Legal Basement Suites & ADU Builders in Hamilton
Build a code-compliant basement apartment, secondary suite, or accessory dwelling unit. Full permit management included.
Check If Your Property Qualifies
Free 48-hour feasibility review for basement suites and ADUs. No obligation.
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📞 343-504-8213An accessory dwelling unit (ADU) is a self-contained residential unit on the same property as your primary home. In Hamilton, that includes legal basement apartments, in-law suites, and detached garden suites. Whatever you call it — ADU, secondary suite, additional dwelling unit — Gateway handles the full process from zoning check through final inspection.
Do You Qualify? 5-Point Check
- Ceiling height: Minimum 6'5" required for basement ADUs (we measure accurately)
- Separate entrance: Options reviewed for your property layout
- Egress window: Code-compliant emergency escape required
- Zoning: Hamilton ADU eligibility verification (we check this free)
- Budget: Investment varies by scope — we provide a fixed-price quote after your free feasibility review
What's Included in Your ADU Build
📋 Permit Management
All City of Hamilton ADU permit submissions handled
🔥 Fire Separation
Code-compliant drywall, doors, alarms
🌡️ HVAC Separation
Independent climate control per unit
🪟 Egress Windows
Legal escape routes with window wells
🚪 Separate Entrance
Dedicated access with proper drainage
🏛️ Zoning & ADU Review
Verify ADU compliance before building
Our 6-Step Process
Free Feasibility Review
We assess your property's ADU potential within 48 hours
Zoning & Code Check
Verify Hamilton ADU bylaws and Ontario Building Code requirements
Design & Layout
Maximize space, light, and rental appeal
Permit Submission
We handle all city paperwork and approvals
Construction
Full build with consistent communication
Final Inspection & Permit
Occupancy permit delivered — legally ready to rent
Accessory Dwelling Units (ADUs) in Hamilton
Hamilton updated its zoning bylaws to allow additional dwelling units on most low-density residential lots within the urban boundary. That means if you own a single-detached, semi-detached, or street townhouse, you can likely add an ADU — either inside your home (like a basement apartment) or as a detached unit in your backyard (a garden suite).
Hamilton's bylaws actually allow two ADUs per property: one inside the primary dwelling and one detached. Most homeowners start with the basement because it's the fastest path to rental income without new construction from the ground up.
Types of ADUs We Build
Basement ADU
Convert your existing basement into a legal, self-contained apartment. The most common and cost-effective ADU in Hamilton.
In-Law Suite
A second unit within your home for family members — with separate entrance, kitchen, and bathroom for privacy.
Garden Suite
A detached unit in your backyard. Hamilton allows up to 75m² gross floor area with specific setback requirements.
Hamilton ADU Grants & Incentives
💰 Hamilton ADU Grant — Up to $40,000 Per Unit
The City of Hamilton's ADU and Multi-Plex Housing Incentive Program — part of the federal Housing Accelerator Fund — provides a direct grant covering 70% of your eligible construction costs, up to $40,000 per unit.
How the grant works: You receive 20% of the grant (up to $8,000) upfront when your building permit is issued. The remaining 80% is paid after your unit passes final inspection.
What it covers: Construction materials and labour, plumbing and electrical for the new unit, and architectural and engineering fees.
Also available: The Ontario Secondary Suite Loan Program provides a separate forgivable loan of up to $50,000 for qualifying ADU projects — meaning you could access up to $90,000 in combined government funding.
Gateway can help you determine eligibility during your feasibility review. These incentives apply to new ADUs, garden suites, and legalizing existing unpermitted units. View the full program details on hamilton.ca →
What Hamilton's ADU Bylaws Require
The rules vary depending on whether your ADU is inside the home or detached, but here are the key requirements we check during feasibility:
- Zoning eligibility: Most R1, R1a, and R5 zones qualify — we verify your specific lot
- Water service: Hamilton now requires a water service assessment before issuing an ADU permit. Upgrades may be needed.
- Parking: No additional parking is required for ADUs under current Hamilton bylaws
- Detached ADU size: Maximum 75m² gross floor area, cannot exceed the primary dwelling's ground floor area
- Ontario Building Code: Minimum ceiling heights, egress windows, fire separation, smoke/CO detectors, plumbing, and HVAC all apply
Building a Space for Your Parents or Adult Kids?
We handle the full design, permits, and build — so your family can focus on what actually matters.
Aging Parents Moving Closer
Your parents want to be nearby — not in a facility. A legal basement suite or garden suite gives them their own private space with a separate entrance, kitchen, and bathroom. Close enough for daily check-ins. Independent enough for everyone's sanity.
Adult Kids Who Need a Landing Pad
Your grown children are back home — or never left. A self-contained suite gives them real independence without the cost of Hamilton's rental market. And if they move on, you have a unit that generates $1,400–$1,800/month in rental income.
New Baby, New Needs
A new child changes everything about how your home works. Having grandparents downstairs — in their own space — means built-in support when you need it most. No awkward guest room arrangement. A real home within your home.
Family Now, Rental Income Later
Build it for family today, rent it when circumstances change. A legal, permitted suite holds its value either way — and the City of Hamilton's ADU grant program can offset up to $40,000 of the cost whether you rent or keep it for family.
A legal in-law suite is the same build as a rental suite — same permits, same code requirements, same fire separation. The difference is how we design the layout. For family use, we prioritize things like wider doorways for accessibility, a kitchenette that feels like home rather than a rental unit, soundproofing between floors, and easy interior access points so your family can move between levels without going outside.
Gateway handles the full process — zoning verification, architectural design, permit submission, construction, and final inspection. You don't need to manage contractors or chase the city for updates. That's our job.
Private Entrance
Separate access for independence
Accessibility Options
Wider doors, grab bars, walk-in showers
Soundproofing
Real privacy between floors
Common Questions
How long does a legal basement suite take to build? ▼
Typical timeline is 3-4 months from permit approval to final inspection. Permits take 4-6 weeks in Hamilton. We coordinate everything and keep you updated weekly.
What is an ADU in Hamilton? ▼
ADU stands for Additional Dwelling Unit (previously called Secondary Dwelling Unit or SDU in Hamilton). It's a self-contained residential unit on the same property as your primary home. This includes basement apartments, in-law suites, and detached garden suites. Hamilton's zoning bylaws (22-132 through 22-138) allow ADUs on most low-density residential lots within the urban boundary.
Are there grants for building an ADU in Hamilton? ▼
Yes. The City of Hamilton's ADU and Multi-Plex Housing Incentive Program provides a direct grant covering 70% of eligible construction costs, up to $40,000 per unit. You receive $8,000 upfront when your building permit is issued, with the balance paid after final inspection. The Ontario Secondary Suite Loan Program also provides a separate forgivable loan of up to $50,000 for qualifying projects. Combined, that's up to $90,000 in government funding. We can help you determine eligibility during your feasibility review.
How do I apply for the $40,000 Hamilton ADU grant? ▼
You apply through the City of Hamilton's ADU and Multi-Plex Housing Incentive Program when you submit your building permit application. The grant covers 70% of eligible construction costs (materials, labour, plumbing, electrical, architectural fees) up to $40,000 per unit. You receive $8,000 upfront when the permit is issued, with the balance paid after final inspection. Your property must be within the Hamilton urban boundary (most are). Gateway handles the full permit submission — we can walk you through the grant application during your feasibility review.
Can I build a detached ADU (garden suite) in my backyard? ▼
On most qualifying Hamilton lots, yes. Detached ADUs are permitted on properties with single-detached, semi-detached, or street townhouse dwellings. Key rules: max 75m² gross floor area, 4.0m setback from the primary dwelling, 1.2m from side and rear lot lines, max 6m building height, and no more than two bedrooms. Corner lots and wider lots tend to work best. We assess all of this in the feasibility review.
Can I build an in-law suite for multi-generational living? ▼
Yes. A legal in-law suite or nanny suite is simply an ADU designed for family use rather than rental income. The build process, permits, and code requirements are the same. The difference is in the layout — we design for family flow, privacy, and accessibility based on who will be living there. Many Hamilton homeowners are building suites for aging parents or adult children who need an independent space while staying close to family.
Can I rent it immediately after completion? ▼
Yes — once you have the occupancy permit, the suite is legally rentable. We deliver the permit at project completion. Most clients start renting within 2 weeks of finishing.
What if my basement ceiling is too low? ▼
Ontario Building Code requires 6'5" minimum. If you're close, we can often adjust. If significantly below, underpinning or bench footing adds cost but makes the project viable. We assess ceiling height free in our feasibility review and give you a clear answer on what's needed.
Do you handle all permits and inspections? ▼
Absolutely. We prepare, submit, and manage all building permits with the City of Hamilton — including the ADU checklist and water service assessment. You never visit the Building Department. We coordinate all inspections and ensure code compliance at every stage.
What's the difference between an ADU, ARU, and secondary suite? ▼
They're all names for the same concept — a self-contained unit on your property. Hamilton uses "Additional Dwelling Unit" (ADU). Ontario's planning legislation uses "Additional Residential Unit" (ARU). Older bylaws used "Secondary Dwelling Unit" (SDU). "Secondary suite," "in-law suite," and "basement apartment" are the common terms homeowners use. They all refer to a legal, self-contained dwelling unit with its own kitchen, bathroom, and entrance.
Can I legalize my existing unpermitted basement apartment? ▼
In most cases, yes. Many Hamilton homes have unpermitted basement units that were built without proper permits or inspections. Legalizing an existing unit requires a building permit, code upgrades (fire separation, egress windows, separate HVAC, smoke and CO detectors), and passing city inspections. The good news: the Hamilton ADU grant program applies to legalization projects too — not just new builds. Gateway can assess what your existing unit needs during a free feasibility review.
Up to $40,000 in Grants. $1,400–$1,800/Month in Rental Income.
Find out if your property qualifies for a legal basement suite or ADU — and how much of the build Hamilton will help pay for. Free feasibility assessment delivered in 48 hours.
Get Free Assessment →Or call 343-504-8213 now