Home Addition Permit Design
Permit drawings for rear, side and second-storey home additions in Ontario. We check zoning and existing conditions early so the proposed addition is developed around a realistic permit path.
What an addition permit package can include
Depending on the project and agreed scope, 828 Design can prepare:
- existing and proposed floor plans
- site plan and zoning statistics based on available survey/property information
- exterior elevations and building sections
- foundation, floor, wall and roof construction details
- building-structural design within applicable BCIN scope and coordination of independent professional input where required
- coordinated HVAC/mechanical, plumbing and energy-efficiency information where applicable
- permit submission support and response to municipal comments where included
What should be checked before the addition is fully designed?
The shape of the addition is only one part of feasibility. We look at the items most likely to affect what can actually be approved and built.
- setbacks, height, lot coverage, gross floor area and other applicable zoning controls
- survey/property information, easements and available building location
- existing foundation, framing and roof conditions relevant to the proposed connection
- grading, drainage, trees and other applicable-law issues where they affect the project
- stairs, exits, windows, fire/life-safety and energy-efficiency requirements
- whether structural, HVAC/mechanical, plumbing or other regulated input is required
Rear and side additions
Rear and side additions can affect setbacks, lot coverage, grading, windows, foundation design and the way new structure connects to the existing house. A zoning review before finalizing room sizes can prevent a layout from being developed beyond what the property allows.
Second-storey additions
A second-storey addition adds a different level of existing-condition review. The design may need to consider the capacity and layout of existing walls, beams, foundations and roof framing, as well as stairs and overall building height. Where professional engineering is required, that responsibility must be taken by the appropriate licensed professional.
Common home-addition permit questions
Do I need a permit for a rear or second-storey addition?
Yes. An addition increases or materially alters the building and requires a building permit before construction.
How do I know how large the addition can be?
The answer starts with the property-specific zoning bylaw, not a generic percentage. Setbacks, lot coverage, floor area, height and other standards can all affect the permitted envelope.
What drawings are commonly needed?
A typical package can include a site plan, existing/proposed floor plans, elevations, sections, construction details and zoning information, with structural, mechanical, plumbing, grading or other supporting information where applicable.
Do I need a survey?
Current survey/property information is often important for additions because the municipality needs to understand the building location, property lines and setbacks. The exact survey or site-plan requirement depends on the municipality and project.
Can you tell if a second storey is feasible before full drawings?
We can perform an early design and existing-condition review, but concealed conditions may only become known through further investigation or construction. Structural feasibility must be addressed within the appropriate design/professional scope.
Can construction start while the permit is being reviewed?
Work requiring the permit should not begin before the permit is issued. Starting early can create enforcement, redesign and inspection problems.
Once the addition permit is issued
Construction must follow the approved permit documents. If the contractor encounters a material site condition or wants to change the approved design, the change should be reviewed before work proceeds because revised drawings and municipal authorization may be required.
What to send for a quote
- property address and municipality
- survey or site plan, if available
- photos of all sides of the house and the proposed addition area
- existing floor plans or prior permit drawings, if available
- a sketch or description of the rooms and approximate size you want
- any zoning review, variance decision, city comments or known property constraints
Related residential permit services
Custom Home Permit Design · Load-Bearing Wall & Structural Opening · Exterior Alteration · Zoning Review · Minor Variance / Committee of Adjustment
828 Design Inc. — BCIN building design & permit services. Content reviewed for current Ontario permit context: August 2026. Requirements are confirmed for the property, municipality and agreed project scope. Qualifications & responsibility →
Thinking about adding space to your home?
Send the address, survey if you have one, and a short description of the addition. We can start with the zoning and permit-design questions that matter most.