According to the city bylaws in Calgary, the grading of lots for new buildings must be done properly so that the water never flows toward the new building or any other nearby properties, but away from those buildings. This bylaw applies to a whole host of new construction projects, including single-detached homes, semi-detached homes, duplexes, multifamily developments, and any structures on industrial and/or commercial sites in the city.
Before any construction project begins, it is very important for builders to become familiar with the city's lot grading tolerance chart. This provides detailed information about minimum grades, grade slip, and the like.
When the job is done, a contractor then has to get an As Constructed Grade Certificate proving that the grade conforms to the bylaws and that the lot has been properly developed. Builders also need to get an As-Built Plot Plan. Both documents must be submitted to Water Services when the project is done.
The reason for grading lots in this manner is simple. When water is allowed to drain toward buildings, it can result in flooding, damp basements, and other such issues. Even if a new build is able to avoid these issues at first, they could grow worse over time if the drainage is not working properly, as the property ages and the water begins to take its toll on the structure and the land immediately around the foundation.
As you can see, it's important to know everything you can about local construction laws before a project begins. Always look into the proper bylaws, understand what documents are needed, and take steps to ensure each project adheres to these guidelines.
Source: City of Calgary, "Lot grading bylaw," accessed Sep. 30, 2016