Notching/cutting joists

Hi,

I have just started work on a small en-suite type shower room, and have to take the waste through the joists.

I have no other option unfortunately (conservatory is sited beyond the other wall) with the way the waste pipe has to run, and will therfore either have to holesaw, or notch the joists (either 2 or 3 no. depending on where I can orientate the drain hole in the shower tray.

My question is - would I have a problem in respect of weakening the joists? the room in question is in the corner of the house, so the cuts/holes would be close to where the joists are fixed to the inner brick course. The house is early thirties built, so the timber is a good size.

Many thanks,

In my unqualified opinion....

Of course it will weaken the joists, making a hole big enough to get a waste pipe through is going to reduce the amount of material considerably.

You could of course strengthen them again by adding wood either side held with big bolts? (ISTR I have seen that done on TV shows).

Thanks Mattylad, I had thought that may be the response.

A joiner friend of mine looked at it and reckoned I wouldnt need to strengthen, its not his house though!!

He advised that as the waste would be 32mm then I wouldn't need to. I think I may need 40mm for a shower tray though, so yes its a fairly large hole.

There are Building Regulations regarding location & size of permitted holes/notches in joists. I assume you are also aware that building a new en-suite is notifyable work! It will also have to comply with all the other relevant Building Regulations &, depending on what your doing, may also require inspection.

Thanks Richad C.

I have done some digging on this site since I did the post, and have found some really useful advice on permitted safe areas to drill joists etc. I reckon I can follow this to keep within regs.

I have completed a ground floor bathroom recently, and followed all the regs etc. in respect of low voltage fans, bonding etc etc etc. Theres a lot to take into account!!

I was an electrician many years ago (do not do this for a living now) I did my sixteenth edition in April 2007, just for my own interest.

I alway pride myself on carrying out a job properly, and doing all the research as and when required.

I was aware of the work being notifiable.

Thanks again.