Basement underpinning in Markham
Subdivision lots take a crane and a bin, and lots along the Rouge add a conservation authority review. The work is in the basement and the house stays supported throughout, so most families stay; each section is dug, formed, poured and inspected before the next. Underpinning lowers a basement floor by extending the foundation walls down in short engineered sections, one at a time, so the house is never sitting on an unsupported wall. The result is legal ceiling height for a suite or a family room.
Markham, on the ground.
Markham is heritage districts in Unionville and Markham Village, 1970s and 1980s subdivisions in Thornhill and Milliken, and newer stock in Cornell and Berczy. Those basements in Markham were never meant to be lived under, and lowering the floor is what turns them into a suite or a real family room. The Markham brief is usually a second storey on a 1980s house, a rear addition behind a heritage house, or a custom home on a deep Thornhill lot.
Read more about building in Markham or the full basement underpinning page.
On the drawing.
A site walk with measurements of the existing ceiling height and a look at the footings
Engineered drawings with the underpinning sequence and the new footing depth
Building permit filed and followed by us
Excavation and pours in numbered sections, each inspected before the next
New slab, drainage, sump and waterproofing where the drawings call for them
A deficiency walk, and a written warranty
Paper first.
Underpinning needs a building permit with engineered drawings, and each section is inspected before the next one is dug; a suite that follows needs its own permit. The City of Markham issues the permit, and heritage designation adds a review to anything visible from the street.
- A building permit with engineered drawings is required in every GTA municipality.
- Each underpinning section is inspected before the next one is dug.
- On a semi, the drawings address the shared wall and the neighbour's foundation.
- A suite that follows needs its own permit for the plumbing, the egress and the fire separation.
The paperwork wall: WSIB, insurance, licences, the HCRA status and the warranty, on one page and dated.
| Driver | What we look at |
|---|---|
| How far the floor drops | Every extra inch of depth is more excavation and a deeper footing. |
| Perimeter length | The number of underpinning sections is set by the wall length, and each one is dug, formed and poured on its own. |
| Soil and water | Clay, sand and a high water table each change the sequence and the drainage. |
| Benching instead | Where the soil or the neighbour's foundation rules out underpinning, benching lowers the floor with a ledge along the wall. |
| What follows | A lowered basement is usually the start of a suite, and the plumbing and finishes come after the slab. |
No price per linear foot on this site. The site walk and the engineer's drawings set the number.
Usually. The site walk measures the ceiling height and checks the footings, and the engineer draws the sequence. the City of Markham issues the permit and inspects each section.
Usually, yes. The house is supported throughout and the work stays in the basement. Noise and dust are real, and the basement is out of use for the duration.
The City of Markham. Additions, second storeys, new houses and second units all need a building permit with engineered drawings.
Most can. The engineer confirms the foundation from a test pit, and the lots in Thornhill and Milliken have the room for a crane.