Mass Timber | Equipment & Technology Resource

Cross-Laminated Timber (CLT): CLT is a structural engineered panel made of 3 or more layers of lumber.  Each layer is oriented perpendicularly to the adjacent layer.  The layers are glued and pressed together.

Glue-Laminated Timber (GLT): GLT is an engineered wood post or beam made from multiple layers of lumber with the grain oriented in a parallel direction.  The layers are glued and pressed together.

Dowel- Laminated Timber (DLT): The wood grain in a DLT panel is parallel (orientation does not alternate).  Lumber is stacked face to face and is held together with hardwood dowels that have been dried to a low moisture content.  The hardwood dowels expand as they gain moisture resulting in a tight fit.

Nail-Laminated Timber (NLT): The wood grain in an NLT panel is parallel (orientation does not alternate).  Lumber is stacked face to face and is held together with nails.

Mass Timber Products are defined as the group of products that are derived from solid sawn lumber of various species.  The derived products include Glue-Laminated Timber, Cross-Laminated Timber, Dowel-Laminated Timber and Nail-Laminated Timber.

Most structures defined as mass timber buildings in North American have been designed and constructed using these products individually or in combination with other wood or non-wood structural materials in Hybrid Solutions (HS).

CLT and GLT products are produced from lumber that is finger jointed and end glued, or solid, to create individual laminations or lamella (luh-mel-lah).  Lamella that are glued together in a CLT panel or GLT beam are lamellas.

CLT lamella are produced from lumber grades with specific characteristics that must meet the ANSI/PRG-320 Standard for Performance Rated Cross Laminated Timber.

GLT lamella are produced from lumber grades that meet both structural and appearance requirements (CSA O122 & O86, and ANSI A190.1 & A117).  The stress and appearance grade requirements of lumber for GLT lamellas “depends on whether the intended end use of a glulam member is for a beam, a column, or a tension member” (Canadian Wood Council description).  Lamella lumber for GLT used in the US requires similar structural and appearance considerations.

Lamellas for DLT and NLT products are specified to “Product Design Guides” for each.  Lumber grades for DLT and NLT lamellas can have both structural and appearance considerations and can be butt jointed or finger jointed.