Oshawa & Durham Region Renovation Experts — Serving the GTA
CornerstoneConstruction
We Listen, We Build, We Deliver
Professional residential and commercial renovations led by Mike Brock. Serving Oshawa, Whitby, Bowmanville, Ajax, Pickering, and Durham Region since 2017.
Every Project. Every Time.
The Cornerstone Certainty Stack
Eight guarantees that protect you from start to finish. No exceptions.
Price Lock Guarantee
Your price is locked before we start. No surprise bills. Ever.
$300/Day On-Time Penalty
If we miss your completion date we pay you $300 for every day we run late.
HEPA Air Filtration
Your home stays clean and dust-free throughout the entire build.
Daily Cleanup
We clean up every single day before we leave. Your home stays livable throughout the entire project.
Real-Time Client Portal
Track your project, approvals, and documents anytime through your JobTread portal. Full transparency from day one.
5-Year Warranty
Every job is backed by a full 5-year workmanship warranty. We stand behind our work long after we're gone.
Owner's Manual
You get a complete Owner's Manual at handover with care and maintenance guides, plus full warranty details.
Fully Licensed & Insured
Ontario licensed and insured corporation. WSIB compliant. Ask for proof anytime.
Home Renovations
Kitchens, bathrooms, basements, and full home renovations across Durham Region. One team, one contract, white glove service on every build.
- Kitchen renovations — $25,000 to $150,000+
- Bathroom remodels — $15,000 to $80,000+
- Basement finishing — legal suites, in-law suites, recreational
- Full home interior renovations
Commercial Fit-Ups
Office, retail, and restaurant fit-ups built to commercial standards. We manage permits, trades, and project timelines from day one.
- Office fit-ups and open concept layouts
- Retail store and showroom builds
- Restaurant and cafe construction
- Commercial permit management
Full Scope Contracting
Multi-room, multi-trade, or complex structural work managed under one contract. One point of contact for everything under your roof.
- Wall removal and structural beam installation
- Multi-room renovations under one contract
- Permit management from application to sign-off
- Full trade coordination — framer to painter
Insurance Restoration
Full project management for insurance claims — water damage, fire damage, and mould remediation. We work with your adjuster from demo to rebuild.
- Emergency flood and water damage repair
- Fire and smoke damage rebuild
- Mould remediation and structural drying
- Full insurance adjuster coordination
Get Started
Find Your Project Fit
Ready to build? Book your free project diagnostic and we will assess your space, scope the work, and give you a fixed price before we start. No guessing. No ballpark numbers.
The Cornerstone Blueprint
We Listen, We Build, We Deliver
Our systematic five-step methodology ensures every renovation project in the Durham Region meets Mike Brock's high standards of excellence.
Phase 01
The Consultation
We listen to your vision and assess your space to understand exactly what you need for your renovation.
Phase 02
Strategic Planning
Mike Brock and our team develop a detailed project roadmap, timeline, and transparent budget for your approval.
Phase 03
Material Selection & Preparation
We help you choose the right materials for your budget and style. Everything is ordered and staged before we start.
Phase 04
The Build Phase
Our skilled tradesmen execute the construction with precision, keeping you updated every step of the way.
Phase 05
Final Delivery
We perform a rigorous quality walkthrough to ensure every detail is perfect before you enjoy your new space.
Renovation Investment Calculator
Select your project type and customize the details to see a rough estimate of your investment.
Google Reviews & Testimonials
Real Stories from Durham Region
See how Mike Brock and the Cornerstone team are building excellence across Oshawa, Whitby, Bowmanville, and the GTA.
"From the 3 options I sourced, Mike was the most professional and punctual. We had a 5pm appointment and true to his word, my bell chimed exactly at 5pm. Throughout the entire process, Mike arrived on time every day, provided daily walkthroughs and next steps, and cleaned up every time. He will now be the only contractor to touch ANY part of my house. Professional: 10/10. Punctual: 10/10. Polite: 10/10. Knowledgeable: 10/10."
"We had a great experience working with this general contractor from start to finish. Communication was clear, timelines were respected, and the quality of work exceeded our expectations. Every detail was handled professionally, and any questions we had were addressed quickly. It's rare to find someone this reliable and skilled — highly recommend."
"Mike completed a large renovation for us in Durham Region. The project was well done, the attention to detail really makes it appear well done. Mike spends all of his time working on your project which makes it extremely easy to meet and review the project as it evolves. Overall a good experience."
"I am so impressed with the quality of work and professionalism of this company. Right from the beginning Mike was very responsive — coming to my home to really understand what needed to be done to give me the results I wanted within my budget. I highly recommend this company for any project."
"Dreams do come true. Mike and his team successfully transformed the kitchen into a stunning space. Their expertise and professionalism are reflected in the quality of their work."
Project Performance Metrics
Building Trust Since 2017
Cornerstone Construction delivers high-end results across Durham Region and the GTA. We listen, we build, and we deliver excellence on every project.
Recent Successes
VIEW FULL PORTFOLIO| Rank | Project Type | Rating | Status |
|---|---|---|---|
| 1 | Whitby Full Main Floor Renovation (Kitchen, Bathroom, Hallway) | 5.0 ★ | Completed |
| 2 | Bowmanville Full Main Floor Renovation (Kitchen, Bathroom, Hallway, Living Room, Dining Room) | 5.0 ★ | Completed |
| 3 | Bowmanville Full House Renovation (Kitchen, 2 Bathrooms, Hallway, Living Room, Dining Room, Basement, Staircase) | 5.0 ★ | Completed |
| 4 | Pickering Kitchen Renovation | 5.0 ★ | Completed |
| 5 | Oshawa Kitchen Renovation | 5.0 ★ | Completed |
Where We Work
Where We Build
Cornerstone Construction has been Durham Region's trusted renovation partner since 2017. We bring professional craftsmanship to every neighbourhood we serve.
Service Areas
Oshawa, Whitby, Bowmanville, Ajax, Pickering, Newcastle, Clarington, Scarborough, Stouffville, and Peterborough
Direct Line
Business Hours
Monday – Friday: 8:00 AM – 6:00 PM
Common Questions
What Homeowners Ask Us
We listen, we build, and we deliver. Here is what you need to know before we start.
Most kitchen renovations take 3 to 6 weeks depending on the size and scope. We give you a detailed timeline before we start and stick to it. Our $300/day on-time penalty means we are accountable if we run late.
Yes. We identify what permits your project needs and handle the process for you. Permit fees are separate from your renovation cost and vary by municipality. We never skip permits — it protects you when you sell.
Yes. Cornerstone Construction Inc. is a fully licensed and insured Ontario corporation. We carry liability insurance and WSIB coverage on every job. Ask us for proof anytime.
In most cases yes. We use HEPA air filtration, daily cleanup, and full plastic sheeting to protect the rest of your home. For major gut renovations we will discuss what makes sense for your situation during the consultation.
Have a specific project in mind?
Mike Brock and the team are ready to help with your next renovation. Book your free project diagnostic or call us directly.
"I started Cornerstone because homeowners deserve a contractor they can actually trust."
Get Started
Ready to Build Your Vision?
Book your free Project Diagnostic. We assess your space, scope the work, and give you a fixed price before we start. No guessing. No ballpark numbers.
- Free walkthrough — no obligation
- Response within 24 hours
- Fully licensed and insured Ontario corporation
Licensed & Insured Ontario Corporation · Serving Durham Region Since 2017 · 5-Year Warranty on Every Job
