How to Underpin a Basement
Underpinning a basement in Hamilton, Ontario
What is underpinning, and when is it required?
Underpinning is the process of strengthening and supporting the property's foundation. This can be done by extending the depth foundation.
Underpinning occurs when homeowners want to improve deficient/failing foundations, implement structural changes to the building for renovations, for example: adding more floors, or when new construction occurs nearby and requires the removal or excavation of soil.
There are various ways to conduct the process of unpinning. However, the most traditional method of underpinning is mass concrete. This method involves extending the old foundation and usually consists of excavating sections below the foundation, one at a time, and backfilling each concentre.
Key factors to consider when wanting to go through the process of underpinning:
When hiring subcontractors, they should have an in-depth understanding of concrete; however, since you're paying for a specialized service, it may be more expensive.
If you are doing an underpinning job, ensure this process is covered under your insurance just in case anything happens. Unpinning typically does not fall under home renovation insurance; you have to add it on.
Get a structural engineer who has done engineering designs for unpinning projects. They can design and review your designs giving them the seal.
To watch a video and learn more about how to underpin a basement properly please click here.
It is important to note: Ontario Regulations for Residential Underpinning
You will be required to provide testing and reports by a professional engineer during the first and last stages of the construction in order to pass inspections.
The documentations required are a site plan, basement foundation plans for underpinning, floor plans, sections, and construction details and notes.
The forms required are:
Application to construct or demolish form - This building permit application is required for all submissions.
Schedule 1: Designer information form - This is required for all designers, engineers and architects when applying for any construction permit.
[City of Hamilton] Commitment to General Reviews by Architect and Engineer - This is required where the foundations of a building are to be constructed below a certain level of footings, if it exceeds 1200 mm of laterally unsupported height, etc. The owner, agent, and professional architect, engineer, or consultant must sign the form.
[City of Hamilton]Tree declaration form - Only required if there is potential damage to private or city trees.
Before and after - Pal Property Solutions’ East 25th project in Hamilton, Ontario
Our East 25th project is a great example of underpinning a basement, as the house was converted into a legal triplex. Originally purchased as a single-family home. Renovation costs included all underpinning foundations, entirely new electrical, plumbing, structural, mechanical, and all interior finishes.
Below are the numbers for the project:
Purchase price: $300,000
Construction Costs and Holding Costs: $350,000
After repair value: $1,050,000
Money Split after partner was paid out (surplus): $190,000
Ready to get started? Don’t forget to download our Getting Your Foot in the Door book which covers the most frequently asked questions as well as lessons learned from our founder, Alex Pal.