Mass timber construction is starting to gain more attention, especially when it comes to tall buildings – but what is it, you may ask? Mass timber is a term used to describe various large engineered wood products that typically involve the lamination and compression of multiple layers to create solid panels of wood. Mass timber construction uses these panels to frame a building’s walls, floors and roofs.
Most Popular Types of Mass Timber Products
Cross-laminated timber (CLT) is made up of three to seven layers of dimensional lumber stacked perpendicular and glued together to create structural panels. They are often used for floors, walls and roofs.
Nail-laminated timber (NLT) is comprised of stacked layers of dimensional lumber and fastening them together with nails or screws. NLT is commonly used in floors and roofs, as well as to construct elevator shafts.
Glue-laminated timber (Glulam) is made by stacking dimensional lumber on edge and securing them together with moisture-resistant adhesives. Glulam boards are often used for floors, beams, columns and arches.
Benefits of Mass Timber Construction
There are numerous benefits of mass timber over traditional steel and concrete for constructing tall buildings. If the timber is sourced responsibly it provides a completely sustainable and renewable building material. Carbon emissions from manufacturing mass timber products are a fraction of those created by the production of steel and concrete.
Many people may wonder what happens to a mass timber building during a fire. Mass timber has a natural tendency to char in a fire, which slows the burning process and helps maintain structural integrity. Mass timber’s resistance to fire can be further improved by enclosing the timber in gypsum board.
Mass timber products are also considerably lighter than concrete. Further, the thermal performance of mass timber is vastly better to its steel and concrete counterparts, which results in lower heating and cooling costs.
Challenges of Mass Timber
Roadblocks to using mass timber for tall buildings in the U.S. include restrictive building codes and a lack of manufacturers creating mass timber products. Currently, most building codes in the U.S. don’t allow wood construction over six stories. Even for shorter buildings, codes haven’t specifically recognized mass timber systems.
Is There a Future?
As perceptions change, and more products are tested and buildings completed, mass timber construction is expected to catch on in the U.S. the same way it has in Europe.