Walk-Up Basement Conversion in Markham, ON | OCM Excavation

We build walk-up basement conversions across Markham — Unionville, Cornell, Cathedraltown, Milliken, and Box Grove — for homeowners who want a code-compliant separate-entry lower suite. A Markham walk-up gives the basement its own daylight door, its own poured concrete stairs, and its own drainage path. We do the dig, the foundation cut, the concrete, and the waterproofing as one job with one crew. Call 416-317-3090 to book a site visit and a fixed-price quote.

The Five Works in a Markham Walk-Up

Every Markham walk-up is five jobs stitched together. We re-grade the lot so surface water flows away from the new opening. We excavate the stair pit — 7 to 8 feet deep at the door — against the basement wall. We form and pour reinforced concrete stairs and retaining walls. We saw-cut the new exterior door opening through the foundation. And we extend the perimeter weeping tile, wrap the new opening in peel-and-stick membrane, and route a dedicated sump line. Done in sequence and by one crew, the work is clean. Split between trades, it leaks.

Why Markham Owners Build a Walk-Up

Multi-generational households are the strongest driver in Markham. Many Unionville and Cornell families build a walk-up so parents or in-laws have a private door without sharing the upstairs entrance. Rental income is the second-strongest driver, particularly in established neighbourhoods near Highway 7 and the future Yonge subway extension. A smaller share of Markham clients build the walk-up to make the basement legally rentable before listing the home, which materially shifts the price the home commands.

Markham Permits and Zoning

The City of Markham Building Standards Department issues the permit for a walk-up. Markham has been actively updating its zoning by-law to align with provincial direction on additional residential units, but each property’s specific setbacks, lot coverage, and yard rules still need to be checked. We supply the field dimensions; your designer drafts the foundation cut detail, the stair section, and the grading plan. Plan 6 to 12 weeks for drawings and permit issuance.

Rock and Soil Conditions in Markham

Northern and eastern Markham sit on shallow bedrock in places. We routinely hit rock within 4 to 6 feet of grade north of 16th Avenue and east of Markham Road, which means we plan the dig with a rock saw or hammer-drill attachment for the Yanmar SV40 (insured on our a Definity commercial policy). South of Highway 7 the soil shifts toward heavier clay, which holds water against the foundation and demands an aggressive drainage tie-in. Either condition is solvable — we just plan it before we dig, not while we dig.

Timeline and Site Conduct in Markham

Plan 4 to 7 weeks on site, weather-dependent. We protect driveways, sod, and interlock with plywood; route spoils through a single covered bin; and stick to Markham’s residential engine-hour rules. Excavation runs 3 to 5 days, the foundation cut and stair forming take about a week, concrete cures for 7 days minimum, and waterproofing and backfill close the job. We pressure-check the new weeping tile before we backfill so problems are caught while the trench is still open.

Why Choose OCM in Markham

We are an excavation company first, which matters when the dig sits against an existing footing. We shore as we go, hand-trim the last foot near the foundation, and brace the wall before the concrete saw runs. We also self-perform the waterproofing and weeping tile work in-house, so the owner deals with one company, not three. Call 416-317-3090 to schedule a Markham site walk.

Frequently Asked Questions

What does a Markham walk-up cost?

Most Markham walk-ups fall between $25,000 and $60,000 for the structural and drainage scope. Rock excavation is the biggest variable — when we hit bedrock above the planned pit floor we price rock work by the day with a not-to-exceed cap so the change order is transparent.

Do I need a permit in Markham?

Yes. Any new opening in a foundation wall requires a building permit from Markham Building Standards. A zoning compliance review is also typical, and a minor variance may be needed if the stair pit pushes into a side-yard or rear-yard setback.

What if we hit bedrock?

Common in north Markham. We bring in a hydraulic hammer or rock-saw attachment, work in lifts, document the rock line for the inspector, and price the rock work separately so you see exactly what you are paying for.

Will the walk-up qualify the basement as a second suite?

The walk-up provides the separate entrance, which is one of the code requirements. The other suite requirements — fire separation, egress windows, ceiling height, smoke and CO interconnection — are handled by your interior renovation. We provide the structural shell; the interior trade finishes the suite.

How long is the project?

Four to seven weeks on site. Permit issuance and drawings add 6 to 12 weeks at the front. Winter pours are possible but slower because the concrete needs heated curing.

Quote Your Markham Walk-Up

Call 416-317-3090 or use our free quote form. See our full service areas, our Markham foundation waterproofing page, our Markham excavation contractor page, and our sibling Richmond Hill walk-up and Scarborough walk-up pages.

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