A four-inch schedule eighty slotted PVC pipe runs beneath the concrete slab with a two-inch gravel clearance maintained on all sides. The invert or center of the pipe requires an eight-inch dimension from subgrade and a minimum four-inch separation layer. The header pipe must be offset a minimum of five feet from perimeter walls or footings.
FRESH AIR INLET HEADER PIPE 4" MIN. 8" 2" CLEARANCE ALL AROUND PIPE 4" SCH 80 SLOTTED (0.02) PVC PIPE SUBSLAB SECTION A - NOTE: PVC HEADER PIPE TO BE OFFSET A MINIMUM OF 5' FROM PERIMETER WALLS OR FOOTINGS. PIPE SHALL HAVE A MINIMUM 2" GRAVEL CLEARANCE ON ALL SIDES.
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