Fash wrote:
I'm sure the answer's here somewhere but I can't find it. Lots of
information about Americans jacking up their houses but since these are
mostly stapled together it's not really relevant to my 1750 townhouse!
The problem is that at some point in the 50's the previous owners of my
house took out a wall in the basement and on the ground floor without
putting in proper support. The beam they used in the cellar went in
sideways (H beam instead of I beam which is about a quarter of the
stiffness.) As a result there is a significant deflection on the beam
in the cellar which translates into a bow in the floor at ground and
first floor level.
I'm having it dealt with by putting in new steels at first floor and
ground floor level. The question is what is the best way of raising the
floors back to approximately level before putting the new beams in? I
don't really want to just preserve the existing bow although some
unevenness will remain after jacking.
Is it is simple as tightening the acrows until they lift the structure
or would I (or at least my builder) be better off using a second set of
Acrows with hydraulic jacks to do the lift with the original acrows
then raised to take the load. This way I could raise it a little on the
hydraulics and then move up the screw jacks to maintain the lift.
Anyone done this before?
All advice (although especially good advice) welcomed.

You have absolutely *got* to take the advice of a structural engineer
over this. Have you really not already done so?

IANAE but surely there would be a real risk of totally buggering up the
house by cranking the structures up as far as their original positions.
Really not worth risking losing your house (life?) over a couple of
hundred quid's worth of fees.

David