AndyM wrote:
Hello all,

I need to replace a 22mm pipe under the kitchen floor. The original
one, it appears, was put in when the house was built as there is no
way I can get a length under the joists.

The joists are 4" x 2" resting on brick supports. The routing would
take the pipe parallel to and 12" from the support.

Q. Can I cut a U shaped notch 22mm deep in the top of each 4" joist,
12" from the support, without seriously weakening the joist?


Possibly, but you'd need to do the calculations to determine whether or not
it is acceptable without comprising the strength of the beam. Have you
considered cutting the old pipe out in sections and then feeder plastic pipe
in instead (e.g. Hep20 or Marley Equator)? Unless the joists are seriously
close together you should be able to fit plastic quite easily.

Cheers
Clive