Avoid Hardwood Floor Trouble

How to Spot and Avoid Trouble in Hardwood Floors

In a comfortable home with slight humidity variations through the seasons, wood flooring responds by expanding and contracting. These changes may be noticeable. During warm, humid weather, wood expands. During dry weather, wood contracts. This seasonal movement is a normal characteristic of wood flooring, and it never stops, regardless of the age of the wood. One of the best ways to ensure that wood flooring will give the performance homeowners expect is to install humidity controls and ensure that they are functioning before the flooring is installed.

Working with humidity controls

A homeowner who chooses hardwood flooring is making an investment in a floor that will last 40 years or more, and he or she should protect that investment by installing humidity controls — a tool that helps the floor maintain a beautiful, trouble-free appearance.

Hardwood Floor Cracks and separations between boards

Nearly every floor endures some separation between boards. In winter, when homes are heated and the air is dry, wood flooring gives up some of its moisture and therefore shrinks. When that happens, thin cracks appear between. This is normal, and homeowners should be forewarned of this. It is acceptable, and customers should not be calling the installers at the first sign of hardwood floor cracks. Once the indoor heat goes off in the spring, and the indoor environment regains moisture, most of these cracks will close up.

Hardwood Floor Cracks in winter — in the drier months — may easily develop to the thickness of a dime (1⁄32 inch) for solid 21⁄4 -inch wide strip oak floors. Floors with lightstained woods and naturally light woods like maple tend to show cracks more than darker, wood-tone finished floors.

The cure for hardwood floor cracks? Homeowners should add moisture to the air during dry periods. It’s their choice — live with the cracks and wait until spring, or else add humidity by opening the dishwasher after a rinse cycle, switching off the bathroom fan or hanging laundry to dry in the basement near the furnace.

Better yet, install a humidifier in the furnace, or an exterior air vent for the furnace burner.

If hardwood floor cracks are a concern, laminated flooring moves less and shows fewer gaps.

Avoid hardwood floor trouble cupping & crowningCupping and crowning “Cupping and crowning” are common complaints that develop with high humidity. Both problems occur across the width of the flooring material.

Hardwood Floor Cupping is when the edges of a board are high and its center is lower. It can occur after water spills onto the hardwood floor and is absorbed by the wood, but high humidity is more often the cause. If the wood expands significantly, compression set can result as the boards are crushed together, deforming the boards at the edges.

Cupping is caused by a moisture imbalance through the thickness of the wood: The wood is wetter on the bottom of the board than on the top. The moisture imbalance can be proven by taking moisture meter readings at different pin depths.

The first step in repairing a cupped hardwood floor is to identify and eliminate the moisture source.

In the kitchen, it may be a leak from the dishwasher or icemaker.

From outdoors, it might be the terrain of the lot, with rain and runoff not moving away from the house and foundation. Indoors, the humidity may need to be controlled, or a plumbing leak may be causing excess moisture in the basement, which migrates up into the subfloor and from there into the wood flooring.

Once the source of the moisture is controlled, cupping can usually be cured. The floor may improve on its own as it dries out over time. Other times, fans may be needed to speed the drying process. Once the moisture content has stabilized, the wood floor can be reassessed. Choices may be to do nothing at all, to recoat the floor or to sand and refinish the floor. However, it should not be sanded until moisture-meter readings indicate the floor is thoroughly dried.

Hardwood Floor Crowning is the opposite of cupping: The center of a board is higher than the edges. Moisture imbalance is sometimes the cause of hardwood floor crowning if excessive moisture is introduced on the top of the floor, perhaps from water used in maintenance or plumbing leaks from an overhead sprinkler system. However, a common cause is that the floor was previously cupped, but was sanded at the wrong time — before the moisture content returned to normal and the board flattened on its own.

It should be noted that some slight cupping and crowning may occur naturally, and should be tolerated:
The bark side of lumber shrinks and swells more than the side closest to the center of the tree.
Largely seasonal in occurrence, it’s common in wider planks. Its appearance can be minimized by using a beveled-edge flooring product with a satin finish, rather than square-edge flooring with a high gloss finish.

Buckled Hardwood floor

The “buckling” of hardwood floors — when the flooring literally pulls away from the subfloor, rising up to several inches in one or more places — is one of the most extreme reactions to moisture that can occur. Fortunately, it is not a common occurrence.

Hardwood Floor Buckling happens most often after a floor is flooded for a time, but there are numerous other causes. On nailed floors, insufficient nailing, incorrect nails or incorrect subfloor construction are possibilities.

On glue-down floors, the causes range from the use of incorrect or insufficient mastics to an inadequate mastic transfer, a subfloor separation or a subfloor contamination.

In flooded hardwood strip flooring, the swelling stress is theoretically high enough to push out walls.

However, before that can happen the nails or the glue holding the flooring to the subfloor will usually give way, so that the floor bulges upward.

If buckling floors are caught early, spot repair and replacement may be possible. Once the standing water is removed, several boards may be taken up from the floor so that air can be circulated across and below the floor more effectively. Once the floor has dried to a more stable moisture level, repairs can usually be made.

Some tips on Hardwood Floor maintenance

The enjoyment of wood flooring depends on some routine but minimal maintenance details. These include:
• Sweep your floors or use a dust mop daily, but do not use a household dust treatment, as this may cause your floors to become slick or dull the finish.
• Vacuum your floor regularly, as often as you would vacuum carpets.
• Clean your floor’s coated surface with a lightly dampened cloth using a recommended cleaning product, and according to the manufacturer’s directions for use.
• Never damp mop a wood floor. In all cases, use minimum water, because water causes deterioration of the wood itself, as well as the finish.
• Buy a “floor care kit” that your installer or flooring retailer recommends instead of counting on a home-made remedy of vinegar and water to clean your floors. Different finishes have different maintenance requirements, and it’s best to follow professional advice in this area.
• Clean light stains by rubbing with a damp cloth.
• Avoid using mops or cloths that leave excessive water on the floor. Never let a spill of water dry on the floor.
• Control humidity levels by use of a dehumidifier or humidifier. You may need to add portable units in some rooms.
• Have your floors recoated periodically as the finish shows wear.
• Do not clean your wood floors with water or water-based products on a regular schedule. Clean only when necessary and clean only the soiled areas.

Cracks in a Hardwood Floor

hardwood floor cracksIt’s that time of year again in the Denver Rocky Mountains area, when we start to see cracks in Hardwood Floors.  With Hardwood Flooring this is both seasonal and common.

Wood Flooring, being a product of nature, has some water in it, all of the time.

The moisture in the hardwood changes as the moisture in the environment changes. When the ambient air dries out, the wood dries out and shrinks. This can cause cracks in a hardwood floor.

Cold winter weather hits hard wood floors twice. When temperatures drop home owners turn on their heating systems and keep doors and windows closed.

The heat dries out the home and the moisture is pulled from the wood floor which causes the wood to shrink and cracks to appear.

This can be somewhat minimized by having a humidifier attached to the heating system.

Wood burning stoves are especially bad for drying out inside air as well as areas directly around furnaces, heating ducts and base board heaters.

The second factor that can effect your hardwood floor is when the air temperature falls below freezing. Most of the moisture falls out of the air as snow, frost, or ice.

So, when we get a long cold spell with ice or snow we experience a lot more shrinkage and cracking in wood floors.

As temperature and humidity changes occur in summer, seasonal cracking should remedy itself. As moisture returns back into to the air moisture is also absorbed back into the hardwood floor. Expansion occures and wood floors return to their original state, as before the winter season.

It is recommended that you do not fill your wood floor throughout the winter months.

When the wood floor expands again in the summer, the wood will either force out the excess fill or boards will warp. Wood must go somewhere as it expands and the force of this expansion could be significant.

It is important to know that this shrinkage is not a flaw in the wood or an installation related problem.

If you desire additional information concerning hardwood flooring seasonal movement please contact us!

Behavior of Wood

The following article was provided by Denver Hardwood Company and is used with their permission.


Hardwood Floor Grain DenverAny article made of wood is liable to more or less warp due to changes in humidity. Wood is a hygroscopic material which means it tends to give off its moisture to a dry atmosphere until equilibrium between the two is established.

Approximately 1% dimensional change takes place with each 3% change in the moisture content of the wood. This applies to hard woods more than soft woods and maple being one of the hardest of the hard woods, the action and changes are more defined.

Air can hold a certain amount of moisture at a certain temperature. Relative Humidity expresses what percentage of this maximum is actually being held by the air. Warm air can hold a great deal more moisture than cold air.

For example, if we take a sample of air at 32 degrees and 100% relative humidity and heat it to 75 degrees, its relative humidity will drop to 20%. Thus we can easily see that heating the air will lower the relative humidity appreciably.

From the above mentioned principles, it can readily be understood how changes in relative humidity can adversely affect wood.

In the following video we can see how moisture changes wood

During the colder season of the year, outside air, which can hold little moisture, enters the room and heated to room temperature. As the air is heated its relative humidity becomes very low; if additional moisture at the higher temperature is supplied, this moisture must be supplied from items in the room.

Wooden articles (since they are hygroscopic in nature) are good suppliers of moisture to the “thirsty” air. In giving off moisture, the drying action takes place in the wood. Results of this shrinking, if severe enough, can be observed by checking, delaminating, splitting and warping. Raising the relative humidity has a swelling effect on the wood and will sometimes close checks and splits.

No matter how thoroughly lumber is seasoned, preshrunk, or finished, some shrinking and swelling in service is inevitable because wood is seldom used under constant atmospheric conditions. Since wood is hygroscopic and responds to changes in relative humidity, its moisture content is constantly changing.

Wood in service generally reaches average moisture content and changes in relative humidity cause fluctuations about this average.

These changes in moisture content do not follow immediately after the changes in atmospheric conditions due to the effectiveness of the finish as a moisture barrier. Even the best of finishes are not one hundred percent effective and they will eventually allow the wood to come to equilibrium with the air if conditions are maintained over a long enough period of time.

Since relative humidity is the most important factor in keeping the wood in good condition every effort should be made to maintain a relative humidity of approximately 35 to 45 percent whenever possible during the heating season. Wood should never be stored in a damp atmosphere.

Special attention should be given to the end grain so that it is completely sealed. Unit heaters are particularly harmful to wood, in that they blow hot air on the top surface only. The sudden change in temperature and the extreme dryness of the air can easily cause warping and checking. Exposure of the wood to the direct rays of the sun can cause similar damage.