Rock Mass Class	Support Recommendations
Rock Mass Class	Rock bolts		Shotcrete	Steel sets
Class I Very good rock	No support required except spot rock bolting
Class II Fair rock	3 m long bolts in crown, spaced 2.5 m with occasional wire mesh	50 mm in crown where required		None
Class III Poor rock	Systematic bolt 4 m long, spaced 1.5 - 2 m in crown and walls with wire mesh in crown	50 - 100 mm in crown and 30 mm in sides		None
Class IV	Systematic bolt 4 - 5 m long, spaced 1 - 1.5 m in crown and walls with wire mesh	100 - 150 mm in crown and 100 mm in sides		Light to medium ribs spaced 1.5 m where required
Class V Very poor rock	Systematic bolt 5 - 6 m long, spaced 1 - 1.5 m in crown and walls with wire mesh, bolts invert	150 - 200 mm in crown and 150 mm in sides and 50 mm on the face		Medium to heavy ribs spaced 0.75 m with steel lagging and forepoling if required. Close invert