What happens if a driveway or walkway is improperly sloped?

expert EXPERT April 26, 2007

Walkways and driveways should slope away from house walls. If they don't, surface water may get into subgrade areas, and damage the walls. If the driveway slopes down to a garage, a wide drain at the garage door is needed.

An improperly draining walk or driveway is one where low spots or unevenness allow water to pond. Ideally, the surface is smooth and sloped to allow water to drain off.

Improper drainage can be caused by

• an imperfect installation
• settlement or compaction of the sub-base
• heaving, cracking, or damage to the surface itself

Ponding water can cause moss in summer and/or ice in winter both of which are slip hazards. It can also lead to damage to the surfaces themselves, particularly freeze/thaw damage. Ponding against the house can lead to water penetration into the building, and damage to the foundation and subgrade areas.

Look for dark stains, moss, or spalling on walk or driveway surfaces. Look for cracks or unevenness that could lead to ponding. On driveways, you may see ruts where cars have compacted the surface. The most important problem to watch for is driveways that slope toward the house. These can cause considerable water damage to the home.