Abstract: An apparatus for use in supporting a window buck frame or surround against crushing and distorting when concrete is poured therearound. An open-type reusable support frame that is inserted into a window buck frame and clamped thereto so that vertical edges of the support frame fit closely within a central ridge extending peripherally around the inside of the window buck frame. The window buck frame is aligned between wall forms, and concrete is poured around the window buck frame. After the concrete has cured and the forms are removed, the clamps are released and the support frame is pulled from the window buck frame that remains in the foundation wall.