Home Additions Toronto | Second Storey, Rear Extensions & More
Expand Your Living Space Without Leaving the Home You Love.
HCRA Licensed & Insured
Home Additions Services in Toronto & GTA
Is your family growing, or do you need more space? If you’re outgrowing your home and find yourself wishing for a bigger living space, a home addition may be your answer.
A home addition increases the total square footage of your home to provide additional living space. Whether you need a larger kitchen, family room, or a new private master suite, our award-winning team at Grand Design Build is here to help.
As your professional home addition and extension service provider in Toronto and the GTA, you can trust us to help you find the right design and plan to complement your existing space and changing needs. Together, we will create a space that feels right for you and your family.
Our Service Includes:
- Indoor-outdoor living spaces
- Operative rooftop terraces
- All-weather decks for dining and entertaining
- Additional bedrooms
- Expanding or adding ensuites Kitchen and dining area
Types of Home Additions We Build in Toronto And The GTA
Not all additions are the same. The right approach depends on your lot size, your existing structure, your neighbourhood’s zoning rules, and what you’re actually trying to solve for. A family that needs two more bedrooms has different options than a homeowner who wants a larger kitchen and a proper dining room. We’ve built all of it. Here’s what we offer.
Second Storey Addition
The most impactful way to double your living space. A full second storey addition adds bedrooms, bathrooms, and flex space above your existing footprint, without touching your lot. Ideal for growing families in established Toronto neighborhoods where lots are too valuable to build out on.
Rear Addition
Extend your main floor into the backyard. Rear additions are one of the most common ways Toronto homeowners expand their kitchen, dining area, or family room. They integrate seamlessly with your existing layout and are often the most cost-effective way to add significant square footage.
Side Addition
When lot width allows, a side addition expands your home laterally. Often used to widen a narrow main floor, add a mudroom, or create a more generous entryway. Works particularly well in semi-detached homes where one side is exposed.
Dormer Addition
A targeted way to add usable headroom and light to an existing upper floor without a full second storey build. Cost-effective, minimally invasive, and effective in attic conversions or semi-finished upper levels.
Garage Addition
Expand or add garage space on your property. Whether you need a second bay, a heated workshop, or a structure that doubles as a studio or guest suite above, we design garage additions that serve multiple purposes.
Basement Extension & Underpinning
Lowering and reinforcing an existing foundation to create a full-height, functional basement. We manage excavation, structural engineering, waterproofing, and interior finishing, everything from underpinning to the finished ceiling.
Why Homeowners in Toronto Choose Grand Design Build
Fixed-price contracts. We don’t bill by the hour or re-price mid-project. Before a single wall goes up, you have a detailed, fixed-price contract that accounts for the full scope of work.
HCRA licensed. Grand Design Build is licensed by the Home Construction Regulatory Authority of Ontario, a legal requirement for builders doing this type of work, and a baseline you should insist on before signing with anyone.
7-year structural guarantee. Every home addition we build is backed by a 7-year structural guarantee. Most contractors don’t offer this. We do, because we build to stand behind.
In-house design and permits. We handle architectural drawings, permit applications, and zoning compliance in-house. No coordinating between a designer, a permit consultant, and a builder.
Dedicated project coordination. Every project has a dedicated coordinator who manages the schedule, the trades, and the communication. You always know what’s happening and what’s next.
Operating since 2010. Over a decade of additions, extensions, and structural builds across Toronto, North York, Forest Hill, Rosedale, Etobicoke, Oakville, and Mississauga.
How a Home Addition Starts At Grand Design Build
Consultation
We start with a site visit and a conversation about your goals, your timeline, and your budget. No pressure, no sales pitch, just an honest assessment of what's possible.
Design
Our in-house design team develops drawings tailored to your lot, your existing structure, and your municipality's zoning requirements. We work through options with you before anything goes to the city.
Permits
We submit and manage all permit applications. Toronto's permitting process has specific timelines and requirements, we've done this hundreds of times and know how to move it forward efficiently.
Fixed-Price Contract
Before construction begins, you receive a fully detailed, fixed-price contract. No surprises. No change orders unless you change the scope.
Construction
Our team manages every trade on site. You have a dedicated project coordinator keeping the schedule on track and communicating progress throughout.
Handover
We do a full walkthrough before handover. Every item on the deficiency list is addressed before we consider the project complete.
Our Exterior and Home Addition Projects
READY TO DISCUSS YOUR PROJECT?
WE OFFER HOME BUILDING SERVICES IN TORONTO
Your home is one of the biggest investments you’ll ever make. Whether you’re building a custom home, adding space with an addition, transforming your space through a renovation, or maximizing your property with a laneway suite, you deserve a builder you can trust to get it right.
At Grand Design Build, we’ve spent over 15 years earning that trust. Through meticulous planning, honest pricing, and efficient construction, we deliver exceptional results without the stress, surprises, or budget creep that too often come with the territory. Every project, no matter the size, is backed by our guarantee, because we don’t just build homes. We stand behind them.
Frequently Asked Questions
What Does a Home Addition Cost in Toronto?
For a fully finished, permitted one-storey addition, budget $300–$500 per sq ft. A 400 sq ft rear extension typically lands between $120,000 and $200,000 depending on site conditions and finishes. Second storey additions generally start at $350–$450 per sq ft given the additional structural work involved. Professional fees, architecture, engineering, permits, add roughly 10–15% on top. For a full breakdown, read our Home Addition Cost Guide.
Do I need a permit for a home addition in Toronto?
Yes. All home additions in Toronto require a building permit. This includes second storey additions, rear extensions, side additions, and basement underpinning. Grand Design Build manages the full permit process, including drawings, application submission, and inspections.
How long does a home addition take?
Most home additions take between 6 and 12 months from signed contract to handover. The timeline depends on the scope of work and the permit review period. Second storey additions typically take longer than rear additions. We provide a detailed construction schedule before work begins.
Can I stay in my home during the addition?
In most cases, yes, though there will be periods of disruption, particularly when structural work is underway or when the roof is open during a second storey build. We plan phasing to minimize disruption and give you advance notice of the most intensive periods.
What is the difference between a home addition and a home extension?
The terms are used interchangeably. Both refer to adding new square footage to an existing home by building outward (rear or side extension) or upward (second storey addition).
Does Grand Design Build handle zoning and setback requirements?
Yes. Our in-house design team reviews zoning bylaws, lot coverage limits, and setback requirements before we finalize any design. We flag potential issues early so they don’t become problems during permitting.
What makes Grand Design Build different from other home addition contractors in Toronto?
Three things:
- We’re HCRA licensed (required for this type of structural work in Ontario)
- We offer fixed-price contracts (your quote is your price)
- We back every addition with a 7-year structural guarantee.
Most contractors offer none of these. We offer all three.