Garage Ceiling Repair & Loose Concrete | Joint Seal

Loose concrete in a garage ceiling is an overhead hazard first and a repair second. The order of work is: make it safe, find out how far the delamination runs, then rebuild the section properly. Sounding the ceiling with a hammer tells you more in an hour than a visual inspection tells you in a week — delaminated concrete rings hollow long before it falls.

Why garage ceilings spall

The ceiling of a parking level is the underside of the slab above. Water gets through the slab — through a crack, a failed expansion joint, a wall penetration or a failed membrane — and reaches the reinforcing steel. Steel rusts, rust occupies several times the volume of the steel it came from, and the expansion pushes the concrete cover off from the inside.

By the time concrete is on the floor, the steel has been wet for years. That is why patching the ceiling without finding the water source is a repair with a countdown on it.

How the repair is done

1. Remove the hazard. Loose and drummy concrete is taken down in a controlled way, back to sound material and behind the corroded steel, not just to the visible edge.

2. Treat the steel. Exposed reinforcement is cleaned. Leaving rusted steel inside a patch guarantees the patch fails from behind.

3. Bond, then rebuild. Overhead patching is the hardest patching there is, because gravity is working against the material for the whole cure. Only industrial-grade adhesives hold — the crack filler and patching material have to bond to the existing substrate and stay there with nothing supporting them. We use Polyforce Plus Adhesive with Polyforce Polymer Cement, which places in sections as thin as 5 mm against the two-inch minimum a conventional chip-out and recast needs. Thin patches are lighter patches, and overhead, weight is the enemy.

4. Coat the repaired area. The rebuilt section is coated so the new concrete is protected from the same water that destroyed the old.

5. Deal with the source. Slab cracks, joints, drains and penetrations above the repair are addressed, or the whole sequence repeats in five years.

Floors, drains and the rest of the turnkey scope

The same visit usually picks up floor patching, and the areas around floor drains are almost always among them. Drain surrounds fail first because water concentrates there, the edge is a thin unsupported section of slab, and every vehicle wheel that crosses it loads it.

Does the garage close?

No. Work is phased bay by bay or level by level. For comparison, a 20-foot expansion joint span needs roughly ten parking spots vacated and takes about two days, and the garage stays open throughout. Most repaired areas are back in service within 24 hours.

A real example

A high-rise residential building on Blue Jays Way in Toronto. We first attended an emergency call to remove an overhead hazard — loose concrete in the ceiling above one of the parking spots. Several weeks later we returned to repair that section of ceiling properly, with an extensive patch installed where the loose concrete had been taken out, plus patching to parts of the garage floor including the area around one of the drains.

That two-visit pattern is normal and it is the right way round. Make it safe now; rebuild it once you know how far it goes.

The opinion, stated plainly

A garage ceiling patch that is quoted without a discussion of where the water is coming from is being sold as a cosmetic repair. Ask the contractor what is directly above the spall. If nobody has looked, the patch is a schedule, not a fix.

Related: overhead and ceiling concrete repair · parking garage waterproofing and repair · thin-patch concrete repair · expansion joint repair · documented projects · common questions