westend wrote:
The problem with using a concrete block is that most guys put nothing under it and nothing on top. When the steel is lowered onto the web or sidewall of the block, it is prone to crack. Part of that is why multiple blocks forming a pier are used under mobile homes. The frame load is spread among the multiple blocks.
If you don't have any steel stands, buy 6 X 6's and cut them into cribbing blocks. Either that, or use at least 4 blocks under every support location.
"Cinder block" is a regional thing. No one in the upper Midwest uses that term. "Concrete" is placed and hardened "cement". "Cement" is a mix in a bag, the stuff rolling around in the truck is "concrete mix". Masonry terminology is easy. Try electrical nomenclature if you need a headache.
Multiple blocks has nothing to do with "strength".. It is more about making a "STABLE PIER".
If you simply placed one block on top of another block you will have a very unstable stack in the direction of the most narrow portion of that stack.
Since you have 8", 10", 12" x 16" blocks, the stack is only stable on TWO of the sides which is the LENGTH of that stack..
Make a stack by setting two blocks you now have a 16", 20", 24" x 16" foot print. This makes for a much more stable stack that will resist being pushed over on all four sides.. Very important as you don't want to see your trailer get pushed off the blocks in high winds or even in normal usage.
I have never seen mobile homes piers set on wood or even having wood put between the steel frame and blocks.. I have only seen an occasional wood wedge placed between the block and steel frame and that is only for shimming the frame to keep the trailer floor level and flat along the length of the trailer..
When done properly there is no shock load placed on the blocks when mobile home is being setup. No shock load = no broken blocks in the process..
Around here most mobile homes will have concrete footings under the block piers. The block are set on the piers and it is all dry stacked. The footings are needed to get below the frost line of about 32" and provide a much larger foot print for the block piers to set on.. Otherwise placing the blocks directly on the ground will result in frost heaves in the winter and in the summer it will drop unevenly creating a need to have the trailer re leveled in a few years..