[Strawbale] R value of light straw clay

[kim thompson]

Hi Rob et al,

I was interested in the stats for light straw clay that were  
mentioned in the  thread
Re: [Strawbale] Breathability of Wood Shakes and Roofing Felt
Can you tell us where those stats and the later R2-3 that Andrew  
mentions come from.

Developing simple language to describe both production of the  
material, and installation seem critical in nudging forward best use  
of it in our buildings.

Thanks.

Kim Thompson
Nova Scotia, Canada


>
> ie At the lowest density possible for a straw/clay mix (~300 kg/m^3  
> (or
> ~18.7 lbs/ft^3), where the straw is just barely coated with clay and
> lightly placed (a mix that would be suitable for use in an attic) the
> R-value is about R-1.44 per inch.
>
> For a mix that would be suitable for a wall application, the  
> density would
> probably be closer to 40 lbs/ft^3 (and quite likely more), so the R- 
> value
> would be something like R- 0.7 per inch or less, meaning that for a  
> cob
> thickness formed by 2x8's, the nominal R-value would be something  
> like R-5
> or less, before accounting for the thermal bridges created by the 2x8
> studs which would further lower the effective R-value of the wall,
> depending upon the stud spacing.
>
>
> ===* ===
> Rob Tom
> Kanata, Ontario, Canada
> <archilogic at chaffyahoo dot ca>
> winnow the chaff from my edress in your reply
>
>
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