ICS Magazine

Facing Down Concrete Moisture Problems

June 24, 2009

Whether it is visible or not, most everyone is aware that concrete is quite prevalent in both residential and commercial construction. However, a problem can develop-and far more frequently than is often realized-when moisture is released from the concrete.



Whether it is visible or not, most everyone is aware that concrete is quite prevalent in both residential and commercial construction. Concrete is first poured (or pumped into the building), and then carpets or hard-surface coverings are installed.

However, a problem can develop-and far more frequently than is often realized-when moisture is released from the concrete. When this happens, carpets glued to the concrete may lose their bonding and begin to look soiled and buckle, VCT adhesive begins to ooze, the flooring may actually lift, and it’s likely that mold and mildew will grow.

If carpeting has been installed, carpet cleaning technicians may be among the first professionals called in to deal with the situation. Because of this, it is a good idea to know some basics about concrete, concrete moisture problems, why problems occur, who might be to blame, and what solutions technicians can offer their clients.

Is It Cured and Dried?
So many buildings today, both commercial and residential, are built under “fast-track” conditions. Typically, contractors and subcontractors have a limited period of time to complete their part of the construction project. If they fall behind, they can be penalized financially and set the entire project behind schedule. This rush to complete the job is often the core reason we have concrete moisture problems. The building may be completed before the concrete has had a chance to dry and cure. If flooring, whether carpet or hard surface, is applied over concrete that has not properly dried or cured, it can become a problem just waiting to happen.

Dry and cured are two different things. A floor may be dry to the touch and the excess moisture used to apply the concrete evaporated, but that does not mean it has cured, which is a chemical reaction that bonds the ingredients with the concrete.

In most situations, concrete slabs require 28 days to cure before a floor covering should be installed. “However, this is a complex issue and may only be true of newly poured concrete slabs,” says Steve Williams, vice president of research and design for U.S. Products, a manufacturer of professional carpet and floor care equipment.

A curing compound can be used to help expedite the curing process, but must be removed before flooring is installed. In some cases, the compound is left on the concrete too long, preventing the moisture from getting out of the slab-the opposite of the application’s intended effect. Additionally, vapor retarders can be applied, which can help reduce moisture problems. However, in many cases they are left out in the interest of saving money.

Detection and Responsibility
Many building professionals incorrectly rule out concrete moisture problems if the floor-covering problems mentioned earlier occur on a higher story in the facility. Although the problem is more common on lower stories, it can occur on any floor. Also, buildings in dry climates, even older buildings that have never had problems in the past, can develop moisture issues. Again, the crux of the problem is not climate or age or on what story the problem is occurring, but whether the concrete was allowed to cure properly.

There are various ways to detect a concrete moisture problem, but according to Williams, moisture meters are the only true way to verify the moisture content of a concrete slab. “Often, concrete in an area experiencing moisture problems is meter tested and compared with a dry area in the same facility not experiencing [moisture] problems. The goal is to get the same meter reading in both the problem area and the dry area.”

If a moisture problem is detected, often the concrete contractor is thought to be the guilty party. However, in most cases, the contractor is just following the specifications of the architect, while also meeting the fast-track demands of the general contractor.

What the Carpet Cleaning Professional Can Do
“If cleaning professionals suspect concrete moisture problems, the first thing they can do is to discuss the possibility with their clients,” says Williams. “Simply cleaning the carpet will not solve the problem. In most situations, the carpet (or other floor covering) will have to be removed, and depending on the seriousness of the problem, disposed of.”

Once the flooring has been removed, air movers and dehumidifiers can be placed at strategic locations throughout the problem area to expedite drying, according to Williams. Additionally, ventilating the area and turning up the heating system to 75 degrees Fahrenheit also will help. Studies have found that using air-conditioning can actually make the problem worse because the cool air can increase condensation on the concrete surface. “However, the flow of air over the concrete, which creates the greatest rates of evaporation, is what’s most important,” he says.

If mold or mildew is suspected, an air scrubber may be necessary. More advanced systems have HEPA filters and multistage filtering systems that help capture contaminants, particulates, mold, and fungal spores. “For greater mobility, select a machine that has a ‘dolly design,’ so even one person can transport the machine,” says Williams. “Also, a machine that can be used vertically or horizontally allows greater versatility.”

Finally, be patient. Remember, it was likely the rush to complete the facility and flooring installation that caused the concrete moisture problem in the first place. In most cases, it takes about two weeks to ensure that the concrete dries, is cured, and the moisture problem has passed.