[Cob] Termite protection of earth floors

[Simon Matthews]

> 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.  
Yes, unfortunately the termites are pretty determined here and will
travel up the cavity of double brick walls to get to the roof structure,
on our property we have seen them build galleries over rocks to get to
wood.

> 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.
I would have thought the mud being wet would be enough for the Boric
Acid to diffuse to areas of lower concentration, i.e. the subsoil,
although i am not sure.

> 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.
I always like the extra insurance of a layer of plastic to help stop any
problems with damp floors. I realise it is not a natural product and
does require petrochemicals for its manufacture but the amount you use
is very small.

Simon