Soil Pipe Through Foundations

[wozza]

Hi All,

 

Converting a single brick wall (old garage) to a brick / block cavity wall.

We have dug down to the bottom of the existing foundations to widen them for the inner block course and are ready to pour the concrete.

However there (as always) is a problem, we have a soil pipe that passes through the middle of the intended new foundation.

We cant move it, we cant remove it - the only option is to pour the foundations around it.

We are waiting for building control to come and have a look before we do anything.

One suggestion from a labourer is to wrap the pipe in 2 inches of rockwool to allow the pipe to move inside the foundation and to prevent the concrete from sticking to it?

 

Anyone suggest anything?

[joe90]

Create a sleeve in 6” pipe cut In half length ways and held back together with tape, the sleeve will be held in the foundation concrete but the soil pipe will float in it. 

[PeterW]

1 hour ago, wozza said:

One suggestion from a labourer is to wrap the pipe in 2 inches of rockwool to allow the pipe to move inside the foundation and to prevent the concrete from sticking to it?

 

That doesn’t work as the concrete compresses the insulation and sticks anyway.

 

43 minutes ago, joe90 said:

Create a sleeve in 6” pipe cut In half length ways and held back together with tape, the sleeve will be held in the foundation concrete but the soil pipe will float in it. 

 

That is the correct approach, or if it’s a new pipe then slide a length of 6” clay over the top and secure in place with some gun foam.   

[Carrerahill]

1 hour ago, wozza said:

Hi All,

 

Converting a single brick wall (old garage) to a brick / block cavity wall.

We have dug down to the bottom of the existing foundations to widen them for the inner block course and are ready to pour the concrete.

However there (as always) is a problem, we have a soil pipe that passes through the middle of the intended new foundation.

We cant move it, we cant remove it - the only option is to pour the foundations around it.

We are waiting for building control to come and have a look before we do anything.

One suggestion from a labourer is to wrap the pipe in 2 inches of rockwool to allow the pipe to move inside the foundation and to prevent the concrete from sticking to it?

 

Anyone suggest anything?

 

Quite a few options for you - BC will have their say. 

 

On the garage I dug the founds deeper and made some basic shuttering so the found took a step and ran under the soil pipe, then stepped back up on the other side then lintels over the top, to correct the height of the lintel to match the blocks either side we made it up with engineering bricks on top of the lintel (single course) so the 150mm lintel + commons = 1 block. We did a solid row of lintels and grouted over the lot so insets and mice etc. couldn't climb up into the wall. We filled the void with gravel - it was low enough that it had no impact on the floor slab.

 

Google image search shows about 100 ways people have done it.

 

I also like the box it out and pour founds over it method, but you will need to make sure BC are happy there is plenty concrete and probably a bit of rebar.

 

 

Edited May 30, 2019 by Carrerahill

[Conor]

Basically you need to build over the pipe with a structure that will take the full loading of the wall above. Normally, this would be a couple concrete lintils resting on pad stones. In your case this will be more difficult as you have limited working room. Good option would be a steel sleeve over the pipe, then encase in concrete. Best practice would be to cut the sewer pipe and slide the new duct over the pipe and make sure the base of the duct is resting on something firm along its loaded length.

[wozza]

Thanks to everyone for your replies - I like the pipe sleeve idea - probably the easiest solution.

 

I will feedback once BC have been and advised.

 

Thanks Wozza.

 

[wozza]

Ok,

So the BCO officer came out - Builders were not on site.

 

I asked about the soil pipe - he gave two options as follows.

 

1 - Wrap the pipe with 100mm insulation and then pour foundations - but to add mesh to the area above the pipe to strengthen the foundations

2 - Shutter the area, pour foundations and use lintels above - fill around pipe with pea shingle

 

I then suggested option 3 as suggested above from Joe90 to sleeve the pipe with a bigger pipe, he said hmmm you could do that, but that he would prefer us to shutter the area and fill with pea shingle as the pipe would be close to the top of the foundations.

 

So we went with option 2 - we poured the foundations to about 30mm under the pipe - used cut sections of a 3 x 2 concrete paving slab to shutter off either side of the pipe then filled the foundations - the slabs have remained in place - once set we filled around the pipe with pea shingle and used a lintel above.

 

Thanks all for your advice.

 

Wozza.

 

 

Edited June 14, 2019 by wozza

[flanagaj]

On 30/05/2019 at 15:25, joe90 said:

Create a sleeve in 6” pipe cut In half length ways and held back together with tape, the sleeve will be held in the foundation concrete but the soil pipe will float in it. 

I am currently researching about installing the foul water drainage and wonder if you can clarify something here.  If you are using trench fill footings, then your soil pipes are put into the ground before you pour the footings, and if you are using slab then can be fitted once the footings are poured?

I'd like to understand the order surrounding pulling the footings / digging drainage trenches and then the subsequent pouring of the footings.

[joe90]

It depends on the height of the pipes in the ground, with my trench footings the pipes went over the top (shallow ground) then built in block/brick work and lintels over. If the pipes are within the trench footings they must be “floating” I.e. not solid within the concrete.