Construction contracts in amounts in excess of $250,000 for facilities shall require contractors to secure a contractors' bond, on a form approved by RUS, attached to the contract in a penal sum of not less than the contract price, which is the sum of all labor and materials including owner-furnished materials installed in the project. RUS Form 168b is for use when the contract exceeds $250,000. RUS Form 168c is for use when the contractor's surety has accepted a Small Business Administration guarantee and the contract is for $1,000,000 or less. For minor construction contracts under which work will be done in sections and no section will exceed a total cost of $250,000, the borrower may waive the requirement for a contractors' bond.