Boring holes through joists

[Jon Fairbairn]

I want to run two pipes along under our landing floor (which means going through all the joists).

Joists are 180×50mm Unfortunately there are already notches and holes, with the result that the calculator here:

which mostly agrees with the wiki says there is only room for one more hole. But it also says that the maximum hole size is

45mm, which means that I could put the two 22mm pipes through one big hole. I don?t want to do that because one is hot and the other cold. So my question is, can I put two 22mm+minimal clearance holes say 66mm apart (3 diameters as per the wiki) and still meet regulations?

[Roger Mills]

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!

[John Rumm]

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:

[GB]

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.

[tabbypurr]

2x7 is wild overkill for a landing, unless it's a vast landing area in a co untry house lined with marble. 3x3 was common. BR are massively OTT on jois t sizes, and it has nothing to do with safety.

NT

[Brian Gaff]

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

[tabbypurr]

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

[The Natural Philosopher]

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

[tabbypurr]

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

[Jon Fairbairn]

Yes, indeed!

Thanks to all for the help.

[tabbypurr]

just chop it into lots of pieces :)

[Brian Gaff]

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