You found the right space. The rent fits your budget. The location works. The landlord seems reasonable. Time to sign, right?
Not so fast. After more than 25 years of commercial real estate transactions across the Greater Toronto Area, I can tell you that the problems tenants face almost never show up on the first walkthrough. They’re buried in the lease document, hidden in the building’s operating history, or sitting quietly in the municipality’s zoning bylaws.
Here is the due diligence checklist I use for every client — whether they’re leasing office space in downtown Toronto, a warehouse in Mississauga, or a retail unit in Barrie.
1. Lease Document Review
The lease is the single most important document in the transaction. Before you sign, every clause needs to be reviewed by someone who understands commercial real estate — not just a general practice lawyer.
Key items to verify:
- Are the premises accurately described, including the exact square footage and any exclusions?
- Does the lease specify who is responsible for repairs to HVAC, plumbing, electrical, and structural elements?
- Is there a demolition clause that allows the landlord to terminate the lease if they decide to redevelop?
- What are your restoration obligations at the end of the term?
- Are there any restrictions on how you can use the space?
Demolition clauses have become increasingly common in Toronto and Vaughan as older commercial buildings are redeveloped. A lease with a demolition clause can be terminated with as little as six months’ notice — devastating for a business that has invested in build-out costs.
2. Financial Analysis
Beyond the headline rent, you need to understand your total occupancy cost.
Review these financial items:
- Base rent and how it escalates over the term
- TMI or operating cost estimates with historical data
- Property tax projections — especially in rapidly developing areas like Vaughan and Simcoe County
- Parking costs and availability
- Utility metering — is your space separately metered or is cost allocated?
- Any special assessments or pending capital expenditures
Ask the landlord for two to three years of actual operating expense statements. The estimates they provide during leasing often look different from actual costs once you’ve moved in.
3. Zoning and Permitted Use
This is one of the most frequently overlooked due diligence items across the entire GTA. Just because a space was previously used for a particular purpose does not guarantee you can use it the same way.
Before committing to a lease in Toronto, Mississauga, Vaughan, or Barrie:
- Confirm the property’s zoning allows your intended use
- Verify that your specific business activity is permitted under the municipal bylaw
- Check whether a minor variance or rezoning would be required — and how long that process takes
- Confirm any required licenses or permits can be obtained
I’ve seen tenants in the GTA sign leases for restaurant or medical office space only to discover that the zoning didn’t permit their specific use, or that the parking requirements were different from what the previous tenant needed.
4. Physical Inspection
Walk the space with a contractor or building engineer, not just the leasing agent.
Inspect these areas:
- HVAC system age, capacity, and maintenance history
- Electrical panel capacity for your equipment needs
- Ceiling height and clear height (critical for industrial tenants in Mississauga and Barrie)
- Loading dock access and clearance for trucks
- Roof condition and any history of water infiltration
- Floor load capacity, especially for warehousing or manufacturing
In older buildings throughout Toronto and Simcoe County, the infrastructure may not support modern business requirements without significant upgrades that become your responsibility under the lease.
5. Building and Landlord Assessment
Your landlord’s financial stability and management quality directly affect your tenancy.
Investigate:
- Who owns the building? Is it an institutional investor, a private owner, or a syndicate?
- What is the building’s current occupancy rate? High vacancy in a multi-tenant building can signal financial stress.
- Are there pending special assessments or major capital projects?
- What is the landlord’s reputation among current tenants?
6. Legal and Regulatory
Don’t overlook:
- Compliance with the Accessibility for Ontarians with Disabilities Act (AODA)
- Fire code compliance and sprinkler system adequacy
- Environmental assessments for industrial properties — Phase I and Phase II ESA reports
- Compliance with Ontario Building Code for your intended use and occupancy load
The Cost of Skipping Due Diligence
The tenants who call me after signing a bad lease all share one thing in common: they rushed the process. In a competitive market like Toronto, there’s pressure to move quickly. But a lease that seems fine on the surface can hide obligations that cost far more than taking an extra few weeks to investigate.
About the Author
Allen Mayer is a Commercial Real Estate Broker with RE/MAX Ultimate Realty Inc., bringing over 25 years of experience helping tenants and landlords across the Greater Toronto Area. From downtown Toronto office towers to industrial parks in Barrie and Simcoe County, Allen provides strategic lease negotiation and market advisory services.
📞 Contact Allen Mayer for a complimentary initial consultation:
Phone: (416) 992-9141
Email: allen@allenmayer.ca
Website: allenmayer.ca/contact
Frequently Asked Questions
What should I check before signing a commercial lease in Ontario?
Before signing, verify zoning compliance for your intended use, review all financial obligations including TMI and escalation clauses, inspect the physical condition of the space and building systems, and have the lease reviewed by a commercial real estate professional — not just a general practice lawyer.
What is a demolition clause in a commercial lease?
A demolition clause allows the landlord to terminate your lease early if they decide to redevelop or demolish the building. These clauses are increasingly common in Toronto and Vaughan as older commercial properties are redeveloped. Always negotiate for adequate notice periods and compensation for your unamortized improvement costs.
Do I need an environmental assessment for a commercial lease in the GTA?
For industrial properties across Mississauga, Vaughan, and Barrie, a Phase I Environmental Site Assessment is strongly recommended. If the property has a history of industrial use, a Phase II ESA may be necessary. Even for office and retail leases, understanding any environmental liability protects your business from future remediation costs.
How long does commercial lease due diligence take in the GTA?
A thorough due diligence process typically takes two to four weeks, depending on the complexity of the lease and the property. This includes document review, physical inspection, zoning verification, and financial analysis. In competitive Toronto markets, start your due diligence as early as possible to avoid being pressured into a quick decision.