Sealing Soil Pipe

[jayc89]

I have an old, approx 5", soil pipe that runs below a solid slab that I need to fill/block/seal before laying insulation etc. I can only see 4" expanding plugs at Toolstation which aren't big enough.

 

The other end of the pipe connects to the mains sewerage pipe below ground level, which I will eventually disconnect when it's dug out.

 

For now, I need a quick/easy way to seal the pipe (opposed to the current plastic bag rammed down it).

 

Will wire wool + expanding foam to the trick?

[saveasteading]

As I have said before, I don't like expanding foam. It is not controllable, goes where you don't want it and not where you do. Also somewhat irreversible.

 

I would leave the plastic bag where it is, perhaps adjusting the position, to act as a stop. Then fill the end of the pipe with concrete or mortar, perhaps in 2 stages.

Let it harden and shrink then paint on a coat of bitumen paint.

 

OR wrap a bag around the outside of the pipe with a tie around it, and fill the hole with weak concrete/mortar.

 

Close off the other end when the time comes too, in case the pipe becomes a home for creeping things, or there is some other pipe connection in the run

[jayc89]

  On 30/10/2021 at 11:22, saveasteading said:

As I have said before, I don't like expanding foam. It is not controllable, goes where you don't want it and not where you do. Also somewhat irreversible.

 

I would leave the plastic bag where it is, perhaps adjusting the position, to act as a stop. Then fill the end of the pipe with concrete or mortar, perhaps in 2 stages.

Let it harden and shrink then paint on a coat of bitumen paint.

 

OR wrap a bag around the outside of the pipe with a tie around it, and fill the hole with weak concrete/mortar.

 

Close off the other end when the time comes too, in case the pipe becomes a home for creeping things, or there is some other pipe connection in the run

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Are there any consequences to using expanding foam (I have a boat load of the stuff!)? The hole that needs blocking is at the end of the run and the next branch is approx 2m away so far enough for the foam not to reach.

[TonyT]

None,

 

foam up way down the hole, let it set and then pour runny sand/cement screed down the hole.

 

 

[Iceverge]

  On 30/10/2021 at 11:36, jayc89 said:

Are there any consequences to using expanding foam

Expand  

 

It might shrink over time. 

[JFDIY]

125mm bungs are available for about £15. 

 

I can find them on eBay and with builders merchants, if it were me I'd be getting rather than making do.

 

You could always (space permitting) use a rubber band coupler to get to 100mm then fit a blank end in that.