Stittsville's older streets near the village core and the newer subdivisions off Fernbank and Abbott both have interlock that moves with the frost. Long driveways and corner lots mean bigger surfaces to keep level.
Retaining walls in the back-lot grading of newer homes are a frequent repair here, usually because there is no drainage stone behind the block.
Lift the sunken or heaved section, fix the base, relay the same pavers and compact them level.
Full excavation, a compacted granular base built for Ottawa frost, and pavers rated for vehicle traffic.
Clean out failed joints, refill with polymeric sand, and seal if you want colour and stain protection.
Rebuild leaning block walls and loose interlock steps with a proper footing and drainage behind them.