A Canadian Construction Lien (also referred to as a Builders Lien in British Columbia and Alberta, or a Mechanics Lien in some other provinces) is a statutory claim against real property by a contractor, subcontractor, material supplier, or labourer who has not been paid for work performed, services rendered, or materials supplied in connection with an improvement to that property. Construction lien rights in Canada are entirely creatures of provincial statute, meaning they exist only because provincial legislation creates them and they must be exercised in strict compliance with the applicable legislation.

In Ontario, construction liens are governed by the Construction Act (R.S.O. 1990, c. C.30, as amended by Bill 142 in 2018). The Ontario Construction Act provides lien rights to any person who supplies services or materials to an improvement, including contractors, subcontractors, workers, material suppliers, equipment rental companies, and design professionals such as architects and engineers. The lien attaches to the owner's interest in the premises being improved and to the holdback funds that the owner is required to retain.

In British Columbia, the Builders Lien Act (S.B.C. 1997, c. 45) governs construction lien rights. The BC legislation uses the term 'builders lien' rather than 'construction lien' or 'mechanics lien.' The act provides lien rights to contractors, subcontractors, workers, and material suppliers who perform or provide work or material for an improvement to land. The lien attaches to the estate or interest of the owner in the land and improvements.

In Alberta, the Builders' Lien Act (R.S.A. 2000, c. B-7) provides similar protections. Alberta's legislation also uses the 'builders lien' terminology and provides lien rights to any person who does or causes work to be done on or furnishes material to be used in an improvement. Saskatchewan uses the Builders' Lien Act (S.S. 1984-85-86, c. B-7.1), Manitoba uses The Builders' Liens Act (C.C.S.M. c. B91), and the Atlantic provinces each have their own mechanics lien statutes.

The construction lien is a powerful legal tool because it creates a security interest in the real property itself. Unlike an unsecured debt where the creditor must obtain a judgment and then attempt to collect, a construction lien claimant has a direct claim against the property that can be enforced through a court-ordered sale of the property. This makes the construction lien one of the most effective collection remedies available to participants in the construction industry. The lien essentially prevents the property owner from selling or refinancing the property without first satisfying the lien claim.

A Canadian Construction Lien is needed whenever a contractor, subcontractor, material supplier, or labourer has not been paid for work performed or materials supplied on a construction project. The construction lien is the primary legal remedy for unpaid participants in the construction pyramid, from general contractors dealing directly with the owner down to the lowest-tier subcontractors and material suppliers.

General contractors who have completed work on a residential renovation, commercial build-out, or new construction project and have not received payment from the property owner need to preserve their lien rights within the applicable statutory deadline. In Ontario, this means registering a claim for lien on the title to the property within 60 days of the last day of supply (the date the contractor last performed work or supplied materials). Missing this deadline means losing the right to lien entirely, with no possibility of extension.

Subcontractors face an even more urgent need for lien protection because they have no direct contractual relationship with the property owner. A subcontractor hired by the general contractor to perform electrical, plumbing, HVAC, drywall, framing, roofing, or other specialized work depends on the general contractor for payment. If the general contractor fails to pay (whether due to financial difficulties, disputes, or insolvency), the subcontractor's only security is the construction lien against the owner's property and the statutory holdback.

Material suppliers who have delivered lumber, concrete, steel, fixtures, appliances, or other construction materials to a job site and have not been paid need to preserve their lien rights. In most provinces, the supplier's lien rights are preserved from the date of the last supply of materials, not the date of the last delivery. Equipment rental companies that have supplied cranes, excavators, scaffolding, or other construction equipment also have lien rights in most provinces.

Labourers and workers who have performed work on an improvement and have not received their wages may also file construction liens, although in practice, wage claims are more commonly pursued through provincial employment standards legislation. Design professionals including architects, engineers, and surveyors who have provided professional services in connection with an improvement may also have lien rights, depending on the province.

The construction lien is also needed as a protective measure even when payment disputes are ongoing. Filing a lien preserves rights and creates leverage for negotiation, as the property owner cannot sell or refinance the property without dealing with the registered lien. Many payment disputes in the construction industry are resolved through negotiation after a lien has been filed, because the lien creates a practical incentive for the owner to settle.

A comprehensive Canadian Construction Lien must contain several essential elements to be valid and enforceable under provincial legislation. The form must clearly identify the lien claimant with their full legal name, business address, and contact information. If the claimant is a corporation, the full corporate name as registered with the provincial corporate registry must be used. The claimant's role on the project (general contractor, subcontractor, material supplier, labourer, or design professional) must be specified.

The property owner must be identified with their full legal name and address. The property against which the lien is claimed must be described with sufficient detail to identify it, including the municipal address, legal description (lot and plan number, PIN or PID, Land Title Office reference), and the province or territory where the property is located. In Ontario, the claim for lien must include the legal description of the premises, and registration is done at the appropriate Land Registry Office. In BC, the lien is filed at the Land Title Office.

The amount of the lien claim must be stated in Canadian dollars. This should include the total contract amount, any payments received to date, and the outstanding balance being claimed. The amount should be calculated carefully, as overstating the lien amount may result in the claimant being liable for damages or costs if the lien is ultimately found to be excessive. The claim should include only amounts properly owing for work performed or materials supplied, and should reflect all credits, holdbacks, and offsets.

The description of the work performed, services rendered, or materials supplied must be sufficiently detailed to establish the claimant's entitlement to a lien. This includes the nature of the work (electrical, plumbing, framing, materials supply), the dates when work was first commenced and last performed, and the contractual basis for the work. The originating contract or agreement should be referenced by number and date.

The statutory holdback provisions must be acknowledged. Most provinces require the owner to retain 10% of each progress payment as a holdback fund. In Ontario, the basic holdback is 10% of the price of the services or materials as they are actually supplied. The holdback must be retained for the applicable lien period (60 days in Ontario, 55 days in BC, 45 days in Alberta from the relevant trigger date). An owner who releases the holdback prematurely becomes personally liable.

The governing provincial law must be specified, as construction lien legislation varies significantly between provinces. Ontario's Construction Act includes prompt payment provisions and mandatory adjudication. BC's Builders Lien Act has different filing requirements and deadlines. Alberta's Builders' Lien Act has its own unique provisions regarding trust funds. The form should reference the applicable statute to ensure compliance with provincial requirements.