[Greenbuilding] Which insulation? How to install?

[Gary BIs]

Hi,
My expertise in this area is little to say the little to say the least -- so, 
keep that in mind.

I converted my crawl space to a conditioned space as discussed in this: 
http://www.builditsolar.com/Projects/Conservation/Insulation/CrawlSpace29238.pdf

I put two layers of poly on the dirt and sealed it around the edges and at seams.
I blocked all the vents and I foam can sealed all around the rim joist.
Then insulated the crawl space walls with polyiso foam board with tape  on the 
seams.

This was easier than insulating the floor above the crawl, and cost less, and 
eliminates potential problems with frozen pipes that might come with a vented 
crawl space and lots of floor insulation.  It also brought my smaller furnace 
and its duct work into the conditioned space.

Anyway, its been about 6 years, and its worked fine for me.  The crawl space 
feels dry.    I suppose I should log the temp and RH for a while.
I do live in a dry climate (SW MT), but the stuff I've read on conditioned crawl 
spaces seems to indicate it works OK over a range of climates.

There is a section at the pdf link that discusses the need for crawl space 
ventilation (or not).

Gary



On 6/1/2012 6:04 PM, Eli Talking wrote:
>
>
> -----Original Message----- Stuart Fix writes:
>
> Humidity within the crawlspace should be controlled via poly on the ground
> and proper ventilation (either passive screens or active fan/humidistat).
> The crawlspace walls are there to stop animals and excessive wind washing.
> The site must be properly graded if you have any hope of a dry crawlspace.
>
> My comment:
> The issue I am trying to understand is how to maintain in a ventilated crawlspace
> to be warmer than dew point.  The vapor barrier on the ground only stops 
> ground sources of humidity.  A high standard thermal barrier in the floor 
> keeps the
> ac cooling from cooling the bottom surface.  However, the shading will keep the
> crawlspace cooler than outside.  Could this cause condensation?
>
>
> John Salmen writes:
> If you don't need a crawlspace I like robs idea of simply building retaining
> perimeter foundation walls and rubble filling them and would use eps FOAM as
> rob suggests (???).
>
> My comment:
> I agree with this, also.
>
> John Salmen writes:
> That would be my bias except I wouldn't bother with a
> slab as they just seem to lag behind the weather and you can throw ply and
> tile or wood floor,  or a thickset tile over foam.
>
> My comment:
> Are you saying that you put plywood subfloor on top of the foam on top of the 
> gravel without a slab or framing?  Can you install a thin set tile directly on 
> the foam?  Have you installed this on your projects?
>
> Thanks for comments.
>
> Eli
>
> www.conservationarchitect.net
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