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10 Answers

Permeability of ASTM D 3909 cap sheet; needing roof to dry to outside

4" of 2 lb closed cell spray foam will go on underside of roof sheathing....so roof needs to dry to outside; hence why I am using #30 felt/tar paper instead of a non-permeable ice & water shield.

However, to get my Class A fire rated system, I need to use an ASTM D 3909 cap sheet over the tar paper. How well is this system going to be able to dry to the outside and will there be any issues with this system?

The roofing material is a synthetic shake; Bellaforte by DaVinci.


In General questions | Asked By eric Mikkelsen | Aug 29 14
6 Answers

Measuring moisture coming thru basement slab


My 2150 SFT ranch home with ICF walls and a full basement has NO vapor barrier (polyethylene layer) under the slab. Just pea gravel surrounded by drain pipes that exhaust into a lake behind the home. Currently I am running a stand-alone dehumidifier continuously and this is keeping the basement at about 35-40% RH. I also have a radon SSD fan installed a few weeks back. The fan is a RadonAway RP140 that uses 14W and is energy star rated.

In GBA Pro help | Asked By Venkat Y | Sep 3 14
3 Answers

EPS / XPS on interior ceiling

Problem: I have a very inefficient home in Southern California that was built in the late '70's with an exposed, pitched ceiling that slopes from 7' all the way up to about 16'. Even with a brand new air conditioning unit, the home is stifling hot with the 90+ degree weather we've had lately; and my AC unit never shuts off.

In Energy efficiency and durability | Asked By Michael Berger | Sep 3 14
33 Answers

Ready to insulate a new home

I am ready to insulate a new home, and need to make a final decision. I need help.
I have been the recipient of many helpful tips and guidance from thes pages as well as other green forums and it's all kind of coming to a head in our new home build as I attempt to make a decision about the insulation we will use. Here is the specs on my houses wall stack up

LOCATION: 47460 On the line of upper climate zone 4 and lower 5

2x6 exterior walls, 1/2 inch sheathing with tyvek, 1.5" polyiso foam with taped seams, vinyl siding

In Energy efficiency and durability | Asked By Anthony Hughes | Aug 8 14
15 Answers

Bio Ethanol Fireplaces

We have a client that is intereted in the use of a Bio Ethanol Fireplace. I am a abit concerened on storing the fuel and the requirement by the manufacture of leaving a window open when using?

In Green products and materials | Asked By Steve Theis | Sep 15 10
10 Answers

Need a knowledgeable builder

I'm looking for a builder/contractor in the Marlboro, MA area that is very knowledgeable about the concepts discussed on this site. Tired of having to explain concepts all the time. Does anyone know any good resources for me to find someone like this? Thanks.

In General questions | Asked By David Russell | Jan 16 14
7 Answers

Mold Growth on Tremco Enviro-Dri (WRB) Walls

Could really use some help from the experts here on the next recommended steps to take to find a solution to the mold growth in my basement. I have a one year old home in Tennessee that was built using Tremco Enviro-Dri and Tuff & Dri products. About 2 months ago, I pulled back the insulation to began to run electric in the basement and found the sheathing and insulation to be damp and mold starting to grow. It appears to be a condensation problem as it was fairly universal across all the exposed framed basement walls, but is worse on the north facing walls.

In General questions | Asked By Chip Keim | Feb 27 12
4 Answers

Double stud wall

Getting ready to build my own home. Looking at a wall assembly of 2" exterior EPS, plywood, 2x6 exterior wall with r22 fibreglass batts, 6 mil poly vapour barrier, 2x4 interior with r14 fiber glass batts and 1/2" drywall. I maintain r30 to the exterior side of the vapour barrier and r14 on the interior side so the 2/3 - 1/3 rule is maintained. I will not have to be concerned with electrical box and plumbing penetrations through the vapour except for items venting or take air from exterior.

In Energy efficiency and durability | Asked By Sheldon Lee | Aug 24 14
15 Answers

Open-cell spray foam in joist areas with polyiso on exterior walls?

From all the reading I have done, am I correct that I don't want to use closed-cell and need to use open-cell spray foam in the band areas of floor joists of the basement to 1st and 1st to 2nd floor areas when I have used polyiso sheathing on the outside of the walls?

I believe that is correct because of the perm is so low for the polyiso and you don't want to use another very low-perm product like closed-cell spray foam sandwiching the Zip wall sheathing. I'm just confirming if I read everything correctly.

In Energy efficiency and durability | Asked By john bell | Sep 19 12
2 Answers

I have a slab on grade, no insulation that I want to insulate and include a vapor barrier in zone 5B. What is the best way?

This is for a summer cabin and I would like to reduce the humidity in the cabin and also reduce air conditioning costs.

In General questions | Asked By Joseph LeBeau | Sep 3 14
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