Increased moisture is the cause of a growing floating floor. The effect will range from no noticeable change in appearance to peaking, cupping, buckling (tenting), warping, delamination, blistered edges, finish damage, squeaking and gaps. Engineered wood, laminate and bamboo flooring are hygroscopic. These materials increase and decrease in moisture content with change in the ambient relative humidity (RH). To better understand hygroscopic, think of the kitchen sponge. The wet sponge absorbs moisture and swells, as it dries it shrinks. That’s what wood and bamboo products are constantly doing though usually in a subtler way. Once exposed to a large moisture gain the effect of the growing floating floor becomes the most severe. Also see Shrinking Floating Floor

Water Resistant Not Water Proof

The exposed face of wood, laminate and bamboo floors are water-resistant, not water proof.  Water-resistant flooring, resist the penetration of water to some degree but not entirely. Luxury vinyl plank and most resilient style flooring products are much closer to water proof (impervious to water).

Moisture Not Always Seen

The surface layer of most floating floors is water and scratch resistant. These floors have protective finishes and coatings such as aluminum oxide and polyurethane. The finish retards surface moisture damage and moisture while not totally preventing it. Moisture might be tracked onto the floor from rain or show. Perhaps too much moisture during maintenance, accidental spills or a peeing pet. This moisture is absorbed at the flooring joints when not wiped up quick enough. With some of the less expensive floating floors, quick enough might mean immediately. With a better quality floating floor, quick enough could be as little as a few minutes or as much as an hour or more.

Often water is not seen at the surface of the floor. It may be flowing below the growing floating floor. A leaking dishwasher, washing machine, toilet bowl, or even a slow pipe leak can result in a lot of water. The moisture may be in the form of water vapor from a crawlspace or concrete slab. Any crack or damage in the concrete slab must be addressed. 

Growing Floating Floor Effects and Cause

BLISTERS:

Excessive moisture during cleaning, spills or even a urinating or vomiting pet may show as blisters along the edge of planks. Blisters crossing between joined plank edges are easily identified as moisture related. The cause of those that effect a single edge can be more difficult to identity.   These blisters are considered site related damage in absence of a warranty that protects the end-user from such damage.

BUCKLING (TENTING):

The growing floating floor expands so much that it lifts off the subfloor. Caused by excessive moisture from above or below the growing floating floor. A pipe breaks, leaking appliance or wet slab from below.  High relative humidity or too much moisture on the floor from above. It can also occur because of the Greenhouse Effect in a closed-up house without an operating or inadequate HVAC system.  Improper installation techniques can aggravate bucking. Improper acclimation, not enough expansion space, failure to leave expansion space between continuous flowing rooms are frequent causes.

CUPPING: 

Cupping occurs across the width of the individual pieces of flooring. The edges are high and the center is lower. It generally develops gradually. Cupping results from a moisture differential within the boards. Usually high moisture on the bottom side of the floating floor planks from plumbing or appliance leaks or vapor emissions from the slab, subfloor or crawlspace. Improper acclimation may result in subtler cupping.  Dry cupping occurs with engineered flooring because of low humidity levels and often associated with checking (cracks) in the face of the board.

DELAMINATION:

Seen as the separation of the floating floor layers. Delamination may be a manufacturing concern because of poor bonding issues. Also, caused by flooding, excessively wet maintenance, or other excessive job site moisture, including extreme fluctuations in the ambient relative humidity.

END-LIFTING: 

The ends of the floating floor have a raised appearance. More common causes include too much moisture during or following installation. End lifting can also be a maintenance or manufacturing related condition.

FINNISH DAMAGE: 

Moisture related finish damage on the edges of an engineered wood flooring occurs much like the blisters on the edge of a laminate floor. Excessive moisture enters at the edge of the boards and finds its way under the finish, resulting in a peeling finish. Even more severe damage is seem when the moisture level of the hardwood increases to the point that the finish on the face of the plank is now peeling. A competent flooring inspector should be able to determine if this is a finish bonding issue, moisture related issue or both.

FACE-CHECKING:

Lengthwise cracks in the veneer of an engineered wood floor. Typically occurring with flooring manufactured at an MC incompatible to the local environment. Face checking can occur from humidity levels not properly controlled. Relative humidity that fluctuates significantly between high and low.

GAPS:

Abnormal gaps, sometimes seen with edge crush (Compression set).  This occurs when a growing floating floor expands from being exposed to extreme moisture. With a floating floor gaps, can also develop as part of the flooring expands into areas without sufficient expansion space and adjacent flooring pulls in different directions resulting in gaps. There are many other causes for gaps, associated with the shrinking floating floor.

GREENHOUSE EFFECT:

The flooring shrinks and swells because of limited air movement and inconsistent humidity levels. A building closed for an extended period with little to no air control or air exchange. Elevated heat such as sunlight through windows, creates condensation and abnormal humidity levels. During this time shrinkage or expansion occurs as the flooring attempts to stabilize with the atmosphere.

SQUEAKY/POPPING:

As floating floor expands from excessive moisture it will often lift enough off the subfloor so that it deflects and squeaks. Flooring locked in at walls or other fixed objects will exacerbate squeaking. Extremely heavy furniture such as a heavy pool table setting on it or cabinets built on top of the floating floor results surrounding expansion. A damaged locking joint or improper milling of the locking system will also result in squeaking and popping. Performing an investigation of the concern should identify the cause.

Preventing the Growing Floating Floor

Prevention of the growing floating floor is a combined effort. Proper product selection, installation environment, the installation and maintenance are all factors in how will the flooring of choice will perform.

EXPANSION GAP:

Inadequate or improper expansion is a major contributor to the growing floating floor. It is important to allow for expansion gaps that are wide enough to allow for growth of the floor. At a minimum, place expansion gaps in the proper locations and as wide as installation instructions call for. On the rare occasion that the manufacturer does not provide instructions, a good rule of thumb, add a gap at least the thickness of the product being installed. On larger rooms add additional expansion space. Remember that the wider the room, the more the growth.

HEAVY OBJECTS SITTING ON:

The weight of heavy furniture such as pool table over 500 lbs. and grand pianos. Even distributed over multiple legs, they may pinch a floating floor against the substrate or cause joint damage. When pinching occurs, the floor is unable to move as a unit. As the flooring expands, it lifts off the substrate. Deflection is seen, squeaking is heard. The floor may even buckle if the moisture level increases enough.  Proper stagger helps to reduce weight caused joined damage.  To help distribute the weight and prevent joint damage, use a wide foot, rubber coaster.

OBJECTS INSTALLED OVER:

Wood and pellet burning stoves, kitchen islands and cabinets installed over a floating floor are an even greater issue. remodeling or new construction avoid laminate under the cabinets. These items locked the floating floor in. When the floor is unable to float, it expands and you have the problems associated with the growing floating floor.

Molding and Trim

PINCHING MOLDING:

Molding and quarter round that pinches a floating floor results in problems such as squeaks and buckling. Pinching occurs from nails going through the floor or into the expansion space. Fasteners should go into the wall are cabinet and not into the floor. The floating floor is also pinched when the molding is pressed to tightly against the floating floor. Always leave a space between the bottom of the molding or quarter round at least the thickness of a business card.

T-MOLDING:

This trim covers the expansion space that is left in non-symmetrical areas and doorways. The expansion gap separates the rooms so that each can float freely while expanding and contracting. Failing to leave this expansion gap, often results in concerns such as buckling, squeaking and gaps.

Environment 

Floating floor installed in a locale with large swings in relative humidity. The relative humidity is routinely low or routinely high, consider installing a built-in humidification system. Remember, most all floating floors perform best at a temperature that ranges between 60-80 degrees Fahrenheit and a relative humidity range of 35-55 percent. Always follow the written guidelines for the product you have installed.

Maintenance

Maintain your floor by following the manufacturers maintenance guidelines. The well-meaning salesperson or friend may have given you good information. On the other hand, the information they gave you or you found on the internet, may end up damaging your beautiful new floor.

Finding the Cause of Growing Floating Floor

The growing floating floor and the shrinking floating floor are closely related by moisture content (MC).  The growing floor is expanding and the shrinking floor is contracting with change in moisture content. As discussed in this article on Growing Floating Floor Cause and Effect, there is one major cause but many effects.  Expert, certified flooring inspectors such as Terry Weinheimer and Kevin Weinheimer investigate problem floors, perform onsite testing and make an in-depth search for the cause. The condition may be site or maintenance related. Other times product or installation related.  Sometimes a variety of concerns. Once determined, the inspector will document the concern and furnish a fully written report to the commissioning party.