Screeding over Soil Pipe

[JLAB]

Hello, 

 

Would someone be able to advise what the best course of action is for laying screed over the waste pipe in the image.

 

The floor has been built up so far with Type 1, Sand, DPC, Concrete. So all that is left to do is insulate and screed. 

 

Does the Soil Pipe need protecting before Screeding, if so, what product? 

 

Would you recommend PIR Boards for the insulation on the floor or another product?

 

Thanks 

[Mr Punter]

If that is a soil pipe you will need access to it as you have a right angle bend.

[jayc89]

Should be ideally be run deeper, below your slab. Looks like the base of the stack also needs a rest bend, as the weight of the stack is sitting on that elbow currently.

 

Cut your PIR around the pipe and foam the gaps? 

[JLAB]

@Mr Punter Yes it's a soil pipe, so would you advise I box in the right angle bend some how, allowing access if necessary? 

 

@jayc89 Ok, so replace the bend with a rest bend, and in terms of screeding over the top of it does it need protecting in any way from the weight of the screed or would the PIR board be enough? 

 

Thanks 

 

[SuperPav]

Here's what I would do (as long as you can rod from the outside to reach the bend): replace the vertical bend (bottom of soil stack) with a rest bend, and replace the second horizontal bend with a sweeping long one. You might need a 15 angle connector further down the soil pipe if that puts it too far away from the wall, but then it's OK. I'd then PIR around it as closely as possible, PU foam any gaps as much as possible, cut it flush, stick a membrane over the top and then screed over that.

[Mr Punter]

I would go for this:

 

You will need to chop a bit out of the bottom block to get the rest bend out at about 45 degrees to the wall.

 

[crooksey]

That doesn't look like it has enough height for PIR and then 50mm of screed? Whats the height difference to the original subfloor?

 

If its a new extension, building regs probably want a decent amount (150min) and up stands, and looking at your patio doors, doesn't look anywhere near enough?

 

You may have to insulate and then float chipboard over it to get the required U value.

[JLAB]

@crooksey From the concrete base to the top of the DPC is 180mm. The architect plans specify 140mm PIR boards and 30mm screed. The rest of the property is on suspended floor boards so I will be running ducting to allow for the rest of the property to be ventilated under the floor boards. 

 

However, floating chipboard over it sounds like a much easier option, are there any downsides to doing it this way rather than screeding? Thanks 

[crooksey]

Doesnt matter about DPC whats the floor height from that concrete base as pictured to the existing floor level? As thats what you are governed by.

 

Floating chipboard is fine over celotex, glue joints etc. More people prefer screed now as you can embed wet UFH in much easier.

Edited January 10, 2024 by crooksey