Extending kitchen over outside drain

24 Mar 2017
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United Kingdom
Hi I am currently extending my house off the back of my kitchen where the kitchen sink currently drains into an outside gulley. The new extension will be built over the gulley and I want to extend this and attach it to a sink and dishwasher on a kitchen island. It will be an internal drain which will need to be airtight as I don't want foul smells from my neighbours toilet coming into the house. Will a u bend from the sink be sufficient to stop foul smells? I'm panicking about what to do at the minute.
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Is the drain/sewer you are planning to extend over serving more than just your house?
At present my kitchen sink attaches to my neighbours main soil pipe. I'm building over this as it runs through my garden. Not sure what to do and my builder is not sure
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So that gulley on the photo will be inside the house under the concrete floor and it needs to be attached to the sink on the island without creating bad smells. It runs into the soil pipe from my neighbours house.
In the past I've mostly rerouted the pipes around the extension, it can be a pain if you come to sell and you don't as a survey will pick up on the drain running under your house and you might have to pay an insurance just incase anything goes wrong but im not sure if that is just for manhole covers! But if you take away the gully and change it to 4" underground pipe you can get a sealed cap that will go to 1 1\2" pipe to run to your sink and you trap will stop smells
Thank you. So I won't need a looped system or anything like that or one of those valves? I'm not planning on moving within the next 30 years anyway
no the pipe slips straight in you can get push fit or solvent weld, id recommend solvent weld just incase it backs up:D
If the sewer from your neighbours runs under your extension then you should have a build over agreement with your water authority. The sewer you are building over is a public sewer.

Are you doing this extension as a PD / notice or full plans and who is signing off building regs?
Planning permission has been granted and I'm using a private building inspector. I just need to know how to connect into the gulley from the island that will be near it . As in pictures . Worried about smells from drain you see.
Get rid of the gulley and make a direct connection to the drain, using an appropriate 110mm to waste connector. Make sure all appliance traps are 76mm seal.

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