Select Page

Underpinning is when the earth beneath an existing foundation is excavated and a new foundation is poured directly under the old one to provide more structural strength and increase the height of a basement. We do this a lot in older homes with basements under 6 feet high when the homeowners wishes to convert the basement to a secondary suite or another full height level of the home. During the process, the house is supported with temporary walls and posts which eventually get replaced with new full height walls and posts, and the deeper foundation. Installing new drain tile around the perimeter of the house is usually one of the last steps of the underpinning process. It is technical and unglamourous work, but something we find very rewarding.

Existing basement and foundation before underpinning.

The old slab is demolished, temporary walls are installed and the old supports are removed.

Footings for new 8 foot posts are formed.

Half of the new foundation is created in the first pour. Rebar will be installed and another round of forms will be installed in the gaps before the second and final pour.

A close up of a form after the first pour.