Do I Need to Sand My Hardwood Floors?

An old floor may look better unsanded.

Old wood floors have character, and sometimes leaving a distressed or pock-marked floor as it is is preferable to smoothing it with sandpaper. Floors that are uneven or that are damaged by moisture or yellowed, however, usually look much better after sanding. Know what kind of flooring boards you have before you start. If the boards have a veneer, sanding may ruin them, and there is an alternative way to restore the finish.

Floors You Must Sand

A floor with major damage, such as holes or cracked boards, must be sanded after the repairs are completed. Moisture or dryness may also result in major damage, causing the boards to cup or form separations. Filling and sanding is the usual prescription for repairing this type of damage. You also usually need to sand a floor if you want to change the color or if the finish has become dull or yellowed enough to detract significantly from the appearance of the wood. Sanding is always necessary to remove an old finish; you can't do it with solvents.

Floors You Don't Need to Sand

Some older hardwood floors were actually made of softwoods like fir or pine, and these woods tend to distress much more easily than hardwoods. Sanding will remove most of the distress marks, which may not be desirable if you want the floor to retain its character. On the other end of the hardness scale, floors made of exotic hardwoods are sometimes best left alone or at most covered with a fresh coat of urethane or oil. As long as the boards are even and not warped, simply restoring the surface luster will improve their appearance with much less effort than sanding.

Floors You Shouldn't Sand

Engineered flooring boards have come into widespread use, and they differ from solid boards because the surface layer of hardwood is very thin. Sanding a floor removes as much as 1/16 inch of material, and sanding completely through the veneer of an engineered floor is possible, especially if it has been previously refinished. Similarly, you should never attempt to sand a floating, laminated floor. Although its surface resembles hardwood, it is usually a stamped pattern and even light sanding will wear off the pattern and ruin the floor.

Alternatives to Sanding

If your floor finish has simply lost its luster, you can restore it by screening the surface and applying a new coat. You screen a floor by replacing the buffing pad on a floor buffer with a 120-grit sanding screen and running the buffer over the floor. The screen will rough up the finish instead of removing it, making it porous and flat enough to accept a fresh coat. If your floor finish has yellowed, it may be because it has a surface coating of old wax. Clean the floor with a wax-removing detergent before deciding on a further course of action.

References

• Hometime How-To: Refinishing Hardwood Floors
• This Old House; Refinishing School: Screening Floors; John D. Wagner