So I looked up the regulations for notching and drilling joists and it says you can drill up to .25 diameter holes. I have 9" Joists so I should be ok drilling a 42mm hole for bath waste? Any problems with this?
Prehaps I should have said 'should not' instead of 'cannot', I certianly wouldn't put a 42mm through a 225mm joist, you have the live load to consider,plus span,etc. See this linky. http://www.diydoctor.org.uk/projects/Notching_joist.htm
That's the site I looked at and calculated that 42mm is less than .25 the dept of the joist, hence thinking I was ok. Did I miss something?
Even if you are going to drill a hole through the joist one of the problems you are going to get is threading the pipe through and you don't want any joints in the ceiling space. Is there no way of running this outside ?
I wouldn't be putting 42mm through a joist either. That floor will have a noticeable more amount of 'spring' to it. Sometimes what the regs say might work, but I wouldn't be rushing in with a hole saw...
That guide says exactly the same as the DIYdoctor link and suggests it is possible - however as Joe95 says to the OP - "don't rush into it".
1. I'd avoid doing it if at all possible. You're right at the edge of what is theoretically permissible, if not slightly beyond it (see 2. below). 2. The holes need to be slightly bigger than the outside diameter of the pipe. 3. You need (from memory) a fall of a minimum of 18mm per metre run on the pipe. To get that fall, not all your holes will be in the centre of a joist, although they won't be far off. You'd have to work it out. 4. All the holes will need to be exactly in line, and at the angle required by the fall. Not easy to achieve. 5. If you are going out through a wall at the end of the run, consider feeding the pipe in from the outside, avoiding joins under the floor.
Some very good points. To the OP DaveHerts: Can you get the pipe alongside a wall? If you can fit it tight against the wall you could use some very tight boxing to cover it.
40mm solvent weld pipe is actually 43mm OD anyway, and I would not want push fit or compression waste out of sight under the floor.
Whereabouts in the bathroom is the bath located Dave, is it miles from an outside wall. Often with a standard bath trap, the floor will need cutting out to accommodate the trap, but the pipe will be above floor level or thereabouts, especially if you use a shallow trap. I hate putting waste pipe through joists for the reasons mentioned above, but if it was say just one joist, then I wouldn't loose any sleep about drilling through it as long as it was in the centre and I braced/sistered the joist. I had to do this on the last big bathroom job I did...it was the only way as basically was converting a large bathroom into 2 shower rooms. I insisted that the one shower go on a riser as it would have meant drilling through several joists to get a waste out, the other needed the tray to be kept as low as possible due to the elderly client. With the joists running parallel to the outside wall, the one nearest had to have a hole drilled through.
How many joists do you need to drill through? If it's just the one/two, go ahead and do it. You're within the regs 'guidelines' so nothing to worry about. If it's 4-5-6, then you won't be able to satisfy the regs and the required fall, so best have a rethink. As CGN, said! didn't see it.
Thought so... If the floor didn't collapse it'd sure feel like a trampoline! It seems just about every time a shower or basin needs to go in, the joists are running the wrong way Could always feed the pipe outside and hang it over the neighbors fence!
Don't worry, I drive past the house occasionally...it hasn't collapsed yet! : Don't worry, I drive past the house occasionally, it hasn't collapsed yet...yet!! Anyway, they were old school joists...really hefty bug***...which I braced as well. Here's the external pipe work...can you spot the 50mm pipe?
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