Best way to finish a room with dirt floor. Is underpinning required?
A bit of a context. This is a two storey cabin. The existing concrete stem walls are basically built on slab and most likely not reinforced. I would like to refinish the bottom floor that currently has a dirt floor. To have enough height in the room I need to have the finish slab basically at the base of the stem walls. I think I would need to underpin the foundations to Keep the water out? What is the best and cheapest way to do it?
A Only underpin/ dig out 4' widths at a time
B. Take half the length of the wall, divide it into 4' segments and label them A, B, C... That's your underpin schedule.
C. Each pour should have horizontal rebar extensions to engage adjacent footing pour.
D. Fill gap between prior day's pour and existing wall with nonshrink grout.
E. Day 1 - Excavate Bay A.
Day 2 - Pour footing/ underpin for Bay A.
Day 3 - Pour nonshrink grout between new and existing.
Day 4 - Excavate Bay B...
I agree with your workplan and I was thinking the same procedures. I am wondering if I can get away with a simple job and extend the existing wall down by 6”, just enough to have a 4” slab on top a 2” insulation.
Nor sure where you live, but you can consider two additional steps for water control.
Include a perimeter drain installed with suitable graded rock fill outside your new footing with suitable water control layer against the below-grade part of your wall/foundation,
and a layer of non-fine fill inside the wall, under your foam.
Not sure where you reside, yet you can consider two extra strides for water control.