[GSBN] Under slab and edge insulation at doorways

Fri Feb 11 01:17:22 UTC 2011

As Kelly mentions, I have used perlite as an underslab insulation in the demonstration project I'm building right now called the 2nd St. LIFE Project. The house has a shallow frost protected footing. Inside that, we used the masonry fill perlite over 5 inches of washed gravel and under the radon barrier. It was placed in woven poly bags (though this was not the original packaging) and tamped to 7 inches, with an R-value of R-21. Any remaining voids were filled with loose perlite before installing the sealed radon barrier. If it had been in woven poly from the manufacturer, it would have saved much time on our part. But overall, we liked the compaction and R-value, and we certainly hope that we find no surprise indoor plant life growing in the earthen floor!

During our research, I had found that Daniel Silvernail had been using perlite and had written about it for CASBA, and on his website at http://63.249.122.147/blog/?p=55.  The Supreme Perlite owner shared example of its use under earthen floors in the NW. I learned that Lydia Doleman and Sukita Crimmel had been incorporating it as well. Perlite has been used in under floor applications with concrete and wood floors as well. 

I am also excited to use sheep's wool batt insulation (I know this is nothing to you all down under) in our roof from Black Mountain USA. Our shipment just came yesterday. 

Laura (always willing to jump off a cliff) Bartels

"Leap and the net will appear" - John Burroughs

Laura Bartels
GreenWeaver Inc.
520 S. Third St., Suite 5 
Carbondale, CO 81623
970-379-6779
www.greenweaverinc.com

We've moved to the Third St. Center 
http://thirdstreetcenter.net/
A community place promoting inspiration, sustainability and creative exchange

On Feb 10, 2011, at 2:44 AM, Kelly Lerner wrote:

> Thanks all for your thoughts on perlite underslab insulation!
> 
> Here's the document that I found after a discussion with Laura Bartels (who, I think, used perlite under her adobe slab in Carbondale, CO). That's what got me started down this exploration path.
> http://www.perlite.org/product_guides/21%20perlite%20for%20underfloor.pdf
> 
> It specifies a water repellant type IV perlite and I will have to check out whether that is available in Spokane. I was also planning on putting 6 mil poly directly under the slab (and wrapping it up the edge), so that the slab is isolated from ground water and radon intrusion. We tend to have dry, well-drained soils in Spokane due to the gravel left by the Missoula floods. Finally, I was going to leave the perlite in bags to aid in the compaction. I think that before I try this on a foundation, I may get a bag of perlite, play with compaction and then  bury it in my backyard under a tree for a few months, then dig it up to check out the capillary action and moisture. 
> 
> On the slab edge detail, Chris, I never do a monolithic pour. I usually use a floating slab within a conventional stemwall with footing (no big seismic concerns in Spokane, yet). The joint between stemwall and the slab falls under the bale wall and that's where I typically wrap insulation up the edge of the slab. The problem comes at the doorways. What I decided yesterday, was to shift the door location in about 3" so that the threshold will cover the insulation joint. 
> 
> I'll keep exploring the perlite, but may stick with high density EPS for underslab now on client projects until I can confirm perlite's performance.
> 
> Kelly "KISS" Insulation Maven
> 
>> 
>> 
>> 2011/2/8 Kelly Lerner <klerner at one-world-design.com>
>> Hi all,
>> In an effort to get away from the global warming potential of and fire retardants in rigid insulation, I'm beginning to design with compacted perlite as under-slab insulation in strawbale houses in Spokane, WA (east side of WA - cold winter - 6800 heating degree days, high desert, dry - about 16" rain/year, water table is usually quite low and soils are well drained). 
>> 
>> I've found a relatively local source for perlite(Portland) and the costs for R-value are comparable to or less than rigid insulation. I'm installing perlite under the slab and wrapping it up the edge of the slab (on the interior of the stem wall - under the strawbale wall), but I'm having trouble detailing "slab edge insulation" at the door ways. Anyone have any experience or thoughts about the right approach? Contact me on or off list. Thanks!
>> 
>> In case you're wondering about perlite, here's a link: http://www.perlite.com/faqs.htm
>> 
>> 
>> Kelly Lerner, Architect
>> One World Design Architecture
>> 509-838-8812
>> www.one-world-design.com
>> 
>> Have you read Natural Remodeling for the Not-So-Green House? Available in Bookstores across the Universe. 
>> www.naturalremodeling.com
>> 
>> 
>> 
>> 
>> _______________________________________________
>> GSBN mailing list
>> GSBN at greenbuilder.com
>> http://greenbuilder.com/mailman/listinfo/GSBN
>> 
>> 
>> _______________________________________________
>> GSBN mailing list
>> GSBN at greenbuilder.com
>> http://greenbuilder.com/mailman/listinfo/GSBN
> 
> Kelly Lerner, Architect
> One World Design Architecture
> 509-838-8812
> www.one-world-design.com
> 
> Have you read Natural Remodeling for the Not-So-Green House? Available in Bookstores across the Universe. 
> www.naturalremodeling.com
> 
> 
> 
> _______________________________________________
> GSBN mailing list
> GSBN at greenbuilder.com
> http://greenbuilder.com/mailman/listinfo/GSBN

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.sustainablesources.com/pipermail/gsbn/attachments/20110210/a17190a2/attachment.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: clip_image002.jpg
Type: image/jpeg
Size: 3970 bytes
Desc: not available
URL: <http://lists.sustainablesources.com/pipermail/gsbn/attachments/20110210/a17190a2/attachment.jpg>