Building an 8ft privacy fence

ezemail24

Junior Member
Jun 5, 2016
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I've haven't been able to find info about building an 8ft wooden privacy fence, so I'm using the info I've found for smaller fences.I'm just doing the back of my yard to block dogs from jumping into my yard and an ugly house behind me. The fence is about 62 feet long.

Should I use 12 ft posts buried 4ft deep with the hole being 12 inches wide? Or should I cut posts to 11ft and bury 3 feet. I plan on filling the holes with concrete spaced about 7.5 feet apart.

The wood I plan to use is pine treated 4x4s for the posts and cedar for the three 2x4 rails and the 1x6 pickets. I also plan to use string and a level to make sure it is straight.

I've checked with my city and the fence limit is 8ft

Any thoughts or advice would be appreciated
 

paperfist

Diamond Member
Nov 30, 2000
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Don't buy the posts from Lowes or Home Depot.

Where do you live? Frost line usually dictates depth, but I don't believe it penetrates more than 3'.
 

ezemail24

Junior Member
Jun 5, 2016
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Don't buy the posts from Lowes or Home Depot.

Where do you live? Frost line usually dictates depth, but I don't believe it penetrates more than 3'.

Tulsa Oklahoma. Are posts from other hardware stores usually better?
 

paperfist

Diamond Member
Nov 30, 2000
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Tulsa Oklahoma. Are posts from other hardware stores usually better?

I just find that PT from a real lumber yard doesn't split and crack as fast as the stuff from HD or Lowes. Generally it's the same with their 2x stuff.

I'm not an engineer, but since you're going 8' up another 1' down might aid you in keeping the fence stable since you'll have more 'anchor' mass.
 

Carson Dyle

Diamond Member
Jul 2, 2012
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Sinking the posts a foot deeper is obviously going to be stronger, but digging 4' deep post holes won't be fun. The natural inclination is to think bigger/deeper is better, but it may not be necessary. I think I'd try to find someone from a fencing company and pick their brains. Maybe even get a job estimate on the fence you plan on building and see what kind of information it provides you.

Another thing to consider is that, depending on the design of the fence, the posts don't necessarily need to be as tall as the fence. With many designs, the posts will be a foot or more below the top of the fence slats. So you may not need/want 12' posts. You might use 10' posts buried 40" with 6'8" above ground, for instance.
 
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KentState

Diamond Member
Oct 19, 2001
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Don't know about your city, but here anything over 6' requires a permit. There will be specific requirements if it applies to you. The other thing to consider is a higher fence catches more wind, which may make 4' more desirable.
 

Greenman

Lifer
Oct 15, 1999
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I just find that PT from a real lumber yard doesn't split and crack as fast as the stuff from HD or Lowes. Generally it's the same with their 2x stuff.

I'm not an engineer, but since you're going 8' up another 1' down might aid you in keeping the fence stable since you'll have more 'anchor' mass.

It's because the stuff at home depot and lowes is hem fir, the stuff from lumber yards is dug fir.
 

SparkyJJO

Lifer
May 16, 2002
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Don't know about your city, but here anything over 6' requires a permit. There will be specific requirements if it applies to you. The other thing to consider is a higher fence catches more wind, which may make 4' more desirable.

He said he already checked withe city (limit is 8' per his post).

While it is more work to dig a 4' hole vs a 3' hole, it should be more stable. I'd go for 4' holes if possible. But like Carson Dyle said, the posts don't necessarily have to be as tall as the rest of the fence as the slats are what determine the height, and they attach to the horizontal boards between the posts. It does depend on what style of fence you're going for.
 

KentState

Diamond Member
Oct 19, 2001
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Difference between a height limit and requiring a permit to build up to that limit.
 

paperfist

Diamond Member
Nov 30, 2000
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It's because the stuff at home depot and lowes is hem fir, the stuff from lumber yards is dug fir.

Thanks. I always just assumed it was because what they sold was junk bottom of the barrel lumber.

It's quite comical (really aggravating) going though a whole pile of their 2x4s to find 6 good, semi straight ones. I don't even bother anymore.
 

Greenman

Lifer
Oct 15, 1999
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Thanks. I always just assumed it was because what they sold was junk bottom of the barrel lumber.

It's quite comical (really aggravating) going though a whole pile of their 2x4s to find 6 good, semi straight ones. I don't even bother anymore.

That's actually a problem with pressure treated material in general. Even the dug fir stuff isn't all that good to start with, and pressure treating process doesn't do it a lot of good.

I have an ongoing project that requires 160 pressure treated posts every year. I have to special order them to get select structural material, and even those have a higher failure rate than #2 fir.
 

DrPizza

Administrator Elite Member Goat Whisperer
Mar 5, 2001
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:) I'm surprised Greenman didn't remind the OP to dig the hole 6" deeper and fill the bottom 6" with gravel. (I think he gave that advice before.)

Depth is going to depend a bit on the subsoil in addition to the frost line. Is it clay? Rocky? Sandy? Heck, in some areas (probably not your area), after 2 or 3 feet, you're hitting bedrock. I've also read that it's not recommended to use concrete, though I have in the past on corner posts. (The last 2 posts in a line.) I believe the reasoning for no concrete is put to rest if your post is sitting on a bed of gravel - the reasoning is that a gap can build between the post and concrete, particularly as the wood shrinks. That allows water in, and the concrete would act like a bowl holding the water, hastening decay. But, with the gravel, any excess water between the post and concrete can get out.
 

NutBucket

Lifer
Aug 30, 2000
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Or just use metal posts. I can't see the point of using wood posts unless it's part of the design (like a classic picket fence). Even then, I'd be tempted to just box a metal post.
 

FeuerFrei

Diamond Member
Mar 30, 2005
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Might want to consider wind pressure. Oklahoma has some potent storms. 8' tall privacy fence would be a major windbreak, depending on where it's located. Maybe add gappage to reduce pressure and use 6x6 posts.
 

HeXen

Diamond Member
Dec 13, 2009
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Mine is 6' and it's all leaning due to wind pressure and Im surrounded by trees and houses. Use lots of concrete to hold it down I guess.
 

Humpy

Diamond Member
Mar 3, 2011
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I'd second the use of steel posts. A 4x4 is probably strong enough but they sure tend to warp and twist a lot, especially sticking 7 or 8 feet out of the ground. A nice pressure treated 6x6x12 piece of doug fir would be more stable and strong enough but costs $50 or $60 a piece?

A 10.5' stick of galvanized 2 3/8" x sch 40 pipe is about the same cost or likely less, super strong and straight. Generally, they only need an 6" or 8" hole down 3.5' so are easier to install too.
 

paperfist

Diamond Member
Nov 30, 2000
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Or just use metal posts. I can't see the point of using wood posts unless it's part of the design (like a classic picket fence). Even then, I'd be tempted to just box a metal post.

A 4x4 metal post? I don't think I've ever seen metal fence posts that were for anything other then chain link.
 

NutBucket

Lifer
Aug 30, 2000
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Humpy is on the same page. They have brackets to attach wood rails to round steel posts. My dad and I built a privacy fence about 20 years ago using that technique. This year he's had to replace some termite eaten boards and rails but that's cake compared to posts.

My dad is nuts though. He used thick wall galvanized pipe and had one end threaded so he could screw on a cap. Those things might fail when the tsunami hit LA.
 

Micrornd

Golden Member
Mar 2, 2013
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Difference between a height limit and requiring a permit to build up to that limit.

That's pretty much the way it is here too.
If you call, they tell you 8' is the limit.

6' only requires a std. permit, over that up to 8' requires a "variance" (more fees basically and a trip before the zoning board, but usually always a gimme if you are "polite")

Over 8' requires the same "variance" (with much more fees and "knowing someone" on the zoning board).

Around here there are 12' high fences next to 4' high fences in backyards in some high end neighborhoods :eek:
Makes it easy to see who is connected and who isn't. :sneaky:
 

Humpy

Diamond Member
Mar 3, 2011
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You don't need a permit for a tall hedge ;)

I did a job in a historic district where the owner wanted a short section of fence installed but the neighbors, city, and design review board were all up in arms about it, each with there own thoughts and complaints about the fence and each other.

We had a trench dug and hacked up the root balls of some 10' evergreen trees so they could be planted about a foot apart to create a living fence. Within a few weeks everyone was suddenly on board with the original plan but the owner was like "Nah, I'm good. Thanks anyway!" :)

I eventually went in and stealth built the fence behind the trees when the property was being sold. The new owner removed the dying trees with the fence being grandfathered in as existing before the sale.
 

purbeast0

No Lifer
Sep 13, 2001
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i had an 8 foot privacy fence put in last year. while i can't give you details since i didn't build it and had a builder do it, our posts are 6x6 i believe, not 4x4. i don't think it is 8x8.

also, 8' is not allowed (at least in my county) really anywhere. luckily our sub division however allows it. normally 6ft are only allowed.

one part of code we did not meet though was that any fence over 6'6 was supposed to be at least 5 feet back from our property line, whereas anything below can be right at the property line. i knew the neighbors wouldn't care for the most part so they put it right on the property line. they did however build it so that in the case someone DID complain and i had a problem with it, i could cut down 1.5 feet and it would be just fine.

also one thing to maybe consider, that i didn't until the builder told me, was that the part that would be facing the street that can be seen from the front of the house, to make it 6 feet tall. then when it starts to go backwards towards the back of your yard, the first section can go from 6 to 8 feet. that way from the front it doesn't look overbearing. i'm glad we took their suggestion on this too, because from the front it looks like a normal privacy fence with a 6ft gate.
 
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