Even after it has been cut, milled, and finished, wood continues to respond to its environment. It absorbs and releases moisture depending on the temperature and humidity of the space around it. Before your new floor is installed, it needs time to adjust to those conditions — a process called acclimation. Skip it, and even a high-quality floor can warp, gap, or buckle within months of installation.
Why Acclimation Is Not Optional
Flooring boards are stored and shipped in controlled warehouse conditions that almost certainly differ from your home. When boards arrive at a different humidity or temperature, they will immediately begin to absorb or release moisture. If they are installed before this adjustment is complete, the movement occurs after the boards are fixed in position — and the floor bears the consequences. Most flooring warranties require documented acclimation as a condition of validity, and installers will often decline to proceed without it.
The Room Must Be at Living Conditions
Acclimation only works if the room is in its normal, occupied state. The building must be fully enclosed — doors and windows fitted, all wet trades (plastering, screeding, painting) complete and fully dry. Heating must be running as it will be day-to-day. The target conditions are a temperature of 15–25°C and a relative humidity of 35–55%. Bringing boards into a cold, unheated shell in the middle of construction and calling that “acclimation” is not effective and will not protect you under warranty.
How to Stack and Store Boards During Acclimation
Boards should be stored in the room they will be laid, not in an adjacent corridor or garage. Remove packaging or open boxes and separate boards with wooden spacers (stickers) so that air can circulate around every board. Never stack boards directly on a concrete floor — lay polythene sheet first to prevent moisture wicking up from below. Boards should be kept away from direct sunlight, radiators, and open windows during the acclimation period. Store the flooring flat and supported so that boards cannot bow or twist.
Measuring Moisture Content Before and During Acclimation
The only reliable way to know when acclimation is complete is to use a calibrated moisture meter. Take readings of both the subfloor and the flooring boards before delivery, record them, and repeat every day or two throughout the acclimation period. Installation should not begin until the board moisture content is within 2–4% of the subfloor moisture content. For a timber subfloor, the target is below 12% MC; for a concrete subfloor, below 75% RH (measured with an in-situ RH probe) or below 3% using a surface probe.
How Long Does Acclimation Take?
Duration depends on the product type, the degree of difference between shipping and installation conditions, and the board dimensions. As general guidance: solid wood flooring typically requires 5–14 days, and sometimes longer for thick, wide boards or in rooms with extreme humidity differences. Engineered wood flooring — which is more dimensionally stable due to its cross-ply core — typically requires 48–72 hours. Always follow the manufacturer’s specific guidelines; these take precedence over general industry guidance and govern the warranty.
Solid vs. Engineered: Does the Acclimation Differ?
Yes — and the difference is significant. Solid wood flooring is a single homogeneous timber section, so it responds fully to any change in surrounding humidity or temperature. Engineered flooring’s cross-ply construction resists that movement considerably, which is why its acclimation period is shorter and its performance over underfloor heating and concrete subfloors is more predictable. That said, engineered boards still need to reach thermal equilibrium with the room before installation — a weekend in the space they will be laid is the minimum in most cases.