Can I put a new drain run into a concrete slab?

[capital1965]

I live in a bungalow and would like to convert a non habitable room into a bathroom and the bathroom into a bedroom. I have attached a floorplan which is not to scale but gives an idea of the layout. The non habitable room was partitioned off from part of the living room to, functions as a bedroom and has no window or possibility of putting one in. The bungalow, built circa the late 60s sits on a concrete slab. I think the first 1.50m of the slab of the living room looking from the bottom of the pic upwards are a later addition.

I would like to convert the bedroom indicated on the plan to a bathroom which means putting a drain run from position marked 1 to the position marked 2 where the existing SVP is.
, a distance of approximately 4M.

My question is, can I dig into the existing slab to put the pipe in without compromising permanently the water tightness of the slab? If so, how would I go about that. I assume there is a polythene DPM under the slab which I would break with my digging. I was thinking of putting the top of the pipe just below the current finished floor level and then covering the whole floor with a floating chipboard covering to reduce the depth I would have to dig to.

 

[Hugh Jaleak]

It can be done but will need to be done correctly and to Building Regs. Not just a case of running a pipe from A to B, depths, fall and access for cleaning all need to be considered. I assume you will be removing the existing bathroom facility and replacing it elsewhere as shown on your diagram.

The drain from existing WC will need to be located, and it's direction established. Building Control are unlikely to permit a change of direction in the drain, under the building, without a chamber being provided, (chambers inside the property are frowned upon for obvious reasons!) This may leave you needing to run a new drain in from the proposed bathroom position to connect to the existing system at a suitable point outside the property, and the old drain run abandoned and sealed.

The new drain run will also need to be laid at an appropriate depth, any sudden changes in the depth of a drain run have to be achieved using the correct methods, which is usally achieved using a ramp or backdrop at a chamber.

The proposed bathroom will also need some kind of fixed ventilation system, if an openable window cannot be provided, usually a an extractor fan removing stale air to the outside. Suddenly, making good the DPM is the easy part!

 

[DIYhard]

Would one of those toilet macerator pumps solve the problem and allow you to leave the slab intact? I've no personal experience of them, but somebody on the forum is bound to know.

 

[Nige F]

One of the problems with a macerator is ... not good ( acceptable to build regs? ) if it's the only WC in the dwelling.

 

[Hugh Jaleak]

As Nige says, Macerators are not suitable if there is only the one WC available. Unfortunately, they are prone to misuse, soon jam up/break down and until fixed, render the WC unusable. Not a good situation to be in.

 

[capital1965]

Thanks for the replies. The drain laying aspects I am good with having recently installed a new run for a garage conversion and put in new chambers and had it all signed off by building control. I can get a straight run to the existing pipe that comes into the existing bathroom with the correct fall. What I don't know how to do and cannot find any information on is how to dig into the existing slab, potentially penetrating the DPM and then make good after putting the new drain run in to stop any ingress of water.