The bottom of the starter strip (the part the bottom panel hooks on to) should be at least 1 in. below the top of the foundation, but the lower the vinyl siding is installed, the better. It protects the sheathing from rain, snow and pests. Most suppliers sell two sizes of starter, 2-1/2 in. and 3-1/2 in. Spend the extra few bucks on the wider stuff and start your siding a bit lower.
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