b'TECHNICAL & RESEARCHAVOIDING COMMON LOW-SLOPE ROOF DESIGN PROBLEMSBy Jim FlickingerS mall details can haveWater MUST Leave the Roofan enormous impact.The following cannot be stated often or strongly Get them right, and theenough: water MUST leave the roof AT ANY COST.likelihood of success can increase exponentially. Get them wrong,There are three ways to achieve the necessary and the results can be disastrous.slope to accomplish the goal: structural slope, This is certainly true in low-slope roofing. Thetapered insulation, or a combination of tapered detailsfrom drainage to penetrations and edgesteel and tapered polyisocyanurate crickets.metalare essential to ensuring a roofs long-termTapering structural steel is the least costly method durability and performance. They are, however,and is generally used in new construction. Adding also the source of the vast majority of roofing- slope of 1/4-inch per foot to a 40-foot-by-40-foot related issues. span requires only a 10-inch difference in the grid Some of these issues are, of course, the resultline of the columns and lengthening the joists by of poor workmanship by the roofing contractor.1/8-inch. Most, however, stem from improper roof design orUsing tapered insulation to accomplish the same specifying the wrong products for the job.task would require an additional 8,400 board feet This article will outline seven points that, if keptof tapered insulation and, if mechanically fastening in mind during the design process, can eliminatethe insulation, fasteners in three different lengths. many roofing-related change orders and reduceAt todays prices, this would add approximately installation time and costs. $13,000 to the projects cost.14 www.mrca.orgMidwest Roofer'