{"id":10537,"date":"2022-05-27T09:13:13","date_gmt":"2022-05-27T14:13:13","guid":{"rendered":"https:\/\/www.imegcorp.com\/?p=10537"},"modified":"2023-04-06T14:45:31","modified_gmt":"2023-04-06T19:45:31","slug":"mass-timber-101-changes-to-the-code","status":"publish","type":"post","link":"https:\/\/imegcorp.com\/insights\/blog\/mass-timber-101-changes-to-the-code\/","title":{"rendered":"Mass Timber 101: Code changes offer building owners much more flexibility"},"content":{"rendered":"

Second in a series based on the IMEG executive guide, <\/span><\/i>\u201cMass Timber 101: A Guide to the Hottest Sustainable Building Material.\u201d<\/span><\/i><\/a>\u00a0<\/span><\/p>\n

By Heather Heidenreich<\/span>\u00a0<\/span><\/p>\n

Cross-laminated timber (CLT) has become a popular building material across the U.S. due to its unique aesthetic, sustainable qualities, and potential cost savings. In response, the International Code Council (ICC) created an ad hoc committee in 2015 to reevaluate the use of wood in tall buildings. Up until that point, only historical data had been available for reference, leaving it up to city councils to decide on their own if their local codes should allow mass timber, and if so, at what parameters.\u00a0<\/span>\u00a0<\/span><\/p>\n

IMEG\u2019s Chicago structural team was involved in the permitting process and building type approval for the first heavy timber (HT) project built in the City of Chicago in over 50 years: a new, 45,000-sf <\/span>multi-use building<\/span><\/a> in the historic Fulton Market District. From the outset, the city did not view glulam construction as equal to heavy timber construction (wood framing members with minimum dimensions and other restrictions to attain fire resistance) as outlined in the Chicago Building Code, even though the International Building Code (IBC) viewed them as the same. The IMEG team used exhibits and testimonials from Wood Council members to show how glulam is indeed the same as heavy timber and received approval from the city to build the project. The City of Chicago ultimately changed their building code provisions as a result.<\/span>\u00a0<\/span><\/p>\n

Other cities are sure to follow, as mass timber was adopted into the 2021 IBC. The code defines the material as \u201cstructural elements of Type IV construction primarily of solid, built-up, panelized, or engineered wood products that meet minimum cross-section dimensions of Type IV construction.\u201d<\/span>\u00a0<\/span><\/p>\n

However, fire protection is a common concern with mass timber construction. Tall structures built with combustible materials would seemingly burn faster, but the thickness of mass timber elements means they char well and are slow to burn. The ICC\u2019s ad hoc code committee recognized that mass timber in combination with concrete provides equal or superior fire protection without the use of gypsum. The committee subsequently divided the Type IV construction type into four sub-categories delegating how much can be used in buildings of varying heights:<\/span>\u00a0<\/span><\/p>\n