Wood Flooring Movement by Species
In this article 7 sections
Wood floors move as their moisture content changes. Species affects how much a board may expand or shrink, but species is only part of the answer. Plank width, grain direction, floor construction, and the range of indoor conditions all affect what becomes visible after installation.
The coefficient table on this page is useful for comparing species and estimating movement across the width of a board. It is not a promise of the exact gap or expansion that every board will show.
What affects the estimate
Moisture change
The calculation uses the change in the wood’s moisture content, measured in percentage points—not the change in relative humidity shown by a thermostat or hygrometer.
Board width
Movement is proportional to width. Under the same conditions, a wider solid plank can show more change across each board than a narrow strip.
Species and cut
Species have different coefficients. Plainsawn boards generally move more across their face than quartersawn or riftsawn boards of the same species.
What a dimensional change coefficient tells us
A dimensional change coefficient estimates how much a particular wood changes across its width for each percentage-point change in moisture content. In this table, a higher coefficient means more predicted movement when board width and moisture change stay the same.
The values are tangential coefficients, which are the practical reference for predominantly plainsawn solid flooring. Wood does not move equally in every direction. Tangential movement follows the growth rings and is normally greater than radial movement across them. Movement along the length of a board is comparatively small.
How to estimate board movement
Moisture-content changecoefficientboard widthestimated width change
Example: a 5-inch red oak board
A red oak board with a coefficient of 0.00369 experiences a moisture-content change from 6% to 9%. That is a change of three percentage points.
3 × 0.00369 × 5 = 0.055 inches
The estimate is about 0.06 inch of width change per board. It is an average calculation, not a prediction for every individual board.
Why the coefficient is not the whole floor
Species comparisons are useful, but they do not decide whether a flooring product is suitable by themselves. A complete decision also considers:
- Board-to-board variation. The coefficient is an average. Grain orientation and natural variation cause individual boards to respond differently.
- Plank width. The same percentage change produces more absolute movement across a wider board.
- Solid or engineered construction. Cross-layered construction can reduce width movement, but engineered flooring still has manufacturer requirements for interior conditions and installation.
- The expected indoor environment. The relevant question is the range the building can maintain through dry and humid seasons, not a single reading taken on installation day.
- Product and installation requirements. Manufacturer instructions, subfloor conditions, expansion space, fastening or adhesive requirements, and the time of installation remain part of the floor system.
This is also why hardness and dimensional stability should not be treated as the same property. A wood can resist denting and still move substantially as its moisture content changes.
Dimensional change coefficients by wood species
Higher number = more predicted width change. The published values are retained below for comparison; the extra decimal places should not be read as a guarantee of exact field performance.
| Wood species | Tangential DCC |
|---|---|
| American beech | 0.00431 |
| True hickory | 0.00411 |
| Jarrah | 0.00396 |
| Red oak | 0.00369 |
| White oak | 0.00365 |
| Hard maple | 0.00353 |
| Yellow birch | 0.00338 |
| Pecan | 0.00315 |
| Brazilian cherry (jatoba) | 0.00300 |
| Black walnut | 0.00274 |
| White ash | 0.00274 |
| Douglas-fir | 0.00267 |
| Southern yellow pine | 0.00265 |
| Heart pine | 0.00263 |
| Black cherry | 0.00248 |
| Santos mahogany | 0.00238 |
| Purpleheart | 0.00212 |
| Wenge | 0.00201 |
| Teak | 0.00186 |
| Padauk | 0.00180 |
| Australian cypress | 0.00162 |
| Merbau | 0.00158 |
| Mesquite | 0.00129 |
Source: National Wood Flooring Association, Wood Species A200 (revised 2023). The U.S. Forest Products Laboratory recommends treating dimensional change coefficients as estimates because species averages, measurements, and individual boards vary.
What this means when choosing a floor
A lower coefficient can be useful, but it does not automatically make one floor better than another. The desired appearance, board width, cut, solid or engineered construction, expected interior conditions, and the manufacturer’s requirements need to work together.
For a broader comparison of construction choices, see solid and engineered hardwood floor types. If wide boards are part of the plan, review the additional considerations on our wide plank flooring page.
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