Lot Grading

Written by Phil Schnetzer, CPI

Certified Professional Inspector serving the Annapolis Valley, Nova Scotia. 10+ years and 1,500+ inspections. ReHome Inspections.

If I had to pick one single issue that contributes most to wet basements in the Annapolis Valley, it's poor lot grading. Not the foundation. Not the weeping tile. Not the window wells. The slope of the lawn. Water follows gravity, and if your lawn directs water toward your home rather than away from it, you will eventually have a wet basement — it's just a matter of when and how much.

The target slopes

The goal is to get surface water moving away from the foundation as quickly as possible. According to Government of Canada guidance on property grading, the minimum standard for a lawn or garden is a 6-inch drop in the first 10 feet away from the foundation — about a 5% slope. That sounds like a lot, but it's actually a gentle grade you'd barely notice walking across it.

Hard surfaces like driveways and patios can get away with a lower slope: a drop of about 1.5 inches over 10 feet (roughly 1.25%) is sufficient because impervious surfaces shed water faster than soil.

Ideally, you want this slope maintained around the entire perimeter of the home. In practice, that's not always achievable — lots are oddly shaped, there are obstacles, and the natural terrain doesn't always cooperate.

When the slope works against you

If your lot sits lower than neighbouring properties, or if the land slopes toward your home (as is common with homes built into hillsides), surface drainage becomes a bigger challenge. In these situations, grading alone won't solve the problem — you need to actively redirect the water before it reaches the foundation.

A swale — a shallow, grass-lined drainage channel — can intercept surface water and route it around the house. Properly positioned, a swale can protect a foundation that no amount of lawn regrading could help. French drains (perforated pipe in a gravel trench) serve a similar purpose underground, capturing water before it reaches the foundation wall.

What's beneath the surface matters too

Grading addresses surface water. But subsurface water is a different problem. Some soils drain well; others hold water like a sponge. Heavy clay soils — common in parts of the Annapolis Valley — don't percolate quickly, which means even a properly graded lot can pool water at the foundation during heavy rain. This is where weeping tile (foundation drainage pipe) matters, and where a proper soil assessment may be needed.

If you have a dry lot but a wet basement, or a good lawn slope but persistent moisture problems, the issue is likely below ground rather than above it.

What I look for on an inspection

On every inspection I walk the perimeter of the home and assess the grading. I'm looking for slopes that run toward the foundation, soil or mulch built up against the siding or foundation (a rot and pest risk), window wells that are holding water, and downspouts that discharge too close to the home. These findings make it into almost every report I write — which tells you how common the problem is.