[Greenbuilding] building floor on top of rigid foam... (basement/garage retrofit)

[RT]

On Sat, 16 Apr 2011 15:53:26 -0400, sat jiwan ikle-khalsa  
<satjiwan_khalsa at hotmail.com> wrote:
>
> we're aiming for about R20 floor insulation (rough passiv haus goal for  
> our region - Mid Atlantic USA).  we're thinking to put 2 layers or two  
> inch rigid foam on top of the existing slab then build a floor with 2x  
> framing members sufficient to bring the height up so 3/4" plywood and  
> carpet on top will meet the other room's height.
>
> would Roxul rigid foam work? is it specified for load applications?

My first question would be:

"Why is (steenking,off-gassing, allergen-magnet) "carpet" even being  
mentioned  ?"

My second question would be:

"Why would one choose to use extruded polystyrene in that situation

My third question would be:

"Why bother with the wood framing ?
	 	   		
(There is no such thing as "Roxul rigid foam" as far as I am aware.)

If I were doing the project, I'd use the less costly and more  
enviro-friendly expanded polystyrene (EPS) rather than the extruded (XPS)  
and leave out the wood framing/ carpet altogether and just cast a 2.5" to  
3" thick concrete slab on top of the EPS, possibly colouring/stamping the  
concrete or laying stone or porcelain tile over if for some reason the  
skills are lacking to produce good quality concrete.

This of course allows one the option of installing hydronic heating in the  
slab if necessary (ie if taking advantage of direct gains isn't possible).



-- 
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Rob Tom
Kanata, Ontario, Canada
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