Thirty percent (30%) of the purchase price (lot and house) is due and payable within 14 days of signing of agreement; Twenty percent (20%) of the purchase price (lot and house) is due and payable upon completion of basement, latest one year after signing of agreement; Ten percent (10%) of the purchase price (lot and house) is due and payable upon residential dwelling being weather tight; Forty percent (40%) of purchase price (lot and house) is due and payable upon substantial completion.