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What Kind of Wood Filler to Use for Cracks in the Floor?

Many products are available to repair cracks in a hardwood floor. Some products, such as wood putty, are simple to use, while others may require sanding or heating during use. Products that are the same color as your hardwood floor are a good option, because they'll blend in without additional staining or finishing. The most important consideration when selecting a wood filler product is whether the hardwood floor has been finished.
  1. Uses

    • True wood fillers are used prior to sanding and finishing a floor to fill in gaps and cracks. Wood filler has a liquid texture and dries to a hard finish. It can be sanded and stained and is very durable. If used to fill cracks after the floor is sealed, it may not match the surrounding wood, and it may not contract and expand with the wood.

    Alternatives

    • Other wood filler products are available to fill cracks in hardwood floors, although they may not be labeled as wood filler. Wood putty, for example, comes in a variety of shades to match the color of your floor. It has a denser texture than true wood filler, resembling clay. Wood putty is the preferred choice for filling cracks on finished and sealed floors. It never dries completely, allowing it to expand and contract with changes in the wood. Shellac sticks are another option for filling small cracks in wood floors. Shellac sticks also come in many shades, but are harder than putty when dry. Shellac sticks must be melted slightly with a hot butter knife or other tool before you can work with them. They also dry harder than wood putty and may require sanding to smooth them.

    Selection

    • Wood fillers are available at home improvement and flooring stores, where knowledgeable salespeople can guide you to the best option for your situation. Products labeled with the NOFMA or MFMA certificate have been tested for durability and moisture content. Online retailers may offer more color choices if a nearby store doesn't carry the right shade wood filler for your wood floors.

    Considerations

    • Cracks in the floor are usually caused by the natural expansion and contraction of the wood due to changes in air temperature and humidity and may not need to be filled. Wood filler is not effective at filling cracks wider than 3/32-inch wide. A wood floor installer or contractor can offer suggestions for repairing severely damaged floors, which may include replacing boards rather than filling the cracks.