Laminate flooring is more than 90% wood. It is a natural product and will always react in direct proportion to the relative humidity of the ambient atmosphere after the installation. Most laminate flooring must be installed as a floating floor system in residential or light commercial installations, with the ability to "expand and contract unrestricted.”

That being said, laminate flooring manufacturers have very clear guidelines designed specifically for expected changes during the life of the floor. Unfortunately, the guidelines are not an exact science; other variables that impact the floor’s expansion and contraction are beyond the control of the manufacturer. But the additional points of information listed here can help to minimize the problems associated with a floating floor system’s limitations as they relate to expansion gaps or joints.

It is important to know that acclimation is critical to a successful installation, because the product (wood-fiber core) must uniformly adjust to the environmental conditions at a slow, controlled rate. Once the product has adjusted to the new environment, changes from that point will always occur with temperature and humidity swings, provided all the rules for installation, maintenance and preparation have been followed. Radical swings in temperature, humidity, or both, for extended periods, or in a short period, of time can adversely affect the finished floor. Other factors that can negatively impact the finished floor in conjunction with environmental fluctuations include: ·Improper adhesive application ·Incorrect adhesive removal technique ·Undulating substrate ·Unwanted deflection due to excessive cushion underneath ·Excessive water during clean-up ·Incorrect foam used over concrete ·Irregular cuts at a fixed vertical surface that does not maintain minimum expansion ·Failure to use an expansion molding at the recommended width and length limits ·Constant exposure to high humidity without additional precautions ·Combining any of the above.

There may be other scenarios not covered here, but this document is meant to make you aware of situations that may parallel those you encounter. Typically, floors that have not been installed to allow unrestricted expansion and contraction may experience buckling; heaving; pulling away from the wall; swelling; joint degradation; and premature wear. Once the floor fails, the only fix is replacement. You can help to avoid that potential liability by doing the following:

Apply adhesive correctly, and that means reading the instructions. Every manufacturer has a different technique for adhesive application. Positioning the planks after application will force the adhesive to the surface of the laminate for a continuous water-resistant seal at the seam.

Just as important as the correct application of adhesive is its removal from the laminate surface. Removal techniques for different brands of adhesive differ greatly, so make sure to follow the instructions for the product being installed. Voids in the seam are open wounds inviting infection via moisture from the atmosphere, during adhesive clean up, or even day-to-day maintenance. Break this rule and extreme expansion is guaranteed.

The substrate under the laminate must be reasonably flat. Undulation beyond the recommendations of the manufacturer may allow unwanted movement, eventually breaking down the glue seal. Once the seal is broken, the product can expand beyond its intended limits due to moisture migration into the unprotected seam.

Unapproved, heavily cushioned foam can also allow gradual breaking of the glue line. Once it is broken, moisture can cause extreme expansion.

Using too much water during clean-up can cause unexpected and excessive expansion and swelling that often will not be reversed during the normal process of evaporation.

Approved vapor retardant foams, or systems utilizing foam and polyethylene, must be used on all grade levels of concrete after it has been determined the MVER (Moisture Vapor Emission Rate) is acceptable. Failure to use the correct foam underlayment on concrete substrates will not protect the floor from moisture, and may cause the floor to buckle, separate, swell, or heave.

All recommended expansion gaps at fixed vertical surfaces must be per the manufacturer's recommendations for normal conditions. Irregularity at the vertical surfaces will interfere with unrestricted expansion.

Attempts to exceed the maximum recommended width and length of an installation without the use of an appropriate expansion system with moldings will prohibit the completed floor to expand or contract unrestricted. This will occur even with additional expansion at the perimeter, due to the weight of the completed floor.

In areas of extremely low or high humidity (30%/90%), you will want to increase the expansion gap at any fixed vertical surfaces such as walls, pipes, cabinets, thresholds, etc. In addition to the expansion gap, the molding must cover the finished laminate by the same amount to counter extreme contraction of the floating floor. The rules apply at door casings, jambs or any case where flooring is slid under.

You may also apply a generous bead of laminate flooring adhesive to all exposed, cut, or factory-core edges at all fixed, vertical surfaces. The adhesive should be spread evenly over the exposed edge so that it creates a protective membrane, covering the entire core. Allow 24 hours for the adhesive to cure before moisture exposure. The sealed edge will reduce radical changes in the finished floor during extreme swings from humid to dry. Check with the laminate manufacturer before utilizing this step to make sure they are in agreement.

Failures can be caused by a combination of any or all of the above. Follow the rules, evaluate the environment, consider how the consumer intends to use the floor, and deliver a system with an expansion gap that is suited for the environment.

Remember, the expansion gap or joint with laminate flooring is a must for long-term performance without problems.