Autumn
- Rain saturates the base
- Poor drainage holds it there
- Fine soil has migrated into the stone over the years
Why driveways heave in Ontario.
Freeze-thaw is the mechanism behind almost every hardscape failure in this province. Understanding it takes about two minutes and changes how you read every quote you are given.
Based in
Whitchurch-Stouffville
Estimates
Free & on-site
Before we start
Written scope
On site
Same crew throughout
The mechanism
Water expands when it freezes.
Roughly nine percent, and it does so with enough force to lift a driveway. Water held in or under the base has nowhere to go when it freezes, so it lifts whatever sits above it. In spring it thaws and drains away, leaving a void — and the surface settles into it unevenly.
Winter
- Held water freezes and expands
- The surface lifts
- Repeated freeze-thaw cycles, not one
Southern Ontario cycles through freezing many times a winter, not once.
Spring
- Ice thaws and drains
- A void is left behind
- The surface settles unevenly into it
This is the year-on-year damage.
What prevents it
Four things, in order of importance.
Drainage
- 2% minimum slope away from the house
- Free-draining granular base
- Downspouts extended past the surface
- Somewhere for water to actually go
The real mechanism. Everything else supports it.
Base depth and compaction
- 300 mm under a driveway
- Placed in 75–100 mm lifts
- Compacted between each lift
- A stable platform that does not consolidate further
Separation
- Non-woven geotextile between base and subgrade
- Stops fines migrating up into the stone
- Preserves the drainage path over years
Cheap on install day, impossible to add later.
Reading a quote
What to ask, and what the answers tell you.
- 80 mmDriveway-grade pavers80 mm units under vehicles, 60 mm on walkways and patios. Using 60 mm on a driveway is the most common shortcut in the trade.
- 25 mmHPB bedding courseScreeded high-performance bedding, kept to one inch. A thick sand bed is a rutting problem waiting to happen.
- 300 mmGranular A base, compacted in lifts12 inches under a driveway, 150 mm under walkways and patios — placed in 75–100 mm lifts and plate-compacted between each one. One deep dump of gravel compacts on the surface and stays loose underneath.
- FabricNon-woven geotextileSeparates base from subgrade so your clear stone doesn't slowly migrate into the clay. Cheap on install day, impossible to add later.
- EdgesRestraint spiked at 250–300 mmPolymeric sand swept and set into the joints. Edges are where interlock starts to walk apart.
Four questions: how deep is the base, in how many lifts is it compacted, is there geotextile, and what is the slope? A quote that cannot answer those is quoting a surface, not a driveway.
Questions
Questions, answered.
My driveway lifted this winter and settled back in spring. Is that normal?
It is common, and it is not fine. Seasonal movement means water is being held under the surface and freezing. Each cycle disturbs the base a little more, so what looks like a surface that recovers is a base that is progressively failing.
Can heaving be fixed without a full rebuild?
Sometimes. If it is localised, lifting the area, correcting the base and improving drainage solves it. If the whole surface moves, the base was never right and no amount of resetting the top will change that.
Does more base always mean less heaving?
Depth helps, but drainage is the real mechanism. A deep base that traps water still heaves. What you want is a deep base that drains, sitting on a subgrade separated by geotextile, sloped so surface water leaves.
Related
Other things we build.
Free estimate
Tell us about the project.
Fill this in and we'll get back to you to book a site visit — usually the same day.
Or call directly(647) 473-3454