In article , Charles Middleton wrote:
Another badly planned project on my part then. I'm not sure what other
options I have and the shower & tray is arriving tomorrow. I thought
that it was safe to put holes in the joists providing that a) it was
close to the supporting wall and b) the hole went through the middle
of the joist and c) the diameter of the hole was no bigger than two
thirds of the joist?

Generally not. You'll find a nice diagram of what is acceptable without
calculations in a guidance note on the Tameside website -
http://www.tameside.gov.uk/tmbc8/note07.pdf

i.e. holes max D/4 at between 0.25 and 0.4 of the span

Having said this, the usual practice in domestic construction is to make
all the joists the same size, said size of course being determined by the
longest span. If the bathroom is over the kitchen and you've got (say)
50x200 joists when you really only need 50x125 over this particular span
then you can obviously chop a lot more out without causing problems but
it would need to be verified by a structural engineer.

--
Tony Bryer SDA UK 'Software to build on' http://www.sda.co.uk
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