How to finish off cavity and floor heights

[Jacko994]

Good evening everyone,

 

I wonder if I can get some help/thoughts on the below -

 

I’m currently in the middle of managing an extension/renovation on our property and I’m trying to get some clarification on how to finish off the cavities at the front and rear openings and tie in the screed.

 

At the rear where we’re going to be having bifolds with a level threshold, I have filled with some celotex insulation. I was going to finish it with a cavity closer but the company installing the bifolds want to knock the course of bricks on the outer skin off to place the bifolds on. 
 

Is this normal practice?

 

It would then mean I can’t use a cavity closer so what would be the best way to close the cavity up ready for screeding? 
 

Any suggestions would be much appreciated.

 

Thanks,

 

Jack

 

[Nickfromwales]

You remove the inner course of blocks. Place insulation vertically up against the inside face of the outer course of blocks (as an upstand) and then run the insulation and screed to meet the upstand.

[Nickfromwales]

Similar to this job. 
 

[Jacko994]

Thanks Nick.

 

what about the dpc that is running across the inner course?

 

Also that inner course is 3 courses high at the moment, above the block and beam. Are you saying to remove all 3 courses, or just the top 1 or 2?

 

Thanks

[Nickfromwales]

19 minutes ago, Jacko994 said:

Thanks Nick.

 

what about the dpc that is running across the inner course?

 

Also that inner course is 3 courses high at the moment, above the block and beam. Are you saying to remove all 3 courses, or just the top 1 or 2?

 

Thanks

You delete that DPC and run the DPM up the face of the skirt insulation upstand. Basically just treat the job as if that inner leaf of masonry had never existed.

 

Remove the lot, down to the same level as the B&B deck, and fly the insulation all the way in to meet the outer leaf of masonry.

 

If UFH, don't forget the 'thermal' expansion skirting that goes on to absorb expansion of the screed.

[ETC]

Might be better with a DPC behind the outer leaf. Personally I’d have treated it in the same way an external door is - precast concrete threshold wrapped in DPC and then taken the DPM across and up the back face.