Mass timber has moved beyond solid-sawn beams and glulam into engineered panels that carry structural loads in large buildings. Mass plywood panels, often called MPP, take the veneer-based logic of plywood and scale it to panel thicknesses measured in inches rather than fractions. The result is a structural product that can form walls, floors, beams, and columns in the same building, fabricated from small-diameter logs that conventional sawmills cannot use efficiently. For engineers new to the material, the sizing options and certification data matter more than the marketing, and the basics of structural timber engineering still apply: know the material properties, the connection behavior, and the limits of the certified product.
MPP is manufactured by laminating layers of veneer into large panels, then cutting beams and columns from the panel stock. Because the process starts with veneer rather than solid logs, dimensions are set by the press and the cutting line, not by the size of the tree.
How Mass Plywood Panels Are Manufactured
Veneer is peeled from small-diameter logs, dried, coated with adhesive, and stacked in alternating or aligned layers before pressing. The MPP process turns logs that are too small for solid-sawn structural members into panels with engineered properties.
The layup is where the engineering happens. Veneer sheets are graded, oriented, and glued in a sequence that controls stiffness in both panel directions, then the stack cures under heat and pressure. Because the adhesive lines are thin and the veneers are uniform, the finished panel carries fewer voids and defects than a solid member cut from a log of the same size.
From Small Logs to Large Members
The feedstock advantage matters where forest management produces a lot of small timber. A tree that cannot yield a 12-inch-square beam can still be peeled into veneer and laminated into a panel that is cut into a beam of the same size. Yield per log rises, and the manufacturer gains a cost advantage over processes that need large logs.
MPP sits in a family of advanced construction materials that includes fiber-reinforced polymers and cross-laminated timber. What separates MPP is the combination of large format, predictable veneer-grade properties, and flexibility in thickness.
Beam and Column Dimensions: What the Numbers Mean
The useful dimensions of an MPP beam line are defined by certification and by press capacity. One current line is APA-certified up to 12 inches wide by 72 inches deep, with the ability to cut stock up to 24 inches thick. Lengths can reach 60 feet, though the press currently limits production to 48 feet.
For a designer, those numbers translate into real options. A 72-inch-deep beam can span long distances or carry heavy loads with a shallow footprint, and a 48-foot length covers most floor and roof bays without a splice. Columns cut from the same stock reach several stories, which is why the product line targets the full structural package of a building rather than one element.
Thickness Increments of One Inch
Panel thicknesses come in 1-inch increments, starting at 2 inches and running to 24 inches. Depending on how the beam is oriented, the increment applies to either the width or the depth of the member.
Width vs Depth Orientation
A beam cut from a thick panel can be oriented with the panel thickness as its depth or as its width. Specifiers confirm the orientation because it changes the section properties and the capacity tables they read from the product certification.
Project teams have built a track record with panelized mass timber in civic buildings, including libraries where the structure is left exposed. Coverage of a Washington mass timber library shows how designers use large-format wood members to shorten schedules while keeping the architecture visible.
Structural Properties and Engineering Data
Engineered wood earns its place in a structural frame through published, third-party-verified properties. For MPP, the APA product certification provides the engineering data: allowable stresses, stiffness, connection values, and the limits of the certified size range.
What Certification Covers
Certification does not cover every possible size. The line is certified to a stated maximum width and depth, and manufacturers seek additional certification as they extend into larger sections. Until that certification lands, design work should stay inside the certified envelope.
Connection design follows the veneer. Screws, brackets, and steel hangers bear on the panel face, and the orientation of the face veneer changes how hardware performs under load. The certification sheet includes connection values, and engineers should pull those tables before detailing, not after.
How MPP Compares With Other Mass Timber Products
Each mass timber product offers a different balance of size, cost, and fabrication. The table below compares the common options for beams and columns.
| Product | Typical maximum depth | Feedstock | Best fit |
|---|---|---|---|
| Glulam | 70+ inches in stock sections | Solid lumber laminations | Long-span beams and arches |
| LVL | 18-20 inches in stock, deeper custom | Veneer, aligned grain | Headers, rim board, and I-joist flanges |
| CLT | Panels up to 10 feet wide, about 16 inches thick | Solid lumber in cross layers | Floor and wall panels |
| MPP | 72 inches certified depth, 24 inches thick | Veneer, layered | Beams, columns, and panels from one process |
Tall wood buildings have pushed all of these products toward their limits, and the data trail for mass timber in tall buildings shows how material properties, not marketing, decide what gets built where.
Using MPP Across the Structural Frame
The commercial appeal of an integrated MPP line is that one manufacturer supplies panels, beams, and columns for a whole building. Most producers make either panels or glulam beams; making both from one process simplifies procurement and keeps the structural package consistent.
Panels and Linear Members From One Supply Chain
A contractor can order floor and wall panels plus the beams and columns that support them from the same source, with the same veneer grades and the same certification basis. That consistency shortens the design-assist loop and reduces the number of interfaces a project team must manage.
Prefabrication pushes the benefit further. Beams and columns arrive cut to length with connection hardware installed, which moves layout and drilling off the critical path. Erection crews set members from the manufacturer’s shop drawings, and the panel floor system ties the frame together as it goes up.
- One certification basis across panels, beams, and columns
- Fewer interfaces between manufacturers and the design team
- Consistent veneer grades and adhesive systems from building to building
- Simpler warranty and liability conversations
The sizing flexibility of MPP also fits the broader family of LVL and CLT mass timber systems used in mixed-use construction, where one building may combine light-frame, panelized, and post-and-beam zones.
Specifying MPP Beams and Columns: A Checklist
Specification starts with the certified envelope and works outward.
- Confirm the section fits within the certified width and depth limits; 12 by 72 inches is the current certified ceiling for the line described above.
- Check the length against press capacity, 48 feet today, and verify transport and crane access for long members.
- Select the 1-inch thickness increment that matches the required section properties.
- Request the APA certification sheet and confirm the allowable stresses for the orientation you plan to use.
- Verify connection details, including the veneer orientation at the face where hardware bears.
- Ask about certification status if the design needs a section beyond the current envelope.
Questions to Ask the Manufacturer
Ask which dimensions are certified and which are only producible. Ask how the 1-inch increments apply to the width or depth of the member. Ask how lead times scale with panel thickness, since press time is the constraint.
The product line keeps evolving as manufacturers push toward bigger sections. Recent structural innovations in cross-laminated timber follow the same arc: new sizes, new certifications, and new connection details arrive together.
Cost and Sustainability Considerations
Cost-competitive pricing is the stated goal of an integrated MPP line, and the economics come from feedstock and utilization. Small logs cost less, veneer yields are high, and cutting beams and columns from standard panel stock keeps waste low.
Comparing Cost Per Cubic Foot
Buyers should compare delivered cost per cubic foot of structural material rather than price per linear foot, because section sizes vary. Include fabrication, connection hardware, and erection labor, since panelized systems often save on the last two.
The carbon story starts in the forest. Veneer peeling uses small logs efficiently, and the finished members store carbon for the life of the building. Buyers should ask for the manufacturer’s environmental product declaration and compare it against the equivalent steel or concrete option for the same span and load.
The sustainability case for mass timber gets stronger when the feedstock is small-diameter timber that would otherwise go to chips or low-value products. The environmental case for mass timber depends on exactly these factors: where the fiber comes from, how much energy the process uses, and what the building displaces.