A serious lack of house construction technicians has produced a trend in which wooden parts of a house are processed by computer aided precut machine and the precut wood is treated with termiticides and/or fungicides at the plant site. We have developed a new system to handle these requirements of homebuilding. This system is a combination of incising machine, spray machine and proprietary oil-borne wood preservatives. The system has the foIlowing characteristics: 1.) Compressive incising with dull blades provides high efficiency and high capacity reservoirs of wood preventive agents. 2.) Six nozzles at the end of flexible hoses which can effectively treat intricately shaped objects. 3.) A spray method which minimizes variation of treating agent composition. 4.) Use of selected high penetrating solvents provides an adeqate penetration and a shorter production time compared to the aqueous high pressure process. 5.) Selective absorption of active ingredients in the direction of penetration is practically negligible. 6.) Effect of wood species on system performance is comparatively low, presumably due to low surface tension of the oil-borne agent.