Flat Roof Repair

Joint Seal Waterproofing is a Toronto-based company, specializing in flat roof repair and waterproofing. Our services cover a vast geographical area, from Hamilton to the City of Toronto, and the surrounding GTA communities.

Throughout our portfolio of flat roof membrane installations and waterproofing, we have had experience with most of the typical membrane types.

Our Flat Roof Repair Services

Hot-Applied Flat Roof Repairs

Waterproofing of tar roofs is done quickly – adhesion (and with it, a long-lasting waterproofing layer) is created, as the specialized materials cool down.

Cold-Applied Flat Roof Repairs

Repairs on roof surfaces covered with EPDM membrane require a series of steps to ensure long-lasting waterproofing. Please refer to the Repair  section below for more details.

Efficient UV-Resistant Flat Roof Repair

Preparation methods for flat roof repair may require leveling the surface with self-leveling materials and heavy sheets, depending on the roof type. After the sheets are installed, joints between them must be detailed. The repair continues with the application of several layers of materials. To complete the process, any roof surface is finished with a UV-resistant protective layer.

Flat Roof Repair Methods

Fixing a flat roof may require crack repair and patching ahead of roof membrane application. Each flat roof membrane installation and design are specified by an engineering consultant.

Crack Repair

To repair a crack on any concrete surface, a clearly defined procedure is followed. Cracks are prepped and then treated with specialized, industrial-strength adhesive, after which they are filled with polymer cement and a waterproofing primer.


Under traditional repair methods, patching concrete requires a minimum of two-inch demolition in the affected area. The use of specialized, industrial-strength materials permits thin-patch applications on any surface – including floor/wall corners and stairs, making the job much more cost-effective and faster.

Fixing Debonded EPDM Membrane

After power washing the surface and fixing valleys with a self-leveling material, a fire-rated protector board is installed. Heavy sheets are then placed to flatten the roof, and the joints between them are detailed. Finally, a five-layer coating is applied: specialized PU-100  primer, PU-500 liquid waterproof membrane, fleece material, another layer of PU-500, followed by UV-resistant coating.

Repairing Delaminated Corners and Edges

Flat roof leaking around the delaminated edges is corrected by using Butyl tape, and detailing them with PU-500 liquid waterproof membrane.

Our Portfolio

For examples of work done on flat roofs, please refer to our flat roof portfolio.

Featured Projects

Ukrainian Orthodox Church of St. Demetrius

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Roof Patio & Unit Waterproofing

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Roof Waterproofing

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North Side Roof

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About Us

Joint Seal Waterproofing, Inc.

Our Contacts

22 Jutland Rd, Unit C
Toronto, Ontario, M8Z 2G9

Phone: (647) 479-4069
US/Canada Toll Free: 1-855-561-4416