Home Additions
More Space.
Same Home. Done Right.
Main floor extensions, second-storey additions, sunrooms, mudrooms, designed and built by one accountable team. Cobourg, Port Hope, and Northumberland County.
25+
Years Experience
120+
Additions Built
1team
Start to Finish
4.8★
Google Rating
What We Build
An addition that matches your home, structurally and visually.
The biggest mistake homeowners make with additions is hiring a contractor who treats it like a standalone build. An addition has to tie into your existing structure, match your roofline, integrate your mechanical systems, and feel like it was always part of the house. We’ve been doing this for 25 years. We know exactly how to make a new addition disappear into an existing home.
The Process
How your addition gets built
01
Site Assessment
We assess your property, existing structure, and setback requirements before anything else. No surprises down the road.
02
Design & Permits
We draw the plans, handle permit applications, and navigate any zoning requirements. You don’t chase paper.
03
Build
Our crew works start to finish with minimal disruption to your home. Structural tie-in is done right the first time.
04
Final Inspection
We handle the municipal inspection and walk through every detail with you before closing the project.
Est. 1999
Family-Owned
Why Cobourg Construction
Additions that look like they were always there.
We’ve built over 120 additions across Northumberland County. The ones we’re most proud of are the ones where you can’t tell where the original home ends and the new addition begins.
That level of integration takes experience. It takes understanding rooflines, load paths, thermal bridging, and how finishes age. It’s not something you improvise on, and it’s exactly what 25 years of building in this region gives you.
Frequently Asked Questions
How much does a home addition cost in Cobourg?
Additions start at $280 per square foot. A 400 square foot main floor extension therefore starts around $112,000. Second storey additions cost more because of the structural work and the roof tie-in.
Can I stay in the house while an addition is built?
Usually yes. Most additions are built onto the outside of the house and only break through at the end, so the disruption is concentrated into a short window rather than spread across the whole job.
Is it cheaper to add on or to move?
Adding on is normally cheaper once land transfer tax, agent commission, legal fees and moving costs are counted. It also keeps you in the neighbourhood you already chose. The exception is when the existing house needs major work anyway.
Do additions need a building permit in Northumberland County?
Yes. Every addition requires a building permit, and anything structural needs engineered drawings. Cobourg Construction handles the application and the inspections as part of the job.
Ready to add on?
Tell us about your home and what you need. We’ll give you an honest scope, real numbers, and a clear path forward.