Avoiding SVP penetrations through our roof

[Bramco]

Quick question hopefully.

 

We're keen to avoid penetrations of an SVP through our roof. Seems crazy to put a big hole in a roof if you don't need to.

 

Currently, we have 4 service pipes through our slab that all meet at a point where there will be a manhole and then there'll be a single run to a manhole on the sewer that runs across the property. On eof these was destined to penetrate the roof.

 

BC have said that if we don't want a penetration in the roof, then we could run another pipe from the manifold back to the house and then run a pipe up the back of the house with a durgo valve at the top. We'd disguise this as a drainpipe, so small bore, not a nasty orange thingy.  The service pipes that come through the slab of bathrooms and loos etc. would then have air inlet valves.

 

Our M+E consultant is doing the traditional sucking teeth pose 'ooohhh  I don't think that would be appropriate'

 

Tbh we're not interested whether it would be 'appropriate', would it work and has anyone done this?

 

Simon

 

[Conor]

You can just use air admittance valves on the stacks. Just hide in a cupboard or false wall or ceiling void. There's nothing in the BC regs saying you must have have an SVP. Some here have pointed out that you may still have issues with positive air pressure building up, an air admittance valve will not mitigate this.

 

[ProDave]

Yes perfectly allowable, except the SVP you run up the wall must go above the roof line, you can get black white or grey pipe, the orange is only for underground.  And then it is the internal pipes that terminate in an air admittance valve at the top of each one.

[saveasteading]

We discussed this a few weeks ago, and I realised that the rules had changed. 

It used to be that you HAD to have an open vent pipe at the end of the run, but could have durgos elsewhere.

The rules now do not require that end vent, but it is allowed.

 

The advantage of the end vent is that it allows air both directions, so a big burp in the depths of the drains will have somewhere to release, other than through your U bends, or wherever else.

So that is smelly and thus needs to be above the roof/ away from windows. 

 

You are right to avoid penetrations through the roof if you can.

[Russell griffiths]

you don’t need to run a separate pipe from the man hole, my vent pipe at the end of the run branches off from the last pipe to exit the house. 
it then runs up the wall of the house. 
it doesn’t need to go above the roof line. If you can comply with below. 
it does have To go  higher than any opening window. 
it must be higher than the roof if you have roof vents that vent the loft, so your pipe doesn’t vent into the loft. 

[Bramco]

Thanks all - great info.

 

Simon

[Nickfromwales]

15 hours ago, Bramco said:

BC have said that if we don't want a penetration in the roof, then we could run another pipe from the manifold back to the house and then run a pipe up the back of the house with a durgo valve at the top.

Are you sure they said a Durgo ( aka Air Admittance Valve / AAV ) ? It is utterly pointless to go to all that length installing anything that does not naturally vent to atmosphere.....Are you sure they did not say a bird cage ( vent ) vs Durgo? The internal AAV's would suffice, and the proposed external rising SVP > AAV is a complete waste of time / effort / money AFAIC.

[Bitpipe]

Our BC waived the need for an external SVP as the houses either side had them and they are to vent the sewer system and provide little benefit to the house itself. He said the requirement is really 1 in 10 properties needing one.

 

AAVs inside the house at end of runs will provide the necessary system ventilation for flushing loos etc.

 

Was a relief as we were this close -> <- to cutting a hole in one of the flat roofs, plumber had left his big holes aw at home that day so we had time to get a second opinion from BC.

[Bramco]

1 hour ago, Nickfromwales said:

Are you sure they said a Durgo ( aka Air Admittance Valve / AAV ) ?

 

Nick, my mistake. There's a long email trail on this one and I remembered the mention of durgo valves but that was in connection with internal terminations.  As you say, would be pointless if the termination wasn't 2 way.

 

37 minutes ago, Bitpipe said:

He said the requirement is really 1 in 10 properties needing one.

 

Ours isn't really close to the other properties connected to the main sewer.  There's a row of semis with the sewer along the back, then it strikes diagonally across a 2 acre field with the original bungalow and our new build. The manhole we'll be connecting to is about 30m away.  Not sure if all that makes any difference.

 

13 hours ago, Russell griffiths said:

you don’t need to run a separate pipe from the man hole, my vent pipe at the end of the run branches off from the last pipe to exit the house. 
it then runs up the wall of the house. 
it doesn’t need to go above the roof line. If you can comply with below. 
it does have To go  higher than any opening window. 
it must be higher than the roof if you have roof vents that vent the loft, so your pipe doesn’t vent into the loft. 

 

Russel, great idea, I'll mention this to the builders.  And there won't be any roof vents as it's all vaulted ceilings and we'll easily be able to get it well away from (and above) the nearest opening window.

[Thorfun]

I wondered about penetrations for SVP and then @Iceverge made this post

 

and I didn't worry about it any more! fitted one of these https://www.slate.uk.com/product/nature-vent/ and it looks great and BCO was happy.

 

[Bramco]

4 hours ago, Thorfun said:

 

 

 

Looks great but.....

 

Ours will be corrugated steel - think cow shed.  Also, the roof build up is essentially roof felt above and airtightness membrane below filled with blown cellulose - so maybe less structurally 'firm' than yours?

 

Simon

[Thorfun]

33 minutes ago, Bramco said:

 

Looks great but.....

 

Ours will be corrugated steel - think cow shed.  Also, the roof build up is essentially roof felt above and airtightness membrane below filled with blown cellulose - so maybe less structurally 'firm' than yours?

 

Simon

yeah, fair enough. we didn't want a pipe sticking out the top of the building and so when these slate vents were mentioned I jumped on it as you'd never really know it was there from the ground.