Leak at soil stack - what are my options?

rubble2

We have just had our soffits, facias and rain water goods replaced ( were white, now black) so I was looking at what would be involved in painting the white plastic soil stack black to match when I noticed a wet patch on the brickwork.

Looking closer there seems to be evidence of a bead of water in the mortar crack directly underneath where the waste pipe exits the wall.

Running the water in the bath/shower and the wash basin along with flushing the toilet doesn't result in any obvious leaks at the various visible pipe joints so I am thinking that the water is leaking at a joint somewhere inside the cavity wall and soaking the bricks from the inside.

There is absolutely no visible signs of damp inside the bathroom and no damp on the kitchen ceiling below. To be honest the problem could have been present for some time and not been noticed (it actually looks more obvious in the photo's than with the naked eye.

I replaced the bathroom about two years ago but I really don't think the leak originated that long ago, I have looked at the only connection I made to the waste system and that is completely dry. The toilet waste connects to a female socket level with the bathroom floor, the waste pipe then descends vertically into the floor space, and must then do a 90 degree turn parallel with the floor/ceiling and then another 90 degree turn through the cavity wall to connect with the stack.

I don't know whether to lift the bathroom floor or attack it externally by getting some bricks removed. What do you think? Thanks.

Section62

rubble2 said:

I don't know whether to lift the bathroom floor or attack it externally by getting some bricks removed. What do you think? Thanks.

What is above the toilet soil pipe connection?  Is there an overflow pipe from the toilet cistern, or from a tank in the loft?

stuart45

I'd start by cutting out some brickwork.

rubble2

Section62 said:

rubble2 said:

I don't know whether to lift the bathroom floor or attack it externally by getting some bricks removed. What do you think? Thanks.

What is above the toilet soil pipe connection?  Is there an overflow pipe from the toilet cistern, or from a tank in the loft?

Actually there are, when they replaced the gutters they asked if the overflows were still needed, I said that the were and he said that he had directed them into the  new gutters. You can't actually see them now from ground level but to my knowledge they have never leaked before. I will see if I can get a better look from the bottom of the garden - thanks.

Update :- I can see the overflows where they protrude from the roofline but are are about 1 metre further along from the soil stack.

rubble2

Should there actually be joints in the waste pipes that are inside the cavity wall? it seems like a risky method to me

stuart45

There shouldn't be a joint in the wall apart from the one you can see in the branch where the pipe comes through the wall. 
Overflow pipes are better where they can be seen.

rubble2

Given that we want to change the stack to black and looking at the condition of some of the gaskets you can see in the second picture I am wondering if we should bite the bullet and gat the whole stack replaced with a new black one?

Any ideas on cost involved? and is it a plumber job or a general builder?

FreeBear

rubble2 said: Should there actually be joints in the waste pipes that are inside the cavity wall? it seems like a risky method to me

No, there should never be joints hidden inside a wall.

But looking at the second picture, the collar of the toilet waste connection is partially buried in the wall - Quite possible this is the source of the leak, especially if the pipework inside has been disturbed at any point. Chip away at the mastic & mortar surrounding the Tee and see if the wall is damp in that area.

stuart45

rubble2 said:

Given that we want to change the stack to black and looking at the condition of some of the gaskets you can see in the second picture I am wondering if we should bite the bullet and gat the whole stack replaced with a new black one?

Any ideas on cost involved? and is it a plumber job or a general builder?

It's a plumbers job, although it's quite simple to replace the branch.

plumb1_2

rubble2 said:

Actually there are, when they replaced the gutters they asked if the overflows were still needed, I said that the were and he said that he had directed them into the  new gutters. Y

Bad idea having them into the gutter as if the tanks overflow you won’t know if the rwp is directly into the gully. That’s why they are called a warning pipe.
Afew weeks ago I got called to a customer who had a astronomical water bill, checked out it was the Cws tank been overflowing for months, 2 yrs ago the cowboy builders directed them into the gutter. problem solved but she still had to pay her water bill.

plumb1_2

90 percent of the time the will either be a branch or soil bend partially in the wall.
Chip out the mortar around the branch, if leaking try using gap filling cement or a good sealant.
Long term solution is to replace.