I have removed a lean-to greenhouse which leaves an exposed concrete base complete with plastic sheet dpm up to side of house wall and patio door. The concrete base surface is just below house dpc level. The plastic sheet is approx. 1 brick depth below surface with its exposed lip folded up against the house wall up to concrete surface where edge is visible.
I wish to deck the base area with slabs.
Do I need to cut back the exposed concrete base to leave a trench where it meets the house wall?