What Causes Carpet Rippling?
Many times, carpet ripples will begin to appear in less than a year after the carpet was initially installed. They sometimes happen in every room in the entire home, while in other cases you will experience them in just one area.
To illustrate why carpet buckles, one must understand a little bit more about how they are installed in the first place.
Stretched-In Carpet Installation
In our first example, we will look at carpet that is stretched in, commonly known as stretch-in carpet installation.
First, wooden strips (also called tackless-strip) that have small nail-like gripping pins protruding from their surface at a slight outward angle are nailed down to the sub-flooring around the edges of the room at a distance of roughly a finger’s width off of the baseboard.
These pins penetrate through the backing layer of the carpet and are what actually holds the carpeting in place.
Next, the pad is installed. If the sub-floor is wood, the padding is typically affixed to the floor using staples. In the case of concrete such as in a basement, an adhesive of some sort is generally used.
Finally, the carpet is attached to the tack-strip along one wall and stretched and hooked on the tack-strip on the opposing wall. This procedure is continued around the entire perimeter of the room.
Traditionally two tools are used for stretching carpeting: knee-kickers and a power-stretchers.
The knee-kicker is a device about 30” in length. Its head grips the carpet while the opposite end is equipped with a cushion that is designed to be struck with the knee. Rugs cannot be properly stretched with a knee-kicker in a medium or larger-sized room.
The knee-kicker is primarily intended to be used only as a means of positioning the carpet. However, in small carpeted areas such as closets, small hallways, etc. where a power stretcher cannot be used, the knee-kicker is used as a stretching tool.
The power-stretcher is basically a lever which braces against one wall and extends the length of a room. At the far wall, a rectangular head grips the surface of the carpet and by pressing down on a handle, there is a lever action applied which stretches the carpet with great force.
Common Causes of Rippling on a Stretched-In Installation
The most common cause of humps in carpeting that has been stretched in is that the carpet was never stretched in properly, to begin with. In small areas, the use of a knee-kicker alone may prove to be sufficient.
However, in medium and larger sized areas, the use of a power stretcher becomes an absolute necessity. Unfortunately, a common shortcut used by many installers is to use a knee-kicker instead of a power-stretcher.
The reason for this is that carpet installers get paid by how many yards of carpet they can install per day. Using just a knee-kicker is much faster and a knee-kicker will usually get enough tension to at least get the carpeting to lay flat. The end result though, is that initially your carpet may look great but might start rippling within anywhere from a few weeks to a year or two after installation.
Within the first year after installation, if you start to see signs that your carpet is rippling, call the company you purchased it from immediately. In many cases, you can get them to send the installer back to remove the ripples free of charge. Remember the maxim that the squeaky wheel gets the oil.
After the first year, however, you will likely be out of luck and are better off hiring a company that specializes in correcting the types of problems that installers typically make.
The humidity isn’t really the cause of the problem here. What’s actually happening is that the latex materials used in the backing of the carpet are absorbing moisture. This causes the latex to expand and can cause carpet buckling if there is not sufficient tension on the carpet.
You may have noticed that if you have visible ripples in your carpet they can look worse on humid days or you may get humps in your carpet that disappear when the humidity returns to normal.
Many times steam carpet cleaning, which uses hot water, can cause your carpeting to buckle severely when you previously didn’t see any sign of a problem. Although the cleaner usually gets blamed for this, they are not at fault (except in the case of improper cleaning leading to excessively long drying time).
Once again the cause is insufficient tension on the latex containing carpet backing brought to light by the high levels of moisture present from the cleaning. Usually, once the carpet dries fully, the buckles will settle down again.
Loose, Missing, or Damaged Tackless Strip
Many times, carpet is rippling up because there is nothing to hold it in place. It is quite common to find loose tackless strip on concrete sub-floors. Securing the strips to the concrete with nails can be difficult depending upon the quality of the concrete and how the concrete was cured.
This can also happen on wood sub-floors if the amount of tension on the tackless strip is too great. In larger rooms and on concrete sub-floors, the width of the tackless strip should be doubled to provide a greater surface area to grip on to thus avoiding this problem.
Another common scenario that leads to missing tackless strip is when you have a room adjoining a carpet remodeled and a tile or wood floor installed. It is typical to find missing tackless strip along the adjoining edge because either the installer doesn’t consider it part of the job he is doing to re-secure the carpet or he just simply may not know any better!
Dragging Heavy Furniture Across Carpet
You should make it a point to never drag any heavy furniture across the surface of a carpet. The tackless strip that holds the carpet in place has little nail-like spikes that grip the backing of the carpet.
The force exerted by dragging a heavy object across the surface can easily be enough to rip the carpet right off the tackless strip, damaging the carpet backing or loosening the strip in the process.
Also, some carpet fiber types such as olefin have a very low melting point and the heat generated by dragging an object over it can be enough to melt it, causing permanent damage in the form of a line across the surface which cannot be removed by carpet cleaning.
Incorrect pad thickness or density. If the padding is too thick, in some cases it can cause the carpet to disengage from the tackless strip, thereby losing tension. A thick, low-density pad can cause delamination.
This is the process by which the latex between the primary and secondary backing layers of a carpet break down and allow the top layer where the carpet fibers are attached to bubble up. Most of the time it is due to a defect in the mixing or application of latex in the manufacturing process.
Other causes can be excessively thick, low-density padding, heavy equipment being moved frequently over the carpet, improper use of solvent spotters or petroleum bases spills on a carpet such as lamp oil for example. Carpet that remains wet for long periods of time is susceptible to delamination.
Carpets can eventually stretch due to normal factors such as the compression of padding in high traffic areas which allows more flexing of the carpet backing, causing it to “relax." This is in addition to the normal decomposing of the latex in the backing materials with age.
Direct Glue-Down Installation
In our next example, there is no tackless-strip and no padding used, so the carpet cannot be stretched in. Instead, the carpet is glued directly to the sub-floor. This is known as “direct glue down” installation.
In both residential and commercial settings, it is found primarily over concrete sub-flooring such as in a basement area. There are advantages and disadvantages to this installation method.
In the case of a flooded basement, for example, padding presents a major problem in that it acts like a giant sponge and can hold a tremendous amount of water. This makes for a much more complicated carpet repair. It will be more costly to dry and the chances of mold and mildew problems will increase if the job is not done properly.
There is also no padding involved, so the water can be extracted from the carpet and dried much more easily. The downside to this is that padding acts like a shock absorber and without it, the carpet will definitely wear out much faster.
Double Glue Down Carpet Installation
The last type of install we will cover and the least common is known as a “double glue down." This is where the padding is glued directly to the sub-floor and the carpet is glued to the surface of the padding. No tackless strip is used and the carpet is not stretched in.
Causes of Carpet Rippling in Glue-Down Installations
Ripples that appear in carpet that has been glued down usually have to do with insufficient adhesive being applied to the sub-floor.
On a concrete sub-floor, high alkalinity can cause adhesive failure. An installer should always test the ph of the concrete before gluing carpet down. A ph range of 7-9 is considered acceptable. Anything higher than a ph of 9 can cause adhesion problems.
Improper Use of Solvents
Improper use of solvent spotters or petroleum bases spills on a carpet such as lamp oil can cause bubbles and ripples in carpet due to delamination of the carpet backing or adhesive failure.
Glued-down carpet that is wet for an extended period of time can cause adhesion failure causing carpet ripples.
This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.
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