Mass timber cost is driven mostly by early decisions: the structural grid and panel sizes, floor thickness as set by structure, vibration, fire, and acoustics, the appearance grade, connection types, and how MEP openings are handled. WoodWorks recommends making these decisions with the fabricator and builder involved, and comparing whole-project cost rather than the price of the frame alone.
What WoodWorks says drives cost
The WoodWorks Mass Timber Cost and Design Optimization Checklists (May 2023) are organized by phase: pre-design, schematic design, and design development. They say structure, vibration, fire resistance, and acoustics usually have the biggest influence on cost, and that vibration often controls floor panel thickness rather than span.
They also warn that a direct comparison of a mass timber frame price with a steel or concrete frame price will not give an accurate overall project comparison. Schedule, foundations, finishes, and installation labor belong in the comparison. The full checklists list each item with resources. Sources verified October 22, 2026. For a whole-building comparison, see mass timber vs. concrete and steel.
Design decisions and where they show up
| Decision | Why it affects cost | Where to see it in the drawings |
|---|---|---|
| Structural grid | Grids sized to standard panels reduce cutting and waste. WoodWorks suggests starting on an 8- or 10-foot module. | Grid plans and framing plans |
| Panel sizes | Larger panels mean less machine cutting and waste. Manufacturers’ press sizes and shipping limit the size. | Panel layout plans |
| Floor thickness | Thinner panels cost less, but vibration, fire, and acoustics may require more. | Floor assembly types, structural notes |
| Topping | Wet versus dry toppings change schedule and building weight. | Floor assembly types, specifications |
| Appearance grade | Architectural grades cost more than industrial grades. | Reflected ceiling plans, finish schedules, specifications |
| Connections | Shop-installed connectors cost less than field-installed ones; stainless or galvanized hardware adds cost. | Connection details, specifications |
| MEP openings | Openings cut in the factory are cheaper and less risky than openings cut in the field. | MEP plans compared with panel layouts |
| Slab edges and geometry | Unique geometries and varying slab edges increase cost. | Floor plans, slab edge details |
Eight cost questions to ask at schematic design and DD
- Delivery method. Has the team chosen a contract model that brings in builder and supplier input before bid? WoodWorks calls design-bid-build without that input neither a best practice nor cost-effective.
- Supplier options. Has the team identified possible fabricators, and are grids sized to work for more than one of them on a competitively bid project?
- Grid adjustments. Could small grid changes let more panels use standard sizes?
- Panel thickness. Which requirement controls floor thickness: span, vibration, fire, or acoustics? Are the structural and acoustic consultants working from the same assembly?
- Exposure. Which ceilings are exposed timber and which are concealed? Can industrial grade be used where the timber is not seen?
- Hybrid options. Has the team considered hybrid systems, such as timber panels on steel beams, where they suit the project?
- MEP routing. Can services run at panel ends or above or below the panels instead of through them? Has the team set a deadline for coordinating penetrations with the fabricator?
- Estimating milestones. Are budgets and estimates scheduled at the end of schematic design, design development, and construction documents?
Make the decisions visible in the drawings
Cost decisions only hold if the drawings carry them through. A grid adjusted for panel sizes in schematic design can drift during design development. A finish grade changed in the specifications may not reach the reflected ceiling plans. Compare the structural, architectural, and MEP sets at each milestone so that the decisions the estimate is based on are the ones the drawings show.
The mass timber drawing coordination checklist covers the later check before fabrication. The 30, 60, and 90 percent design review guide explains how to run milestone reviews.
Where Groundbook fits
Upload the architectural, structural, and MEP drawings with the relevant specification sections, and run a cross-discipline review. Groundbook flags potential disagreements, such as an opening shown on an MEP plan but missing from the structural panel layout, with links to each source sheet. Your team decides what each finding means for the fabrication package. Groundbook does not check structural capacity, fire ratings, or the fabricator’s model.