Interlock Repair & Re-Levelling · Cambridge
Interlock Repair and Re-Levelling in Cambridge
The pavers on a sunken driveway are almost never the problem. They are the symptom. Re-levelling fixes the base they sit on and puts the same stones back.
Re-levelling is the most common interlock job in Cambridge for a simple reason: a great deal of interlock was laid through the 1990s and 2000s on bases that were thinner than the ground needed, and the ground has spent fifteen or twenty winters making the point. The surface goes wavy at the garage apron where the base is thinnest and the water collects, sinks where the tires sit, lifts along the edge where the restraint has gone, and tips at the bottom step where the fill has settled.
Heave or settlement
The two look alike from the kitchen window and they are different problems. Settlement is downward and permanent: the base or the subsoil consolidated, often because it was never compacted or because water washed fines out of it, and the surface followed. Frost heave is upward in winter and partly back down in spring, and it needs three things according to the National Research Council's building digest on the subject: a fine-grained soil, a supply of water and a freezing plane. A driveway that is high in March and lower in June is heaving; one that is low all year has settled. The repair for each starts underneath, but what goes back in is different: a heaving section needs fabric and drainage as much as it needs depth, while a settled one mostly needs the base rebuilt and compacted properly.
What the job involves
- Mapping the problem. A straightedge and a level across the whole area, not just the obvious dip, so the repair does not stop one bay short of the next failure.
- Lifting and stacking the pavers in order, so the pattern and the weathered colour go back where they were.
- Finding out what is underneath. This is the moment the quote either holds or changes. Fifty millimetres of sand over clay is a different job from a decent base that has lost its edge restraint.
- Rebuilding the base: adding and compacting granular to depth, fabric over clay, a drain where water is collecting, new edge restraint.
- Re-screeding, relaying, cutting any broken units out for matched replacements, compacting and re-sanding with polymeric sand.
Repair or rebuild
Re-levelling one area is worth doing when the rest of the surface is sound and the cause is local: a washed-out apron, a settled trench where a utility was repaired, a failed edge. It is not worth doing when the lift reveals that the whole base is a few centimetres of sand over clay, because the next dip is already forming a metre away. In that case the honest quote is a full rebuild using the existing pavers, which saves the material cost but not the labour. You will be told which situation you have once the first pavers are up, before the rest are touched.
A single-area re-levelling is often a day. A full lift-and-relay of a two-car driveway is three to five days, similar to a new installation less the paver cost.
Frequently asked questions
Can you reuse my existing pavers?
Usually, yes, and it is the point of re-levelling. Weathered pavers also match each other, which new ones would not. A few broken or badly stained units get replaced with the closest match available; some older paver styles are discontinued, and we tell you that before starting.
Why does the dip keep coming back after someone re-sanded it?
Because sand in the joints does nothing for the base. If the dip is from settlement or washout underneath, topping up the joints hides it until the next rain. The pavers have to come up and the base has to be corrected.
My driveway sank where a gas or water line was repaired. Is that different?
Yes, and it is one of the most common re-levelling jobs. The utility trench was backfilled and settled over a few years. The fix is to lift the pavers over the trench, compact the fill properly in lifts, rebuild the base and relay. We request locates through Ontario One Call before excavating near any service.
Serving Cambridge and surrounding areas. Contact us for a no-obligation quote specific to your property.