Waste pipework design (pictures!)

[fefe]

Hello everybody

The following is the general drainage design for our planned extension. There will be a bathroom upstairs, a cloackroom under the stairs and the kitchen in the groundfloor extension.

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• fefe
• 24 Apr 2008
• 3

Here is the plan for the upstair bathroom, with the WC branch shown in red. It goes right to the soil stack.

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• fefe
• 23 Jun 2008
• 1

Now I was wondering if I can avoid any additional venting and connect branch pipes for the basin, bidet and bath to the WC branch, lke this:

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• fefe
• 23 Jun 2008
• 2

or should I do something like this

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• fefe
• 23 Jun 2008
• 2

or this:

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• fefe
• 23 Jun 2008
• 2

or something else? What do you think?

Thank you in advance for your time!

 

[SortedPlumbing]

in my opinion i would go with Solution C aslong as the pipe going into the stack is correctly pipe sized, and would be worth while fitting anti siphon traps at the bidet and basin.

Solution B - would possible cause induced siphonage
Solution A - would prob work but when Wc is flushed there could be a chance of induced siphonage aswell

 

[plummerman]

I would agree with sorted plumbing in the design of discharge system for the waste's. You'd need to to run a minimum of 2" pipe the entire lengh of the run with the excepted size waste;s tee'd in for each branch. Baring in mind tho, some buliding inspectors can be W@nKers , and demand the dischare values are correctly worked out and appropriate pipework fitted to suit. (For example: i had a w/m, dishwasher and sink on 2" and he made me upgrade it to 3" just because he could i reckon)

 

[fefe]

Thanx for the advice guys! I checked for 'solution C' as you suggested. Space is very limited but it should fit despite the added pipework.

Still, to completely avoid induced siphonage and any problem with the inspector, I'm now reconsidering an additional vent.

The vent pipe would be behind the WC, and would go up to the loft, before connecting to the main vented stack, as follows:

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• fefe
• 24 Jun 2008
• 2

Would this solution completely eliminate the induced siphonage issue forever?

BTW, [warning, silly question...] do vented pan connectors exist?

 

[Azazel]

Solution A would work, but you need to use deep seal anti-vac traps on the basin and bidet, and a deep seal p-trap for the bath.

hope that helps

 

[ChrisR]

Use A with an air admittance valve on the bath trap. "Anti vac" traps can be noisy. You only need one AAV, at the first waste.
EG one of these:

NB your basin and bidet waste pipes need to be 40mm not 32, and at 3m I'd use 50mm for the bath or it'll empty slowly.

 

[fefe]

Thanx everybody, that was GREAT help!!

So, the following is the layout now:

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• fefe
• 25 Jun 2008
• 2

Question: regarding traps, what is the difference between a 3"/75 mm seal and a 1.1/2"/38 mm seal ? Which one is right for 40 mm pipes?

Also, a bath trap for a 50 mm pipe isn't very easy to find apparently

 

[fefe]

OK, got it, just in case somebody else needs to know:

'The seal dimensions below refer to the approximate depth of water trapped in the bend'

Time to go shopping now

 

[doitall]

Bad idea .

Flush the loo and the **** blocks the wastes

C was/is the only option except for the bidet which may have to be below the 110 branch

 

[fefe]

OK, but what if I send the wastes into the horizontal 110 mm pipe from the top, like this?

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• fefe
• 27 Jun 2008
• 1

Solution C may not fit anymore if I have to use an individual waste for the bidet. Our space there is very limited.

For C, what would be the required size for the pipes going into the stack from basin/bath and bidet?

Also, why do you say the bidet waste may have to go below the branch? Regulations?

Feeling a bit confused now...

 

[doitall]

Height dear poster.

Unless you want to jack the bath and bidet up a couple of hundred mill it won't fit.

Do a google for Doc H

 

[fefe]

OK, thanx about doc H.

I just measured everthing and I think gradients (1.8 mm per meter minimum) will be no problem, given our floor void space.

Just one more silly question.

Assuming I do option C above, would the following branch be ok for the purpose?

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• fefe
• 27 Jun 2008
• 1