Issue link: http://digital.corporatepress.com/i/133387
facility asset management Floor Covering Distress: The Pros and Cons of Current Repair Strategies By Martin R. Maingot, P.E., S.E. P lacing floor coverings over concrete slabs is not a new concept. Low-permeability floor coverings have been installed over concrete slabs for more than a century. However, advancements in concrete construction and floor covering technology over the past 25 years have caused flooring performance problems to reach critical levels. "Fast-track" scheduling (overlap of construction and design phases) tends to worsen the problem with significantly less concrete drying time; value engineering that eliminates vapor retarders; and a growing number of low VOC adhesives with considerably greater moisture sensitivity than in the past. While some problems can result from flooring not being installed in accordance with manufacturer's recommendations, more floor covering problems are now related to excessive moisture within the concrete slab and moisture migration through it. Option 1 – Liquid-Applied Moisture Suppression Systems Pros: Odds of effectiveness – High Destructive to existing structure – Low to Medium Cons: Cost – Medium Disruption to tenant - Low to Medium THE OPTIONS Concrete slabs with excessive moisture content must have the moisture isolated from the adhesive and resilient floor covering. Currently the most effective solution is to 1) remove the existing flooring, 2) shotblast the concrete surface, 3) install a liquid-applied moisture suppression membrane topped with a skim coat of cementitious underlayment, and 4) reinstall the original or new floor covering. This option can provide a longterm solution that would permit installation of future floor coverings without having to renew the moisture suppression coating each time. It has been found through testing that "water-based," "water-borne," or "water-reducible" coatings are not as effective in moisture suppression as epoxies with 100 percent solids. It has also been found that solutions of alkali silicates are essentially ineffective for this purpose. While the 100 percent solid epoxy coatings cannot be applied under existing interior walls, experience has shown that moisture vapor movement does not increase through uncoated adjacent areas of the slab (i.e., under existing interior There are a number of options available to repair flooring distress caused by moisture vapor. The following repair outlines represent the most current mitigation strategies and provide valuable insight as to the associated advantages and disadvantages for each option. Facilities Manager | may/june 2013 | 37