Specifications are prepared by the architect for the purpose of giving the owner, the builder, and the contractors full and accurate descriptions (kind, quality and dimensions) of the various materials and appliances to be used in the building and the manner in which the various parts of the work are to be performed. The specifications are sub-divided so that a part of them applies to each of the trades to be employed. They are used in connection with the plans in making up estimates of the cost of the building. The specifications become part of the agreement with the contractors and they are required to make their work and materials conform to its requirements.