A general contractor can normally charge by the hour or by the project. A reliable Plainsboro general contractor normally charges anywhere between $35 to $40. A general contractor can get involved with the actual physical work, or they hire subcontractors to work for them. A general contractor can charge based on the cost contract agreed upon. A cost contract can come in 3 different types; fixed price, time and materials cost, and cost plus a fee. In a fixed price contract, a contractor bids for the project for a certain price and that will be how much your project will cost. In a time and material contract, charging will be made in an hourly basis for the workers, and will have a markup fee for the materials and markup for all the subcontractors. Cost plus contracts are generally the same with time and material contracts, but the contactor sets a preset fee instead of markup. The fee will be dependent on the total cost of the project and the percentage return can decrease if the total cost exceeds what has been declared.