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Q: What causes squeaky floors?

A: It doesn’t matter how old your home is — squeaky floors can develop at any time, and for a variety of reasons. Poor workmanship, inadequate design or materials, faulty use of fasteners and even Mother Nature can all be to blame.

Squeaky floors and stairs can definitely be annoying. They’re created by several conditions, so the key to fixing them is determining the cause of the problem.

One of the most common reasons that homes develop squeaky flooring is the condition of the wooden subflooring.

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That’s the layer of planks or plywood that lies between your home’s interior flooring and the floor joists.

The primary flooring can be made of wood, laminate or carpet, but the subfloor is most often made of wood and is attached to the floor joists underneath.

Subflooring must be tightly connected to the floor joists. If there is a gap between the subfloor and the primary floor and floor joists, or if the subfloor is loose, the floor will sit slightly above the joists, causing the subflooring to lower and rise when you walk on the floor.

As it moves, it slides on the nails used to keep the subflooring in place, and that causes the telltale squeaking noise.

Flooring changes can also occur due to weather and humidity.

Wood is a porous material that continuously expands and contracts with changes in temperature and moisture content.

The constant change from season to season causes the wood to expand and contract on a regular basis, which can cause most fasteners to weaken over time. This process can also shift the wood or warp it over time.

Another possible culprit is metal ductwork.

If your home has heating and air-conditioning vents under the floors and the vent surfaces are visible on the floor, they could be causing the problem.

If the vents are not installed properly, there’s a chance that as you walk across the floor, pressure on the metal will cause a squeaking noise.

A more complicated cause of squeaking floors has to do with the floor’s construction.

Carpenters sometimes use diagonal X-shaped bridging between the floor’s joists.

Joists are typically placed at least a half-inch from one another. If these joists touch one another after the flooring is complete, a squeak can result.

If a loose subfloor is the culprit, the repair requires securing the subfloor to the floor joists, which is relatively simple if the floor joists are easily accessible.

If the squeak is caused by a loose area near a pre-existing nail, the subfloor can be secured with a new nail or screw. If a gap has occurred between the subfloor and the main floor, a wedge may need to be placed in the space.

To make sure you correctly identify and solve the problem, consult a qualified flooring professional.

HomeWork is the weekly column by the Master Builders Association of King and Snohomish Counties’ Remodelers Council about home care, repair and improvements. If you have questions about home improvement, send them to

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