About Cornerstone Waterproofing

You'll work directly with owner Saverio LoMonaco from the first inspection through the final walkthrough. Our crews are Cornerstone employees—no subcontractors or salespeople in between. Saverio personally oversees every waterproofing system, foundation repair, and underpinning project we complete.

We've waterproofed more than 2,500+ Toronto basements since 2004. Saverio brings decades of hands-on waterproofing and foundation expertise and personally oversees every project from start to finish. Every installer is WSIB compliant, trained in-house, and specializes in Toronto's older foundations and challenging clay soil conditions.

Most projects include our 20 year warranty covering labour and materials in the areas we treat. Unlike vague "lifetime" warranties, ours is clear, provided in writing, and signed by Saverio. We outline coverage and maintenance responsibilities up front and invite you to call for full details. When a service has different terms, we explain them before work begins.

Yes. We secure any required City of Toronto permits for foundation work, underpinning, and basement entrances. We keep you updated at every milestone so you always know what's happening on site.

We believe in honest, upfront pricing. After your free site assessment, we provide a detailed written estimate that breaks down exactly what waterproofing work will be done and what it will cost. No pressure, no bait-and-switch tactics. Many clients tell us they chose us because we were the only contractor who explained waterproofing costs clearly before asking them to sign anything.

Both. We assess your specific basement water problem and recommend the right solution—whether that's interior drainage with a sump pump system, exterior excavation and membrane installation, or a combination approach. Some basements only need interior waterproofing. Others require exterior work. We explain the pros and cons of each for your specific situation.

Yes. We work directly with property managers, building owners, condo boards, and commercial contractors on waterproofing, foundation repair, and concrete projects for multi-unit buildings, retail spaces, parkades, and commercial properties. We provide detailed quotes, coordinate with building schedules, handle all permits and inspections, and maintain thorough documentation. Our owner-led approach ensures clear communication and accountability—whether it's a single-family home or a commercial building.

Most contractors offer vague "lifetime" warranties without explaining what's covered or what voids it. Our 20 year warranty is: • Clear – We explain exactly what's covered in the areas we treated • Documented – We provide written coverage summaries so you can call for full details and understand what is protected • Honest – We proactively explain what voids it (like subsequent construction or landscaping that damages the work)

Call or text us at 416-879-4593 or use the contact form on this site. Saverio will schedule a convenient time to visit your property, assess your basement waterproofing needs or foundation issues, and provide a written estimate with no obligation. We serve all of Toronto and the GTA and prioritize fast scheduling.