Compare complete building options with the same program and scope, not structural material prices alone. Mass timber often carries a small structural premium but can shorten the schedule and lighten the foundations, and those effects only show up when the whole building is priced and scheduled.
What published numbers say, and what they do not
In “Putting Numbers to ‘It Depends’” (International Mass Timber Report, 2023), Emily Dawson summarizes experience from U.S. commercial mass timber projects. The article reports that there is generally a premium for a mass timber project, up to 15 percent, with a median project premium of less than 2 percent. It reports that the total construction schedule can be reduced by up to 25 percent, and that a 20 percent reduction is now the norm. It also states that a timber building on average weighs only 20 percent as much as a steel or concrete structure, with the largest foundation savings in high seismic zones.
These are industry-wide summaries, not a prediction for your site. Soil, seismic zone, local labor, supplier lead times, and the design itself all move the result. Use them to decide what to study, then price your own options. Sources verified October 22, 2026. Within a mass timber scheme, see how design decisions affect mass timber cost. Lighter structure matters most for mass timber vertical additions.
Compare these factors on every option
| Factor | What to compare | Where the evidence is |
|---|---|---|
| Structure | Material, fabrication, and erection cost for the same grid and spans. | Structural drawings, supplier pricing, estimates |
| Schedule | Fabrication lead time, erection duration, and when follow-on trades can start. | Supplier schedule, construction schedule |
| Foundations | Footing and pile size for each option’s building weight, soil, and seismic demand. | Geotechnical report, foundation design |
| Floor-to-floor height | Structure depth plus the services below it. Exposed timber can change how ducts and pipes are routed. | Building sections, MEP routing, ceiling plans |
| Finishes | Ceilings, fireproofing, and finishes each option needs, including protection for timber that must be covered. | Code analysis, reflected ceiling plans, finish schedules |
| Fire and acoustics | Protection and assemblies needed to meet the construction type and acoustic goals. | Code analysis, assembly types, acoustic report |
| Insurance | Builder’s risk and property insurance terms during construction and in use. | Broker feedback, insurance playbook submission |
| Coordination effort | How much must be finalized before fabrication, such as penetrations and connections. | Project schedule, design and fabrication milestones |
Keep the comparison fair
- Same scope. Price the same program, area, and performance targets for each option. A timber option with exposed ceilings and a concrete option with dropped ceilings are not the same finish scope.
- Same assumptions. Use one soil report, one seismic basis, and one schedule start for every option.
- Include schedule value. A shorter schedule can change financing, general conditions, and when the owner earns income. Agree with the owner how earlier completion is valued before comparing totals.
- Use design guidance early. The WoodWorks design and cost optimization checklists are meant for designers and builders to work through together, and many topics should be discussed with fabricators.
Weight matters most on difficult sites
Lighter structures reduce gravity and seismic loads. WoodWorks notes that seismic forces are directly tied to a building’s mass, and that mass timber’s light weight is one reason it suits vertical additions on existing buildings. On good soil with simple footings, the saving may be small. On poor soil, in high seismic zones, or on top of an existing building, it can decide whether the project works at all.
Count the coordination cost honestly
Mass timber moves many decisions earlier. Openings, connections, and hardware are usually settled before the panels are cut, so design and coordination effort is front-loaded. Insurance can also take more preparation; the Mass Timber Insurance Playbook encourages early engagement with insurers. Build these into the comparison instead of discovering them after the system is chosen.
Where Groundbook fits
Once you choose a system, the drawings have to agree with it. Upload the architectural, structural, and MEP sets with the specifications, and run a cross-discipline review. Groundbook flags potential disagreements, such as a ceiling plan that assumes exposed timber while the code analysis requires protection, with links to each source sheet. It does not estimate cost, schedule, or carbon, and it does not choose the structural system.