EXCAVATION
Trench excavation must be 5 inches greater than the trench depth and a minimum width of
either 25 or 34-1/2 inches, depending on which system is being installed. Soft and/or
shifting soil subtrates may cause cracking of the concrete and consequent movement of the
trench. It is critical that the concrete be poured on an adequate foundation.
25 inches (356mm) minimum f/ Z-874-12
34-1/2 inces (508mm) minimum f/ Z-874-21
Summary of Contents for Z-874
Page 3: ...FRAME CONFIGURATION ...
