Internal or external Soil Pipes

[iMCaan]

Hi

 

My builder has followed the architect's drawings and fitted four big brown soil pipes internally. I can understand one of these is required for the cloakroom on the ground floor but the other three are solely for the first floor bathrooms. I understand I can hide them with a timber frame and plasterboard. However, I can't see any benefits of them being inside. Therefore, I prefer put them externally straight out of the bathrooms on FF. Does anyone see any issues with running the soil pipes externally?

 

At the moment the soil pipes are just sticking out about a 600mm from block and beam GF (both GF and FF are block and beam). We have not yet installed the UFH. Would it be better to cut down the soil pipes flush with block and beam floor and cap them off?

 

Your comments are highly appreciated.

[Russell griffiths]

Depends if you want a sleek modern house or a 1960’s style thing. 

I haven’t seen an external soil pipe for 20 odd years. 

They should have been designed in to be lost in wall voids/ back of cupboards and so on. 

[crooksey]

Running them externally also creates a weak point for insulation/draught proofing. Much better to run them inside, any decent architect will have designed them in a way to be out of sight by the time all walls are up etc.

[iMCaan]

Thank you for the comments.

 

The most concerning are the ones in the living room and in the kitchen. The third is in the garage. All three are in the corners. All three would need boarding up.

 

I suppose my main concern are leakage and the noise from while the waste/water gushes down the vertical soil pipe?

The other concern is a leakage, which would cause a stinking damage.

[crooksey]

Soil pipes leaking is very rare, they are sealed pipes, so the toilet/sink would leak and not the pipe (if installed correctly).

 

Usually box in with two layers of acoustic plasterboard and some acoustic insulation inside.  Bad call from the architect placing in the living room though.

 

[kandgmitchell]

and they should be air tested before finally closing them in...

[iMCaan]

20 hours ago, crooksey said:

Bad call from the architect placing in the living room though.

I don't think there's any better place he could have put them other then running them externally. 

 

20 hours ago, kandgmitchell said:

and they should be air tested before finally closing them in...

That's news to me. They are big pipes, big diameter. Who would do the air testing? Plumber?

 

Thanks

 

[ProDave]

The two separating the living rooms (walls with bifold doors)  I would look at aligning the walls with the pipes, so using perhaps 5 by 2 studs centred on the pipes so the pipes become completely encased in that bit of wall with no visible boxing in.  That would take some carefull planning probably at foundation time if they are load bearing in any way.

 

The air testing, buy the testing kit from somewhere like Screwfix and do it yourself.  Up here BC want to witness a test so it is handy to have your own kit to save paying the plumber to come and do it when BC come.

[saveasteading]

41 minutes ago, iMCaan said:

. They are big pipes, big diameter. Who would do the air testing? 

Presumably 110mm? That is standard. The kit costs about £50 plus plugs and it's easy.

[iMCaan]

17 minutes ago, ProDave said:

The two separating the living rooms (walls with bifold doors)  I would look at aligning the walls with the pipes, so using perhaps 5 by 2 studs centred on the pipes so the pipes become completely encased in that bit of wall with no visible boxing in.  That would take some carefull planning probably at foundation time if they are load bearing in any way.

Thanks @ProDave Those walls are load baring with steel beam on top of them, which is taking the load of concrete block wall on the FF.

 

20 minutes ago, ProDave said:

The air testing, buy the testing kit from somewhere like Screwfix and do it yourself.  Up here BC want to witness a test so it is handy to have your own kit to save paying the plumber to come and do it when BC come.

If I remember correctly my BC said he will next call out when loft insulation goes in. He never mentioned anything about air testing. However, I will buy the testing kit for my peace of mind.

 

[iMCaan]

11 minutes ago, saveasteading said:

Presumably 110mm? That is standard. The kit costs about £50 plus plugs and it's easy.

That's correct. Will definitely buy the kit.

[Mr Blobby]

Just for some balance, we are running one external pipe, two internal. 

Our reason for this is that we must vent the pipe furthest from the sewer while the other two can have AAVs.  Also the external venting pipe is on the hidden side of the house so nobody will ever see it unless they go looking for it. 

And it would have been even uglier to route the pipe from the FF bathrooom down through the kitchen below.  And I didn't want a hole in the roof. 

Also, there is some evidence that a venting soil pipe loses more heat if it is installed internally than externally.  Something to do with the column of cold air running the height of the house if it is vented where an external pipe holds cold air only from the wall to the water trap.

 

Do you have AAVs on all your pipes? 

 

Edited November 9, 2023 by Mr Blobby

[Russell griffiths]

6 minutes ago, Mr Blobby said:

Just for some balance, we are running one external pipe, two internal. 

Our reason for this is that we must vent the pipe furthest from the sewer while the other two can have AAVs.  Also the external venting pipe is on the hidden side of the house so nobody will ever see it unless they go looking for it. 

And it would have been even uglier to route the pipe from the FF bathrooom down through the kitchen below.  And I didn't want a hole in the roof. 

Also, there is some evidence that a venting soil pipe loses more heat if it is installed internally than externally.  Something to do with the column of cold air running the height of the house if it is vented where an external pipe holds cold air only from the wall to the water trap.

 

 

 

This is exactly what I have done, scruffy side of house where the ASHP sits and the gas bottles, this side has a soil pipe as a vent up the house, the rest are internal with air admittance valves.  

[Nick Laslett]

I’ve just tested my soil waste pipes. Three good YouTube tutorials. 

 

 

 

 

Not all manometer kits are equal. My BES one was crap. Horobin with brass connectors was much better. Like this one. 
 

https://www.wolseley.co.uk/product/horobin-boxed-drain-test-kit/

[saveasteading]

30 minutes ago, Nick Laslett said:

Horobin with brass connectors was much better

Agreed. And the tubes are more flexible.

But you'll be using it only twice.

[saveasteading]

There must be thousands of these every year,  used once, thrown in the van, then replaced next time.

[Gus Potter]

On 08/11/2023 at 11:49, iMCaan said:

My builder has followed the architect's drawings and fitted four big brown soil pipes internally.

As if you probably don't have enough on your plate below is a link to Polypipe

https://www.polypipe.com/housing/above-ground-drainage-faqs

 

Which says...

 

"Can below ground PVCu drainage pipe or fittings be installed for above ground sanitary pipework?

 

Below ground PVCu drainage pipe and fittings can only be used underground, they are not manufactured to the correct standards or material formulation for above ground applications, Building Regulations Part H state that PVCu materials for above ground gravity sanitary pipework should be to BS EN 1329"

 

Below ground pipes tend to be brownish.

 

In terms of internal or external pipework.. internal pipework is fine, specify this often.. but recognise that at some point someone is going to put something daft down the toilet or a lot of fat or a decorator is going to wash out some fast set or Polyfilla down the sink. So long as you think about.. where will the blockage occur and make sure you can rod the drain form one end or the other. What you don't want to do is have big access hatches in your nice decor / tiling or other finishes.

 

 

 

 

 

 

[bassanclan]

The wise architect groups the bathrooms together above the ground floor wc...

[bmj1]

We did internally but using the blue acoustic soil pipes, to avoid hearing anything

[Gus Potter]

8 minutes ago, bassanclan said:

The wise architect groups the bathrooms together above the ground floor wc...

The best Architects have a good knowledge about structural design and the best SE's have Architectural knowledge and that make projects come alive. Often at reasonable cost. Of course all need to have imagination.. without that.. it's a race to the bottom and that is not good!

 

But that comes at a cost as you are paying for years of experience. Once you get to a certain age in the design world (I've been at this construction / design world for nearly forty years and the lines get blurred), I think of myself as a designer that knows a bit but learns new stuff all the time from all the posters on BH for example.

 

Thanks to you all.

 

 

 

[iMCaan]

Thank you all, this is very useful information.

 

AAVs are not on the plans @Mr Blobby. We've not yet extended the pipes to bathrooms to the FF. Does a window and a mechanical vent do an equivalent job as a AAVs? If not, then I'll probably will have AAVs on the pipes if I decide to keep them internally.

 

I don't mean to brag but our dominant (which was the objection in the original planning application) stone house with bay windows stands out on the street with brick houses. Therefore, I can't see people taking much notice of the pipes. Furthermore, the pipes will be obscured by trees in the garden and adjoining house.

 

Thanks for YouTube videos, will check them out.

I was looking at the drain air testing product on Screwfix but didn't get it because of poor reviews. I'll check out Horobin.

 

 

 

Edited November 10, 2023 by iMCaan

[Mr Blobby]

18 minutes ago, iMCaan said:

 

AAVs are not on the plans @Mr Blobby. We've not yet extended the pipes to bathrooms to the FF. Does a window and a mechanical vent do an equivalent job as a AAVs? If not, then I'll probably will have AAVs on the pipes if I decide to keep them internally.

 

 

 

If the soil pipe is internal and terminates in the loft (or even lower) then it must have an air admittance valve on the top.  An AAV is a one-way air valve to stop stinky air leaving the pipe into the house but allows air down into the pipe to so that big stools go whoosh into the sewer.  All good.  But AAVs are not always possible.  Afterall, the sewer needs to vent and this is why venting pipes go through the roof (if internal) or run outside attached to the wall. 

 

You may need the pipe furthest from the sewer to be vented.  It is worth finding out if this is is the case.  

 

If that wall next to your lounge is near to the boundary and not too visible and venting at the top, then I'd put that one outside.  That's what we did.  Avoids a hole in the roof and untidy boxing.  

 

External pipes at the front or back are not good. 

When hidden away at the side they can be ok. Sometimes.

 

 

Edited November 10, 2023 by Mr Blobby

[iMCaan]

Thanks @Mr Blobby

 

The sewer runs through the back garden towards the garage. The lounge side soil pipe would just about be the furthest away from the sewer. It won't completely be hidden. At the back of the house is a field which will be developed sooner or later. I was considering taking the lounge side soil pipe outside and dropping it at the back corner (dining area) next to the rain gutter downpipe. Twists and turns but it'll be higher up. Obviously, keeping both rain and foul water pipes completely separate.

 

We will be installing an inspection chamber. Do all soil pipes need venting or just one?

Can the vent pipe be smaller in diameter than soil pipe which I believe is 110mm?

The lounge side is a gable end. There's no window above the FF on-suite bathroom. How high does the vent pipe needs to be from the on-suite window?

 

 

 

[Mr Blobby]

On 10/11/2023 at 18:19, iMCaan said:

I was considering taking the lounge side soil pipe outside and dropping it at the back corner (dining area) next to the rain gutter downpipe.

 

Oh no, I wouldn't do that.  Drop it vertically straight into the ground to minimise pipe on the wall.

 

On 10/11/2023 at 18:19, iMCaan said:

Do all soil pipes need venting or just one?

 

No.  If you need to vent any then its usually the furthest from the sewer connection.  If you vent that one then you should be ok with AAVs on the rest which means no holes in the roof if you box them in internally.  Our architect had drawn all our soil pipes as internal but then our M and E people had specified them all as venting with a hole in the roof.  Neither of these was a good solution for us.

 

On 10/11/2023 at 18:19, iMCaan said:

We will be installing an inspection chamber.

 

I think you need and IC on change of direction and junction, but I'm no expert on this.  It's to do with rodding the pipes.  I would think you'd need 2 or 3 IC installed. 

 

On 10/11/2023 at 18:19, iMCaan said:

How high does the vent pipe needs to be from the on-suite window?

 

I think the top of the pipe needs to be 900 mm above the top of the window.

 

 

... on a completely seperate issue, maybe lose the chimey?  Your neighbours won't like the smoke, and if you insulate and airtight then you'll never need the heat from a log burner.

 

[iMCaan]

Thank you.

 

I would have liked a chimney as it would have given the house a bit more character, however, the builder talked me out of building a chimney. Trying my best to insulate and airtight the house but I think it's below par compared to what other buldhub members are using.