably is 10-20 yards away.

Curious to read your responses.

In General questions | Asked By Minneapolis Disaster, 6B | Dec 1 11
13 Answers

I am planning a 15 x 15 foot interior dimension addition with slab on grade foundation, ICF walls , 12 inches of exterior XPS rigid foam and exterior brick veneer. I plan to tape and seal the rigid foam to the ICF but am not sure of the best way to attach the brick veneer.

In Green building techniques | Asked By Tim Ward | Nov 24 11

Some "half-baked" Food for thought...

Table-top (Kitchen) experiments/demonstrations....

Explanation of Diffusion and Osmosis

some cool Molecular Graphics

In Energy efficiency and durability | Asked By John Brooks | Dec 3 11
4 Answers

We have a flat roof deck above living space, and are building the surface drainage slope up with sleepers, etc., above the plywood deck (with more plywood, and waterproofing above the sloped area). This creates an at-present uninsulated (and unvented) area between the 2 layers of plywood. Should this be insulated?

In Green building techniques | Asked By Elizabeth K Suzuki | Dec 2 11
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