Hiding bathroom waste pipes

[Dave]

The bathroom re-fit is about to move from plan to implement but I still have a couple of questions:

Can I run the toilet soil pipe between the joists to the SVP? what's the minimum fall/slope? Is there any type of pipe that would make this easier?

I'm going to sit the shower tray on the floor (bedded on marine ply and mortar?) and run the waste between the joists too. Is there any reason not to join-up with the bath waste before the SVP? Is there a shower waste that can be cleaned from above? Is there any point using one of these "vortex" shower wastes? What's the minimum slope?

I want to run the basin waste in a new stud wall but it's going to be a real pain to drill the (big) holes in all the studs, the alternative is to saw (big) notches once it's built. Is there a narrower pipe that people use in these circumstances?

[Andy R]

I ran a basin waste pipe with no fall over about 6 metres and never had any probs.

Rgds

Andy R

[mrcheerful]

My loo pipe had to be exposed, so I built a shelf around it and tiled it, very useful. All my waste and water pipes are concealed, the bidet, basin and bath wastes all run to a single pipe that goes into the stack, after coming round a corner and dropping a foot. I had to add a vertical pipe that rejoined the stack to admit air or I got a siphon effect that made the other waste pipe glug when you emptied the bath or the basin/bidet. As long as you have a continuous fall of as much as practical there will be no problems, completely level or even worse a dip in the middle will give you stinking, blocked pipes. I got the shallowest shower trap I could find and put the shower tray as high as practical. You can get flexible waste pipe that might help your basin problem, but why cant you bring the waste to the floor? or have you got a non pedestal basin?.

mrcheerful

[Dave]

It probably will be a semi-pedestal, but even if I dropped to the floor the waste would need to run through all the joists, whereas if I put it in the stud wall I can drop gently to the end and then turn left into the SVP.

[John Rumm]

The maximum fall should be no more than 90mm / meter (and no less than

18mm). This is to prevent the siphoning problem that you observed, and also to stop the water flowing away too fast and in the process depositing any solid matter that was flowing with it.

[John Rumm]

You can, between 18 and 90mm / meter according to the building regs document.

so long as there is not a large vertical displacement between them all then no.

You can get some there the grate and inner section of the waste can be removed from above. This gives you some access to clean or retrieve stuff from the trap.

34mm is the minimum for a basin IIRC. Aside from the weakening of the studs (which may not matter if the wall is only a partition), a hole saw will do the job easy enough.

[Dave]

That's useful info, is it the same for all wastes (loo, basin, etc) and pipe sizes (50mm and 100mm)?

[Dave]

oops sorry, 'just saw your other reply. Thanks!

[John Rumm]

Have a look at building regs approved document H, that has loads of info on all sorts of sewage and water drainage etc.

[Dave]

Thanks again, I keep forgetting about that site and it's really useful.

[dave]

John Rumm wrote in message news:... To run the waste through the studs, in my opinion is a bad idea. Firstly 34mm out of a 75mm or even 100mm timber is a bit much. You then have the pain of geting them in the correct line and angle of the cut and how are you going to feed the pipe through if you use a hole cutter and if you notching through a successive amount of studs doesn't sound like a good idea. You would be better off going down to the floor, through the sole plate of your stud partition and under the floor. A shower trap can be cleaned from above, but I have fitted a shower tray on 4"x2" timbers givving me 4" of clearance to make accesibility to the shower tray easier in the event of a bad blockage.( its also a bit easier to work with when connecting ).