Effect of payment to lienholder
18If an owner, contractor or sub-contractor makes a payment to a lienholder for or on account of a debt due the lienholder for work done or material furnished to be used as mentioned in section 4, for which debt the owner, contractor, or sub-contractor is not primarily liable, and within three days thereafter gives written notice of the payment to the person primarily liable, or his agent, the payment shall be deemed to be a payment on the contract with the person primarily liable, but not so as to affect the percentage to be retained by the owner as provided by section 15 or any further deduction required by section 16.