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1 Answer

Rim joist insulation

I have several questions about insulating the rim of the 1st floor platform above the basement of my 2001-built house. I have recently found condensation on the rim joist after cold nights under the squares of the open-faced FG bat that had been shoved between the I-joists. I removed the FG and no longer get condensation, but would like to reinsulate effectively.

I plan on installing rigid foam between the I-joists, and need to determine what R value is appropriate for Northern Colorado.

In Energy efficiency and durability | Asked By William Fryer | Dec 21 12
28 Answers

Larsen truss questions

Hello. I was hoping to get some more feedback from the GBA folk.

We have just framed a small house in an area with a -32 design temperature. our plan is to attach a Larsen truss to a conventionally framed wall. the wall detail is as such: 2x4 stud wall, sheathed with 5/8' t+g OSB, 8"-ish Larsen truss, cross-strapped with 1x, rainscreen, cedar siding. we have to use batt insulation because dense-pack or wet-pack cellulose is not available (we will use blown cellulose for the attic).

In General questions | Asked By erik olofsson | Oct 3 12
1 Answer

Hybrid Wall - Closed Cell Spray Foam Flash w/ Exterior Insulated Sheathing

As I was searching through the various posts related to the use of insulated sheathing on the exterior envelope I have not seen anything for or against the use of exterior insulation in combination with 2# closed cell spray foam (1-2" thick) on the interior cavity. My first thoughts were combination may allow you to reduce the thickness of the exterior insulation, aleviating some of the window/trim detail concerns and still help you reduce the likelihood of the dew point occuring at the sheathing (both are basically vapor impermeable).

In Energy efficiency and durability | Asked By Michael Burke | Dec 20 12
16 Answers

Question concerning condensation

I just moved into a newly constructed house in zone 5A this past October. It has SIP walls, slab on grade (stained & sealed) with radiant and cellulose in the ceiling at R-42.

I know this is a new house and there will be a lot of moisture from the 2x's and drywall that will eventually go away, but it seems that I have a more than average amount. My Pella Proline windows have 20-30% condensation that is dripping all over place. The Therma Tru doors are fine (front and patio), but the brass hardware is dripping wet.

In General questions | Asked By Bud Weiser | Nov 29 12
12 Answers

Best wall system for a 200+ year home?

Hi I am still in the planning phases of designing a home in zone 6. I was recently looking at building a ~R50 double stud wall with a 3/4" rain screen gap clad in fiber cement siding.

I am 27 years old and plan to live in this house for hopefully 50+ years. I would like assistance determining if I am better off with a low maintenance lifetime siding like brick. Since I'm still fairly young does the added initial expense of brick have a favorable return on investment over 50 years or more when passed on into future generations?

In Energy efficiency and durability | Asked By Shane Fairman | Nov 3 12
6 Answers

Building with ICFs -- will it lower the EMFs?

HI,, I am building in SD with ICF construction for the basement and main floor. One poster suggested a metal roof to create a faraday cage. I am looking to keep the EMF's low and would like all the input I can get. I didn't realize I could use the rebar in the walls to my advantage. I am not sure about pricing on a metal roof. If I didn't use a metal roof, do you have any other options?

In General questions | Asked By Kami Kline | Dec 19 12
5 Answers

OSB before Rigid Foam?

I'm planning the renovation of a small (920sf) home in Indiana (Zone 5). The original home is 112 years old, but at some point it there was an addition (yes, it is still only 920 sf). So the original exterior walls have no sub-siding (sheathing) but instead has a very hearty lathe on the interior of the stud wall. The exterior siding and the hearty lathe both have to go. The addition has 1x6 sheathing boards on the exterior of the studs, hung horizontally.

In Green building techniques | Asked By William Wagnon | Dec 19 12
10 Answers

Spray foam and fire

I have read, without verification, that spray foam will become an accelerant when heated to a high degree. There was a new house that was built by a reputable builder, they used spray foam and the house burned very quickly. There was no evidence of arson.

I have a client who wishes spray foam and I prefer sprayed cellulose. Does any one have evidence other than anecdotal?


In General questions | Asked By john winkler | Nov 30 12
14 Answers

Is an HRV/ERV system necessary?

My husband and I are building on our own a small house that we've tried to make as green as possible. Neither of us are familiar with green building (he's conventional framer) and we rely on this website and green building books to answer our questions. The one thing I'm stuck on is, do we need to have an HRV or ERV system? We are building the house as tight as possible, sealing all leaks, and have an inch of rigid foam on the exterior and will have R-21 cellulose interior insulation. The house is 24x24, two floors and an unfinished basement.

In GBA Pro help | Asked By Morgan Clark | Nov 27 12
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