advice re: building regs for ensuite, soil pipe

[nojoble]

Hi,
Please could you advise me about a soil stack?

I want to put a toilet and washbasin in a new ensuite toilet. The pipe will have to run almost 5m to the outside wall, then turn 90 deg and run nearly 4m to the existing soil stack. I've only got 30cm of drop, is that enough?

Also, do I need to vent the soil pipe or will it be OK with the existing vent on the existing soil stack?

thanks for your help.

 

[freddiemercurystwin]

Good and bad news. The fall you needs is ideally 25mm per metre so 225mm overall (1:40). You can have your 90° bend OK too and no need for an AAV. However you are limited to 6m overall length, at least if you get Building Control involved, as you are legally bound to. Unless you don't bother in which case it will probably be OK, maybe add a rodding point at the 90° bend.

 

[nojoble]

thanks Freddy!

sorry to sound so ignorant, but what's an AAV?

 

[freddiemercurystwin]

Air Admittance Valve. Or a vent on the end of an SVP.

 

[nojoble]

Hi, I'm confused now! I've had a look at section H and I don't understand it. On page 9, Table 2 seems to me to suggest that the maximum length of unventilated branch pipe is 15m, however Diagram 3 on the same page says it's 6m as Freddy said.

Please can somebody explain this to me?

Thanks again!

I've attached pictures of Table 2 and Diagram 3.

Untitled

• nojoble
• 12 Nov 2012
• 1

Untitled

• nojoble
• 12 Nov 2012
• 1

 

[freddiemercurystwin]

Edit: I think if you add an AAV (ie a vent next to the bog) you can go longer than the 6m. Poo pipes are not my speciality!

 

[nojoble]

Thanks Freddy!

Mine neither, and I'm happy to keep it that way!

 

[Nige F]

Hi, I'm confused now! however Diagram 3 on the same page says it's 6m as Freddy said.

Please can somebody explain this to me?

Thanks again!

]

That diagram is for a "single stack" setup - as is the large radius bend @ the bottom of the stack - another old chestnut . A good rule of thumb is - get the vent into open air , AAV`s are for penny pinching New Build boxes

 

[indus]

What function does the AAV perform?

Thanks

 

[freddiemercurystwin]

Its a one way valve that lets air into the head of the svp, without it, as you flush away an almighty turd and the 8 litres of water with it, can drag away the water traps in other services on the drain run.

 

[indus]

Thanks

 

[nojoble]

Hi, I'm confused now! however Diagram 3 on the same page says it's 6m as Freddy said.

Please can somebody explain this to me?

Thanks again!

]

That diagram is for a "single stack" setup - as is the large radius bend @ the bottom of the stack - another old chestnut . A good rule of thumb is - get the vent into open air , AAV`s are for penny pinching New Build boxes

Thanks Nige,

I assume mine is a 'single stack' setup. I've posted a couple of pictures of what I hope to do!

overiew picture

• nojoble
• 9 Nov 2012
• 1

side view picture

• nojoble
• 9 Nov 2012
• 1

 

[Nige F]

Ideally you need to get a vent behind or close to the WC - that`s a L-o-n-g run you could reduce the vent to 3 inch ( I would ) but really you need to ask Build control ( they might OK an AAV ) I don`t do B.C on my houses - in fact I hate all bureaucrats . Freddy is right although just the water flowing has the same effect

 

[freddiemercurystwin]

I don`t do B.C on my houses - in fact I hate all bureaucrats

Maybe not but maybe you may apply common sense or a rational approach but people out there need saving from themselves, the forum is testament to that!

 

[nojoble]

Thanks Nige and Freddy for your insight!

Much appreciated