Toronto interlock drainage repair, water redirected
Most settled interlock is a drainage problem that showed up as a paving problem. Water washes fines out of the base, freezes in what is left and lifts the surface. Fix where it runs and the repair stays fixed.
When we open a settled area, the base under it is usually not missing, it is washed. The fine material that locks the stone together has been carried out by water running through, leaving something closer to loose gravel that compacts under load. Find where that water enters and you have found the repair.
In Toronto the three usual sources are a downspout discharging straight onto the pavers, a lawn or garden grading back toward the paved area, and a perimeter with no edge restraint letting the field creep outward until the joints open.
We look at the surface wet where possible, or flood a section, because a dry patio does not show you the low point.
Shoot the grade
Levels across the area tell us what fall exists now and how much is available before the door sill or the lawn gets in the way.
Change the run
Re-grade the base where there is room, or cut in a channel drain and pipe it out where there is not.
Close the perimeter
Edge restraint replaced or installed so the field stops spreading and the new grade holds.
Where It Goes
Fixing the paving without fixing the water
These four pages are the reason a re-levelling job can need a second visit years later. Water carries the fines out of a base, freezes in what is left, and the surface drops. Change the surface and not the run, and the same thing happens again.
So the questions here are where the water arrives, whether the grade can shed it, and if not, where a drain can sensibly put it. That last one matters, because sending runoff onto a neighbouring property turns a paving job into a dispute.
