In this occasional series, Steve Harris, senior vice president of Middlebury, VT-based warehouse design consultancy Bread Loaf Corp., answers questions about building a better distribution center.
Q. I’ve been told my distribution center should have a flat roof? Why?
A. A “flat-roofed” system usually incorporates a conventional braced frame and a membrane roof sloped from a high eave to a system of interior roof drains. Such a building requires additional interior piping to handle storm water, a detention pond to allow for controlled discharge of roof water, and a somewhat intensive thought process during design. Flat-roofed systems also end up costing about 15% more than their pre-engineered cousins, which typically have sloping roofs, rigid frames, metal sliding, and standing seam-roofing systems. But the extra expense is worthwhile, for several reasons:
Lower operating costs. Snow and ice are retained on a flat roof, thereby improving insulation during the winter. At the same time, truck docks remain free of ice buildup under the rear wheels of trailers and the damage caused by falling debris. It is also safer to stand on a flat roof than a sloped one, making access to equipment much less time-consuming and dangerous for maintenance people.
Enhanced safety and convenience. A flat-roofed building has no low eaves, so all the facility’s walls are free of cascading water, snow, or ice. A dramatic illustration comes from John Alexander, chief financial officer of Portland, ME-based furniture cataloger Sturbridge Yankee Workshop. The company’s pre-engineered sloped-roofed headquarters is annually beset with the miseries of wet walls, damaged cars, an occasional smashed office window due to monster icicles, and even evacuations due to the rupturing of gas lines mounted on the exterior.
Improved operational consistency. In a pre-engineered warehouse, vertical clearances to the roof (and the frames that support it) are all different, depending upon where you are on the floor. In a flat-roofed structure, vertical clearance is the same wherever you happen to be. This is particularly important for forklift operators trying to dodge overhead hazards.
Do you want to make your warehouse smarter? E-mail your questions to firstname.lastname@example.org, and Steve Harris may answer them in future issues.