Knocking down foundation blocks in internal doorways

[WWilts]

It is normal to build foundation blocks up to DPC level in internal doorways, and then knock them down? External doorways yes. But internal?
I suppose the blockwork serves a shuttering purpose for the concrete slab.

Still, knocking down the blocks mutilates the DPM and leaves a small void (65mm deep) at the thresholds of internal doors.
Challenge now is how to restore the damp proof floor layer.
 

[Jenki]

Personal experience says foundation blocks to max 2 course "below" DPM. Externally you don't want to see them. and DPM level should be 150mm above ground level.

Its common (old practice) to build the external internal skin to DPM using concrete commons  / thermalite coursing bricks, and then knock out these out at thresholds. but that has issues.

Internally sounds crazy / wrong 

Depends a lot on construction type - Timber floor / beam and block / slab on grade etc etc - need some more info but doesn't sound correct...

 

[shuff27]

I'm going through this process atm, timber frame with brick outer skin.

 

Internal walls - no blocks in door openings as liquid screed wants to flow throughout the GF.

 

External walls - brickie ran the blockwork across the door openings but we did have a debate about it - we both thought it would be better not to have doors stting on blockwork as presumably that would make a cold bridge.  Better to have doors sitting on 150mm insulation plus screed in principle but I'm waiting to see what my chosen screed/UFH contractor advises.  If neccessary we'll knock out the offending blocks.

 

On the flip side, having external blocks all round the perimeter did make it easier for the timber frame joiners to install the timber sole plate.

[Brickie]

I’ve been doing footings (& nothing else) for around 18 months now since relocating & the norm is to leave all doorways out,so the insulation layer is continuous & runs right out to the external leaf at doorways.