[Greenbuilding] Basement EPS with plywood (acceptable)

John Salmen terrain at shaw.ca
Sat Jul 13 10:50:42 MDT 2013

Tried that. The fiber industry uses formaldehyde as the binder to achieve
densities. Higher densities more resin. Roxul states the urea is cured with
little potential for offgassing. Technically I am not sure what they are
talking about as curing reduces strength and ultimately density. The use of
formaldehyde is generally a compromise between emissions and strength. The
residential 'comfort board' I think reflects that compromise with a density
of only 745 psf. EPS type 1 (the lowest density) is about double that. I
would be concerned about using it as long term structure (under partition
walls, etc.). 


My experience with the product was that it was,  dusty, noxious and worst of
all inconsistent in density (roxul) - imagine a beehive hairdo. You can
crush the board with your foot or punch your fist through - so it was
difficult to work with as a board stock.


I could see using the higher density commercial roofing boards but then
would be concerned about offgassing.


From: Greenbuilding [mailto:greenbuilding-bounces at lists.bioenergylists.org]
On Behalf Of Alan Abrams
Sent: July-13-13 6:26 AM
To: Green Building
Subject: Re: [Greenbuilding] Basement EPS with plywood (acceptable)


because XPS has a significantly higher global warming potential than EPS,
I'd prefer the latter--even at somewhat lower R-value per unit of thickness.
Others on this list (John Salmen) have written extensively about using
adhesives instead of mechanical fasteners to connect the components.  


it raises another idea--to use rigid mineral fiber instead of foam.  Roxul
comfort board is rated at R-4 per inch, and is said to compress only 10%
under 743 LBs per SF.  dunno how that extrapolates to ordinary live loads,
but it still suggests a double, staggered layer of plywood, mechanically
fastened.  many other advantages, including dimensional stability, fire,
rot, and pest resistance, high permeability, and low embodied energy.  

Alan Abrams


On Fri, Jul 12, 2013 at 10:55 PM, Sam Ewbank <g.l.ewbank at gmail.com> wrote:

>From the green building archives.  A similar application to what you are
looking to do but with the suggestion of using 1.5" EPS





On Fri, Jul 12, 2013 at 9:52 PM, John O'Brien <john at boardom.ca> wrote:

Friend is doing some work, looking to put down 1" EPS, with floating
plywood, tapcon'd down, followed by some floating laminate.

Would this be considered an acceptable base, or would it be beneficial
to bump up to XPS or run a double layer of 1/2" ply staggered for more
point load compression protection?






Sam Ewbank


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