Apparatus and method for treating by injecting a fluid treatment material into the bodies of porous structures such as those formed from concrete, brick, stone, marble, and wood. The apparatus for use in the method includes an applicator head having an inner chamber and an outer chamber surrounding the inner chamber both of which chambers are connected with a vacuum source. The inner chamber is also connected with a source of pressurized liquid treatment material. The method is non-invasive in that the fluid treatment material impregnates the porous structure without the need to break open, destroy, repair, or replace any part of the structure, and includes the steps of engaging the structures with the applicator head, drawing a vacuum on at least the outer chamber to secure the applicator head to the structure, and supplying the pressurized liquid treatment material to the inner chamber to and onto the surface of the structure to impregnate the structure to be treated.