People who overvalue privacy may find creaky floors reassuring, because creaks prevent anyone from sneaking around the house -- but most people just find them annoying. Hardwood, engineered and laminate floors can all creak, and the problem can often be traced to the subfloor, but not always. Many times it's the flooring installer's fault, and sometimes it's just the weather. Excessive moisture or dryness can shrink and swell boards and make them squeak.
You can usually distinguish a loose subfloor by the persistent creaking it makes when you walk around on a certain part of the floor. The creaks mean the subfloor has lifted off the floor joists, and that could be because the builders used particleboard instead of plywood or high-grade OSB. Another reason for lifting subfloors is the failure to attach them properly. Instead of spreading adhesive on the joists and affixing the subfloor with screws, many builders save time by simply nailing the subfloor with a nail gun -- and nails often miss their mark.
If the squeaking is confined to a particular floorboard, or it affects many floorboards, the subfloor may again be to blame. Flooring cleats often back out of particleboard and low-grade OSB subfloors, and when a board lifts, it rubs against its neighbor when you walk on it. If boards are lifting, the cause may also be that the installer used an insufficient number of nails. On the other hand, the installer may have installed the boards correctly but may have forgotten to acclimate them, and the boards may have swelled or shrunk after installation.
Squeaking Laminate Planks
When laminate flooring planks squeak, the cause may lie in the subfloor -- but it's never a question of improper nailing of the planks, because they aren't nailed. If the subfloor wasn't leveled properly, boards can bend and squeak when you walk on them. Moreover, laminate floorboards are susceptible to swelling and shrinking in changing humidity -- perhaps even more than nail-down flooring boards. When the underside of a plank gets wet, swells and pushes against its neighbor, the locking mechanism weakens, allowing the boards to move instead of staying locked against each other. The squeaking often continues even if the planks dry out and shrink back to their normal dimensions.
Remedies for Squeaking
You can often remedy squeaking caused by lifting floorboards or swelling laminate planks by dusting the floor with talcum powder and brushing it into the joints. The powder lubricates the edges of the boards and stops the squeaking temporarily -- you'll have to repeat the treatment periodically to control squeaking. You can also choose to screw down lifting nail-down boards, either from above -- using trim or breakaway screws -- or from under the floor, using short screws that won't break the surface of the floor. One way to stop subfloor squeaks is to insert shims into gaps between the subfloor and the floor joists. Another way is to drive screws into the joists from above to hold the subfloor down.