All contracts for such work to be done outside the state shall require that it be executed under conditions of employment which shall substantially conform to the laws of this state respecting hours of labor, the minimum wage scale, and the rules and regulations of the department of labor and industries regarding conditions of employment, hours of labor, and minimum wages, and shall be favorably comparable to the labor standards and practices of the lowest competent bidder within the state, and the violation of any such provision of any contract shall be ground for cancellation thereof.