We recommend a 4″ to 6″ compacted layer of GroundSmart^™ Rubber Mulch. A 4″ inch compacted layer is International Play Equipment Manufacturers Association (IPEMA) certified to provide up to 10 ft of critical fall height protection, a 5″ compacted layer will provide up to 12 ft and a 6″ compacted layer will provide up to 16 ft of critical fall height protection. When assessing how much rubber mulch you need, be sure to measure from the highest point where someone could jump or fall.