fencepergolawoodworking
Trying to figure out how bad of an idea is adding a ~3-4’x6-7’ pergola type ”roof” supported by pressure treated fence posts.
How to understand if it will hold or not? It's in the US PNW, so no severe weather, but strong winds are not uncommon a couple of times a year and, obviously, rain.
Pea gravel for the base of the hole makes sense...for drainage. On the sides, less so. I'd opt for crushed rock which will compact better when tamping. If tamped properly, you likely don't even need concrete.
You have numerous choices to deal with the gate hinge issue. For a round post you can clamp on this type of hinge and then bolt its flat plate to the gate:
Alternatively you could drill a horizontal hole through the metal post and install the bolt type hinge pin to be mated with the type of bolt on hinge strap in the second following picture:
A third option is to use the following U-bolt type hinge point mounted on the post. Then use a lag bolt hinge pin screwed into the gate framing:
Best Answer
Vernacular architecture - what's the worst that could happen?
Build it and see if it fails.
If it fails, build it again stronger. Seems unlikley to kill anybody or ruin your house if failure happens.
Vernacularly sturdier - don't cantilever it, add two more posts on the open side. Or let it fail, if it's going to, then do that when rebuilding.