Soil pipe slight misalignment - to adjust or not

[lxbn]

About 6 months ago I had a new WC installed. On the black plastic soil pipe run outside the property, as the pipe length was not long enough a connector and an additional length of pipe had to be fitted by the installers. I noticed recently that the run is not completely straight as the pipes were connected slightly out of true and I was concerned about the flow. It's not much, but the inserted length of about 1 metre is nearly level.

As the installation and the drop, is according to regulation (passed by building control), should I worry about this little bit? The area is a little difficult to reach and the joint seems to be stuck fast. The builder, not the plumber, who worked on the project tried to straighten it out, but it wouldn't budge.

I'm not sure how these joins are usually made, ie just push fitted or with the use of glue but is there a way to work the pipe and connector without stressing it or should I just leave it as it is?

 

[Goldberg]

Is it possible for you to post a photo of the pipework that you're concerned about?

 

[Nige F]

I metre nearly level I got a fall of 25mm on a 6metre run and it still works -JUST .. It will be altered

 

[lxbn]

Untitled

• lxbn
• 20 Jul 2009
• 1

This is the best I can do. The pipe runs along the top of the first floor flat roof. Picture taken from window above. To get the best perspective, I'd have to go to the far end of the flat roof which is difficult for me to do.

The builder put the roof tile under the join for leverage, but wasn't able to get any movement in the join. He didn't force it too much for fear of damaging the pipe.

 

[Goldberg]

Those look like ring seal joints, so they will move, but they will also resist movement, especially if they've been there a while and baked in the sun. A strap wrench is useful for getting them to start turning.

That long run of nearly horizontal soil pipe looks like a problem waiting to happen - could steps not have been taken to raise the higher end even more, to create a better gradient?

From what you've said the pipe length is at least 4 metres. The design aim for the flow rate is >= 0.70l/s. For a branch from only one WC this generally translates to between 1:40 and 1:23, so the fall over 4 metres should be between 10cm and 17cm - is that what you've got?

 

[lxbn]

Thanks Goldberg I'll get my builder to try it using straps.

Untitled

• lxbn
• 20 Jul 2009
• 1

I know it doesn't look like it from the pic I posted before so I looked around and found this pic which shows the complete run. I just looked and the fall is within the parameters as you described. The installation was discussed between the plumbing company and council building control to ensure that the fall met building regulations. On final inspection the building controls guy was quite happy with it.

 

[Goldberg]

No, that's competely useless - the first metre has a fall of about 50mm, which is 1:20, i.e. too steep, then the remaining 3 metres have a fall of about 50mm, which is 1:60, i.e. too shallow.

The pipe should be supported by being clipped to the wall, and there's plenty of scope for making the gradient both correct and constant over its length.

 

[lxbn]

So if the pipe is straightened at the joint, making it as if it were one single length of pipe, there would be an even fall along it's entire length. The pipe is supported from underneath, so an extra support would be placed under the join.

 

[Goldberg]

You and I aren't going to agree on what constitutes "properly supported", so all I can really do is recommend that you support it in the way that the pipe manufacturer stipulates.

 

[lxbn]

I know what you are saying about pinning it to the wall with brackets.

The pic perhaps does not show it clearly, but in this case the pipe is not along a wall so the support has to be under it. With the support it has, the builder was even able to stand on it trying to free the join. But I accept that generally the soil pipe would be bracketed to a wall. Thanks for the input.

 

[Nige F]

That pipe is solvent welded -that`s why it won`t move . There is no wall to bracket it off. There are special pads that are for fixing pipes on flat roofs. Available from DRAIN CENTER -part of the Wolseley Group. In Sussex, if you asked me to do the job. That`s what I would have used And I`ll bet it wouldn`t have cost a lot more Also it should be vented at the end where it comes out the wall. I`m only doing this because I get bored being retired I`m nearly as good as S*ftus

 

[TicklyT]

Looking at the first picture, I wonder if part of the problem is a result of using a 92-1/2 degree bend at a 90 degree change in direction.

 

[lxbn]

That pipe is solvent welded -that`s why it won`t move .

Oh dear! I was trying not to think about that possibility! May have to check with the plumbing company whether the joint was indeed weld joined. If that is so, how can the joint be freed? Still using straps - with extra muscle?

Softus takes no prisoners - you escaped with the word 'nearly'!

 

[Nige F]

Looks like Terrain/Polypipe solvent (both ends) . To be pedantic the issue isn`t with the length of near level pipe, it`s more the lack of proper supports. It`s not an issue that will actually cause a problem . In fact there are a few worse than that in a Seaside Town I live near . But then it`s only sad old gits like me who look @ the architectural details as I sit in traffic queues

 

[Hugh Jaleak]

From the picture Id agree thats a solvent welded joint. It looks very like a Terrain fitting to me, there's no 'bulge' where the ring seal would be located.

There is no 'undo' possible. The only solution would be to cut offending section out and replace. However I would think there would be enough 'flex' over that length of pipe for it to be correctly aligned and supported.