The head contract being abandoned is a triggering event for the lien filing period.
Time for filing claim of lien
20 (1) If a certificate of completion has been issued with respect to a contract or subcontract, the claims of lien of
(a) the contractor or subcontractor, and
(b) any persons engaged by or under the contractor or subcontractor
may be filed no later than 45 days after the date on which the certificate of completion was issued.
(2) A claim of lien that is not governed by subsection (1) may be filed no later than 45 days after
(a) the head contract has been completed, abandoned or terminated, if the owner engaged a head contractor, or
(b) the improvement has been completed or abandoned, if paragraph (a) does not apply.
(Builders Lien Act, s. 20, emphasis added).
A contract or improvement is “abandoned”:
[O]n the expiry of a period of 30 days during which no work has been done in connection with the contract or improvement, unless the cause for the cessation of work was and continued to be a strike, lockout, sickness, weather conditions, holidays, a court order, shortage of material or other similar cause.
(Builders Lien Act, s. 1(5)).