Why is my patio cracking after winter in NB?

Patio cracking after winter in New Brunswick is almost always caused by frost heaving — the freeze-thaw cycle lifting and shifting your patio base, which cracks the surface above it. This is one of the most common hardscaping problems in NB, and it comes down to either an insufficient base depth or poor drainage underneath the patio.

Here's what's happening beneath your feet: when water saturates the soil or gravel base under your patio and then freezes, it expands by roughly 9%. In New Brunswick, frost penetrates 1.2 to 1.5 metres deep, which means that expansion force is enormous and relentless. If your base wasn't built deep enough, or if water is pooling under the patio rather than draining away, you'll see cracking, lifting, and uneven sections every spring — and it gets worse each year.

The most common cause is an undersized base. A properly built patio in NB requires a compacted granular base of 8 to 12 inches (200-300mm) of clear crushed stone, depending on soil conditions. Clay-heavy soils — common in the Fredericton area and the Saint John River valley — hold water and are especially prone to heaving. Sandy soils drain better but still need adequate depth. Many patios are installed with only 4-6 inches of base, which is simply not enough for a Zone 4-5 Maritime winter.

Drainage is the second major factor. Even a properly deep base will fail if water has nowhere to go. Your patio should slope away from the house at a minimum grade of 1% to 2% (about 1/8" per foot). If water is pooling on or around the patio, it's finding its way into the base and freezing there.

The type of patio matters too. Interlocking pavers actually handle freeze-thaw better than poured concrete, because individual units can shift slightly and be re-levelled without full replacement. Poured concrete slabs crack more dramatically and are harder to repair. Natural stone on a sand-set base sits somewhere in between.

What You Can Do

Start by assessing the drainage around your patio — look for areas where water pools during spring melt or heavy rain. Check whether the slope directs water away from the house. If sections are lifting more than others, that's often where drainage is worst.

For a temporary fix, cracked pavers can sometimes be re-levelled by lifting them, adding or removing bedding sand, and resetting. Concrete cracks can be filled with flexible polyurethane caulk (not rigid mortar) to allow for movement.

For a permanent fix, the patio typically needs to be fully removed, the base excavated to proper depth, drainage improved (sometimes with a perforated pipe), and the patio rebuilt correctly. This is not a DIY project — improper base work will just repeat the problem.

When to Hire a Pro

Hardscaping repairs and rebuilds absolutely warrant a professional. A qualified landscaper or hardscaping contractor will assess your drainage, soil type, and existing base before recommending the right fix. Getting it done right once is far cheaper than resetting a patio every few springs.

If you're ready to get it assessed, New Brunswick Landscaping can match you with a local hardscaping contractor for a free estimate — no cost to you, covering all of NB from Saint John to Fredericton to Moncton and beyond.