BuildRules/Hamilton/Additional dwelling unit

Hamilton project guide

What do you need for an additional dwelling unit in Hamilton?

Check Hamilton additional dwelling unit requirements for internal units, building permits, zoning, addressing and inspections.

1 min readReviewed Oct 1, 2026

The short answerConditional

Hamilton has a dedicated ADU team for building permits in existing single-family dwellings, including up to two internal units and one detached unit.

An ADU is a separate self-contained residential unit that can be within, added to, or detached from the principal dwelling. Internal ADU work is explicitly included in Hamilton’s permit-required list.

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What changes the answer.

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

Internal ADUBuilding permit requiredConditional

Hamilton lists adding internal additional dwelling units among permit-required interior work.

Official sourceCity of HamiltonBuilding Permit Application Requirements · Residential permit-required projects and exemptions

Verified2026-10-01Open proof

Dedicated reviewADU permit teamInfo

Hamilton states that a dedicated ADU team reviews and issues permits for existing single-family dwellings including internal units.

Official sourceCity of HamiltonAdditional Dwelling Units · Internal and detached ADU permit program

Verified2026-10-01Open proof

Unit typeCan be internal, added or detachedInfo

The City defines an ADU as a separate self-contained unit located on the property of the principal dwelling.

Official sourceCity of HamiltonAdditional Dwelling Units · Internal and detached ADU permit program

Verified2026-10-01Open proof

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ADU building permit application
Existing and proposed floor plans
Zoning and addressing information
Life-safety and construction details
Plumbing/mechanical information where applicable

Open the focused permit checklist

Fees and timing

TimelineConfirm the current municipal review stream after the application is accepted as complete.

FeesConfirm the current Hamilton fee schedule for the exact permit class.

Next steps

Confirm the intended number and location of units
Check zoning and addressing requirements
Prepare the ADU permit drawings
Submit to the City and complete required inspections

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BuildRules principle

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

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

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