Hardwood Flooring

Relatively new floor installation.

Substrate is 3/4 plywood. Conditioned and finished basement below the hardwood floor in the Main Living area.

What other than failing to properly acclimate the hardwood would cause cupping, curling, splitting and cracking of the floor finish?


What type of hardwood is it?

How long has it been down do the owners go south for the winter and shut off the heat .
A little more information might help.
Do they run a wet swifter over the floor to pick up the dust?
Is there a humidifier on the heating system?

Try this site:http://www.floortest.com/

Hardwood is Oak.

Forced hot air heat.

Furnace does have a humidifier.

Full time family residence.

Flooring was installed in March 2007.

Joe, Hardwood can also be Brazilian cherry, which gets milled out of the country and shipped to the US to be finished.
It is also a traded commodity, so if your not careful of who you buy from you could purchase several boxes that actually came from different mills and do not match each other. Many times the tolerances are out by only a 1/8 of an inch, but if your laying a 200 square foot floor and the pieces do not fit properly you will have problems.

Also with prefinished oak you have many of the same problems with quality, the main one being that it does not get finished after it’s installed.

Your scenario sounds to me like a moister problem or perhaps it was installed without the correct amount of fasteners.

Too dry?



Joe Is this a relatively new house? where is the floor curling?

Does the house have a main center beam and what is it made of?


House is approximately 25 years old. Center Hall Colonial.

Flooring covers the Living Room, Dining Room, Entry Hall and Den/Office. (approx. 1500 - 1800 square feet)

Basement is finished. Beam and framing are not observable. Deficiency is sporadic throughout all areas of flooring.

Do they have pets that are not house broken? I’ve seen that a lott.

Joe, I would have to say that the floor was not acclimated as you said or not enough fasteners were used.

Maybe this will help.

In-use" Moisture ContentDifferences of more than 4% between the expected in-use average moisture content of flooring and the in-use average moisture content of underfloor construction are likely to cause problems such as cupping. The greater the difference the more severe the problems. A significant difference of 8% or more may result in buckling of the floor when the underfloor is the higher moisture content.

Common moisture sources and their corrections are:
• Airborne (Relative humidity) exceeding 55% in the home - dehumidify airspace.
• Wet basements - ventilate and dehumidify.
• Crawlspaces - add ventilation on a timer; modify lot topography, proper drainage of moisture away from the home.
• Home is dry (gapping) - add a humidifier to your furnace; get the relative humidity between 45 and 50%.
Solution: Allow time for the correction to take effect, let the floor improve on its own.

**[FONT=Verdana, Arial, Helvetica, sans-serif]Cupping and Crowning


“Cupping and crowning” are common complaints that develop with high humidity. Both problems occur across the width of the flooring material.
Cupping is when the edges of a board are high and its center is lower. It can occur after water spills on to the floor and is absorbed by the wood, but high humidity is more often the cause. If the wood expands significantly, compression 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 first step in repairing a cupped floor is to identify and eliminate the moisture source. In the kitchen, it may be a leak from the dishwasher or icemaker. From the outdoors, it might be the terrain of the lot, with rain runoff not moving away from the house and foundation. Indoors, the humidity 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 floor can be reassessed. Choices may be to do nothing at all, to recoat the floor or to sand and refinish the floor. However, nothing should be done until the moisture-meter readings indicate the floor is thoroughly dried.
Crowning is the opposite of cupping: The center of a board is higher than the edges. Moisture imbalance is sometimes the cause of 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. It’s 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.

Marcel:) :slight_smile:

Felt,the same type you would use under shingles,should be used as a moisture barrier under hardwood floors.Especially if the floor is over a humid area such as a basement.
Big box stores wiil try to sell you on a “paper moisture barrier” but there is nothing better than good ole’ felt,(tar paper).
I’d be willing to bet none was installed.
You may be able to tell by pulling up a floor register if there is one.

Expansion joints


Very good point, and I should not have forgotten that in my post.

It is imperative that any solid wood flooring maintain a minimum of 3/4" expansion capability along the parallel with the grain installation for movement.
The expansion on the end grain side to wall can be reduce slightly.
The size of the room would obviously affect how much expansion is required.

Check the flooring Manufacturers suggested installation procedure for whatever type of flooring is being used. Procedures will vary according to the species and make or style of flooring. That is the most important step with Hardwood Flooring.

Marcel :slight_smile:

That is really good to know, I do have a question and will the floor move that much after it’s fastened with nails or like I use staple’s?

The last experience I have had was with Bamboo Flooring and because parallel to grain met up with granite flooring tile, the Manufacturer let us reduce the expansion to 5/8" and use a cork infill for a joint that kind of blended in with the flooring.
The end grain expansion was limited to 5/8" on both sides.

Different scenario would be a gym floor, 1" no exception.
It all revolves around the Humidity environment control. The Manufactures test there products on a particular scale and if any that fall beyond those parameters, then the product will most likely fail.

Hope this helps.

Marcel :slight_smile: :slight_smile:

Cherimie, I am a strong advocate of this same method, but everytime I bring it up with the younger intellectual Generation, I get call the old man that can’t follow the times. ha. ha.
I tell them usually that this old man can still have a few tricks up the sleeve that still work, and this is one of them. It also prevents squeaks that can be annoying with a new hardwood floor. But, I guess you could always try the baby powder in the cracks! Right? ha. ha.

Marcel :slight_smile: :slight_smile: :smiley: