damp course into new extension

[bluebaron]

Evening all,

Was just wondering on how to integrate my DPM from my new extension (solid slab) in the existing house.

Clearly i'll be running the DPM over the footing wall at the current DPC level on the new externals but on the internal 'join' I have a bitumen paint under some parquet flooring (house is 1922).

I could take up the section of existing a bit and overlap the DPM say by 300mm or can i just cut it alone the internal join and then insulate and screed over the whole lot?

Thanks

 

[bluebaron]

Oh any another question the levels are driving me mad!

I have a DPC currently 70mm below FFL.

Using this as reference does the following work?

Slab is
150mm MOT
20mm sand/DPM
100 concrete
75mm Celotex
65mm screed
30mm floor finish

total 440mm

If i start the MOT 370mm (440-70) below DPC (reference point) then I should end up at the FFL?

My sanity thanks you in advance!

 

[John D v2.0]

My only comment is 30mm is very thick for a finished floor, even solid wood flooring would only be about 20.

 

[bluebaron]

I have solid Parquet flooring at present so pretty thick maybe Ill go 20mm can always make it up with screed later if i need to. Thanks