Underlayment and Nail-Down Hardwood Floors

Cork underlayment is a granulated product that is held together with small amounts of binder and Suberin – the natural waxy substance found in cork. Underlayment is a loose product without structural properties. cork underlayment It is unable to hold nails, screws or staples in place.

Cork underlayment is an unfinished product. Its structure is not enough to hold itself together after being pierced hundreds or thousands of times. It maintains its integrity through pressure. The pressure of a floor sitting on top of it allows cork underlay to maintain structural adhesion and function properly.

For this reason, it is considered improper installation to nail or staple hardwood flooring when cork is the underlayment.

“Can I nail or staple cork underlayment?”

NO, the cork will break down to produce cork dust that will eventually work its way up through the seams of the floor. If the cork is pierced it rubs against the nails (or staples, or a screw) which causes it to slowly break down to its original form – loose granulated cork. These loose grains will become air borne causing dust problems. This break down of the cork can occur in a relatively short time. If the installer offers a warranty on his or her work they may have to come back and, at their own expense, remove the floor and start again.

“How can it be done?”

Cork underlayment, like wood, can be glued in place*. It can be glued to existing plywood subflooring in much the same manner as hardwood is glued. Normally the wood adhesive is troweled on and the cork lay over the glue. The adhesive must be allowed to cure or “set-up” before the hardwood is installed. The hardwood is then glued, following standard techniques, to the cork underlayment.

This may add time and some extra costs materials and labor, but the results are a warm, stable, quiet hardwood floor that is easy to live with.

*It is important to note, that cork underlayment should not be glued straight to concrete. Cork is not a vapour barrier and cannot be used in place of proper moisture management.

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