1st fix plumbing questions

[markyyyyyy]

I have gutted my bathrooom

Floors ripped up, joists exposed, plasterboard ripped off stud walls and back to brick all apart from 1 wall.

I am installing my pipework in the joist space, and i would like to know how i go about getting my 32mm waste pipe to come down from the sink trap and connect into the waste pipe coming from the showe (to the right as you look at the pic). The waste will exit the house to the left as you look at the pic.

My concern is that because the stud wall is on top of a joist, i will have to gouge a huge hole out of the joist in order to allow the pipe to run underground. is this what i need to do?

Also when drilling with diamond core bits, does it matter whether done from inside or outside the house?

Cheers

 

[johnny2007]

My concern is that because the stud wall is on top of a joist, i will have to gouge a huge hole out of the joist in order to allow the pipe to run underground. is this what i need to do?

No, you can use an S trap.

Also when drilling with diamond core bits, does it matter whether done from inside or outside the house?

If double skin, drill from inside and the the outside until you see the pilot coming from outside (someone got to help you here).
Then use that pilot hole to drill from outside and end up with a clean hole inside and outside.

 

[johnny2007]

I might be a bit over cautious, but from basin I expand immediately to 40mm and when i join other waste (shower) i expand to 50mm.
A bit over the top but never had a blockage and/or gargle.

 

[markyyyyyy]

No, you can use an S trap.

If double skin, drill from inside and the the outside until you see the pilot coming from outside (someone got to help you here).
Then use that pilot hole to drill from outside and end up with a clean hole inside and outside.

thanks for your reply.

I forgot to mention that it is a wall hung semi pedestal i am installing in which i though the waste runs down the stud wall and under the joists, therefore concealed? I'm trying to visulise how the finished product would look

 

[johnny2007]

Had this for 15 years never blocked

https://www.amazon.co.uk/McAlpine-X...=mcalpine+pedestal+trap&qid=1591131618&sr=8-2

 

[johnny2007]

Just realised is a wall hung.
In that case needs on site inspection or clear pictures.

 

[markyyyyyy]

Just realised is a wall hung.
In that case needs on site inspection or clear pictures.

what do you want pictures of inparticular? I will get some decent ones for you... really want to keep it all concealed behind plasterboard / under floor

 

[Gasguru]

It looks like the soleplate is not actually over the joist in which case you can drill straight down and through it.
You can't notch the joist but you may be able to drill a hole at the centreline providing you comply with the building regs diagrams (position of holes)...google joist notching.
It is preferable to run the basin waste separately to the outside (to avoid the risk of backflow and shower trap gurgling)..is that possible? Perhaps you would not need to run it through the joist.

 

[markyyyyyy]

yes it is actually slightly off the joist (the other side of the stud wall is a bedroom). Would drilling into the sole plate not cause an issue? If so, i could bring it under the joists in bedroom and back into the bathroom with a 90 degree bend followed by another 90 degree bend straight outside? Is it okay to have a left and right 90 degree bend near enough straight away?

 

[markyyyyyy]

yes it is actually slightly off the joist (the other side of the stud wall is a bedroom). Would drilling into the sole plate not cause an issue? If so, i could bring it under the joists in bedroom and back into the bathroom with a 90 degree bend followed by another 90 degree bend straight outside? Is it okay to have a left and right 90 degree bend near enough straight away?

although if i am going to be drilling through the joist anyway i mayswell do it directly under the vertical drop of the waste pipe (from basin) and then run it outside

 

[Gasguru]

although if i am going to be drilling through the joist anyway i mayswell do it directly under the vertical drop of the waste pipe (from basin) and then run it outside

There should not be any problem drilling through the soleplate.

Indeed go through the joist centreline providing you are compliant with the regs...see the diagram, you can't just drill anywhere along the length of the joist.

Do not use knuckle (tight radiused) bends...use a swept (long radius) bends.

 

[johnny2007]

I wouldn't drill a 40mm hole in a joist supporting a wall, unless reinforcing it with a metal plate.
Go in the stud wall, down between the joists and straight out where you can then run a 50mm pipe and join the shower waste outside.