How deep to bury posts for fence?

Feb 19, 2007 15 Replies

I am going to try to put up some wood fences 6' tall located in south Florida.



I talked to one contractor and they told me they will need to dig the post



24" deep and pour concrete. Some told me 48" deep. Some said 24" deep at intermediate posts but 48" deep at corners or gate posts. Any idea what is a good depth?

I am now thinking I will do it myself.



The posts will be spaced 4' apart. The post will be dug XXX inches deep and with concrete. Now regarding the standard dog eared pressure trested privacy wood fence panels, they come in 6'x8' so they will have to be nailed onto three posts. The panels have three horizontal pieces of wood. If I nail them right onto the posts, the panel will "stick out" by the width of the wood member. Should I notch the post a little so the horizontal member would be mounted flushed?



Thanks in advance,



MC


There are three types of posts in a fence design. they are: corner posts, bracing posts, and line posts. Your design only uses corner posts and line posts.

Corner posts are usually given different treatment than line posts. Just sink the corner posts in concrete and leave the line posts with plain soil or some kind of good draining material. 24 inches is good enough for all of them. that way you can bury 8 foot posts two feet deep. When fences fail it's almost never because the posts came out of the ground.

Notching the post is unecessary but when it's your fence you can build it any way you want. Although the panel will stick out it will look just the same as any other fence since they are all built that way. Spacing your posts at 4 feet is too much work. 8 feet is adequate spacing between post.

A lot of decisions depend on the type of soil and local weather conditions. In my area a rule of thumb is to bury one foot for every 1 1/2 foot of fence, a 6' high fence would have posts 4 feet in the ground. This is because if the frost gets under the post it will push it upwards, secondly is because our soil is clay loam which can get soft in spring allowing a fence to be pushed over by winds.

Your area doesn't have frost, and there is no spr>> I am going to try to put up some wood fences 6' tall located in south >> Florida.

The appropriate depth will vary according to what you've got for dirt, and what your expected wind-load is. If you're doing it yourself, set the posts as deep as your rented soil-auger will go. I wouldn't notch the posts, less because it sacrifices strength than because each cut is an invitation to rot.

Here's a novel idea, contact your local building department. Or, you can hope someone from around the globe has the correct answer for you.

Good rule of thump 1/3 the height. 6' = 2" deep. Another thing to do if you are going to poor concrete around the post put about 6" of gravel around the post otherwise your just making a bucket to hold water around the post.Even a couple shovel loads of dirt is better than just concrete. Don't think PT is not going to rot . Another option witch would be even better is metal post I have even seen them with brackets welded to them to hold your 2X4 runners.

Consider 2.5" metal posts. They're cheaper, stronger, need less foundation, never rot, and are easier to work with. With ours, we drilled them and used lag-bolts to attach horizontal runners. The pickets were screwed to the runners.

I cannot find the post depth requirements, I will keep on looking. I talked to a few contractors who said it does not matter what it is because every one does it 24" deep anyways.

I did find that posts have to be 4' apart since hurricane Andrew came through in 92. So I have to do it 4' apart even though it is a lot more posts.

Thanks,

MC

Metal posts? Can you elaborate? Do yo umean the metal posts used by chain linked fences?

Thanks,

MC

Again, ask your local building dept.; they will tell you the appropriate depth. I would imagine that in Florida you can probably go with 24", but up in western New York by Lake Ontario, where the ground freezes, we have to go 42" deep to avoid frost heave.

I saw them at a hardware store in the Seattle area. They were a 2" diameter like a chain link fence but they had brackets welded on the to hold your 2X4 runners. I have also seen quiet a few wood fences using metal post so I'm sure there more than one manufacturer and type. If I was going to build a fence for myself I would hunt them dawn.

do yourself a favor and just split the difference. buy 9' 4x4's and sink them 3' into the ground for a 6' fence. if you want stronger corners use cement.

mike.........

Simpson Strongtie sells oversized pipe stirrups for just this purpose.

Almost anywhere in the Miami area, if your post hole is more than 2' deep the bottom will probably be sitting in water --

So may be I should dig 28", put in 4" of sand and gravel then put in post, and add concrete cement around it.

MC

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