Design Freres Mass Ply Panel to the NDS

Freres Engineered Wood (Freres Lumber Co., Lyons, Oregon) manufactures Mass Ply Panel (MPP), a mass-timber panel built from Douglas fir laminated veneer lumber. It is recognized under APA Product Report PR-L325, rated to ANSI/APA PRG-320. SPEC Toolbox designs the panels to the NDS, using the report’s reference design values in allowable stress design.

The integration covers the Freres Mass Ply Panel, built from nominal 1-in. Douglas fir LVL layers that are parallel-laminated, cross-oriented and pressed into a solid panel in PRG-320 layups.

• Grades F16 and F10, made from 1.6E and 1.0E Douglas fir LVL respectively.
• From about 2 to 12 in. thick (2 to 12 plies), in widths of 4, 8, 10 and 12 ft and lengths up to 48 ft.
• Applications in floor, roof and wall panels.

At a glance, in the US scope the Freres MPP supports:

• Load-bearing floors, roofs and walls.
• Allowable stress design (ASD).
• Dry service (solid-sawn moisture content below 16 percent).

• A veneer-based mass panel. MPP is built from Douglas fir LVL layers rather than sawn lumber, giving a dense, dimensionally stable panel with unglued edge joints staggered between layers.
• Reference design values in both directions. The report tabulates effective bending capacity, bending and planar-shear stiffness, and planar shear in the major and minor directions, for the F16 and F10 grades.
• Wide, long panels. Panels are produced up to 12 ft wide, 48 ft long and 12-1/4 in. thick, for wide floor and roof plates with fewer joints.
• Fire resistance to two hours. MPP may be designed for fire exposure up to 2 hours by calculation per NDS Chapter 16 and IBC Section 722.

The Freres MPP panels are available across the SPEC Toolbox CLT modules, worked in ASD to the NDS:

• CLT floor, CLT wall and CLT shear wall.

and in the connection modules:

• the screw connection module and the panel-to-panel connection details (spline, butt joint and half-lap);
• CLT floor-to-glulam beam, CLT floor-to-floor and CLT wall-to-wall connections.

Panel behaviour is taken from the integrated database with the reference design values of PR-L325, including the equivalent specific gravity used for fastener design.

Design follows the ANSI/AWC NDS under the IBC and IRC. APA Product Report PR-L325 publishes ASD reference design values for the MPP panels, rated to ANSI/APA PRG-320: effective bending capacity, bending and planar-shear stiffness, and planar shear, in the major and minor directions, for grades F16 and F10. These are adjusted per NDS Section 10.3 (cross-laminated timber). Connections are designed per NDS Chapter 12 using the report’s equivalent specific gravity and minimum nail geometry. The panels are made from Douglas fir LVL and are for dry service (solid-sawn moisture content below 16 percent); fire resistance is determined by calculation per NDS Chapter 16, for up to 2 hours. The ASD reference values convert to LRFD strengths through the NDS format conversion where required.