We are having a gazebo built on the end of a new deck. The deck is about 4 feet off the ground at the point where the gazebo will go and the contractor wants to use 4x4 posts dug into the ground all the way to the roof of the gazebo, to support the deck/and structure. The gazebo is 12x12, will have a double roof with cupola. With the roof I'm thinking it will be about 12' tall give or take. I know the inside will be about 8 feet clearance.

Will this be sturdy enough or should we use 6x6 posts?

  • 2
    How many posts? Jun 12, 2012 at 13:13
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    It is difficult to image what you need to do. You know how the design looks like but I can hardly see what you mean. Do you have a plan? or drawing? The structure of the gazebo it self has immense impact on the way to support it. Nobody can support their answer with out proper design drawing and specification. ie(how long is a piece of string?) It impossible to answer without more detail please.
    – Piotr Kula
    Jun 14, 2012 at 8:55
  • The supports are entirely dependent on what it's supporting. So you need an engineer to look at load spans, dead weights, live weights, foundation type, structure type, materials being used, etc. Impossible for us to answer in a forum like this.
    – DA01
    Oct 5, 2012 at 20:46

1 Answer 1


Get an architecture plan and take it to the city for a permit. They will tell you if the supports are sufficient. Despite the obvious statement that you should always get a permit, you should definitely get a permit for anything built outside because otherwise a complaint from a neighbor can force you to tear it down.

Supporting the roof is not a problem. Supporting the weight of all the people that could fit inside it is a problem. I have a 12'x14' deck that required 10 concrete posts driven 5' deep (the frost line where I live in Canada) in order to be able to support a full load of people that could possibly fit during a big party or something. It would have been 15 posts if it wasn't bolted to the house foundation. I could hold an elephant on it, but that's what the city demanded (and rightly so).

Note: Wood should not be driven into the ground. It'll rot. Either float it on concrete pads or put concrete posts down to below the frost line (if any).

  • True, though note that lots of places allow freestanding structures of certain sizes to be built without permits.
    – DA01
    Oct 5, 2012 at 20:39
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    An elephant is about exactly what IS required and is reasonable. At 60 lbs/sf live load (typ. code requirement), ignoring any greater snow loads, you need to hold up 10,000 lbs total, just about the weight of an adult bull! :)
    – bcworkz
    Oct 5, 2012 at 21:13
  • @DA01, good point. I suspect a 12' tall gazebo exceeds that, however. Also, if a structure is not up to code, it probably doesn't matter if you're within those size restrictions. Oct 5, 2012 at 21:14
  • Just for fun... Here's my deck: youtube.com/watch?v=K7-cEEfFIQs Oct 5, 2012 at 21:14
  • Depending on the location, the snow load from the gazebo roof actually can be considerable, and needs to be taken into account in addition to the live load from people. An engineer or other relevant professional should size the posts.
    – Hank
    Oct 6, 2012 at 17:28

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