Negative grading (contre-pente): what it is, how serious, what it costs

Around a house, the ground should slope down away from the foundation, so rain and snowmelt drain toward the street or the yard. When it slopes the other way, toward the house, it is called negative grading; a French report says « contre-pente » or « pente négative ».

It often happens over time: the backfill against the foundation settles and forms a dip. A driveway, a patio or pavers sloping toward the wall do the same thing.

Negative grading sends water against the foundation with every rain. The foundation drain has more to handle, and the water eventually finds a crack or a joint to get in.

With no sign of water in the basement, it is mostly yard maintenance. It becomes more serious when the report also notes signs of water entry, efflorescence or downspouts discharging at the same spot, or when a finished basement hides the walls.

Regrading the ground along one side of the house: $600 to $1,400, and all around it: $1,600 to $3,800. The downspouts are often extended at the same time: $100 to $250 per downspout.

Correcting the slope of a paved driveway or a patio is a separate quote, depending on the surface to redo.

These are ballpark figures for Quebec, to be confirmed with quotes.

1. On which sides does the ground slope toward the house?
2. Did you see signs of water in the basement on those sides: stains, efflorescence, a damp smell?
3. Does a driveway, a patio or a walkway send water toward the foundation?

Does your report mention negative grading? Upload it: in five minutes, I tell you what comes first, what to have checked and what to ask the seller.

For a small area, often: add well-compacted soil against the foundation and slope it away from the house. Keep a gap between the soil and the bottom of the siding, or moisture will wick into it. For a driveway or a patio, hire a contractor.