Sinking Posts in ground...

[doechsli]

While it's cold, I'm planning my summer project. I am going to build a shelter for my grill (and me) to protect from rain. Anyway, the plan calls for two 6x6 posts sunk in the ground 8 feet apart and a small cantilever roof. I'd like for the posts to have 7.5 feet of clearance. My question is will a 10 foot 6x6 with 2.5 feet sunk in the ground be enough support? Frost line so I have been told is 24 inches in my locality (Louisville, Ky). What are best practices for sinking a pole in the ground to delay rot?

 

[mako1]

Well,the 120-30 + 7.5 but you will need something to support the leading edge of the roof on the 8' span.I don't see this as a cantilever?
If so what do your plans call for.More info would be good so I can give a good answer.I am not trying to talk down to you but do you really understand what cantilever is?

http://en.wikipedia.org/wiki/Cantilever Basically ,a cantilever is only supported at one end and has the structure to support the remaining span.That's why I question the posts?

 

[doechsli]

http://lumberjocks.com/projects/65776

The link above has a link to what I am trying to do.....

 

[bud16415]

I personally would want more in the ground. Not so much for frost as for tipping. You can look at it two ways 2.5 feet would be fine providing you pour enough concrete around it to give enough weight to make it stable. Or you could go with longer poles.

I put a 6x6 x 12’ in for my farm bell totally over kill from the weight it was to carry but I went down 4 feet with my hand PHD. It wasn’t that hard to do. For that roof I personally would want 4 foot in the ground and forget about the concrete. Just compact it well as you go when you fill the hole.

 

[havasu]

I only want to comment on the structure and say that is a nice DIY project, and is going to look great. Me living in So Cal, we don't have heaving or frost line concerns, so I won't comment on the built itself.

 

[slownsteady]

I like that design, but first thing that crossed my mind was that's a pergola. No roofing material and no snow load. I don't know what your snow expectations are in Louisville, so I 'll just throw it up as a thought.

 

[doechsli]

So what I am hearing is 12 feet with 4 feet or more in ground if tamping or if using concrete then 2.5 feet will likely be enough. I hear conflicting stories on how to set the posts.....some say a gravel bed to prevent standing water some say sonotubes. Advice there?

 

[nealtw]

If I understand what you are building. it's an umbrella on two posts. Then wind is your next concern, I would want 1/3 of the post in the ground.

Wood in wet underground does not rot, the place to worry about rot is at ground level. A sono tube works fine with a footing but you want the concrete to fill the hole to support the post, just make sure the sides of the holes are straight up and down until you are past frost level. If the concrete flairs out, you can still have frost lift.

 

[mako1]

Thanks for the link.You lnow w hat they say about picture .I agree with neal. I always crown the concrete a bit at ground level to help with water runoff.

 

[bud16415]

Hi again Dennis

We don’t know the soil conditions where you are building this. Around here many fence poles and grape poles are just sunk in the soil and last many years 30 or more. Adding concrete adds mass so my point was enough mass would counteract tipping just as depth would. Pressure treated (not surface treated) that is intended to be in contact with soil will last as long as you will ever need it to. The way I like to back fill a pole like this every few inches of fill I use a 2x4 or 4x4 to pound the soil back in tight around the pole. You can also use the tamping to correct for level as you are going up with the fill.

 

[nealtw]

Around here any wood that has been treated for contact with the ground has been insised.