Charles Bishop wrote:

In article Zs_le.7390$tv3.1003@trnddc06, wrote:


Edwin Pawlowski wrote:

"Joseph Meehan" wrote in message


Well few builders will put a beam in larger than necessary to carry the
weight of the structure. You need to know what it is already supporting.


Once you determine that, I'd still put in a vertical support under the beam
while I was doing the lifting.



And I would make the vertical support have a very large base
in order to NOT crack my concrete floor with a point load.


Say you use a 4x4 as the support. Isn't there a max base size that's going
to do any good? If it was 3/4 plywood, at some size of the plywood and
load, woulnd't the ply "buckle" upwards and reduce the area that is
transfering the load to the concrete?


Of course! But you don't have to use plywood, in fact, I
wouldn't use plywood. I would use a steel base with
reinforcing gussets to transfer the load to as large an area
as possible and place that on a sheet of plywood.

Of course, it is also possible that the I beam in question is
large enough to support whatever he is going to lift without
any help at all. Impossible to determine from here. But if it
isn't, and you use a support, then you had better spread the
load, hope there is a footing under that point, install a
footing under that point, or just hope for thick concrete and
no cracks.

--
Robert Allison
Rimshot, Inc.
Georgetown, TX