I'm going to build a simple privacy fence between 7' and 8' tall. There will be no space between the boards. I would like to know if 4'x4' posts be strong enough, or should I use 6'x6' posts?

4x4 will be strong enough for anything shy of a hurricane, but you will need 10' - 12' long posts anchored in concrete.

In most places I have worked, anchoring them in crete will only hold water to the poost and make them rot out quicker. Compacted gravel is the better backfill soil.

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