What Humidity Should Hardwood Flooring Be Installed At?

Quick answer

Hardwood should be installed only after the home is at stable, normal living conditions and the flooring, subfloor, temperature, and humidity meet the product requirements. There is no single humidity number that applies to every hardwood floor.

Manufacturer instructions, wood species, plank width, solid versus engineered construction, subfloor type, and regional climate all affect the acceptable installation range.

Why humidity matters

Wood flooring gains and loses moisture as indoor conditions change. If hardwood is installed when the home is unusually humid, dry, hot, cold, or still under construction, it may move later when the house returns to normal living conditions.

Acclimation is really about matching the flooring to the jobsite conditions required for that product. Waiting a certain number of days does not help if the HVAC is off or the home is still drying out.

• High humidity can contribute to swelling, cupping, or tight boards.
• Low humidity can contribute to seasonal gaps.
• Construction moisture can create temporary conditions that are not normal living conditions.
• Concrete slabs and crawlspaces can affect the moisture balance below the wood.

What to check first

Before installation, confirm the HVAC is operating, wet work is complete, and the home is within the flooring manufacturer's required temperature and humidity range.

Then check flooring and subfloor moisture readings. The installer should compare the readings to the product requirements rather than relying only on the calendar.

• Verify the required humidity and temperature range in the product instructions.
• Confirm normal HVAC operation before acclimation and installation.
• Check wood subfloor or concrete slab moisture requirements.
• Avoid storing hardwood in garages, porches, or unconditioned rooms unless allowed.
• Document readings if the manufacturer or installer requires it.

Solid vs engineered hardwood humidity concerns

Solid hardwood is generally more sensitive to moisture movement than engineered hardwood, especially in wider planks. Engineered hardwood can be more dimensionally stable, but it still has limits and can gap, cup, crown, or delaminate when conditions are wrong.

The correct humidity range should come from the exact product instructions. Product construction, wear layer, core, width, installation method, and jobsite conditions all matter.

When to call a professional

Call a professional if the home has unstable HVAC, recent construction moisture, crawlspace moisture, concrete slab concerns, radiant heat, wide planks, or a history of hardwood movement.

A professional can take moisture readings and decide whether the issue is acclimation, conditioning, subfloor moisture, or an unsuitable environment.

Example scenario

Hardwood is delivered to a house where drywall finishing just ended and HVAC has not been running consistently. The boards sit in the living room for a week, but the home is still humid from construction.

That week of storage may not count as proper acclimation because the material is adjusting to temporary jobsite moisture, not stable living conditions.

Common mistakes

The biggest mistake is treating the visible symptom as the whole problem. Noise, gaps, peaking, crowning, and moisture concerns usually start with movement, moisture, substrate support, or product-specific installation requirements.

• Treating acclimation as only a number of days.
• Installing before HVAC is stable.
• Ignoring subfloor moisture readings.
• Assuming engineered hardwood has no humidity limits.
• Storing hardwood in unconditioned spaces before installation.