Soil pipe access branch questions

[Stu666]

About five years ago we had a toilet fitted under the stairs. The builder put in new pipes for the toilet and sink waste. The sink waste is teed into the soil pipe via 32mm and a strap boss, but there isn't much of a fall on the pipe and I've had problems with standing water freezing and blocking it. It has now started to leak where it connects to the boss. I was always puzzled as to why they did this, because there is a socket they could have used lower down on the access branch, which presumably would have given it the necessary fall?

My plan of attack is to remove the existing waste pipe, plumb new 32mm pipe into the lower socket and blank off the strap boss socket. But before I do this, is there any glaring reason why I shouldn't? If it is feasible, can anybody tell me what sort of cap I need to purchase to blank off the strap boss? The socket measures approximately 60mm across. Also, what size hole would I need to cut into the lower socket for 32mm pipe?

Thanks in advance.

 

[Hugh Jaleak]

To blank off existing Boss, use a new Boss Adaptor, and appropriate size plug to suit. Cant remember hole saw size offhand, (although 63mm is coming to mind), but measure the Boss on the junction and that'll tell you what you need. Once the Boss is open, you use a Boss Adaptor to suit size of waste pipe, in this case, 32mm.

 

[Stu666]

To blank off existing Boss, use a new Boss Adaptor, and appropriate size plug to suit. Cant remember hole saw size offhand, (although 63mm is coming to mind), but measure the Boss on the junction and that'll tell you what you need. Once the Boss is open, you use a Boss Adaptor to suit size of waste pipe, in this case, 32mm.

Much appreciated, thank you.

Do you have any opinion as to why the builders used a strap boss instead of going straight into the existing boss on the access branch?

 

[Hugh Jaleak]

Do you have any opinion as to why the builders used a strap boss instead of going straight into the existing boss on the access branch?

For ease of installation is my guess. Straight run, one bend required.

Personally like to put some fall on the pipework, and use 45º bends to get into the stack. Means water cant hang about in the pipe and less risk of it freezing in cold weather.

 

[Stu666]

Had a crack at this today. Think it went OK. Blanked off the strap boss as suggested and ran a new pipe to the lower boss socket after first cutting a 54mm hole. New rubber adaptors seem a much better and snug fit than the old one. I thought about using silicone just for belts and braces but my old tube had gone off. Is silicone essential for something like this or should push fit be enough?

Also, any idea what I can use to support the pipe to prevent it sagging like the last one? I bought a couple of clips but unfortunately the pipe is too far off the wall for them to reach. Probably about 2 - 3 inches in the middle.

 

[thomp1983]

Could you not use a couple of 45 connectors near the svp to get the pipe tucked into the wall so you can then clip it.

 

[Stu666]

Could you not use a couple of 45 connectors near the svp to get the pipe tucked into the wall so you can then clip it.

Good thinking. I am such a dunce!

 

[Hugh Jaleak]

As above, 'dog leg' pipe into boss to get it close to the wall. Push fit is all that is required to make the seal, silicon lubricant only to provide ease of making the joints.

Old Plumbers trick, if clips are still too far off the wall, cut a couple of pieces of 15mm copper tube to required length to use as spacers, then longer screws as required into the wall to give sufficient grip.

 

[Stu666]

I've noticed that although I've cured the main leak from the old strap boss adaptor, there is still a small leak from beneath the strap boss itself. It looks as though whatever has been used to seal it to the soil pipe is failing. I'm thinking I might as well just remove the strap boss if it's no longer being used, but what to seal the hole with? I'd rather avoid cutting the soil pipe/coupling if possible. I did notice that when the drains were surveyed recently, the contractors cut an inspection hole in the access branch so they could fit their camera in. It is visible in my photo just below the boss sockets. They seem to have sealed with a rubber device which has a bolt attached to it. Seems to be doing the job. Does anybody know what this contraption is called?

 

[Hugh Jaleak]

The rubber bungs are an access point, made by Fernco. However to fit one you'll need to firstly get the strap boss off, (and assuming it was fitted somewhere near properly in the first place, it should have been solvent welded on, and therefore wont come off without damage), and secondly, the hole will need to be the right size, if its too small, making it bigger with holesaw, without a centre drill will be extremely difficult.

If you can get it off, I'd be tempted to look a solvent welding a piece of uPVC over the hole, jubilee clip(s) or cable ties around the lot to hold it in place whist it all fuses, or if it's stuck fast, then another option in these situations is to use 'Gap Filling cement' which is designed to seal any cracks between the Strap Boss and the pipe.

 

[Stu666]

The rubber bungs are an access point, made by Fernco. However to fit one you'll need to firstly get the strap boss off, (and assuming it was fitted somewhere near properly in the first place, it should have been solvent welded on, and therefore wont come off without damage), and secondly, the hole will need to be the right size, if its too small, making it bigger with holesaw, without a centre drill will be extremely difficult.

If you can get it off, I'd be tempted to look a solvent welding a piece of uPVC over the hole, jubilee clip(s) or cable ties around the lot to hold it in place whist it all fuses, or if it's stuck fast, then another option in these situations is to use 'Gap Filling cement' which is designed to seal any cracks between the Strap Boss and the pipe.

Thanks, very useful info.

I have my doubts the strap boss was installed properly. Although it is secure, whatever was used to fix it appears to be breaking down, hence the leak. It is whitish in colour. Not sure if solvent weld dries white, but I'm thinking it could be regular old superglue or even grab adhesive. I'll have a fiddle with it; if it seems like it will come off without too much of a struggle, I'll order one of those Fernco bungs. Seems like the easiest solution for a non-tradie like me.

 

[Hugh Jaleak]

Not sure if solvent weld dries white

It will do on black pipework.

 

[Starlyte]

Why is the pipe passed by the outside, instead of by the interior and joining the sewage pie behind tge wc with an anti return valve?
It is really small and must freeze so easiy otside.
Maybe going lower with 45° x 2 instead of 1 90° may empty it better and resove the freezing thing.
You could also put some indulating cover at least on the small one.
I don't know if it freezes regularly where you are.
I even had my big sewage pipe feeezing one winter! Put me a bit in the sh##!

 

[Stu666]

Why is the pipe passed by the outside, instead of by the interior and joining the sewage pie behind tge wc with an anti return valve?
It is really small and must freeze so easiy otside.
Maybe going lower with 45° x 2 instead of 1 90° may empty it better and resove the freezing thing.
You could also put some indulating cover at least on the small one.
I don't know if it freezes regularly where you are.
I even had my big sewage pipe feeezing one winter! Put me a bit in the sh##!

It's just a small hand basin waste pipe. No room internally to hide the pipe. It doesn't get cold enough to freeze pipes very often here else I'd try insulating it.