I-joists are ‘I’ shaped engineered wood structural members designed for use in residential and non-residential construction. The product is prefabricated using sawn or structural composite lumber flanges and OSB webs, bonded together with exterior type adhesives.
I-joists are manufactured and distributed by a number of North American producers. Most supply I-joists in lengths up to 60 feet, and the most common depths, in inches, are 9-1/2, 11-7/8, 14 and 16. Because most I-joists are manufactured to proprietary standards, APA recommends that you refer to the manufacturer’s literature for recommendations and more detailed product descriptions.
There is no harmonised European standard for I-Joists so manufacturers have to make an application for a European Technical Assessment (ETA) which measures a specific I-joist against test requirements laid down in a European Assessment Document (EAD) or a European Technical Approval Guide (ETAG). (Also see Official Guidelines).
North American I-joists are manufactured according to proprietary manufacturing standards and do not follow a single voluntary national standard. For design recommendations and product specifications, please refer to the individual manufacturer’s information.