Water, Water, Everywhere… BY GREGG LOWES, MUNTERS INC.
Consider a 20 litre pail of paint with 35% solids by volume. Sixty five percent of that pail, or about 13 litres, has to evaporate inside the space for the paint to dry. Environmental and IAQ demands have replaced most solventbased adhesives with water-borne systems. Floor slabs can hold free moisture for months after final cure. Needless to say, new construction has lots of moisture challenges.
We have a love-hate relationship with water. This is especially true when it comes to our buildings. During construction of new industrial or commercial buildings, water is a key ingredient in concrete, drywall finishing, painting, and many adhesives and mastics. Once the building is occupied, we want lots of water in our sprinkler systems, plumbing and washing facilities. And for maintenance crews, a good swig of bottled water is refreshing after hours of working on a hot roof or driving a floor polisher half the night. The hate part comes in when we lose control. When a sprinkler head breaks, when the roof leaks after a major deluge, or when that new slab won’t dry enough to lay the new vinyl floor. And when the general contractor has a September occupancy deadline, the drywall is taking two days between coats, and the flooring contractor just informed him it will be another four weeks before the slab is dry enough for flooring install, water is not his friend.
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Getting the Climate back in Control In the world of moisture management, time is a critical factor. Construction schedules can be compromised by uncontrolled moisture issues. Even new materials, when improperly staged or allowed to remain wet, can begin to degrade in a few days. A water “event” in an older building has a very small recovery window. Mould can take hold in less than 72 hours if moisture is not dealt with, posing serious health concerns and escalating recovery management and costs. To solve moisture problems and preclude the possibility of mould growth, many companies are turning to Mun-
School Plant Officials Association of B.C. Spring 2008
ters, employing their desiccant dehumidification technology to speed new construction projects and achieve comprehensive drying after a water event. Desiccant dehumidification equipment works by first adsorbing moisture in the air into the desiccant rotor. The equipment then delivers that deeply dried air into the space. Materials with a high moisture concentration give up that moisture to the dry air, which has very low vapour pressure. With the air movement (positive pressure from the equipment) the moisture is carried away and pushed out of the space. Contractors routinely get overnight drying times for drywall finishing. Concrete slabs can meet moisture content specifications in often half the time. Moisture sensitive materials such as wood flooring, plywood, millwork and gypsum board can be safely staged on site. Even water damaged drywall can be recovered, rather than torn out, without loss of structural strength if it is dried before its lamination fails. New hardwood flooring and millwork installations also benefit from tar-
