I plan to build a 16′ by 18′ cabin on a granite outcrop in Ontario. The build site has no soil on it. The cabin will rest on 6 piers of varying heights from 10″ to 36″ dictated by the flow of the solid outcrop. I want to use 22″ barrels as forms to build the piers. The barrel bottoms will be cut out and scribed to the contour of the outcrop. About 4″ of concrete will be poured into the form and 6″ to 8″ boulders will then be set in the concrete and against the outside the form ….followed by more concrete and boulders and so on, The inner part of the form will have rebar and be filled with concrete. Eventually I will cut away the barrel to expose a rock pier…akin to a slipform wall.
Any comments about the feasiblity of this approach is appreciated.
Replies
You will end up with a round concrete pier, with very little, if any, of the boulders showing. The conrete will surround the bolders.
I suggest you pour the structural piers first, then add the rocks as a veneer.
Go for it......
It might not be all that pretty but it sounds like your plan will work if you get your concrete around the boulders with minimal voids.
concrete or mortar
Thanks for the replies.
A couple of questions.........do the piers need to be pinned to the outcrop? and should the boulders be set in mortar instead of concrete and only the rebar in the centre placed in concrete?
Thanks
Mauri
yes, pin your piers. I also would prefer to make the piers solid concrete and then veneer it with your stone.