Plumbing Question

Hole in the joist to run 40mm bath waste pipe

Hi there,

I am wondering if somebody can please help and guide me.

Basically, I am living in a maisonette property on ground floor for over 3 years and I never had any drain blockage issue but since last week I am facing very worst bath tub blockage issue and we have to rip off the ceiling to check the leak and blockage and only then we found that the waste pipe is of size 32mm and not 40mm and also notice that there is joist and during property building time they have run the pipe work in a very wired way and make a hole in the woods and joist of 32mm to run the pipe and also the main stack pipe is behind the kitchen wall so to access that we have to either break the wall and then replace the pipe with 40mm till the joist and then put the reduce and then again run the 40mm pipe and hopefully that will solve the nightmare problem.

So I would like to know the best possible options to solve this problem.

1. Is it OK to make another hole in the joist to run 40mm pipe?
2. Is it possible to make the existing hole bigger, currently it's 32mm?
3. Is it OK to make a bigger hole in the woods, currently 32mm?
4. Will it make any difference if we break the wall and replace the pipe to 40mm till joist and then from joist till bath tub?
5. I have been reading about one shot drain cleaner , so it is safe to use that instead of breaking the wall?

I have called the plumber and he has tried vaccum and snake spring but no luck :'( so I don't really understand what to do so Please help me.


2 Answers

Best Answer

Please state size of joists? E.G. depth and distance apart
Also length of waste pipe run and how many joists it passes through
before it terminates in to the soil stack

Answered 4th Aug 2014

Boiler Homecare

Member since 6 Jan 2010

Hi Iqbal,
As James Wilkinson suggests, the answer will have a lot to do with the size of the joists! A bath of water with a person in it can weigh in excess of 1/4 ton.
You should not remove more than 30% of a joist, and this should only be done in the first 30% from a wall. Is it not possible to run the pipe out the wall without going through the joist, around the outside of the building before going back into the stack?
Chemical cleaners are normally OK with glued waste pipes, but you should not use with push fit/compression connections...and if a snake will not clear I doubt chemical acid will.
Hope this helps

Answered 21st Mar 2015

Stewart Building and Roofing

Member since 12 Dec 2014

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