A person claiming a lien under section 1921 of this title, shall file for record in the clerk's office of the town where such real estate is situated, a written memorandum, signed by him or her, asserting his or her claim, which shall charge such real estate with such lien as of the visible commencement of work or delivery of material to the extent and subject to the exceptions provided in sections 1921 and 1922 of this title. Several such liens, asserted as aforesaid, shall be paid pro rata, if the sum due or to become due from the owner thereof is not sufficient to pay the same in full.