Wood Floor Acclimation: Does It Matter?

Short answer: does it matter?

In most cases, yes, though the details depend on the product. Wood takes up and gives off moisture as the surrounding air changes, and it swells and shrinks as a result. Acclimation means letting the flooring adjust to the conditions inside the building before it is nailed, glued or floated, so that it does not move much after installation.

Because products and climates differ, the installation instructions from the flooring manufacturer should always be your first reference. Some manufacturers ask for a set period and some give a moisture target. Where those instructions conflict with general advice here, follow the manufacturer, as ignoring them can also affect a warranty.

Why wood needs to adjust

Wood is hygroscopic: it exchanges moisture with the air (see the ideal humidity for wood furniture for the same principle indoors). Boards stored in a humid warehouse and then installed in a dry, heated home will tend to lose moisture and shrink. Boards that go from dry storage into a damp building can swell. A floor locked in place at the wrong moisture level may react later with gaps between boards or, in more severe cases, pressure that pushes boards upward.

Acclimation is meant to bring the flooring close to the moisture level it will live at in the finished room, which is why the building’s heating, cooling and humidity conditions matter as much as the boards themselves.

What can go wrong if you skip it

Possible problems include:

Gaps opening between boards as wood dries and shrinks.
Cupping, where board edges rise higher than the center.
Crowning, where the center rises higher than the edges.
Buckling or lifting if swollen boards have nowhere to expand.
Squeaks and loose joints.

Not every installation shows these problems, and moisture from the subfloor, leaks or seasonal swings can also cause them. Acclimation reduces one common risk, but it is not a guarantee.

How to acclimate wood flooring

Get the room ready

Common advice from manufacturers and installers includes:

Finish wet work first, such as drywall, painting and concrete, so the building has dried out.
Have the building enclosed and the heating or air conditioning running as it will normally be used, often for a couple of days before the flooring arrives.
Keep a steady, comfortable room temperature and moderate indoor humidity. Many guides cite temperatures around 60 to 80 degrees Fahrenheit and relative humidity in the range of roughly 30 to 50 percent, but exact ranges vary by manufacturer, so check the instructions for your product.

Store and stack the boards

Bring the flooring into the room where it will be installed, not a garage or porch.
Keep boxes off bare concrete and away from exterior doors, vents and direct sun.
Many manufacturers suggest opening the packaging, or at least loosening it, so air can reach the boards. Some products, however, are designed to stay sealed until installation. Follow the product guidance.
Solid wood is often stacked with small spacers between layers so air can circulate. Do not lean boards upright against a wall.

Check with a moisture meter

Time on the calendar is a rough guide. A moisture meter is a better one. Typical advice is to measure both the flooring and the subfloor and to compare them.

Pin-type meters are common for wood. Settings differ for different species, so set the meter correctly and use the instruction sheet.
Take several readings across several boards and spots, and keep notes over multiple days.
Many installation guides ask that the moisture content of the flooring and subfloor be within a small difference of each other, and that the readings stop changing. Specific numbers vary by manufacturer and board width, so use the figures in your instructions.
For concrete subfloors, moisture testing follows its own methods, so check the flooring maker’s requirements.

How long it takes

Guides often mention anywhere from a few days to a couple of weeks for solid wood, with longer times in some climates or for certain products. Rather than counting days, aim for stable readings. If the boards were shipped from a very different climate, or the building is not yet at normal conditions, expect to wait longer.

Solid vs engineered vs other floors

Solid hardwood moves the most with humidity and is the type most commonly advised to acclimate.
Engineered wood (see is engineered wood hardwood) is built from layers and is generally more stable, but manufacturers differ. Some require acclimation and some say little is needed. Do not assume either way.
Laminate floors are usually advised to sit in the room for a period before installation as well, though the instructions vary. See our overview of types of wood laminate flooring.
Unfinished boards are often sanded and finished on site, and moisture stability matters for the finishing stage too. Our article on unfinished and finished wood explains how those differ.

What is the “Rule of 3”?

Different sources use the phrase differently, and there is no single universal definition. Because of that, treat it as a rule of thumb at most. Some flooring contexts refer to a three-way check of the room, the subfloor and the flooring being at similar conditions, but that is not an official standard. Rely on your product instructions instead.

Downsides of engineered wood

Engineered wood has trade-offs. The wear layer is thinner than solid wood, so it can often be refinished only a limited number of times, which matters if you plan to change its look later (see how to change the color of a hardwood floor). Quality varies between products, some are more sensitive to standing water, and a thin veneer can show wear sooner. On the other hand, it is usually more dimensionally stable than solid wood.

Best month to buy flooring

There is no month that is reliably best. Retail promotions and demand vary by store and region. Some people find fewer installers are busy in colder months, but this varies. A better way to think about timing is to buy when you can store the flooring indoors and install it soon after it has settled, rather than leaving it in storage for a long time.

Common mistakes

Leaving flooring in a garage or an unheated space.
Installing before the building has reached its normal temperature and humidity.
Relying only on a number of days.
Not measuring the subfloor.
Starting while paint, plaster or concrete is still drying.
Ignoring manufacturer instructions.