Provides requirements for materials, construction, finishes and hardware for steel windows, sills, window boards and doors manufactured from the F range, or the heavier W20 range, of steel window sections. Including weathertightness performance for weather-stripped opening light windows and fixed light windows. Shows provision for glazing of frames but excludes glass. Gives window and door types and size limitations and describes optional features to be agreed between manufacturer and purchaser. Includes recommendations for the site assembly of composites and marking. Plus information on security and safety.