[Cob] Lava Rock

[uli hamann]

Hi  i'm getting ready to finally build the walls on my house. Did the roof
first   35ft inside diameter  round.   Roof is supported by center log and
12 posts around the circumference sitting on concrete foundation and
stemwall.Since i am doeing this alone i am considering adding some 1.5 to
2inch lava rocks that are locally available (bellingham wa) Some folks in
victoria bc have buildt one using 3/4 inch lava rock which is not locally
available.So my thought is to try the larger rock here to maybe increase the
R value, speed up the mixing and make the cob lighter and easier to handle.
I have a kubota backhoe (running on biodiesel)to do the mixing. Anyone have
any pros or cons to add to my already overloaded brain as to how viable this
plan is???      thanks       uli