CR-21 Hardscaping and Irrigation Systems Exam| Questions and Answers| 100% Pass|Updated 2026

CR-21 Hardscaping and Irrigation Systems Exam| Questions and Answers| 100% Pass|Updated 2026 What is the minimum thickness of brick for the exterior wall of a fireplace? a) 6 inches b) 8 inches c) 10 inches d) 9 inches 8 Inches What is 1/2 inch of accumulated organic material in a grassy area called? a) mulch b) ground cover c) stolons d) thatch layer Thatch Layer What should be provided as a cover for the drain tile before installing the pond liner where subdrain is used?a) 4 inches of pea gravel b) screen with 1/4 inch mesh c) a pool grate d) 8 inches of medium sized rock 4 inches of pea gravel How do you properly plant ground cover? a) in a circular pattern b) in rows, each row staggered c) in groups of 2 d) 18 inches apart in rows In rows, each row staggered You are going to pour a concrete pad that is 16 feet by 22 feet and 4 inches thick, how many cubic yards of concrete are needed? a) 7.3 b) 6.3 c) 3.3 d) 4.34.3 cubic yards 4.3 cubic yards 4inches --- 0.333ft Cubic feet to cubic yards /27 16220.333=117.3333 117.3333/27 = 4.3 cubic yards How wide should the footer be for a CMU wall? a) equal to the width of the block b) equal to the depth of the frostline c) three times the width of the block d) twice the width of the block Twice the width of the block How does a contractor know how to fill a trench to a certain grade? a) by guessing b) the type of soil c) by available backfill d) the specifications The specificationsHow many 8inch x 8inchx16inch concrete masonry blocks will be required for a wall that is 8 feet 8 inches high and 104 feet long? a) 936 b) 1088 c) 1124 d) 1014 1014 blocks 8 feet * 12 inches = 96 inches + 8 inches = 104 inches 104 inches / 8 inches = 13 for height 104 feet * 12 inches = 1248 inches 1248 inches / 16 inches = 78 for length 13 * 78 = 1014 blocks What is the maximum height above grade of a wooden deck that a CR-21 license may build?