Most owners, designers and contractors are familiar with the concept of moisture mitigation. What isn’t always understood is the gravity of what moisture mitigation will do for a facility or what could happen if it’s neglected. Concrete construction, for good reason, is at the center of the moisture mitigation conversation. From flooring failures and liabilities to the serious implications of sick building syndrome, tackling the issues of excess moisture in concrete slabs can’t be ignored.
Concrete Slabs and Moisture are an Unwanted Combination
While water is a requirement for the formation of any concrete mix, the extent to which it retains moisture can vary wildly based upon the mix used or environmental factors. The target relative humidity level (RH) before flooring can be safely placed is 80 percent or lower. Several flooring subcontractors will even arrive with expectations that the RH reach target levels before installation can begin or a warranty is applied. Trapped moisture can migrate to the surface of a concrete slab and severely warp flooring materials, costing owners thousands of dollars in repairs.
The Realities of Sick Building Syndrome
Moisture trapped in concrete slabs and other areas can have serious health implications for tenants. According to a report by the Environmental Protection Agency, $3.5 billion is spent on asthma-related medical costs attributed to exposure to mold and dampness every year (in the United States). Reduced productivity, absenteeism and spiking litigation costs can all result from the unsafe presence of excess moisture. Control of moisture in concrete slabs is important in the fight against sick building syndrome, especially since it is among the most difficult sources of moisture to detect. After flooring is installed, a buildup of moisture at the surface of slabs can cause mold build up to go unnoticed even before flooring deterioration.
Available Moisture Mitigation Solutions
Topical moisture mitigation treatments such as concrete PH blockers are available, though they will cost $4 per square foot in addition to the labor costs of installation.
Cementitious overlays, or a cementitious coat, can be applied to the surface of a slab after the concrete has cured.
Rapid-drying concrete, however, is the sole concrete-only moisture mitigation option. A self-desiccating product, rapid-drying concrete will dry to acceptable RH levels in less than 45 days, cutting the need for additional labor costs or moisture mitigation materials. Predictable and fast-curing, rapid-drying concrete was designed in response to recurring concrete moisture issues and the trend of fast track construction.