Mechanic's Lien is the lien that gives rights to the mechanics such as contractors, sub-contractors, or suppliers to file for their unpaid fees.
This lien gives rights to the mechanics to file a case against the person who used their services but after the work done refused to pay the remaining cost.
In such cases, when a mechanic files 'Mechanic's lien' the property on which they offered their services will come under public property, which means that the unpaid amount will be carried on the property. So if the person wants to sell his/her property either the next party will pay the unpaid amount or that party will force the previous one to clear the account. This lien is also known as 'construction lien' or 'property lien'.
So, in the given example, City Roofers will go for 'Mechanic's Lien'.
