Weber GENESIS GENESIS 1500 Owner's Manual page 9

Recommended concrete pad requirements
We recommend a pad a minimum of 40 inches left to right,
20 inches front to back and 4 inches deep (1.85 cubic feet).
Figure 4.
Note - Cubic feet is determined by multiplying length times
width times depth and dividing by 1728.
20"
Figure 4
If you use a concrete bag mix, use the mix for maximum
strength. An average 80 pound bag of concrete mix will
make approximately 2/3 of a cubic foot of concrete.
Note - Follow the concrete bag mix, manufacturers
recommendations concerning pad preparation, gravel,
sand, etc. Figure 5.
Figure 5
CAUTION: Allow fresh concrete to cure completely
before attempting to anchor the barbecue to the
concrete.
40"
4"
Concrete Pad
Crushed stone,
sand or gravel
Earth
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