Concrete floor and DPC height changes

[DJ_DIY]

Hi

Sorry about asking another question. This time it's to do with the concrete floor. The extension was to have the following make up for the floor:

150mm Type 1
Blinding sand
Radon Barrier
100mm Celotex
DPM
100mm Concrete
20mm UFH
10mm Self levelling
4mm vinyl

The top level of the concrete was meant to be 34mm below the hall way Finished Floor Level so I could add the UFH, SL and the vinyl. I agreed to do the kitchen floor and utility floor to match. The concrete is 15mm too low at worse and varies across the 28m2. No good for UFH, but I haven't got the UFH so i cant test.

1) FFL is only 12mm above DPC and in some places the dpm and the vertical celotex isn't level with the concrete. Is 10-12mm enough for SL to cover DPM? Im worried that any movement in the DPM will crack the SL. I can't give the UFH company wall to wall measurements. I'm having sand and cement render and plaster on the wall which won't cover the stuck out celotex either. To be clear the builders followed the dpc level from the house and utility they were joining into. The celotex stuck up higher than the concrete was them however. Do I need a builder to cut through the DPM and level the Celotex?

2) The builders left a cavity across the front where the bifold doors will be. The 600mm sides of that wall have been built on to hold the steel. The radon and dpm go across the top of the inner skin and under the blocks on the outer skin. How do i fill in the cavity with concrete around the barrier?

3) In one area where they've decided to bring a 110mm waste pipe (there was no need and now i need to build a wall at more expense) through the insulation i only have a few cm of concrete and I can stick my hand between the concrete and DPM and between the DPM and radon barrier and i can feel the insulation. Do i just get this packed with some sand and cement?

Any ideas welcome please?

Sorry that was so long.

Thanks

 

[noseall]

Hi

Is 10-12mm enough for SL to cover DPM?

No.

Do I need a builder to cut through the DPM and level the Celotex?

Vertical perimeter insulation gets swallowed up by the skirting and dabbed board thickness.

How do i fill in the cavity with concrete around the barrier?

This detail should have been sorted at pre-DPC setting out stage. Remove the inner course of blocks and fill in up to the back of the outer leaf using radon DPM below.

Do i just get this packed with some sand and cement?

Probably. Not sure what you are doing here...?

 

[DJ_DIY]

No.

Didnt think so.

Vertical perimeter insulation gets swallowed up by the skirting and dabbed board thickness.

I wanted to use sand and cement render. I cant take any photos at the moment as its all covered up with a dpm sheet so my house doesn't flood. The vertical insulation should be level with the top of concrete though? WUNDA UFH provide their own thermal bridge for the perimeter.

This detail should have been sorted at pre-DPC setting out stage. Remove the inner course of blocks and fill in up to the back of the outer leaf using radon DPM below.

Is the attached image correct please?

Probably. Not sure what you are doing here...?

Please see attached image. Yes, this is after concreting.

Thanks noseall

 

[DJ_DIY]

Hi @noseall

Weather looks good so im going to have a go at this tomorrow. Can you confirm the following please:

Cut the radon and DPM
Knock out the inner course of blocks along the whole bifold area.
Add sand across cavity concrete and under removed blocks
Flatten and rejoin radon barrier. As it currently goes up and down inner course there will be a bit to remove. Where the bifolds start and end, joining the radon could be tricky. Almost need a vertical piece.
Is it worth concreting an inch or two against the inside of the outer skin so the bifolds have more area to attach to? Concrete directly on radon barrier is ok?
Add 100mm celotex (cut down) between current celotex and outer skin
Add 20mm vertical insulation against the outer skin on top of the 100mm celotex
Lay dpm over the top of the insulation and up to the DPC on outer skin
Concrete in the gap.

Apart from folding tough barrier, it doesn't sound that painful.

Thanks