Soil pipe run query

[Kevste123]

Hi

Planning to install an en-suite bathroom. Due to joists running in wrong direction I am looking to drop the wc waste directly down to the floor below on a 90 degree pan connector and then horizontally with a 1:40(?) fall about 3.5m to stack. This would have to go through the boiler cupboard and out the external wall. Above the boiler cupboard is a concrete lintel where in an ideal world I would come out but I don't want to touch this so will need to get the pipework under it, into single skin block.

 

On the image which option would be preferrable:

 

1. Drop down about 0.5 metres into room below, 90 degree turn from vertical to horizontal, 2x 45s to come out the wall above boiler flue then a 90 into stack (main image)

2. Drop down to ceiling level, 90 degree turn from vertical to horizontal, little jiggle to get under lintel and then connect directly into back of stack through wall (red line)

3. Drop down about 0.5 metres into room below, 90 degree turn from vertical to horizontal and connect directly into back of stack through wall (blue line)

 

I'm aware that options 1 & 3 would need a fair bit of boxing in and I'll need to create a "feature" to keep the missus happy. Option 2 avoids this but I'm not sure about the two 90s to get around the lintel.

 

Cheers

 

[Mr Punter]

None of this looks great.  You will need rodding access.  3 looks the least problematic.  For access and rodding, outside the building is "nicer".

[Kevste123]

I agree none of the options are great. BCO did come around and said he would approve if rodding access was provided . Unfortunately I can't go outside the building as I don't own the boundary, it is my neighbour's garden. The other option I was looking at was macerator but that was a last resort.

[Kevste123]

I think something like this could work and still be functional, make it look like a fancy shelf for plants.

[Mr Punter]

On 31/01/2025 at 14:47, Kevste123 said:

The other option I was looking at was macerator but that was a last resort.

 

Absolutely right.  I would rather just use a bucket and slop out, prison style, than have a macerator.

[Nickfromwales]

52 minutes ago, Mr Punter said:

 

Absolutely right.  I would rather just use a bucket and slop out, prison style, than have a macerator.

+1. 
 

5 hours ago, Kevste123 said:

I think something like this could work and still be functional, make it look like a fancy shelf for plants.

Have you allowed for air admittance, as this will be needed once the flushed water etc gets to the second vertical drop (eg at the outside branch)? 
Either that pipe extending up the outside wall to become an SVP or a stub-stack with and AAV on it if the former isn’t possible?

 

On 31/01/2025 at 12:45, Kevste123 said:

Hi

Planning to install an en-suite bathroom. Due to joists running in wrong direction I am looking to drop the wc waste directly down to the floor below on a 90 degree pan connector and then horizontally with a 1:40(?) fall about 3.5m to stack. This would have to go through the boiler cupboard and out the external wall. Above the boiler cupboard is a concrete lintel where in an ideal world I would come out but I don't want to touch this so will need to get the pipework under it, into single skin block.

 

On the image which option would be preferrable:

 

1. Drop down about 0.5 metres into room below, 90 degree turn from vertical to horizontal, 2x 45s to come out the wall above boiler flue then a 90 into stack (main image)

2. Drop down to ceiling level, 90 degree turn from vertical to horizontal, little jiggle to get under lintel and then connect directly into back of stack through wall (red line)

3. Drop down about 0.5 metres into room below, 90 degree turn from vertical to horizontal and connect directly into back of stack through wall (blue line)

 

I'm aware that options 1 & 3 would need a fair bit of boxing in and I'll need to create a "feature" to keep the missus happy. Option 2 avoids this but I'm not sure about the two 90s to get around the lintel.

 

Cheers

 

The ‘blue’ option is perfectly fine, and should produce the least amount of ‘noise’. 
I’d change the 1st orange 90° bend off the WC to a longer radius ‘rest’ type bend to quieten things even further.
 

 

Plan on boxing this in with 100mm of acoustic rockwool.

[Kevste123]

4 hours ago, Nickfromwales said:

Have you allowed for air admittance, as this will be needed once the flushed water etc gets to the second vertical drop (eg at the outside branch)? 
Either that pipe extending up the outside wall to become an SVP or a stub-stack with and AAV on it if the former isn’t possible?

I should've mentioned, that pipe on the outside wall is the existing SVP, so I don't think I will need a separate AAV?

 

4 hours ago, Nickfromwales said:

I’d change the 1st orange 90° bend off the WC to a longer radius ‘rest’ type bend to quieten things even further.

I had no idea they could be used internally, I thought they had to be used underground only. Something about them not being compliant with BS whatever. Although there would be no issue with UV damage, so if they can be used internally that would be ideal. 

[Nickfromwales]

16 hours ago, Kevste123 said:

I should've mentioned, that pipe on the outside wall is the existing SVP, so I don't think I will need a separate AAV?

 

I had no idea they could be used internally, I thought they had to be used underground only. Something about them not being compliant with BS whatever. Although there would be no issue with UV damage, so if they can be used internally that would be ideal. 

Yup. They’re fine for internal use. The rest bends will make the flushed water much quieter, so I would do that if it was a job I was doing for a client. 👍. 
 

If it’s an SVP then obvs no need to an AAV 👌✔️. 

[Kevste123]

Thanks for all your help. Should I aim for a 1 in 40 fall on the horizontal section or 1 in 80?

[Nickfromwales]

6 hours ago, Kevste123 said:

Thanks for all your help. Should I aim for a 1 in 40 fall on the horizontal section or 1 in 80?

BCO will want 1:60 ideally, or 1:80 if needed, but at 1:40 it may fail (if they give a shit that is). They're only really bothered about the ground and down / groundworks / manholes etc, and MAY ask about the SVP / AAV, but not many do tbh.