[Cob] Coblist Digest, Vol 15, Issue 12

[Kindra Welch]

I would not use straw under a floor: as straw clay it will take too long to dry (when new or when some spill happens in the future). 

 Vermiculite and Expanded clay are both better options. I have used pumice before (sized 1/4”-) and it was so fluffy it would not stay compacted and was hard to apply the floor over. We made islands of plywood scraps to help spread our weight out when applying the subfloor (3-4”troweled in wet). You might have to mix the vermiculite with just a touch of clay to make it solid enough to bear weight without moving.   Or if you do have larger pumice  available: put in the large pumice stones first then fill the gaps with vermiculite.   Kindra



On Mar 21, 2017, at 12:00 PM, coblist-request at deatech.com wrote:

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>   1. straw clay in floors (ROBERT ALCOCK)
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> Message: 1
> Date: Tue, 21 Mar 2017 11:59:38 +0100
> From: ROBERT ALCOCK <ralcock at clientes.euskaltel.es>
> To: coblist at deatech.com
> Subject: [Cob] straw clay in floors
> Message-ID: <f97df7a127cc.58d115aa at euskalnet.net>
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> 
> Hi all,
> 
> We're deciding what kind of insulation to put in the subfloor of the new cob/straw bale houses we're building in northern Spain (http://abrazohouse.org/the-place/buildings/el-manzanal/)
> 
> The options we're looking at are either (a) vermiculite or expanded clay, or (b) light straw clay.
> 
> Does anyone have experience of using light straw clay in a subfloor (underneath a cob floor)?
> 
> We would be using a plastic vapour barrier, perhaps with the addition of a gravel drainage layer on top of the plastic.
> 
> Of course we are concerned about the moisture hazard. Any advice would be more than welcome!
> 
> Yours in cob,
> 
> Robert http://abrazohouse.org
> 
> 
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> End of Coblist Digest, Vol 15, Issue 12
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