DPC/ DPM in Pier supporting RSJ

[Robert90]

First post her, so please go easy!
I’m currently removing a load bearing wall, engineer spec’d 2x Steels bolted together with spacers, 2X solid brick piers (330x450) and foundation taken down to competent ground/ existing foundation level.

I’ve taken the wall out & dug 2X holes for the foundation (750x500) depth of 600mm from slab (not much of an existing foundation) we’re now down to compacted clay.

I can’t seem to find a definitive answer online as to where the DPC/ DPC should be be installed in relation to the pier.

There is an existing DPM underneath the concrete floor slab (approx 150mm below ground level/ Slab level) and I assume the new DPM needs to be tied into this? BC have confirmed the depth of the footings are fine but forgot to ask at the time about the DPC (engineers mentioned it but not stated on the plans).

In the past I’ve installed DPC 150mm (approx 2 bricks up from exterior ground level), However as it’s a pier I’m stumped.

My idea was to fill C20 mix in the holes until I reach just below existing slab, cover the new foundation(750x500) with DPM overlap the existing slab DPM and build the brick pier on top (first course would be built from just below slab level, I’d then pour screed around the pier to bring it to existing slab level which would secure the DPM to the same level as the DPM in the existing floor and prevent any moisture traveling ip the pier.

Any advice would be appreciated!

Cheers

[aeromech3]

Does this help

[oz0707]

Think of it as dpm for floor, dpc for pier

Build pier up to dpc level or 150mm above ground then connect new domain to existing, bring to rear side of pier and up to dpc level. At that point the dpc for pier can meet the dpm and fold down over the top