In tall mass timber buildings, timber columns and connections move vertically through axial shortening, creep, shrinkage, crushing perpendicular to grain, and connection settlement. Check that the drawings show how cores, facades, partitions, and vertical MEP services accommodate that movement, and how the structure can be adjusted in the field.
Where the movement comes from
The WoodWorks solution paper Differential Material Movement in Tall Mass Timber Structures, written with Fast + Epp, lists the main sources of vertical movement: column axial shortening, column creep, shrinkage of columns, beams, and panels, crushing of beams and panels perpendicular to grain, and settlement at connections. It explains that wood shrinks far more across the grain than along it, so beam depth and panel thickness in the vertical load path add up over many floors.
The paper’s main concern is the effect on vertical mechanical systems, exterior enclosures, and interior partitions, and the movement of the timber frame relative to concrete core walls and facades. It also notes that IBC Section 2304.3.3 requires wood-framed projects over three stories to include an analysis of shrinkage effects. Read the full paper for the calculation methods. Sources verified October 22, 2026.
Interfaces that must allow for movement
| Interface | Why it moves differently | What to look for in the drawings |
|---|---|---|
| Timber frame to concrete core | Concrete cores shrink much less than the timber frame beside them. | Beam and panel connections to the core that allow vertical adjustment, such as oversized embed plates. |
| Column to column | Beam and panel shrinkage adds up if columns bear on beams at each floor. | Column-to-column bearing that keeps beams out of the vertical load path, with shims for field adjustment. |
| Facade and glazing | Exterior columns shorten while the facade system may not. | Movement joints and slip connections in the cladding and curtain wall details. |
| Interior partitions | Floors above deflect and settle onto walls below. | Head-of-wall slip connections that let the structure move without loading the partition. |
| Vertical MEP services | Services that run from the core into timber floors span two structures that move by different amounts. | Riser supports and expansion provisions where services cross between the core and timber floors. |
| Elevators and stairs | Where a shaft is concrete and the floors are timber, the floor moves relative to the shaft. | Landing and door sill details that account for the floor moving relative to the shaft. |
Eight movement checks for the drawing set
- Shrinkage analysis. Confirm the structural documents state that shrinkage and movement were analyzed, and where the expected values are recorded.
- Load path. Trace the vertical load path at typical columns. Note where beams or panels sit between columns, because that is where shrinkage and crushing accumulate.
- Field adjustment. Look for shims, adjustable connectors, or other details that let the installer correct elevations in the field.
- Core connections. Check every beam and panel connection to the core for a detail that allows vertical movement and placement tolerance.
- Facade joints. Compare the structural movement assumptions with the movement joints shown in facade and curtain wall details.
- Partition heads. Confirm partition types attached to the underside of timber floors use slip or deflection head details.
- Risers and shafts. Check plumbing, mechanical, and electrical risers for supports and expansion provisions where they pass from the core into timber floors.
- Consistent values. Compare the movement or deflection allowances stated in structural notes, facade specifications, and partition details. Different numbers need a question.
Learn from a built project
The WoodWorks paper describes Brock Commons Tallwood House in Vancouver, an 18-story hybrid building with 17 stories of mass timber over a concrete podium and two concrete stair cores. A specific concern there was the effect of vertical movement on mechanical services running through the CLT floor panels next to the concrete cores. Details at the timber-to-concrete interface were designed to allow adjustment, because concrete construction tolerances are larger than mass timber tolerances.
The paper notes that construction documents that explain how to make field adjustments at material interfaces are an important part of the long-term solution. When you review a set, look for that guidance, not only for the structural connection itself.
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.