Understanding a Squeaky Floor and How to Fix Them

There are many reasons wood floors squeak. Squeaks can start with how the floor was installed, or they can be caused by conditions that change after the floor has been in use for a while. Either way, understanding wood moisture content (MC) is key.

It starts with making sure the wood’s MC is right for the space before installation. Skipping this step risks MC-related squeaks, no matter how good the joists, nails, subfloor, or flooring are. Checking MC with a wood moisture meter during installation helps you catch moisture problems that can make a floor squeak.

Causes

How is MC connected to squeaky floors? Manufacturers kiln dry wood flooring to a target MC, ideally close to the equilibrium moisture content (EMC) it will reach in use.

But even after that carefully controlled start, wood naturally absorbs and releases moisture as the relative humidity (RH) around it changes.

When MC rises, wood expands, and when MC falls, wood shrinks. These changes can shift contact points, joints, and other places where squeaks start.

All wood species do this, and some shrinkage or expansion is normal. Measuring MC with a moisture meter helps contractors avoid the larger dimensional changes that cause squeaks after a floor is installed.

Other Possible Causes

• Inadequate nailing
• Weak subfloors that squeak when they flex
• Flooring nailed onto particleboard subfloors
• A subfloor that’s too thin
• Flooring installed in the wrong direction relative to the joists
• Insufficient or incorrect adhesive

The Cure

Prevention starts below the flooring itself. Measuring MC is an essential part of quality control during installation, and installers need to know the MC of both the wood flooring and the wood subfloor. When the wood’s MC is in balance with the RH of the air around it, it has reached its EMC.

That’s why measuring the subfloor’s MC with a wood moisture meter should be one of the first steps in installing a wood floor.

If a floor already squeaks, weak subflooring can be strengthened. From below, shims can be wedged between the joists and the subfloor. Nails can also be added to secure the subfloor, and gaps can be filled with putty or injected with wood adhesive.

That takes a lot more material and effort than a quick moisture meter reading that could have flagged an MC problem before the flooring was installed.

Free Download – 4 Reasons Your Hardwood Flooring Failed

Wood Moisture Assessment

Measuring the subfloor with a wood moisture meter shows whether its MC is too high. If it is, give the subfloor more time to dry before installing the flooring. Many installers, professional or otherwise, assume wood’s MC is set once it leaves the lumber mill.

It isn’t.

Wood’s MC keeps changing as the RH around it changes, until it reaches balance with its surroundings. A moisture meter lets you measure and manage MC during installation and long afterward.

Wagner Meters makes moisture meters well suited to wood flooring installation and to checking other building materials in a home. The Orion^® 930 Dual Depth Pinless Wood Moisture Meter measures the MC of common hardwoods, softwoods, and exotic species at 1/4″ and 3/4″ depths.

Wagner Meters also makes the Orion 950 Smart Pinless Wood Moisture Meter, a non-invasive meter that measures MC in wood and also reads ambient temperature and humidity. It can show EMC and dew point for the space, and its relative measurement mode checks non-wood building materials such as drywall, OSB, and MDF.

Shop Orion Moisture Meters

Larry Loffer

Larry Loffer is a senior technician at Wagner Meters, where he has over 30 years of experience in wood moisture measurement. With a degree in Computer Systems, Larry is involved in both hardware and software development of wood moisture measurement solutions.

Last updated on October 9th, 2026