Concrete Slab Moisture & Gym Floors

Concrete has been around for a very long time.

What's the difference today?

What used to take a year or two to build is done today in record time. Under ideal conditions, a typical slab takes the first month to reach compressive strength and then approximately 41 days for every inch of the pour. So a 6-inch concrete base can take approximately seven months to be "dry" enough to receive many flooring types. If it rains? The clock starts all over again. Also, mechanical finishing of the surface along with some surface sealers (AS™ F710 makes reference to not having them) creates a dense surface that can impede free water from leaving the slab. The drive in construction has been to build it faster, smarter and cheaper.

Adhesives have changed. Given the understanding of VOCs and responsible indoor environmental care, the "good stuff," which may have contained less-than-desirable components, was removed. Today's adhesives are either very low VOC or VOC-free, but can perform as well if not better than before with higher tolerances. The needs have driven innovation. It is best when concrete along with its building envelope is stable and predictable.

Testing has also evolved. Contractors have learned the importance of testing prior to installation. Failures due to moisture problems have encouraged this. If a flooring system does fail because of this, it can be like the "Gun Fight at the OK Corral" with everyone pointing fingers. There is lingering debate about who performs those tests. Trained and experienced professionals should be the rule of thumb. Now that testing is generally mandatory, the rise of moisture mitigation systems is dramatic, and some of them cost as much as the flooring did in the first place.

Better documents, such as ACI 302.2R, discuss the design and construction of concrete slabs to receive moisture-sensitive floor coverings. This stems from a collaborative effort between AS™ and ACI. AS™ F710 discusses the preparation of concrete slabs to receive resilient flooring, but can also be used for soft surfaces such as carpet, wood and other flooring types.

With our new means of communication, training events can be held much easier and with less cost, allowing easier connection from manufacturer, to contractor, to customer, to GC and architects. It is important to understand the interconnectivities between concrete and flooring.

Skilled and experienced labor is needed, especially for specialty materials such as sport flooring. As hands-on training is a challenge, this newfound mode of virtual training is a blessing. Contact is so much easier now. Solving problems in real time whether in an architect's office or on a jobsite is considerably more efficient, and we still get to have some semblance of human contact.

Also, there are slip sheet membrane systems that have been around a while, but their benefits were not completely understood. Not only do these assist with higher moisture tolerances, but they also help with eventual cracking and minor joint movement, which can compromise other types of mitigation systems. They are cost-effective and typically warrantied by the manufacturer. A single-source solution is an attractive selection for most owners.

It really is an exciting time. The capacity to communicate is far easier. The ability to have a conference with multiple parties involved is almost instantaneous and quite effective. Having a great product, a good system in accordance with the project, and communication beforehand? This is the best way to avoid problems later.