What Is Jatoba Wood’s Dimensional Stability?
Jatoba, also called Brazilian cherry, has moderate dimensional stability: it moves as its moisture content changes, though not as much as less stable woods. Published shrinkage figures are about 5.3% radially and 8.5% tangentially from green wood to oven-dry. Those are not seasonal floor-movement predictions. Dry materials, a suitable subfloor, and required movement gaps are essential.
If flooring specifications feel like a codebook, the key distinction is simple: a wood’s lab shrinkage rating describes its potential change across a very large moisture range. It does not tell you exactly how far a finished floor will move in your home. Jatoba’s movement depends on the flooring, installation, and indoor moisture conditions.
Wood dust from cutting or sanding can irritate some people, so use suitable dust collection and follow tool safety guidance. That concern is separate from dimensional stability, which is the focus here.
What Jatoba’s dimensional-stability rating means
Dimensional stability describes how much wood changes size as it gains or loses moisture. Jatoba has moderate stability, not exceptional stability. Its published shrinkage figures show that it can move, especially across the grain, so moisture control and installation clearances matter.
Jatoba is also known as Brazilian cherry, though it is not a true cherry species. For flooring, the important point is not the name or hardness alone. Even a hard wood can expand, contract, cup, or develop gaps when its moisture conditions change.
The terms “radial” and “tangential” describe directions within the wood:
- Radial shrinkage is across the growth rings, from the center of the tree outward.
- Tangential shrinkage is along the growth rings, around the tree.
- Longitudinal shrinkage is along the grain; it is usually much smaller than across-grain movement.
The reported 5.3% radial and 8.5% tangential figures describe change from green wood to oven-dry wood. That is a broad laboratory range, not a forecast that an installed floor will shrink by those percentages. Finished flooring is installed at a much narrower moisture range.
How Jatoba’s shrinkage numbers compare
Shrinkage numbers help describe a species, but they do not predict the movement of a particular floor. Compare them only when the source uses the same test method and conditions. For installation decisions, the product’s moisture readings, plank width, and manufacturer’s instructions are more useful.
| Measure | Jatoba figure or meaning | Practical use |
|---|---|---|
| Radial shrinkage | About 5.3% | Laboratory change across growth rings |
| Tangential shrinkage | About 8.5% | Laboratory change around growth rings |
| Difference between figures | Tangential is higher | Boards can respond differently depending on grain orientation |
| Seasonal floor movement | Not given by these figures | Depends on actual moisture change, board width, layout, and installation |
The difference between radial and tangential shrinkage helps explain why wood can distort as moisture changes. It does not mean every Jatoba board will cup. Grain pattern, how the board was cut, moisture conditions on each face, and the support beneath the floor all play a role.
I read species data as a warning about what to control, not as a stand-alone pass-or-fail rating. For Jatoba, the useful conclusion is that moisture imbalance can cause real movement, so the floor needs a dry, sound base and room to move.
What causes Jatoba flooring to move?
Wood exchanges moisture with the air around it. When indoor conditions change, wood moisture content can change too. Jatoba may expand as it gains moisture and contract as it dries; the size and direction of movement depend on the floor’s construction and the moisture conditions.
Temperature often matters because heating and cooling can change indoor relative humidity. Relative humidity is the amount of water vapor in the air compared with the maximum it could hold at that temperature. The wood responds to moisture, not to a temperature number by itself.
Uneven moisture is a particular concern. If the underside of a floor takes on more moisture than the top, boards may cup, meaning their edges rise relative to the center. If the floor dries, gaps can appear between boards. Moisture from a slab or subfloor can also contribute to edge lift or adhesive problems.
Common causes to check include:
- A damp wood subfloor or concrete slab.
- Indoor humidity that changes widely between seasons.
- Flooring installed before it has reached moisture conditions suited to the building.
- Missing movement space at walls or fixed objects.
- A floor restrained by trim, cabinetry, partitions, or transitions.
A moisture barrier cannot correct every problem. It must be part of a tested, compatible flooring system, and it does not fix active water intrusion or an unprepared substrate.
Jatoba flooring substrate inspection and subfloor preparation
The subfloor is the structural base beneath the flooring. It must be dry, firmly attached, sound, and flat enough for the selected product. For solid Jatoba over framing, use an approved wood subfloor over joists meeting at least L/360 deflection; do not install solid hardwood directly over concrete.
L/360 is a measure of floor stiffness under load. It means the floor’s deflection is limited to about one part in 360 of the span. It is a minimum support guideline in this installation context, not a guarantee that every assembly meets every local requirement or product instruction.
Before installation, check:
- Support: Confirm the joists and subfloor meet the flooring manufacturer’s requirements. Repair loose panels, squeaks, and areas that move.
- Flatness: Prepare the surface to within 3/16 inch over 10 feet or 1/8 inch over 6 feet, unless the product requires a tighter limit.
- Wood moisture: Use a calibrated pin-type moisture meter on both the flooring and wood subfloor. Compare the readings, not just one reading on its own.
- Concrete: Consider only engineered Jatoba products approved for concrete, with the specific moisture-control system approved by the flooring and adhesive makers.
For wood subfloors, a common NWFA-based guideline is a moisture-content difference of no more than 4 percentage points for strip flooring under 3 inches wide, and no more than 2 points for planks 3 inches or wider. Follow stricter product instructions where they apply.
For an approved engineered floor over concrete, moisture testing may call for ASTM F2170, which measures in-slab relative humidity, and/or ASTM F1869, which measures moisture vapor emission rate. There is no single acceptable RH or MVER limit for all products. Use the lowest limit required by the flooring and adhesive system.
Installation technique and moisture control
Acclimation means conditioning flooring at the job site according to the manufacturer’s procedure. It is not simply leaving boards in a room for a set number of days. The goal is to confirm that the flooring’s moisture condition is suitable for the expected indoor environment and the installation system.
Use this sequence to reduce avoidable movement:
- Inspect and correct the subfloor. Verify support, attachment, flatness, and dryness before laying flooring.
- Measure moisture in the flooring and wood subfloor with a calibrated pin meter. Record readings and compare them with the product’s requirements.
- Choose an approved assembly. Over wood framing, use the required plywood or OSB subfloor and underlayment configuration. Over concrete, use only an engineered Jatoba product approved for that use.
- Follow the specified fastening or adhesive method. Do not improvise a membrane-and-adhesive combination; materials must be approved together.
- Stagger end joints as directed and leave the required perimeter and intermediate expansion space.
- Fit trim and transitions so they hide the movement gap without pinning the floor.
A half-inch perimeter gap is a common minimum reference, not a universal rule. Room size, plank format, and the installation system may require more. Do not trap the floor beneath fixed cabinetry or partitions unless the product instructions expressly allow it.
Worked installation scenarios: where stability is won or lost
These are practical scenarios, not reports of a specific job. They show how the same Jatoba flooring can face different risks depending on the base and installation choices. In both cases, the manufacturer’s instructions and test limits control the final decision.
| Scenario | What the installer finds | Stability-focused response |
|---|---|---|
| Solid Jatoba over wood framing | Wood subfloor is sound, flat, and within the product’s moisture requirements | Confirm joist support, compare moisture readings, then install with the approved fastening method and required clearances |
| Engineered Jatoba over concrete | The slab has not yet been tested | Test using the method required by the product and adhesive makers; do not install until readings meet their limits or an approved mitigation system is in place |
| Damp subfloor beneath flooring | Readings exceed the system’s allowable range or show an unresolved moisture source | Stop and find the source. A membrane alone does not make an untested or wet assembly safe to cover |
In the first scenario, the key is not that Jatoba is immune to movement. It is that the support, moisture readings, and installation details are checked before the floor is fixed in place. In the concrete scenario, engineered construction may be suitable, but only as an approved assembly.
If a substrate is moisture-compromised, do not install over it and hope the floor will settle. Excess moisture can lead to cupping, edge lift, adhesive failure, or persistent gaps.
Maintaining Jatoba’s dimensional stability
Maintenance cannot prevent all seasonal movement, but stable indoor conditions can limit the moisture swings that drive it. Keep temperature and relative humidity within the flooring manufacturer’s service range. Clean spills promptly and use entry mats to reduce water and grit reaching the floor.
Avoid using trim as a clamp. Baseboards and transitions can cover expansion space, but they should not lock the flooring in place. If gaps or raised edges appear, check for changes in indoor humidity and moisture below the floor before attempting a repair.
Conclusion
Jatoba has moderate dimensional stability. Its published 5.3% radial and 8.5% tangential shrinkage values describe green-to-oven-dry laboratory change, not expected seasonal movement in a home. The practical safeguards are a dry, flat, suitable substrate, compatible moisture readings, an approved installation system, and required movement clearance.
Frequently asked questions
Is Jatoba dimensionally stable?
Jatoba has moderate dimensional stability. It can expand or contract as its moisture content changes. Its laboratory shrinkage figures describe a broad moisture range, so they should not be treated as a direct estimate of seasonal movement in an installed floor.
Does Jatoba flooring expand in summer?
It can expand if it gains moisture, but the amount depends on indoor conditions, board width, and installation. Seasonal timing alone does not predict movement. Follow the product’s humidity range and keep the required expansion space clear.
Does Jatoba shrink in winter?
It can contract if it loses moisture, which may contribute to gaps between boards. Heating can affect indoor humidity, but the result varies by building and climate. Use the flooring maker’s service range rather than assuming a fixed seasonal gap.
What do Jatoba’s radial and tangential shrinkage figures mean?
Radial shrinkage measures change across the growth rings, while tangential shrinkage measures change around them. Jatoba is reported at about 5.3% radial and 8.5% tangential from green to oven-dry. These are lab values, not seasonal floor predictions.
Can solid Jatoba be installed over concrete?
Do not install solid hardwood directly over concrete. Engineered Jatoba may be suitable only when its manufacturer approves the concrete assembly and specifies the moisture testing, vapor control, and adhesive system.
How much moisture difference is acceptable before installation?
A common NWFA-based guideline is no more than 4 percentage points between flooring and wood subfloor for strips under 3 inches wide, or 2 points for planks 3 inches or wider. Follow stricter product-specific requirements.
How much expansion space does Jatoba need?
Use the flooring manufacturer’s required perimeter and fixed-object clearance. A half-inch gap is a common minimum reference, but larger rooms or different products may require more. Keep trim from pinning the floor.
Can a moisture barrier solve a damp-slab problem?
Not by itself. The slab must be tested, and the flooring, adhesive, and moisture-control system must be approved as an assembly. If test results exceed the system’s limits, use only manufacturer-approved mitigation before installation.
(This article was written by one of our staff writers, Marcus Vance. Visit our Meet the Team page.)
