Should the old garage slab come out before a new garage is built?

An old slab can be thin, unreinforced, cracked or poured over a base that was not prepared for the new design. Those are common possibilities to investigate, not facts that can be declared from the date of the garage. A surface patch can hide cracks or a second pour, and a level floor can still have unsuitable material beneath it.

Ask the designer what information is needed to assess the existing floor. Exposed edges, available drawings and site observations may help, but the plan for a new garage must reflect the actual support and footing arrangement. A demolition contractor can expose a condition; it cannot certify that the old concrete is suitable for a new building.

The replacement may have a different footprint, different loading or a new footing layout. An existing slab cannot simply be assumed to align with those requirements. If the permit drawings specify removal and a new base, retaining the old floor by convenience would leave the builder working against the approved design.

The owner should review the slab decision with the designer before booking concrete removal. The City of Mississauga Building Division confirms permit requirements for the proposed new garage. Concrete removal is separate from the broader residential demolition of the old structure; the slab scope can be defined without turning this into a guide to taking down the garage.

Where the garage floor joins a driveway that will remain, a sawcut defines the agreed line. It reduces uncontrolled cracking as the garage slab is broken out. Check that the builder wants that exact edge and that the driveway apron does not conceal a footing, service or concrete that must also change under the new plan.

Exterior ground disturbance calls for current utility information through Ontario One Call and investigation of private services. The driveway locate guide explains why paint on the surface does not cover every private run. Protect the approach during load-out so equipment does not damage the very paving the cut was meant to preserve.

Lifting the first pieces can uncover granular fill, an older slab, buried debris, drains or an uneven base. These conditions affect the builder's preparation for the new floor. The crew should document something unexpected and let the designer or builder decide whether more removal is needed rather than extending excavation on its own.

Specify whether the agreed end condition is exposed base, removal of unsuitable material or another handoff described in the plans. A newly opened area may need protection against access or water before the builder takes over. The owner should identify who is responsible for maintaining it between demolition and construction; removing concrete does not itself create a ready-to-pour foundation.

An existing slab can stay only when the designer or engineer accepts it for the proposed new garage and the approved drawings reflect that choice. The decision should consider the actual floor and support, not simply that the concrete appears solid. If the plan permits partial retention, the boundary between old and new work must be clearly marked.

CoreCut Demolition Mississauga can sawcut at the agreed apron, remove the specified garage slab and load material out without treating the remaining driveway as disposable. We flag concealed conditions for the builder to review and leave the work at the stated limit. Request a site walk with the new garage drawings and the surfaces that must remain identified.