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Underpinning Toronto

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An option for homeowners who want to add extra square footage to their homes, particularly appealing as real estate values around the GTA continue to rise, is underpinning the basement.

With rising prices some of us don’t want to buy a new home. Creating additional square footage in the existing home starts to make more sense. Maybe all you have currently is a crawl space and you need more head room for storage. Many people are also looking to build revenue-generating basement apartments, especially at a time when there is a crying need around the GTA for rental housing.

Or, especially in older homes, the foundation has degraded, or was poorly built. Perhaps there has been slippage in the land that the current footing is built on. Perhaps there have been renovations done on the floors above and there is extra weight on the home’s foundation. Underpinning will reinforce the existing foundation, making the home safer to live it.


It’s a complex process, and it will be disruptive for everyone involved, but the return-on-investment will be substantial.

What is underpinning? It’s an industry term. Technicians are literally lowering the basement of the home.

As you can guess, this isn’t a job for amateurs. It requires expertise. It requires professionalism. It requires workers who are accredited and insured. It’s vital to determine the right excavation levels for the home. It’s vital to know the footing arrangement, and the plans and details for moving or extending load-bearing walls. It goes without saying that underpinning done incorrectly can be dangerous and dire for those who live in the home.

Technicians will dig under the existing foundation and add a new concrete footing extension to the basement perimeter, and a new concrete floor slab.

Underpinning requires inspections and engineering reports throughout the entire project. City inspection is free but engineer reports are an additional cost. Reports may be required at the sole discretion of the city inspector.


Companies like Canada Waterproofers can help you find engineers to have the necessary drawings done up, determine building code requirements and obtain permits from the city, all related to the depth of the excavation, concrete work that needs to be done, the re-routing of furnace connections, as well as plumbing and electrical.

If you want to do that on your own, make sure the engineer is licensed and can show you a record of past jobs that were completed successfully. Typical cost for drawings and permits is between $2,500-$3,500, depending on the size of the project.

Make sure the contractors for the job are licensed and insured. You should talk to your insurance company about also buying additional insurance for this, but keep it in mind if you hire an unlicensed, incompetent contractor to save a few bucks, and the structural integrity of the basement gives way during the underpinning process, don’t count on your insurance company paying you the damages and repairs.


According to the contractors at Canada Waterproofers (with over 25 years of experience) this is the process. Canada Waterproofers has underpinned hundreds of basements around the GTA:

  • Protect work areas with tarps, all equipment and ductwork is moved out of the way
  • Temporary supports are installed by technicians to stabilize the home while the underpinning work is being done
  • Technicians will excavate and underpin the wall in sections as per the drawings and permits until completely underpinned. Is the soil underneath the foundation strong enough to support the home? That’s a factor to weigh when determining the type of underpinning that will be done. In some cases soil that’s deemed to be too weak to support the home is replaced with concrete, a process that’s done section by section. All of this is done by professionals in consultation with structural engineers
  • Remove and dispose soils for lowering the basement to the agreed height
  • Install a new plumbing and interior waterproofing system, including a sump pump pit, to make sure the new area remains dry. Install a battery-powered or water-powered back-up sump pump in case there is a power outage
  • Install an interior waterproofing membrane and weeping tile, connected to the new sump pit, below floor level. This waterproofing system will capture any groundwater and pump it out to the exterior of the home
  • Encase the weeping tile with gravel. Pour clear gravel (four inches thick) throughout the completely lowered area of the basement
  • Pour new 25 MPA concrete (higher strength concrete, since it will be supporting greater loads and traffic) throughout the basement with a trowel finish (helicopter when possible)
  • Keep in mind the time required to underpin a basement. After concrete is poured stage-by-stage the technicians need to give it time for the concrete to “cure”, the process that leads to the desired strength and durability. It’s only then that the temporary supports are removed
  • Clean-up work areas and remove access debris from the site

Canada Waterproofers has a 15-year warranty on underpinnings.


House prices in Toronto and the surrounding areas keep rising. As prices rise then usable space becomes a premium. Underpinning is a great way of making that unusable basement into something that can become part of your home. Underpinning means reinforcing an existing foundation or digging out the foundation to add ceiling height.

Underpinning/ basement lowering your home and finishing that unused space will add a huge amount of value to the property. With house prices at a record high, it is much cheaper to underpin your home than it is to buy somewhere else.

Canada Waterproofers can underpin your home at an affordable price and do it safely, as we have all the skills and training needed.

Considering underpinning your Toronto home?

If you are considering having your basement underpinned then it is very important to ask all the right questions, as underpinning can be dangerous if it is performed incorrectly. Ask your contractor these questions:

  • Are you licensed?
  • Do you have all the correct insurances?
  • Do you need drawings and permits?
  • Do you need the city to inspect your work?
  • Do you have references?

If your contractor answers YES to all of these questions then you are probably safe, but be sure to check all their credentials out before any work is started.

Main stages of underpinning a Toronto home

  • Once you have chosen your contractor – which hopefully will be Canada Waterproofers! – then you are ready to get your drawings done
  • Canada Waterproofers can provide you with contact information for a few engineers if you wish to get your own drawings and permits
  • If on the other hand you don’t wish to get involved with all the hassle of dealing with the city, Canada Waterproofers can provide all of the needed drawings and permits.
  • Typical cost of drawings and permits range between $2500-$3500 depending of the size of the project.
  • Underpinning your home is a big expense and can be disruptive, but the benefits out way the disadvantages.
  • That unusable space now becomes a welcoming, finished basement, with 8-foot ceiling height, which adds square footage and value.

Here is what to expect once an underpinning or basement lowering project is started.

  1. Basement cleared
  2. Basement demolished
  3. Transporter installed into window
  4. Bin arrives for soils
  5. Concrete floor removed
  6. Walls are underpinned by sections
  7. Inspections of all individual sections
  8. Soil is removed and disposed
  9. Interior drains are replaced
  10. Interior waterproofing installed
  11. Sump pump installed
  12. Sewage ejector installed if needed
  13. Gravel installed
  14. Vapor barrier installed
  15. Concrete is poured with trowel finish
  16. Work areas cleaned

These are the basic steps that you would expect to see as the process of underpinning your home is undertaken. Canada Waterproofers is the best underpinning company in Toronto, Scarborough, Etobicoke, Mississauga, Oakville, and the surrounding areas.

So if you’re looking for integrity, honesty and reliability, then Canada Waterproofers and our highly skilled workers are here for you.

Call today and receive a free assessment of your home to see if underpinning is right for you.

Thank-you from the Canada Waterproofers Team.

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