Basement Underpinning in Richmond Hill, ON

OCM Excavation & Construction is based in Richmond Hill, and basement underpinning is the work we know best on home turf. If you bought a Bayview Hill, Mill Pond, Oak Ridges or Jefferson Forest home with a 7-foot basement and you want a real lower level — full ceiling height, an in-law suite, a home theatre, a legal rental — we dig under your existing footings in measured pin sections, pour new concrete piers, and rebuild the floor 18 to 36 inches lower than where you started. Call 416-317-3090 to book a Richmond Hill site visit.

Why Richmond Hill Homes Get Underpinned

Richmond Hill housing splits into two camps. Older Mill Pond and Yonge Street homes from the 1950s through the 1970s, with low basements and original block foundations. And the larger Bayview Hill, Westbrook and Jefferson homes from the 1990s and 2000s, which already have 8-foot basements but where owners want to dig further for media rooms, gyms with platform space, or full nanny suites. We underpin both. The Mill Pond houses we usually take down 24 to 30 inches. The newer estate homes we typically take down 18 to 24 inches and add a walkout if grading allows.

The third common Richmond Hill case is the new-build secondary suite. The Town of Richmond Hill now permits accessory dwelling units, and a lot of homeowners are converting basements into legal rentals to offset Richmond Hill mortgage payments that have not gotten any easier. That conversion almost always means underpinning to hit the Ontario Building Code height minimum.

Richmond Hill Soil Conditions

Richmond Hill sits on the Oak Ridges Moraine and the surrounding Halton Till. The Oak Ridges section is sand and gravel — generally good for drainage but loose, which means our shoring and pin sequencing matter. The Halton Till sections, mostly south of Elgin Mills, are dense clay with stones, which is structurally strong but holds water against your foundation wall. We size the dewatering, the weeping tile and the pier widths to whichever soil profile we hit. If you are in Oak Ridges or Jefferson, expect more attention to slope stability during the dig. If you are in Mill Pond or south Richmond Hill, expect more attention to drainage and waterproofing.

Richmond Hill Permits

Underpinning in Richmond Hill requires a building permit from the Town of Richmond Hill Building Division at the Municipal Offices on Major Mackenzie Drive East. You need stamped structural drawings from an Ontario-licensed Professional Engineer, a site plan, and where you are creating a secondary unit you also file a Second Suite registration. Permit fees vary by floor area and scope — the Town publishes the current rate schedule on its website. We pull the permit, coordinate the engineering, and book inspections at footing, framing and final stages.

Typical Richmond Hill Underpinning Cost

A typical Richmond Hill detached with a 1,000 to 1,400 square foot basement footprint lands in the $50,000 to $90,000 range for full underpinning, depending on depth, soil, and whether we add waterproofing, a new slab, weeping tile, sump system and rough plumbing for a suite. Larger Bayview Hill and Westbrook houses with 1,800+ square foot basements run higher. We do not give a real number until we have walked the basement and measured. Anyone quoting underpinning over the phone is guessing. To book the walk-through call 416-317-3090.

Equipment We Bring to Richmond Hill

Richmond Hill lots are usually wide enough that we can stage a Yanmar SV40 mini-excavator in the side yard or back. That lets us work faster than full hand-dig, which keeps the project window shorter and your cost down. On tight infill lots near downtown Richmond Hill where we cannot get a machine in, we revert to hand-dig with barrows. Either way, the underpinning sequence is the same: pin sections, shore, dig, form, pour, cure, repeat.

Other Richmond Hill Services

If you are underpinning, you will likely also waterproof. See our Richmond Hill foundation waterproofing page and our Richmond Hill excavation contractor page. We also cover neighbouring cities — see underpinning in Vaughan and underpinning in Markham. Full coverage at our service areas.

Frequently Asked Questions

How long will a Richmond Hill underpinning job take?

For a standard Richmond Hill detached, structural underpinning runs 5 to 8 weeks. Add 2 to 4 weeks for waterproofing, slab pour, weeping tile and rough-in for a secondary suite. Larger estate homes with 1,800+ square foot basements can run 10 to 12 weeks. Weather, soil conditions and permit timing all move the needle.

Can I add a legal second suite after underpinning?

Yes, and that is one of the most common reasons we are called in Richmond Hill. After we underpin to code height, you file a Second Suite registration with the Town of Richmond Hill, complete the framing, fire separation, egress windows and HVAC requirements, and get a final inspection. We coordinate the underpinning side of that process and refer the framing trades if you need them.

Does Richmond Hill require an engineer for underpinning?

Yes. The Town of Richmond Hill Building Division requires stamped structural drawings from a Professional Engineer licensed in Ontario before they issue an underpinning permit. Engineer fees are separate from our quote and usually run $3,500 to $7,000 depending on house size and complexity.

Will my house move or crack during underpinning?

Underpinning done properly causes minimal movement. We work in pin sections — typically 3 to 4 feet wide — and only open one section per side at a time, with the rest of the foundation fully supported. Hairline cracks in drywall happen occasionally and are normal. Structural movement is not. Our process is engineered to keep your house exactly where it was.

Do you handle the permit, or is that on me?

We handle it. You hire the engineer (or we refer one), they produce the stamped drawings, we file the permit application with the Town of Richmond Hill, coordinate revisions, and book the required inspections at the right stages. You sign as the owner on the application. We do the rest.

Book Your Richmond Hill Underpinning Quote

Call OCM at 416-317-3090 or use our free quote form. We are local to Richmond Hill, we know the soil, and we know what the Town inspectors look for. Get a number on your basement.

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