My deck is 20' by 24'. Should we use 6x6 posts or 4x4 posts? Which will look better on such a large deck?
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I wouldn't even consider using a 4x4 post on a deck that big unless it was more of a patio. First most code requires 6x6 or greater for decks. Then you could have some huge warping issues with 4x4s - if you used them and they are more than a couple of feet you better strap then. Also you can notch the 6x6s for rails and stuff - you won't be able to nothing a 4x4 without taking out its whole top. This doesn't even get into strength comparisons.