[Cob] Termite protection of earth floors

[Bernhard Masterson]

Hi Simon, I don't have experience with termites but here are a couple of thoughts.

1) Do termites in Australia get into cob walls or other DRY earthen masonry? If it is not an issue with dry earth masonry then I wouldn't worry about extra precautions to protect your floor against termites.  If separated from the earth by a capilary break of drain rock then your floor should be completely dry.  

2) In order for the boric acid to migrate into the soil your floor would need to get so saturated that water would flow through the flooring materials.  Otherwise it will just remain as a salt in the dry floor mix. I think the boric acid will be more effective in the sub-floor mix rather than in the finish coat.  Stop the critters before they get so close to the surface.  I would also recommend a sub-floor (over the drain rock) made of crushed gravel (road base can be ideal on its own depending on the mix), sand, and small amount of clay slip.  This mix is tamped in place.  It has so much rock and so little soil in it that there isn't much room for termites.  And I should think they would choose many other places to collinate before the floor.

3) I wouldn't put down plastic sheeting under your floor unless you are going to have air conditioning running on a regular basis.  The cooler indoor climate will pull moisture from the soil below the house and in that case a vapor barrier could be helpful.

- Bernhard 



Get under a sustainable lifestyle umbrella, the carbon is going to hit the fan.

____________________________________http://bernhardmasterson.com

Natural building instruction and consultation


> 
> Message: 1
> Date: Mon, 26 Nov 2012 17:10:14 +0800
> From: Simon Matthews <simon at karrak.id.au>
> To: coblist at deatech.com
> Subject: [Cob] Termite protection of earth floors
> Message-ID: <1353921014.6874.16.camel at simat-laptop>
> Content-Type: text/plain; charset="UTF-8"
> 
> Hi,
> 
> I was thinking of making an earth floor termite resistant by adding
> Boric Acid to the mud mixture. Here are some links to a couple of
> research papers that imply to me that it maybe a good idea.
> http://www.treesearch.fs.fed.us/pubs/20253
> www.ctahr.hawaii.edu/gracek/pdfs/234.pdf
> 
> As the Boric Acid is water soluble, i was thinking one would have to lay
> plastic sheeting under the Boric Acid impregnated mud. I don't know if
> the termites eating holes in the plastic sheeting maybe a problem.
> 
> Another thought is putting the Boric Acid in the top coating of mud that
> will be impregnated with Linseed Oil which would hopefully stop it
> leaching into the ground below. I wonder if the Boric Acid will
> interfere with the polymerisation of the Linseed Oil, or the structure
> of the mud. I was thinking of using a concentration of Boric Acid of
> between 2-4% by volume of floor mud.
> 
> I would be interested in anyone else's thoughts and experiences with
> Boric Acid in mud floors and also about Termites and mud floors
> generally.
> 
> Thanks
> Simon Matthews