Products / Columbia Green Pre-Grown Tray System

The Pre-Grown Tray is Columbia Green's turnkey modular green roof: patented (7,603,808), interlocking 24 in x 24 in trays of heavy-duty recycled polypropylene (88% post-consumer recycled content, made in Washougal, Washington) with a channelized bottom for stormwater retention, grown with plants chosen by the designer, most often sedum, and shipped at about 90% plant coverage. The technical sheet prints a 4.625 in media depth, a dry weight of 15 to 20 lb per square foot and a saturated weight of 25 to 30 lb per square foot (the web page gives 30 psf), a 100 mil empty tray weighing 3.6 lb, about 100 lb per planted tray for handling, retention of up to 70% of annual precipitation, a minimum roof slope of 1/8 in per 12 in, and installation directly on the membrane or protection layer between 45 F and 95 F. It cites ANSI/SPRI RP-14 for wind design; the pre-grown tray sheet's wind paragraph names the Planted-In-Place Tray as the #2 ballast system, so the maker's copy does not make clear which tray that rating refers to. The tray carries a Declare label as Red List Free.