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

Cross-Laminated-Timber-CLT

ANSI/APA PRG 320-2025: Standard for Performance Rated Cross-Laminated Timber

ANSI/APA PRG 320 is the American National Standard for Performance-Rated Cross-Laminated Timber (CLT), establishing requirements for dimensions and tolerances, structural performance, test methods, quality assurance, and product marking for CLT panels manufactured from solid-sawn lumber or structural composite lumber. The standard defines product performance classes — including basic and custom CLT grades and layups — and provides the design values that engineers and specifiers need to incorporate CLT into building designs using either Allowable Stress Design (ASD) in the U.S. or Limit States Design (LSD) in Canada. For manufacturers, PRG 320 sets the qualification and ongoing quality assurance framework required to certify CLT products; for code officials, it provides the recognized benchmark for confirming that CLT used in construction meets consistent, performance-based criteria.

Download ANSI/APA PRG 320

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ANSI/APA PRG 320 Scope and Key Requirements

ANSI/APA PRG 320 provides the requirements for manufacturing, qualifying, and marking performance-rated cross-laminated timber (CLT). It serves as the recognized product standard for CLT in North America, used by manufacturers to certify their products, by engineers and architects to specify CLT with published design values, and by code officials to verify compliance with building code requirements.

Scope & Application

  • Applies to CLT panels made of at least three orthogonal layers of graded sawn lumber or structural composite lumber (SCL) bonded with structural adhesives

  • Covers CLT intended for dry service conditions, such as most covered structures, where equilibrium moisture content remains below 16% in the U.S. or 15% (not exceeding 19%) in Canada

  • Does not cover finger joining, edge gluing, or face gluing between CLT panels, or camber of CLT panels

Key Requirements

  • Panel dimensions and tolerances for thickness, width, length, squareness, and straightness

  • Component requirements for laminations (species, grade, size, moisture content, and surface preparation), adhesives, and lamination joints (end, edge, and face)

  • CLT performance criteria including basic and custom grade and layup definitions, structural performance requirements, and appearance classifications

  • Plant and process qualification through block shear and cyclic delamination testing of manufactured qualification panels

  • Mechanical property qualification through flatwise and edgewise bending and shear testing to confirm published design values

  • Adhesive elevated temperature performance evaluation using the Compartment Fire Test method (Annex B) to guard against char layer fall-off during the cooling phase of a fire

  • Ongoing quality assurance for end joints, face joints, and edge joints, including daily sampling and testing requirements during production

  • Certification and product marking by an approved agency, with required mark content including CLT grade, thickness, mill identification, and conformance to PRG 320

Download ANSI/APA PRG 320

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