BuildRules/London/Home addition

London project guide

Do you need a permit for a home addition in London, Ontario?

Check London home addition permit requirements and the published residential review timeline.

1 min readReviewed Oct 1, 2026

The short answerConditional

Yes. London lists additions to existing buildings among projects that require a building permit.

The application must satisfy the Ontario Building Code, zoning and any other applicable approvals.

Make this useful for my project

Know what matters

What changes the answer.

Start with these conditions. The official reference is attached to each one.

AdditionPermit requiredConditional

London lists an addition to an existing building among projects that require a permit.

Official sourceCity of LondonBefore you apply for a building permit · Residential permit triggers, exemptions and review timelines

Verified2026-10-01Open proof

ZoningReviewed with the permitInfo

The City states that permit review checks London’s Zoning By-Law and other applicable approvals.

Official sourceCity of LondonBefore you apply for a building permit · Residential permit triggers, exemptions and review timelines

Verified2026-10-01Open proof

Property-specific approvalsMay also applyInfo

The permit process checks other approvals needed for the specific property and project.

Official sourceCity of LondonBefore you apply for a building permit · Residential permit triggers, exemptions and review timelines

Verified2026-10-01Open proof

Your preparation checklist

Your preparation progress

0 of 5 ready

Your progress is saved in this browser. Come back whenever you’re ready.

Building permit application
Site plan
Floor plans
Elevations and sections
Structural and energy information

Open the focused permit checklist

Fees and timing

TimelineLondon lists a 10-business-day statutory review timeline for additions to single-detached, semi-detached, cluster and townhouse homes once complete.

FeesConfirm the current London permit fee for the exact project class before filing.

Next steps

Check zoning feasibility
Define the addition footprint
Prepare site and building drawings
Submit the complete permit package

Same project, different city

See how this rule changes across Ontario.

Compare the source-reviewed answer for this project across every municipality BuildRules currently covers.

Compare home addition rules by city

Better decisions, together

Get everyone on the same page.

Send this to your designer or contractor before agreeing on the scope.

Paid research brief

Get a clearer plan before you spend.

Turn the published rules, documents, timing and questions to verify into one project-specific preparation brief.

39 CADone-time

See what’s included

Research guidance only. Municipal approval and professional design are separate.

A little help with the next step

Move your home addition forward.

Tell us what kind of help you need. We’ll save the request with your project and municipality so a relevant provider can respond if a match is available.

BuildRules principle

Do not confuse “no permit” with “no rules.”

Zoning, overlays, safety rules and other constraints can still apply.

Keep exploring

Your next useful question.

A connected project guide or a practical next step, picked for this topic.

All project guides

Related project

What do you need for an additional residential unit in London, Ontario?

London treats ARUs as a dedicated permit path with zoning review, site planning and construction drawings.

1 min read

Related project

Do you need a permit for a deck in London, Ontario?

London combines height and attachment in its homeowner guidance and also publishes zoning setback information for decks.

1 min read