Section 503 - Application of act(a) Number of residential units.--This act shall not apply to improvements to real property which consists of six or fewer residential units which are under construction simultaneously.(b) Owner's exclusion.--This act shall not apply to contracts for the purchase of materials by a person performing work on his or her own real property.(c)Prohibition on waiver.--Unless specifically authorized under this act, parties to a contract or other agreement may not waive a provision of this act by contract or other agreement.Amended by P.L. TBD 2018 No. 27, § 1, eff. 10/10/2018.1994, Feb. 17, P.L. 73, No. 7, § 3, effective in 60 days.