Boring holes through joists

I ain't a structural engineer but, in my experience, these rules are a bit conservative, and deviating slightly from them is unlikely to bring the house down. I would have thought that two (say) 25mm holes a reasonable distance apart would be preferable to one 45mm hole.

I assume that you're using plastic pipes, 'cos feeding copper pipes through holes in joists would be a bit of a challenge?!

Are you doing something which needs to be inspected by a BCO? If not, and if the holes will be hidden by floorboards and ceilings, I wouldn't worry too much.

Others may disagree!

No, I would agree with that....

If near the ends of the joist, then notches are preferable to holes, and nearer the mid span holes are preferable. If you have unused notches when you are done, you can restore the strength with couple of glued up folding wedges:

Do you need all the existing holes and notches, or could you strengthen the joists by screwing some offcuts of timber across some of them?

Not that it's going to collapse, either way, but it might make it less bouncy/noisy.

NT

I was just going to say, how do you know if a hole is bored or not, sorry must be the way my brain works.... Brian

When did it last do anything? Hence we know it must be bored.

Rubbish. It all depends if its in a 'sleeper', or not...

Or whether it's been nogging. Beam me up scotty.

Yes, indeed!

Thanks to all for the help.

just chop it into lots of pieces :)

Well I think I recall writing an article on the Wannacry exploit last week, maybe I'm infected? Brian