What is Mass Timber?

Mass Timber is a new category of wood product that can revolutionize how the world builds.

It is comprised of multiple solid wood panels nailed or glued together, which provide exceptional strength and stability.

It’s a strong, low-carbon alternative to concrete and steel.

new code changes were passed for the 2021 code cycle that allow mass timber buildings up to 18 stories tall.

Source: Think Wood

Popular Types of Mass Timber

CLT "Cross Laminated Timber (CLT) panels consist of layered lumber boards (usually three, five, or seven) stacked crosswise at 90-degree angles and glued into place. Finger joints and structural adhesive connect the boards. Board thickness typically varies between 5/8 inch to 2 inches, with board width ranging from 2.4 to 9.5 inches.The panels can be manufactured at custom dimensions, though transportation restrictions dictate their length. Alternating grains improve CLT panels’ dimensional stability. This strength affords designers a host of new uses for wood, including wide prefabricated floor slabs, single-level walls, and taller floor plate heights. As with other mass timber products, CLT can be left exposed in building interiors — up to 8 stories in the 2021 IBC, offering additional aesthetic attributes. Like other mass timber products, CLT can be used in hybrid applications with materials such as concrete and steel. It can also be used as a prefabricated building component, accelerating construction timelines." - Think Wood

GLT "Glue Laminated Timber (GLT) component, wood laminations (dimensional lumber) are positioned according to their stress-rated performance characteristics. In most cases, the strongest laminations sandwich the beam to absorb stress proportionally and ensure longevity. The laminations are jointed end to end, allowing for long spans, and are bonded with a durable, moisture-resistant adhesive. The laminations’ grains run parallel with the member’s length to improve its strength. Glulam members come in standard and custom sizes. Depths range from 6 inches to 72 inches, and widths range from 2.5 inches to 10.75 inches, according to APA. Components are cut to length when ordered and can surpass 100 feet. Commercial projects often require longer spans and accommodate bigger loads than residential projects, meaning custom widths and depths are often required. In addition to straight spans, glulam can also be used for curved and pitched applications." - Think Wood

NLT "Nail Laminated Timber (NLT), dimension lumber is placed on edge with individual laminations mechanically fastened together with nails or screws. The boards are nominal 2x, 3x, and 4x thickness. Width is typically 4-12 inches. NLT gets its strength and durability from the nails/screws that fasten individual pieces of dimensional lumber into a single structural element. NLT’s revival is due in large part to domestic availability. The mass timber product does not require a dedicated manufacturing facility—compared with other building materials like cross-laminated timber (CLT)—and it can be fabricated with readily available dimensional lumber. This allows project teams and manufacturers to use locally sourced materials." - Think Wood

DLT "Dowel Laminated Timber (DLT) is similar to nail-laminated timber (NLT), without the use of screws or nails. To form DLT members, softwood lumber panels are stacked like NLT and friction-fit together with hardwood dowels. The dowels hold the boards together, and the friction fit—achieved by the differing moisture content of the softwood panels and the hardwood dowels—affords additional dimensional stability. Dowels also can be inserted diagonally, offering additional resistance. Because DLT does not use nails or screws, it is easier and safer to mill and route. The lack of an adhesive is also attractive for projects looking to maximize the use of wood." - Think Wood

Photos: Think Wood

Why use Mass Timber?

Project sites require 90% less construction traffic
15 times lighter than steel and 5 times lighter than concrete
Small-diameter logs are ethically harvested and replanted
Leaving behind old-growth trees, promoting healthy forests
"Carbon sequestration." 50% of the dry weight of wood is carbon
Mass Timber buildings are ~25% faster to construct than concrete
Modular construction is much faster at closing the building envelope
Factory CNC precision, with a climate-controlled manufacturing process
The warm appearance and aesthetics of timber are inviting and welcoming
Replacing steel with Mass Timber reduces CO2 by between 15% and 20%
During a fire resistance test of a 5-ply cross-laminated timber (CLT) panel wall the panel exceeded 1,800 Fahrenheit and lasted 3 hours and 6 minutes. Far more than the two-hour rating that building codes require.