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What is the minimum fence post length for a 20ft privacy fence?

What is the minimum fence post length for a 20ft privacy fence?

Old 06-19-17, 06:06 AM
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What is the minimum fence post length for a 20ft privacy fence?

Hello team,
I am building a linear 20ft privacy fence at the edge of my patio. It will be very basic and be 5ft high with 4x4 posts every 4 feet. I will then just install 3/4" wood lattice between them. Now I first regrettably listened to Home Depot sales people and purchased the metal fence post stakes and after driving them in the ground they were not stable at all! BTW I live in chicago midwest burbs and the frost dept is 42". Now my million dollar question is do I have to REALLY dig the holes at least 42" deep for this little fence? I plan on using concrete to pack the posts.
Thanks for all replies
Old 06-19-17, 06:25 AM
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The main reason for fence posts to be deep has nothing to do with frost. A fence in Texas should probably have posts just as deep as yours in Chicago. It's the wind you have to be concerned about... you want your fence to stay plumb.

A general rule of thumb is that fence posts should be set 1/3 to 1/2 as deep as the fence will be tall.

So a 6' fence would need posts that are 24-36" deep. Some of that depends on your soil too. You would obviously not want to go with the minimum in sandy soil.
Old 06-19-17, 06:32 AM
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Thank you for quick response! Thats what I wanted to hear
Old 06-19-17, 08:30 AM
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Post depth

It is always a matter of opinion... Everyone has their own individual opinions and no matter what we would all think the other guy is wrong...

In this my opinion is this.. You are installing a lattice fence on those posts... The posts as you have mentioned are installed on post stakes purchase at the local HD store.

Yes , I am very familiar with those stakes. I have on many occasion had to remove a fence that had that applicaction. In some cases what a pain, in some cases it was so simple to remove the fence I was not sure how it stood up as long as it did.

Lattice fencing panels.. ; Lattice does not need a very secure base to hold itself up. It is lightweight, it has holes in it.. The wind will hit these panels and the wind will travel right through the panels without a lot of restriction.
The panels themselves are very lightweight. 4 FOOT centers on the posts assure you have significant strength in support for Lattice work. The good thing about the posts being on 4 foot spacing is that the lattice panels will not bow in time.

I do not agree that the posts need to be so far down... 24 -30 is very sufficient...

Frost line... digging the posts, back filling with a stone base to allow water run off... cement them in place and you should be very good to go for many years to come.
If anything you might need to adjust a height here and there over time... But if you installed the fence yourself you should have no problem with adjusting the height whenever need be.

Of course, this is just my opinion... I have installed thousands of fences over the last 30 years... and I would trust my own gut feeling for my own fence if this is what I was planning to do in my own yard.

Of course,... please keep in mind... If this were not lattice and this were a solid stockade fence of sorts, this whole piece of advice gets rethought... and trust me I too would go with the deeper holes...
But still, 4 foot spacing between posts.... that is a bit much for most fences... except Lattice. Very good idea in my book.

Good luck with your project...

Greg's Fence... NJ

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