Renovation Contractor in Oshawa & Durham Region
Renovation Contractor in Oshawa & Durham Region
From kitchens to basements, Cornerstone Construction delivers fixed-price renovations for homeowners across Oshawa, Whitby, Bowmanville, Ajax, Pickering, and Durham Region. Insured, WSIB covered, and backed by our 8-point Certainty Stack.
Every service comes with daily cleanup, our Price Lock Guarantee, and a 5-year workmanship warranty.
For homeowners who want a better kitchen without managing five different trades.
Custom and pre-built cabinetry, countertops, flooring, pot lights, plumbing, and electrical. We build kitchens that work as hard as you do. Starting from $25,000.
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For homeowners who want a bathroom that actually works, not just looks good in photos.
Full gut and rebuild, ensuite upgrades, powder rooms, heated floors, glass showers, and custom tile work. Starting from $15,000.
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For homeowners who want real living space out of the square footage they're already paying for.
Family rooms, home offices, legal apartments, and guest suites. We finish basements that add real living space and real value. Starting from $40,000.
Turning it into a legal apartment? Read Is My Basement Legal? first.
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For homeowners with a project that doesn't fit a neat category and needs one contractor running the whole thing.
Have a project that doesn't fit one category? From one-week flooring and wall-removal jobs to multi-month builds, we manage the full scope from design to handover. One point of contact. One contract.
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For homeowners tackling multiple rooms at once who don't want to juggle separate contracts and separate trades.
Multi-room and full-home renovations done as one coordinated project — kitchen, baths, flooring, and finishes rebuilt to a single standard. One team, one contract, one timeline.
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For homeowners who need more square footage instead of more renovation inside the same walls.
Square-footage additions, second storeys, garages, and in-law suites. We extend your home with attention to structure, code, and the look of the original build.
Learn MoreWhy Cornerstone
We built this company on one belief — homeowners deserve a contractor they can actually trust.
Every residential renovation is backed by the Cornerstone Certainty Stack — eight written guarantees, not sales talk.
Mike Brock runs your project himself. You know who is in charge and how to reach him.
Once we sign, your price is locked. Changes to the scope are priced and approved by you in writing before the work happens.
Every renovation is covered by our 5-year workmanship warranty. On renovation projects, you also get a full Owner's Manual at handover.
What Our Clients Say
Experience the Cornerstone difference through the words of homeowners we have served across Durham Region.
"Mike was the most professional and punctual contractor I have ever worked with. He understood how to bring my 10-year vision into reality. If it is not straight then it is not correct. He will make sure that it is. He will now be the only contractor to touch any part of my house."
Recent Projects
Real Cornerstone projects from start to finish — full scope, materials, and the problems we solved along the way.
Main Floor Renovation in Bowmanville
View project → OshawaCustom Kitchen Renovation in Raglan, Oshawa
View project → BowmanvilleWhole Home Renovation in Bowmanville
View project → ClaringtonMain Floor Renovation in Clarington
View project → OshawaMain Floor Condo Renovation in Oshawa
View project → WhitbyGourmet Chef's Kitchen in Whitby
View project → CourticeWhole Home Renovation in Courtice
View project →The Cornerstone Way
Three promises. One team. One contract.
Before we touch a single wall we sit down with you. We learn how you use the space, what matters most, and what your budget can do. Then we build a plan around that.
The trades on your job are vetted and held to our standards. Level 4 drywall, daily cleanup, and HEPA air scrubbers on heavy dust days. We build like it is our own home.
Your price is locked and your schedule is in writing. When we hand the keys back you get a 5-year workmanship warranty and, on renovation projects, a full Owner's Manual. That is the Cornerstone standard.
Common Questions
We serve Oshawa, Whitby, Ajax, Pickering, Bowmanville, Clarington, Newcastle, Port Perry, Scarborough, Whitchurch-Stouffville, Port Hope, Cobourg, and Peterborough.
It depends on the scope. Kitchens start at $25,000, bathrooms at $15,000, and basements at $40,000. You get a written price before any work begins, and it is locked once you sign — not an estimate that changes once we start.
Most kitchens take 3 to 8 weeks depending on the scope of work. We give you a written timeline before we start. On projects of $15,000+ that run about a month or longer, our $300/Day On-Time Guarantee credits you $300 for each day we miss the completion date for reasons within our control.
Both. We work with custom and pre-built cabinetry depending on your budget and goals. We walk you through the options at your consultation.
Yes. Every renovation is backed by a 5-year workmanship warranty. On renovation projects, you also get a full Owner's Manual at handover.
Click Start Your Project Diagnostic, fill out the short form, and we aim to get back to you within 24 hours.
When your project requires a permit we handle the entire process and tell you upfront what is needed and why.
From Durham Region to the GTA, Mike Brock and our team deliver excellence. Book your free project diagnostic and get a fixed price before we start.
Durham Region's trusted renovation contractor. Led by Mike Brock since 2017. We Listen, We Build, We Deliver.
