Home additions in Toronto
Plan a second storey, rear or side addition around your existing home.
Review the house, lot and space you need before developing the design. Grand Design Build coordinates the design, permits and construction around the agreed project scope.
Make room for the way you live with a second storey, rear or side addition.
Grand Design Build coordinates the design, permits and construction of home additions and house extensions in Toronto. Whether you need another floor, a larger main floor or a renovation with an addition, we review your house and lot before developing the plan.
A house extension or custom home addition should work with the rooms you already have. We consider the connection between old and new, the structure, stairs, daylight and outdoor space, so the extra floor area has a clear purpose.
The work we plan
The right addition depends on your lot, your house and how you want to live, so we check zoning before we draw.
Add bedrooms, bathrooms or family space above your existing home. A second floor addition needs careful planning for the existing structure, foundations, stairs and roof. We assess those constraints alongside the layout you want.
A rear home extension adds space at the back of the house for a larger kitchen, dining room or living area. The plan considers the connection to existing rooms, the yard, daylight and the structure between the original house and the addition.
Use suitable space beside the house for a wider layout, entrance or additional room. We review setbacks and lot coverage, including the space between the addition and property boundaries, before developing the design.
Explore whether roof space can become a bedroom, bathroom or study. Structure, stairs, headroom, insulation and possible dormers need to be considered together, along with any proposed changes to the roof.
Plan a better layout and more space as one project. The addition and existing rooms should work together, whether the scope includes a larger main floor or a full house renovation. If you are weighing both routes, compare a home addition with a new custom home.
Coordinate drawings, City of Toronto permits, any Committee of Adjustment application and construction around the agreed scope. Your proposal identifies inclusions, responsibilities and how permit fees, Committee fees and survey costs are handled.
Start with the house, lot, access and the rooms you need. Review the usable floor area, height and outdoor space together.
Consider how the existing foundations and structure relate to the proposed work.
Agree the layout and key selections so the construction scope can be reviewed clearly.
Keep questions, decisions and updates organised through the project coordinator.
Every home addition follows the same six steps, from the first visit to handover.
Talk through your project
Tell us what no longer works in your home and what you want the addition to change. Start with a call or a visit to our design centre.
Review the existing structure, setbacks, height, lot coverage, floor space index and angular plane. These affect how much can be built and where. Establish whether the design fits the zoning rules as written or needs a minor variance application.
Work through the layout, structural approach and key finishes. Review the proposed scope, exclusions and responsibilities.
Coordinate the City of Toronto permit drawings and application work within the agreed scope. If a minor variance is needed, plan the Committee of Adjustment application and allow for review comments, decisions and any further requirements.
Coordinate trades and the construction sequence. Keep changes and decisions documented, with updates through the project coordinator.
Review the completed work, record any outstanding items and agree how they will be addressed. Confirm the applicable closeout and warranty documents.
Modern home with white walls, black windows and a front lawn.
Open hallway with wood floors and a staircase.
Loft living space with sloped ceilings and skylights.
A home addition is planned as part of the whole house, with exterior materials, window positions and roof connections considered together.
New space needs to connect to existing rooms, with circulation, daylight and floor levels reviewed as part of the design.
An attic or upper-floor conversion needs an assessment of structure, headroom, access and services before the scope is agreed.
The build is the part people picture, but design and permitting come first. Your coordinator sets the schedule in the contract before you sign.
Before construction
Review the approval route and application responsibilities before construction. Your proposal identifies how City fees, Committee fees and survey costs are handled. Read our Toronto home addition planning guide for the decisions to work through before building.
Review setbacks, height, lot coverage and parking requirements. Floor space index, or FSI, relates floor area to lot area. An angular plane sets an angled limit on building height and shape where it applies.
Establish whether the proposal fits the zoning rules as written or needs a minor variance application to the Committee of Adjustment. Application requirements and decisions must be confirmed for the property.
Plan the layout and structural design together, including the connection between the original house and addition.
Coordinate the submission, respond to examiner comments and allow for revisions during review. Confirm how permit fees, Committee fees and survey costs are handled in the proposal.
Check the property for heritage conditions, protected trees and any Toronto and Region Conservation Authority, or TRCA, requirements. Establish the reviews needed before finalising the work.
Plan the required construction inspections and track outstanding items through closeout.
Review how the existing foundations and structure relate to the proposed addition, alongside the house, lot, access and usable floor area.
Review the schedule in your contract before signing, including design, approvals and construction. Allow for the proposed scope, site conditions, any Committee of Adjustment process and the likely disruption.
Grand Design Build did a rear addition, second storey, and all our bathrooms on a house in the Beaches. March to September 2025. We were told end of September and moved back in the second week, so a bit ahead of schedule. Fixed price contract, and the final cost was exactly the contract number. That mattered a lot to us. We decided to change few items for bathrooms and kitchen halfway and there were no issues with the change orders, and the pricing was really fair even though a fixed contract was signed. There were no pushback. The office project coordinators and the site supervisor were really helpful the entire way through. They also kept the site tidy for six months straight and our neighbours never once complained. Respectful crew. Recommend them.
Adam Tremblay
Rear addition and second storey, the Beaches
2 months ago
I had a really good experience working with Grand Design Build on my home renovation and rear addition project. Their team was professional, knowledgeable, and easy to work with throughout the process. They took the time to understand our needs, offered helpful suggestions along the way, and also provided complimentary interior design support, which was a great added value. They were responsive and attentive to questions as they came up, and the project stayed on track from start to finish. I would recommend Grand Design Build to anyone looking for a reliable custom build and design company in Toronto.
Hasan Gumus
Home renovation and rear addition
4 months ago
Planning resources
Explore our existing neighbourhood pages for relevant service information. Your property’s conditions and the proposed scope determine the next planning steps.
Can't find your neighbourhood?
We build across Toronto and the GTA. These are the ones we work in most, not the only ones we work in.
Bring your questions to the consultation. We will walk through the details with you.
Yes. A home addition requires a City of Toronto building permit. The proposed design and property conditions determine whether other approvals are needed. We review zoning, any Committee of Adjustment application, other property requirements and the application responsibilities as part of planning your addition.
Cost depends on the type of addition, its size, the existing structure and foundations, the approvals your lot needs and the finishes you choose. A second storey addition and a rear extension are priced differently, and design, engineering, permit fees and surveys sit on top of construction. We review your house and lot first, then price the agreed scope. Our home addition and house extension cost guide explains each factor.
The schedule depends on design, approvals, site conditions and scope. A second storey addition and a rear extension involve different work. Review the proposed schedule before signing, including any Committee of Adjustment process and the likely disruption.
A second storey can add space while retaining more of the yard. A rear addition may suit a larger main floor. The better option depends on your structure, lot, layout and priorities, rather than one approach being better for every bungalow.
It depends on the work and whether safe living areas and essential services can be maintained. Structural work, roof removal or changes to services may require temporary relocation. Plan living arrangements around the assessed construction sequence.
Homeowners often use the terms interchangeably. A rear or side house extension builds outward. A second storey addition builds upward. Both add floor area to an existing home.
We coordinate design, permit work and construction around the agreed project scope, with a project coordinator keeping communication organised. The aim is a practical addition that works with the house you already have.
Start here
Tell us where you need more room and how you want to use it. We can discuss the next step towards reviewing your property and planning the addition.
Contact us (416) 920-6066
