The present invention relates to new and unique designs that improve and enhance the section properties of load bearing structural members, which have particular, but not exclusive, application in connection with aluminum extrusions for use in screened pool, patio and porch enclosures. The invention utilizes one or more reinforcing inserts or slats which attach to a structural member such as a hollow extruded beam to increase the effective wall thickness of the beam in the area where the slat is applied.