[Greenbuilding] Which insulation? How to install?

[John Salmen]

In making decisions like this you always should question your bias and goals
and the complexity of any solution. 

The conditioned space needs adequate floor insulation regardless of how you
provide it - I would say the goal should be r30 as a min.

If you are doing a crawlspace then the goal there is to create a decent
accessible space - which is around 30". Meeting the code criteria of a
crawlspace mitigates vapour and gas concerns to some degree. It also
alleviates the curses of future workers who have to navigate that space.

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 (???). 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.

Rolled steel joists are another solution over a moist crawlspace where you
might want good spans and be concerned about wood - and you can run foam
over top of them. But rubble and earth you can trust and steel just like
wood will eventually fail (so provide a decent space for future solutions).



-----Original Message-----
From: greenbuilding-bounces at lists.bioenergylists.org
[mailto:greenbuilding-bounces at lists.bioenergylists.org] On Behalf Of RT
Sent: May-28-12 11:00 AM
To: Green Building
Subject: Re: [Greenbuilding] Which insulation? How to install?

On Sun, 27 May 2012 15:05:21 -0400, Eli Talking <elitalking at rockbridge.net>
wrote:

> I was planning on the addition being built over grade slab,but one day 
> my contractor client got so enthusiastic with
> her excavator that she assumed a crawlspace and excavated accordingly.   
> It will be a crawlspace.

Rather than futz with all of the challenges/headaches associated with a
wood-frame floor, I'd tend to stick with the original plan to utilise a slab
as floor, but elevating it to the top of the stem wall foundation now that a
hole has been dug.

It could be a suspended slab if it is desired to utilise the volume beneath.
One option to accomplish this would be to make it a composite slab. There
are pre-formed ribbed sheet metal pans which enable free-spans of 15 feet
using only a 3-inch topping (ie 5" overall thickness including 2" depth of
the pan) but one could forego the cost of the pans and do a slab of about
the same thickness by inserting a beam.

The simplest would be to just fill up the crawlspace with a load or two of
stone, leaving enough room for insulation  (EPS rather than XPS would be
fine in this situation) and then cast the slab on top.

If one prefers to minimise the use of high embodied-energy cement and
concrete, there's no reason an earthen floor (or hybrid variation thereof)
couldn't replace the concrete in the second option.

And contrary to AA-Man's preferences stated recently in another thread (ie
cork it) , I think that a heavy mass floor is more beneficial from a thermal
perspective and pragmatically superior to a wood-framed one.


-- 
=== * ===
AOD257
Rob Tom
Kanata, Ontario, Canada

< A r c h i L o g i c  at  Y a h o o  dot  c a  > (manually winnow the chaff
from my edress if you hit "reply")

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