A steel beam with a cross section resembling the letter I. It is used for long spans as basement beams or over wide wall openings, such as a double garage door, when wall and roof loads bear down on the opening
Frank Mayhue, Home Building Manual, Construction Glossary from Home Building Manual, USA 1999. http://www.homebuildingmanual.com/Glossary.htm, (Home Bulid - Amer) {518}
Complete Design, Inc. (Construction Design Specialists), Dictionary of Construction Terminology, Washington, USA 2015. http://completedesign.cc/client-resources/dictiona ry-of-construction-terminology, (Const - Amer) {836}