P-Trap burried in concrete slab for Freestanding Bath

[tvrulesme]

I'm in the process of slowly converting a garage into living accomodation. The garage currently has a concrete slab floor which will need to be insulated and screeded etc. 

 

One part of the garage will be the master bathroom. I have a basic layout and know that I will have a freestanding bath so would like to chase the concrete for the drainage as I will need to hire a floor saw for another job so may as well get this chased at the same time. Layout of the bathroom is below (red lines show 50mm waste, blue 110mm waste):

 

 

My question is regarding a P-Trap for the bath waste. Is it advisable/recommended to have the P trap burried in the slab so I have max wiggle room above to connect to the freestanding bath or would you just poke a 50mm though the slab (with a 90 degree bend) and have the trap above the slab? i.e. A or B in this picture?

 

 

 

 

 

[joe90]

I would not bury a p trap in a concrete floor with no wriggle room to fit the bath, why not use a bath trap https://www.screwfix.com/p/mcalpine-bath-trap-white-40mm/84362. Above slab, short length of 40mm pipe then 90’ bend down into concreted pipe work, far more flexibility and you are able to change/clean the trap in future. Also with this you don’t have to sweat about accurately placing the under slab pipe work.

Edited August 5, 2023 by joe90

[Dave Jones]

surely you are going to have to remove the slab before you start to get insulation in ? or do you have the head height to go over it with 150mm insulation and 75mm screed ?

[tvrulesme]

3 minutes ago, Dave Jones said:

surely you are going to have to remove the slab before you start to get insulation in ? or do you have the head height to go over it with 150mm insulation and 75mm screed ?

Thanks Dave. Yes I'm lucky enough to have load of head height but I'll chase for the 110mm so that the other layers are unintterupted as much as possible. Slab will need levelling a little bit but there's not too much in it

[tvrulesme]

6 minutes ago, joe90 said:

I would not bury a p trap in a concrete floor with no wriggle room to fit the bath, why not use a bath trap https://www.screwfix.com/p/mcalpine-bath-trap-white-40mm/84362. Above slab, short length of 40mm pipe then 90’ bend down into concreted pipe work, far more flexibility and you are able to change/clean the trap in future. Also with this you don’t have to sweat about accurately placing the under slab pipe work.

Yes I thought this would be the way to go. I was balancing the extra wiggle room above for the bath vs trying to get accuracy when I haven't even figured out which bath I'm going to get yet. 

[Temp]

Our waste exits out the back of the bath. From there we used a flexible pipe to connect to the waste in the floor. We actually used a longer length than needed in a path like this..

 

 __________

|

|__________

 

so the whole bath can easily be moved away from the wall for cleaning. Wall mounted taps and spout.

Edited August 5, 2023 by Temp

[tvrulesme]

28 minutes ago, Temp said:

Our waste exits out the back of the bath. From there we used a flexible pipe to connect to the waste in the floor. We actually used a longer length than needed in a path like this..

 

 __________

|

|__________

 

so the whole bath can easily be moved away from the wall for cleaning. Wall mounted taps and spout.

Wow and I thought I was cleaning obsessed. Hats off to you. Do you not need to unscrew the feet from the floor to do this?

[Temp]

19 minutes ago, tvrulesme said:

Wow and I thought I was cleaning obsessed. Hats off to you. Do you not need to unscrew the feet from the floor to do this?

 

No ours is a "boat bath" with no feet. Trap fits between bath and floor. 

 

We find we get a lot of fluf and dust down between the bath and wall but it only gets cleaned back there once or twice a year.