Hiding waste pipe

[preecy]

Novice DIY'er hear so bare with me... I've just started ripping out our old bathroom suite. The old basin was built into a cabinet and was situated at one end of a boxed in bath. The new basin and bath are a freestanding style. The waste pipes were hidden by the old cabinet and boxed in bath but now there are gone they'll be exposed. Not a problem I thought, I'll lift a few boards and drop them below the floor. However, there's at least 4 full height joists between the waste pipe needs to be and the soil stack. Its a new'ish house with thin stud/plaster walls so they're not really thick enough to hide behind these either. Am I ok to cut holes into the joists so I can drop the pipes below floor?

 

[footprints]

As a rule of thumb I was always told not to cut more than 1/6th the depth of a joist most waste pies will be much more than that. Even more with the drop that will be required.

 

[preecy]

My joists are 220mm high and the waste pipes are just standard 40mm. So I could make 40mm cuts but obviously I'd have no slope for approximately 2m, ie: the distance between the waste pipe u bend and soil stack. Do you think this is a bad idea?

 

[footprints]

Yup not good, the joist would need to be 240mm to have a 40mm cut in practice you would need a bit deeper cut to allow clearance and 2 metres of flat pipe is not a good idea. It would be slow to run away and prone to debris building up on that section.

Modern houses often have rather "flimsy" construction for example '70s and 80s built houses often have wider spaced joists that make floors bounce a bit. I had to beef up those in mine to stiffen up the bedroom floors.

Would it look very bad to box it in?

 

[Charnwood]

the joist would need to be 240mm to have a 40mm cut in practice

Basin waste pipe, 32mm surely.

 

[preecy]

the joist would need to be 240mm to have a 40mm cut in practice

Basin waste pipe, 32mm surely.

sorry yeah its 32mm.

I could live with a boxed in section along the wall but its me who to put up with the missus moaning

guess i'll have to box it in as I don't fancy notching the struts from one end of the room to the other. Also there would be very little, if any, slope.

 

[RickyLee53]

Basin wastes 32mm. Use a whole saw. Gradually get lower in the joists.

 

[preecy]

Thanks for all the suggestions. I decided to bring the stud wall out a couple of cm's so that I could chase the pipe. The wall needed plastering/skimming anyhow where i'd pulled all the old tiles off so new plasterboards probably saved me some time.