[Strawbale] R value of light straw clay

[kim thompson]

Thanks Peter and Andrew.
I don't have the Minke book, in  translation, yet.
But hope to soon.

kim


On 12-Nov-06, at 4:36 PM, Peter van Balen wrote:

> Minke (clay expert at University of Kassel, Germany) cites density  
> figures
> similar to the ones given by Rob Tom: i.e. lightest, possible only in
> theory, 300 kg/m³; lightest, only possible with very careful  
> preparations,
> 500 kg/m³, but in building reality even this will compact to at  
> least 700
> kg/m³. For such a 700 mix he gives a lambda of 0.21 W/mK (which  
> you'll have
> to convert to your own non-metric R-value yourself I'm afraid).
>
> Peter van Balen
> France
>
> ===================
>
> From: kim thompson <shipharbour at ns.sympatico.ca>
>
> 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
>
> ==============================
>
> From: "Rob Tom" <ArchiLogic at yahoo.ca>
>
> That being said, I do wonder if the cob is providing any appreciable
> insulation value at what is a critical area (gable ends) WRT  
> building heat
> loss.
>
> 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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