When a new home is constructed, it is essential that the lot be graded properly to ensure that surface drainage is directed away from the building and does not cause problems or damage to neighbouring properties. It is also important that the house be situated so that the top of the foundation wall is at least 6 inches above the adjacent ground level, to avoid water entering any masonry weep-holes and to prevent rotting at the bottom plate of the framing.

The Ontario Building Code sets out the requirements for lot grading and drainage etc. during construction, in part as follows:

  • -The building shall be located or the building site graded so that water will not accumulate at or near the building and will not adversely affect adjacent properties.
  • - Exterior foundation walls shall be extended not less than 150 mm (6") above finished ground level.

The main factors to be considered in the grading of a lot after construction are that the lot should be sloped away from the house for a distance of at least 5 feet, no additional surface drainage should be directed onto adjacent properties and existing overall surface drainage patterns should be changed as little as possible.

For lots within current Plans of Subdivision, a Subdivision Grade Control Plan showing elevations and the overall drainage pattern is prepared by the Developer and must be conformed with as a condition of the issuance of a building permit.

For any other lot, an individual drainage plan for the lot would have to be prepared which takes into account the existing drainage patterns and elevations of adjacent properties, the street, etc.

Downspouts from roofs should discharge at grade onto a splash pad at least one meter away from the building and should not be directed towards adjacent properties. A well-defined swale along the side lot line should be established.

The result of a well-planned and properly executed grading and surface drainage system is a lot free of ponding, with no adverse effects to the adjacent properties to the ultimate enjoyment and benefit of all.

Contact Us