George wrote:
"RobertL" wrote in message
...

I want to support my ground floor joists. This is partly to take the
weight of a piano and also because the joists do deflect rather a
lot anyway when weight is put on them (such as bookcases, cookers
etc.
The joists in these houses (8"x2" at 18" centres) are, apparently,
of rather poor quality and have shrunk and bent in every house in
eth development. They were built in 1964 - part of the "Span House"
movement. When the floor deflects the walls that are built on it
(of block) move and crack which is not nice.

Under the house the gap between the earth to underside of each joist
is about 50cm. This is too big for a car scissor jack - I had
imagined using a row of scissor jacks. It's too small for an ACROW
prop.

One simple solution is to use some wooden 4"x2" props with
carpenter's wedges to adjust the height. But I am worried about
creating a damp- conducting path up to the joists even if I stand
the base on damp proofing membrane.

Does anyone have any other suggestions?

Robert


House bricks and put a piece of insulation in between the joist and
the top brick ie plastic sheeting doubled over.

Might also be worth putting some noggins/dwangs in between the joists at
regular intervals to stop the joists twisting as they get loaded. Our
builder did this when sorting out our wonky dining room floor.

Tim