[GSBN] Perlite u/floor insulation

[Tom Woolley]

Dear Andy

Perlite was used quite a lot on the WISE building I think
There can hardly be a building in the world that doesn't have more  
moisture and wetting issues than it has
I have copied this email to Pat Borer who was the architect with David  
Lea, so you can ask him
I dont think the perlite is on the CAT web site
http://info.cat.org.uk/questions/wise/what-materials-were-used-build-wise
However you can download a presentation which shows the perlite in use  
I think
www.bath.ac.uk/ace/uploads/images/BRE/.../shanks%2014.00.pdf
I think there are two kinds of perlite ...one is much more moisture  
resistant

We use closed cell eps in floors here as there seems to be unlimited  
amounts of recycled eps available ...we would never use new for the  
reasons you give but its better to recycle it than it going into  
landfill

Good luck

Tom


On 4 Apr 2011, at 10:57, Andy Horn wrote:

> Hi
> I am trying to get more info on the use of Perlite for underfloor  
> insulation. (been to www.perlite.org)
>
> I am involved as a consultant to a project in Johannesburg, where we  
> are using under floor hot water heating for winter (pipes are being  
> embedded inside a concrete slab) and so need to insulate under the  
> slab. I have suggested we look at using a layer of 100mm of Perlite.
>
> However, the Project manager has just come back to say we must use  
> the closed cell polystyrene as he is worried about the Perlite  
> absorbing water and is concerned that as a result it will loose its  
> insulating properties. We have quite a water logged site with lots  
> of clay and silt in the soil and the buildings in question are being  
> dug into the back of the slope.
>
> Various info says it is “water repellent” but I notice the details –  
> the 2 that I could find – included some kind of a capillary break  
> under and over the Perlite or a layer of plastic damp proofing  
> underneath (as would be under a concrete slab anyway) and a layer of  
> “oil paper” on top to separate it from the concrete. I also see it  
> is used in insulating lightweight screeds and concrete work…..where  
> it clearly retains its insulating properties despite being  
> encapsulated in concrete with its relatively high moisture content…… 
> or does one treat the Perlite in some way to prevent it absorbing  
> moisture???
>
> Can anyone input here ….as while we can get the Perlite here, the  
> suppliers have no experience with using it in the building industry…… 
> and I am loath to let the project use the closed cell polystyrene as  
> it is a particularly environmentally damaging material which, uses  
> benzene and ozone damaging HCFC’s in its manufacture.
>
>
> Any input would be really valued,
> Thanks
> Andy Horn
>
>
> <image001.gif>
>
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Tom Woolley

Rachel Bevan Architects
80 Church Road
Crossgar
Downpatrick
BT30 9HR
tom.woolley at btconnect.com
028 44 830988
www.bevanarchitects.com



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