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This article is general information only and does not constitute legal advice. For your specific situation, consult a qualified solicitor or tenancy service.
In Ontario, a landlord who included a “no pets” clause in a lease found themselves facing a fine of up to $35,000 per offence, even though the tenant had signed the agreement. That figure from the Landlord and Tenant Board (LTB) isn’t just a warning for the careless — it shows how a single illegal clause can turn a standard lease into a legal liability. Here’s what you actually need to know.
Lease addendums are common in Canada, but they’re not a free-for-all. Each province has its own rules about what you can and cannot add. I’ve seen landlords try to slip in clauses that sound reasonable — like banning pets or limiting guests — only to find those clauses are automatically void under the Residential Tenancies Act. Understanding the difference between a legal addendum and an illegal one can save you time, money, and a trip to the tribunal.
What a Lease Addendum Actually Does
A lease addendum is essentially a contract patch. It modifies the original lease without replacing it. The key thing to understand is that the entire original lease remains in effect except for the specific clause being amended. This is different from an amendment, which changes an existing term — like adjusting the rent amount on a specific date. An addendum adds something new.
What I tend to notice is that many landlords confuse addendums with amendments. If you’re changing the rent amount, that’s an amendment. If you’re adding a rule about where tenants can park, that’s an addendum. Getting this wrong can create confusion about what’s actually enforceable. For a deeper look at how lease terms interact with provincial caps, check out our guide on rental price caps in Canada.
Why Getting Addendums Wrong Costs Real Money
The Residential Tenancies Act (RTA) in Ontario is clear: any clause inconsistent with the Act is automatically void, even with a tenant’s signature. This isn’t a minor technicality. In 2024, a landlord who collected a $6,400 damage deposit was ordered to return the full amount plus interest and filing fees. That’s a direct cost from a single illegal clause.
Across Canada, the stakes are similar. In British Columbia, the Residential Tenancy Branch provides standard forms like the RTB-1 that already cover most essential terms. Adding illegal clauses doesn’t just waste paper — it gives tenants a defence in disputes. If a landlord tries to evict based on a clause that contradicts the RTA, the tribunal will side with the tenant.
The real-world complication here is that many illegal clauses sound perfectly reasonable. “No pets” seems straightforward. “No guests overnight” feels like common sense. But under the RTA, tenants have the right to guests for any length of time and roommates without landlord consent. Municipal bylaws on overcrowding are enforceable, but a blanket ban on guests isn’t. This is where a landlord-tenant legal service can help clarify what’s actually enforceable in your province before you put pen to paper.
Where People Go Wrong With Lease Addendums
Pet Clauses That Violate Provincial Law
The most common mistake I see is landlords adding “no pets” clauses to leases. In Ontario, under RTA Section 4, any clause that prohibits pets is automatically void in non-condo rentals. This includes “pets prohibited,” “no animals,” and even size or breed restrictions. The exception is condominium corporations, which can prohibit certain pets through condo rules — but that’s a condo rule, not a lease clause.
What landlords can do instead is include a pet responsibility clause. This requires written consent for pets and covers damage liability and cleanup. It’s a legal way to manage pets without running afoul of the law. The clause must be written in plain language, use at least 10-point font if typed, be physically attached to the lease, and include the tenant’s written consent.
Occupancy Restrictions That Go Too Far
Another frequent error is limiting who can live in the unit. Clauses like “no guests overnight,” “no roommates without landlord approval,” or “maximum 2 occupants” are generally unenforceable. Tenants have the right to have guests for any length of time and to take on roommates without landlord consent. Subletting requires landlord permission, but that permission cannot be unreasonably withheld.
The nuance here is that municipal overcrowding bylaws are enforceable. So a clause that says “no more than 4 occupants in a 2-bedroom unit” might be legal if it aligns with local fire codes. But a blanket “no guests” clause isn’t. If you’re unsure about what’s reasonable in your area, a Canadian landlord-tenant lawyer can review your specific wording.
Illegal Deposit and Fee Clauses
Landlords sometimes try to charge “damage deposits” or “pet deposits” beyond what the law allows. In Ontario, only a refundable security deposit is permitted. A $500 “pet deposit” is illegal. Similarly, charging fees for additional occupants or requiring a “key deposit” beyond the actual cost of replacement is prohibited.
What makes this tricky is that some fees are legal. For example, landlords can charge for parking spaces, storage units, or laundry facilities — as long as those are optional services, not mandatory fees tied to the tenancy itself. The line between a legal service fee and an illegal deposit can be thin, and getting it wrong means refunding the money plus potential penalties.
Vague or Conflicting Language
Even legal clauses become unenforceable if they’re poorly written. An addendum that says “tenant must maintain the property in good condition” is too vague to enforce. What does “good condition” mean? A better clause would specify “tenant must keep carpets professionally cleaned every 12 months and provide receipts upon request.”
Another common issue is addendums that conflict with the original lease. If the lease says “no smoking” but the addendum says “smoking allowed on balcony,” which one controls? The addendum should state clearly that it overrides the original lease in case of conflict. Without that language, you’re left with ambiguity that benefits neither party.
→ Scroll right to see all columns
| Clause Type | Legal in Ontario? | Enforceable? | Alternative |
|---|---|---|---|
| No pets allowed | No | No | Pet responsibility clause with written consent |
| No guests overnight | No | No | Municipal overcrowding bylaw reference |
| Damage deposit | No | No | Refundable security deposit only |
| Pet deposit ($500) | No | No | Pet damage liability clause |
| Written consent for pets | Yes | Yes | Use Section 15 of Standard Lease |
| Parking rules | Yes | Yes | Separate parking addendum |
How to Write a Lease Addendum That Holds Up
Start With the Right Format
Every addendum needs the basics: the parties’ names, the property address, the original lease date, and the addendum’s effective date. Reference the specific lease section you’re modifying — for example, “This Addendum modifies Section 9 (Pets) of the Lease dated January 1, 2025.” Then state that the addendum becomes part of the lease and controls in case of conflict. Something like “Except as modified by this Addendum, all other terms of the Lease remain in full force and effect” is standard and effective.
Include signature lines for all parties. An unsigned addendum is just a piece of paper. Both landlord and tenant must sign, and if there are multiple tenants, all of them need to sign. In British Columbia, the age of majority is 19, so anyone under that age cannot legally sign a lease or addendum without a guarantor.
Know When to Use an Addendum vs. an Amendment vs. a New Lease
This is where I see the most confusion. Use an addendum to add new terms or clarify existing ones without replacing the lease. Use an amendment to change existing terms — like adjusting the rent amount on a specific date. Use a new lease when the relationship or deal structure has materially changed, such as adding a new tenant, changing the unit, or significantly altering the rent.
For example, if you’re adding a parking space, that’s an addendum. If you’re increasing the rent mid-lease (where legally allowed), that’s an amendment. If a new tenant moves in, that’s a new lease. Getting this wrong can create legal gaps where neither party knows what terms apply.
Keep Language Plain and Specific
Legal clauses must be written in plain language. Avoid legalese like “hereinafter” or “party of the first part.” Instead, say “the landlord” and “the tenant.” Be specific about what’s required. Instead of “tenant must keep the property clean,” say “tenant must remove all garbage from the unit weekly and place it in the designated bins.”
If you’re typing the addendum, use at least 10-point font. Handwritten addendums are harder to enforce because they can be challenged as unclear or incomplete. Attach the addendum physically to the lease — don’t just mention it verbally or in an email. The tenant must receive a copy and provide written consent.
Address Emerging Issues Like Smoking and Insurance
Two areas where addendums are becoming more common are smoking policies and insurance requirements. A smoking addendum can specify that smoking is prohibited inside the unit and within a certain distance from windows and doors. This is generally enforceable as long as it doesn’t conflict with local bylaws or human rights codes (for example, medical cannabis use).
Insurance requirements are another growing trend. Many landlords now require tenants to carry renters’ insurance with a minimum liability limit. This is legal in most provinces as long as the requirement is reasonable and the tenant can provide proof of insurance. The addendum should specify the minimum coverage amount, what it must cover (liability, contents, etc.), and how often proof must be provided.
Frequently Asked Questions
Can a landlord add a “no pets” clause in British Columbia? ▾
What happens if a tenant signs an illegal addendum? ▾
Can a lease addendum increase rent mid-lease? ▾
Do both parties need to sign a lease addendum? ▾
Can a tenant refuse to sign a legal addendum? ▾
Are lease addendums province-specific in Canada? ▾
Write Addendums That Work, Not Ones That Backfire
The most effective lease addendums are the ones that never need to be tested in tribunal. They’re clear, legal, and signed by both parties. They add value by preventing disputes rather than creating them. If you’re a landlord, the safest approach is to stick to what your province’s standard lease already allows and use addendums only for genuinely new terms like parking or smoking policies. If you’re a tenant, knowing what’s illegal gives you the confidence to push back on unreasonable clauses.
Remember: this article is general information only. For advice on your specific situation, speak to a qualified solicitor or tenancy adviser.
If this was useful, you might also want to read Tips for Negotiating Lease Break Fees When Renting in Canada.
Sources and Further Reading
Understanding Subletting Restrictions in Lease Contracts — A closer look at what tenants and landlords need to know about subletting rules across Canada.
Rental Price Caps: What You Need to Know Before Renting in Canada — Explains how provincial rent control limits affect lease terms and addendums.
Tenon10 (2025). What You Can and Can’t Add to the Ontario Standard Lease. 🔗
Wonder Legal Canada. Lease Amendment Agreement. 🔗
LawDepot Canada. Lease Amendment. 🔗
Government of British Columbia. Residential Tenancy Forms. 🔗
