Jarvis / Design & build
Questions homeowners ask before they start
Cost, permits, timing, design and who does what, answered with the source for every number. Questions about one kind of work are on that service's page.
Before you begin
Good questions.
Clear answers.
From the first estimate to the last inspection, here’s what to expect. For the details of your own home, talk with James.
Cost and quotes
How much does a home addition cost in Ontario?
We price GTA home additions at about $350 to $600 per square foot in 2026, and a single-storey rear addition of 300 to 700 sq ft at $180,000 to $450,000, before 13% HST. A second storey of 600 to 1,200 sq ft runs $300,000 to $800,000. Our pricing page lists every range and what moves it.
Is the estimate free?
Yes. The first estimate from Jarvis Contracting is free. Call James on (289) 892-4169 or send the enquiry form on our contact page to arrange it.
Are the prices on your site a quote?
No. They're our 2026 ranges for each kind of work. Jarvis Contracting prices your job after James has seen the house, because the same addition can cost very different amounts depending on the foundation, the structure and the finishes. The first estimate is free.
Do you work fixed price or cost-plus?
Fixed price. Jarvis Contracting prices the whole project in a detailed proposal, and you sign the contract with a 10% deposit, before any design work begins. If a design selection or a finish changes the price, the change goes through a change order you sign. Our guide to fixed price and cost-plus explains how the two compare.
Can a contractor charge more than the estimate in Ontario?
Not by much. Under Ontario's consumer protection rules, the final price of a renovation can't exceed the estimate by more than 10% unless you agree to changes, and any renovation over $50 needs a written contract.
Permits and rules
Do I need a building permit for an addition in Ontario?
Yes. Under section 8 of Ontario's Building Code Act, an addition needs a building permit from your municipality before work starts. If it breaks a zoning limit, such as a setback or height, it also needs a minor variance from the Committee of Adjustment first. We prepare the drawings and make the applications.
How long does the town take to issue a building permit?
The Ontario Building Code gives a municipality 10 business days to decide a complete permit application for a house without one unit above another, and 15 for most other small buildings. The clock starts only when the application is complete, and a minor variance has to be decided before that.
Can I add a basement apartment or a garden suite to my house?
Usually, on a serviced urban lot. Ontario's Planning Act lets you have up to three units without a rezoning: two in the house and one in a garden suite, or three in the house. Your town's zoning sets the size and setbacks, and some towns, such as Whitby, require the unit to be registered.
Which building code applies to my project?
The 2024 Ontario Building Code has been in force since 1 January 2025, and every permit application made from 1 April 2025 must use it. We draw and build to it; the town's examiner and inspector check the work against it.
Timing
How long does a second-storey addition take?
Our West Lynde second storey, a bungalow taken to two storeys with a new kitchen and two bathrooms, took about four and a half months on site in Whitby in 2023. Design and the permit come before that, and a house that needs a minor variance waits for the committee of adjustment too.
How long does a larger renovation take from start to finish?
Greenwood, a rear extension and a new top floor on a Toronto house, took 10 months from the permit and the interior design through construction. Smaller jobs take less; you get a schedule with the contract.
What happens if you find a problem behind a wall?
We stop and tell you what we found and what it costs before we fix it. On one main floor that was asbestos on the pipes and risky wiring from a previous owner, and the job still finished on time. On Bellamy it was asbestos, fire hazards and a point load, and we handed the house back on the promised date.
Design
Do you do the design yourselves?
Yes. Jarvis Contracting's design is run by James's wife through her studio, Juliette Interiors: she measures, draws the floor plans, builds a 3D model and presents your finishes to you in our office. Structural drawings come from a structural engineer, and on larger jobs we work with an architect.
Can I see the design before it's built?
Yes. Once the floor plans are settled, our designer builds a 3D model of the rooms with the textures and finishes in it, so you can see the kitchen or the new floor before anything is ordered.
What is design-build?
Design-build is one firm designing your project and building it, so the plans are drawn by the people who price and build them instead of tendered to builders afterwards. At Jarvis Contracting the designer and the builder are a married couple.
Working with us
Where does Jarvis Contracting work?
Jarvis Contracting is based in Ajax and works across Durham Region, Ontario and the Greater Toronto Area. The Areas page lists each town we serve, with its permit rules and fees.
Who will I deal with during the project?
James Jarvis on the build, from the first site visit to the handover, and our designer at Juliette Interiors on the design. You have one point of contact for the construction.
Do renovators need a licence in Ontario?
No. The Home Construction Regulatory Authority licenses builders of new homes, not renovators: it says renovating an existing home generally doesn't make it new. Licences that do apply on a renovation are the electrical contractor's, through the Electrical Safety Authority, and a gas fitter's TSSA certificate.
Is an addition covered by Tarion?
No. Tarion's warranty covers new homes, and the HCRA says a renovation or addition to an existing home generally doesn't make it a new home. For an addition, your protection is the written contract and the warranty it sets out.
What warranty does Jarvis Contracting give?
Jarvis Contracting gives its own written warranty: one year for defects in workmanship and materials, two years for the plumbing, heating and electrical systems and for water coming in through the building envelope, and seven years for structural defects. It depends on normal homeowner maintenance, excludes misuse, neglect, wear and tear and other people's alterations, and claims must be made in writing within the period. It isn't a Tarion warranty.