Cross-Laminated Timber

Cross-Laminated Timber (CLT)

Innovative solid wood panels offer new large-scale design options

Cross-Laminated Timber (CLT)

CLT Basics

Cross-laminated timber (CLT) is a large-scale, prefabricated, solid engineered wood panel. Lightweight yet very strong, with superior acoustic, fire, seismic and thermal performance, CLT is also fast and easy to install, generating almost no waste onsite. CLT offers design flexibility and low environmental impacts. For these reasons, cross-laminated timber is proving to be a highly advantageous alternative to conventional materials like concrete, masonry or steel, especially in multifamily and commercial construction.


A CLT panel consists of several layers of kiln-dried lumber boards stacked in alternating directions, bonded with structural adhesives, and pressed to form a solid, straight, rectangular panel. CLT panels consist of an odd number of layers (usually, three to seven,) and may be sanded or prefinished before shipping. While at the mill, CLT panels are cut to size, including door and window openings, with state-of-the art CNC (Computer Numerical Controlled) routers, capable of making complex cuts with high precision. Finished CLT panels are exceptionally stiff, strong and stable, handling load transfer on all sides.

Photo courtesy of Structurlam Products, Ltd.

Common CLT Applications

CLT is commonly used for long spans in walls, floors and roofs.

CLT Sizing

Finished panels are typically 2 to 10 feet wide, with lengths up to 60 feet and thickness up to 20 inches. Widths up to 18 feet and lengths up to 98 feet are possible, but uncommon.

CLT TrademarkThe APA Mark of Quality

APA trademarks appear only on products manufactured by APA member mills. The mark signifies that product quality is subject to verification through APA audit—a procedure designed to assure manufacture in conformance with APA performance standards or the standard shown in the mark.

CLT Publications

Cross-Laminated Timber: North American CLT vs. Imported ProductCross-Laminated Timber: North American CLT vs. Imported Product

Cross-laminated timber (CLT) manufactured in North America must meet stringent product standards and be certified to the ANSI/APA PRG 320 Standard for Performance-Rated Cross-Laminated Timber. CLT manufactured outside of North America may not meet these performance standards.

Download >





ANSI/APA 320 Standard for Performance-Rated Cross-Laminated TimberANSI/APA PRG 320 Standard for Performance-Rated Cross-Laminated Timber

Provides requirements and test methods for qualification and quality assurance for performance-rated CLT, which is manufactured from solid-sawn lumber or structural composite lumber.

Download >


Resource Library

Access a complete list of APA publications about Cross-Laminated Timber in APA's Resource Library.