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Relocating kitchen sink and dishwasher during kitchen remodel

Postby rdw » Wed Sep 09, 2020 7:10 pm


I am planning on remodelling our kitchen.

I would like to move the kitchen sink and dishwasher, which currently discharges to the existing soil vent stack pipe, to another location in the kitchen.

I am looking for options to solve my problem.

The options I am considering are

1. Cut a channel from the new sink / dishwasher location to the base of the soil vent pipe and then connect to it there.

I suppose this would depend on how deep the elbow joint is and whether I could get the necessary depth for the pipe and the fall required to go about 3 meters across the kitchen.

I can not see the elbow joint above / at the floor level, which I suppose is a good sign. If this is a viable option, would I have to connect a 110mm pipe or could I get away with a smaller bore, as its only a sink and dishwasher.

I suppose, if this is a viable option, I will need to do some exploratory work around the base of the SVP to see where the elbow starts.

2. There is a straight run from where I propose to put the sink and dishwasher to the existing inspection chamber.

However this run will require going across the kitchen, through the living room door between the kitchen and living room, across the living room floor and then out of the house under a set of patio doors to the inspection chamber, which is just outside the patio doors. The total run will be about 8 meters.

This run will be dead straight, but will mean going under the living room. The existing soil stack and pipe also goes under the living room, but when the house was built, 1972, the living room was the garage.

Again if this is an acceptable solution would I need a 110 mm pipe or could I get away with a smaller bore as only for a dishwasher and kitchen sink.

In this remodel I am also thinking of adding a wetroom, and I have another query regarding the drainage of that.

But I will ask in a separate thread. The two drainage systems will be independent of each other apart from joining to the same inspection chamber.

Any advice / experience will be gratefully received

Thanks in advance

Kind Regards

New sink run proposed 2.png
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Postby rdw » Thu Sep 10, 2020 11:17 am


Sorry to reply to my own post, but I have been doing some research and reading part H of the building regs. I have come to section 1, clause 1.11 and am looking at diagram 2.

I have measured from the bottom of the pipe to floor level at the inspection chamber and it is 510mm.

With that in mind and knowing there is a drop between the bottom of the svp to where I measured, and that the pipe from the kitchen sink and dishwasher will also have to drop from below floor level to where it enters the stack.

Then I don’t think I will be able to achieve the required 450mm between the bottom of the pipe entering the stack and the bottom of the stack.

So with that in mind I have come up with another solution

1. I still have the direct run through the living room to the inspection chamber, called proposed sink and dishwasher run 1.

2. I have come up with a second solution that I am calling proposed sink and dishwasher run 2,

That runs from the corner where the sink and dishwasher will be, into the wetroom, to a rodding point due to the change of direction and then join up with the new run out of the wetroom to join up with the existing redundant drainage channel under the living room.

See attachment and picture below for a better explanation

Questions are same as before though

1. Can I do what I propose?
2. What is the better option for the kitchen sink and dishwasher, 1 or 2?
3. Can I use a smaller bore pipe than 110mm for the kitchen sink and dishwasher?

Thanks in advance.
Kitchen and Shower run proposed 3.png
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