Foundation Waterproofing in Markham

We are OCM Excavation & Construction, based in Richmond Hill and running foundation waterproofing jobs across Markham since 2008. If your basement leaks after a heavy Rouge-watershed storm, or if your 1970s Markham Village bungalow has never had its footing tar touched, we dig, clean, membrane, and drain it properly. Owner Ofer Hadad runs every site personally. Call 416-317-3090 for a free on-site assessment anywhere from Unionville to Box Grove.

Why foundation waterproofing in Markham needs local skill

Markham is not one job. The waterproofing problem looks different in every pocket of the city, and the permit picture changes with it.

Unionville heritage district — homes from the 1800s through mid-century with original parging, brick footings, and clay tile drains long past their service life. Side-yard access is tight, mature trees are everywhere, and the Markham Tree Preservation By-law 2023-164 protects any tree 20 cm DBH or larger measured at 1.37 m. We plan our excavation route around those trunks before we break ground.
Markham Village — older builds with cinder-block foundations, dry-stacked stone in the oldest pockets, and weeping tile that’s typically clay or early PVC. Block walls move water through every horizontal joint when the membrane fails.
Cornell — planned-community subdivisions with rear-lane housing. Lot grading is engineered but the rear-yard slope often funnels surface water straight against the back foundation. We retrofit drainage with the lane access in mind.
Cathedraltown — estate lots with deep basements, often walk-outs. Full-size excavator can reach the wall, and the dig depth can hit 8-9 ft along the low side.
Berczy Village, Greensborough, Box Grove — 2000s-2010s subdivisions on engineered fill over clay. Builder-grade dimple board and damp-proofing, not true waterproofing. Twenty years in, the joints are weeping.
Rouge River corridor — properties in east Markham backing onto the Rouge are inside TRCA’s Ontario Regulation 41/24 area. If your dig touches a regulated slope, valley wall, or watercourse setback, we pull the TRCA permit before the excavator moves.

Soil under Markham is mixed clay and sand depending on the subdivision. Clay holds water against the wall for days after a storm — that’s what cooks an old membrane and finds every crack.

Types of foundation waterproofing we do in Markham

Exterior excavation waterproofing — the real fix. Dig to the footing, pressure-wash the wall, parge cracks, apply a rubberized membrane, lay dimple board, install new perforated weeping tile in clean stone with filter cloth, backfill with proper drainage layers. This is what stops the leak instead of catching it.
Interior weeping tile and sump pit — when exterior access is blocked (attached garage, neighbour right-of-way, mature protected trees), we break the slab, run interior drain to a new sump pit, install a pump on a battery backup, and re-pour the slab.
Drainage retrofits — disconnecting downspouts from foundation, regrading the first 1.5-2 m around the wall to a 2% slope away, replacing failed weeping tile sections.
Sump pits — new pit installs, pump upgrades, battery backup systems for storm-season outages.
Window wells — replacing rusted-through steel wells with poly or galvanized, installing wells where there were none, adding drainage to the bottom of the well so it doesn’t fill and dump straight into the basement.

Our foundation waterproofing process

On-site assessment — we walk the basement, check the grade outside, locate the leaks, look at what’s currently there.
Locates and permits — Ontario One Call goes in. If a SALT permit is required under Markham Site Alteration By-law 2011-232, we file it. If a protected tree under By-law 2023-164 is in the dig zone, we apply for the tree permit and brace the trunk and roots. If the property is inside the Rouge corridor, we file with TRCA.
Excavation — full-size or mini-excavator depending on access. We strip back to the footing, stockpile clean topsoil separately.
Wall prep — pressure-wash, hand-clean, hydraulic-cement any active leaks, parge cracks.
Membrane and drain — rubberized waterproof membrane on the wall, dimple board over top, new weeping tile in 19 mm clear stone wrapped in filter cloth, tied to existing storm or to a new sump pit.
Backfill, grade, restore — backfill in lifts, restore grade to 2% away from the wall over the first 1.5-2 m, replace sod or hardscape we lifted.

What affects waterproofing cost in Markham

House age and foundation type — Unionville heritage stone or brick footings take longer to prep than poured concrete in Cathedraltown.
Depth and run of wall — full-perimeter dig versus a single problem wall.
Access — rear-lane houses in Cornell allow a full-size excavator; a Berczy Village backyard behind a 1.5 m gate means mini-excavator and slower spoil hauling.
Markham SALT 2011-232 — if the job moves enough soil to trigger a Site Alteration permit, we factor in the permit application time and any conditions the city attaches.
Markham Tree By-law 2023-164 — protected-tree permit fees and root-protection fencing add cost if a 20 cm DBH or larger trunk is inside the work zone.
TRCA Rouge River corridor — properties in Box Grove, Cornell, or anywhere backing onto the Rouge inside the Reg 41/24 area need a TRCA permit, which adds review time.
Soil disposal — Markham clay and old fill have to be hauled under O. Reg. 406/19 excess-soil rules. Receiving-site fees vary.
Restoration — pulling and resetting interlock, replacing a deck section, sod replacement.

For a full breakdown of how we approach the work across the region, see our foundation waterproofing GTA page. For Markham excavation work generally, see our Markham excavation contractor page, and for service-line and drainage trenching specifically, our Markham trenching page.

FAQ

Do I need a permit to waterproof my foundation in Markham?

Waterproofing itself usually doesn’t trigger a building permit, but the dig can. If the volume of soil disturbed crosses the threshold of Markham Site Alteration By-law 2011-232, a SALT permit is required. If a protected tree (20 cm DBH or larger under By-law 2023-164) is in the work zone, a tree permit is required. Rouge corridor properties may need TRCA approval under O. Reg. 41/24.

Exterior or interior waterproofing — which is better?

Exterior is the actual fix because it stops water before it reaches the wall. Interior weeping tile and a sump pit manage the water once it’s already in. We recommend exterior whenever access allows and the trees and structures around the foundation can be worked around. Where they can’t, interior is a sound second option.

How long does a typical Markham waterproofing job take?

A single problem wall is often 2-3 days. A full-perimeter exterior dig on a typical Markham Village or Berczy Village home runs 5-8 days depending on depth, access, and weather. Heritage Unionville jobs with tree protection and tight access can stretch longer. Permit time is on top of dig time.

My basement leaks only during heavy rain — is that still a waterproofing job?

Often yes. Storm-only leaks usually mean the membrane and weeping tile can’t keep up with peak flow. The cause can be as simple as a downspout dumping next to the foundation or grade sloping toward the wall, or as serious as a failed membrane and clogged weeper. We diagnose the actual cause before recommending a scope.

To book an on-site assessment in Markham, call OCM Excavation & Construction at 416-317-3090.

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