RCW 86.09.175: Installment contracts—Approval.

Contracts entered into by districts for construction or for services or materials, may provide that payments shall be made in such monthly proportion of the contract price, as the board shall determine thereon, as the work progresses, or as the services or materials are furnished, on monthly estimates of the value thereof, approved by the state director. Before the district shall enter into any contract, the plans, specifications and form of contract therefor shall be approved by the state director.