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Construction Liens in Ontario What They Are and How They Work

Ontario

Under Ontario's Construction Act, contractors, subcontractors, suppliers, and workers who are not paid for work or materials on a project have the right to register a lien against the property. A lien can affect a sale, a refinancing, or a new mortgage and every property owner and lender needs to understand how they work.

What Is a Construction Lien?

A construction lien is a statutory claim against real property registered by a person who has supplied services or materials to the improvement of that property and has not been paid. The lien attaches to the owner's interest in the land and gives the lienholder a security interest the right to share in the proceeds of any sale of the property, up to the value of the unpaid claim.

Construction liens in Ontario are governed by the Construction Act (formerly the Construction Lien Act), which was significantly reformed in 2018 and 2019 to modernize the lien and prompt payment regime.

Who Can Register a Construction Lien?

Any person who has supplied services or materials to an improvement of the property and has not been paid can register a lien. This includes:

Critically, a subcontractor can register a lien against the property owner's land even if the owner paid the general contractor in full if the general contractor did not pay the subcontractor. The lien right runs against the property regardless of who caused the non-payment in the contracting chain.

For property owners: You can do everything right pay your general contractor in full and on time and still have a subcontractor's lien registered against your property if the GC failed to pass payment down the chain. The holdback mechanism (see below) exists precisely to protect against this risk.

The Mandatory Holdback

One of the core protections of the Construction Act is the mandatory holdback. An owner is required to hold back 10% of the value of services and materials supplied (as certified or stated in each certificate or progress payment) until the lien period has expired and all liens have been discharged or expired.

The holdback is a trust it is held for the benefit of all potential lienholders. An owner who releases the holdback before the lien period expires does so at their own risk: they may be personally liable to lienholders if the holdback was insufficient to satisfy claims.

Lien Deadlines Critical Time Limits

The Construction Act contains strict limitation periods for registering and perfecting liens. Missing these deadlines extinguishes the lien right entirely:

ActionDeadline
Register a lien (general)60 days after the date of last supply of services or materials to the contract
Register a lien (where a Certificate of Substantial Performance is published)45 days from publication of the Certificate of Substantial Performance
Perfect a lien (commence action and register certificate of action)90 days after the lien was preserved (registered)
These deadlines are absolute. A lien that is not registered within the prescribed period, or not perfected within the prescribed period after registration, expires and is extinguished. There is no discretion to extend. If you believe you have a lien claim, consult a construction lawyer immediately the clock is running.

What Happens When a Lien Is Registered?

When a lien is registered against a property:

Vacating a Lien by Posting Security

If a lien is registered and the owner disputes its validity or amount, the owner can apply to the court to have the lien vacated by paying the amount of the lien (or an amount ordered by the court) into court or by posting a lien bond. This removes the lien from title the property can then be sold or refinanced while the underlying dispute is resolved in litigation.

Vacating a lien by posting security is common in construction disputes where the owner cannot wait for the litigation to resolve before completing a sale or refinancing.

Prompt Payment and Adjudication (2019 Reforms)

The 2019 reforms to the Construction Act introduced a prompt payment regime and a statutory adjudication process for resolving payment disputes quickly during construction (rather than waiting for full litigation):

The Navigating Lien Rights in Modular Construction (Publication)

I co-authored a publication on Navigating Lien Rights in Ontario's Modular Construction Landscape (July 2024), which examined how lien rights apply in the context of modular construction where components are manufactured off-site and delivered for assembly. If you're dealing with lien issues in a non-traditional construction context, the analysis of how the Construction Act applies to off-site manufacturing is worth reviewing.

Bottom line: Construction liens are a powerful remedy for unpaid contractors and suppliers but they come with strict timelines, technical requirements, and serious consequences for both lienholders who miss deadlines and property owners who fail to maintain holdbacks. If you are involved in a construction dispute involving unpaid work, get legal advice immediately. The time limits are unforgiving.

References & Further Reading