House Extensions in Ontario
More Space, More Comfort, More Value
Why Extend Your Home?
Sometimes moving isn’t the right answer when you need more space. Whether your family is growing, you need a home office, or you simply want a larger living area, a house extension is the perfect solution. Instead of starting fresh in a new neighborhood, you can expand your current home while staying in the community you love.
At GWC General Contractors, we specialize in designing and building house extensions across Ontario that meet both your lifestyle needs and the Ontario Building Code. From side and rear extensions to second-storey additions and garage conversions, we create functional, stylish spaces that feel like a natural part of your home. Our team takes care of everything—permits, planning, inspections, and construction—so you can enjoy a smooth, stress-free process.
- Stay in the neighborhood you love without moving
- Add valuable living space for your family
- Increase property value with smart design
- Customize your home for comfort and lifestyle
- Ensure compliance with Ontario regulations
Types of House Extensions We Offer
Rear Extensions
Perfect for expanding kitchens or living rooms.
Side Extensions
Add extra space without compromising your backyard.
Second-Storey Additions
Double your space and add new bedrooms or offices.
Sunrooms & Family Rooms
Create bright, open spaces for everyday living.
Garage Conversions
Transform unused garages into livable areas.
Custom Extensions
Designed around your unique needs and budget.
FAQ
A house extension is the structural expansion of a home to create more living space. Types include:
- Rear extension (e.g. kitchen, family room)
- Side extension (e.g. garage or mudroom)
- Second-storey addition (on a bungalow or garage)
- Bump-outs (small additions with minimal foundation work)
- Sunrooms or enclosed porches
Yes. Any structural addition to your home requires a building permit.
You may also need:
- Zoning approval or variance
- Grading & drainage plan
- Conservation authority clearance (if near protected land or floodplain)
Your extension must comply with:
Zoning Element | Description |
Lot coverage | Max % of land occupied by buildings (e.g., 40%) |
Setbacks | Distance from property lines (e.g., 1.2m side) |
Height restrictions | Especially for second-storey additions |
Floor space index (FSI) | Max allowable living area per lot |
🔍 Tip: Check your municipality's interactive zoning map (e.g., Brampton, Mississauga, Toronto).
Approximate cost ranges (Ontario, 2025 rates):
Extension Type | Cost per sq ft (CAD) |
Rear or side extension | $200 – $350 |
Second-storey addition | $250 – $500 |
Basic bump-out | $150 – $250 |
Sunroom / 3-season room | $100 – $200 |
Estimated timeline:
- Design + permits: 2–5 months
- Construction: 3–6 months (weather and size dependent)
- Total project time: 5–10 months
Projects during winter may face delays.
In most cases, yes, especially for rear or side additions. However:
- Second-storey additions may require partial vacancy
- Structural wall removal may involve temporary relocation
You’ll likely need:
- Architect or BCIN designer
- Structural engineer
- General contractor
- Licensed trades (plumber, electrician, HVAC)
- Permit consultant (optional but helpful for variances)
Yes, if:
- Your extension encroaches setbacks
- It exceeds lot coverage or height limits
- You’re in a heritage or conservation area
A Committee of Adjustment (COA) hearing is required to approve minor variances.
Yes. You must:
- Strengthen or reinforce existing foundation
- Address roof removal and rebuilding
- Plan for temporary weatherproofing
- Ensure structural load meets Ontario Building Code
Engineering approval is required.
Typical stages:
- Footings / foundation
- Framing
- Rough-in inspections (plumbing, electrical, HVAC)
- Insulation & vapor barrier
- Final occupancy inspection
City inspectors will visit at each phase.
Yes. Once the extension is complete and assessed by MPAC, your property value (and taxes) will likely increase based on added square footage.
Not usually. Most cities require:
- Side yard setback: ~1.2m minimum
- Rear yard: varies (often 7.5m or more)
- Front yard: based on street average
In tight lots, variances may be needed.
Extensions typically don’t qualify, but if your addition includes:
- Energy-efficient upgrades (windows, insulation): check Enbridge or CMHC programs
- In-law suites / secondary units: some cities offer incentives
Our House Extension Process
House Extension Completed
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- Consultation & Design – We listen to your goals and create a tailored design plan.
- Permits & Approvals – All applications and city approvals handled by our team.
- Construction & Inspections – Skilled craftsmanship and regular inspections ensure quality.
- Final Handover – We walk you through the finished extension, ready to enjoy.