the first set of fence details you posted is great
but
NONE of the Simpson post bases / column bases are designed / meant to be used in free standing post configuration (ie a fence post or flag pole) Read the catalog notes.
From the catalog
Post bases do not provide adequate resistance to prevent members from rotating about the base and therefore are not recommended for non top- supported installations (such as fences or unbraced carports).
cheers Bob
lateral loading from wind, snow, etc.
"fftt" wrote: ===================================== Your concept is good but the devil is in the details.
NONE of the Simpson post bases / column bases are designed / meant to be used in free standing post configuration (ie a fence post or flag pole) Read the catalog notes.
A 4x4 post embedded in concrete in the ground has a decent "moment capacity". To get a fence post connected to a "concrete chunk" via a metal connector to perform the same as an embedded post requires a bit of design; especially the fastener size and pattern.
Its not as simple as it appears ....... a moment capable connection; wood to concrete via metal connector winds up being a pretty hefty piece of hardware ====================================
Agreed.
If you go back and check my post, you'll notice that 10 GA metal (1/8"+) is spec'd as well as standard 1/2", "J" bolt anchor bolts in the concrete.
You will need at least a 3/8" inside radius for the 90 degree turn to minimize stress concentrations. (You need a press brake operator with a little talent)
Think of this as a 30 ft tall lighting pole, secured with four (4) mounting bolts to a concrete cylinder.
The design approach is similar.
I doubt anything in the Simpson catalog comes close to the above.
You will have a better chance finding something in the Valley pole catalog.
Lew
Here are several designs of commercially available post anchors from Simpson:
would come close to being suitable for a free standing post application.
Lew
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Lew-
You're preaching to the choir.......
and your design, though sound in concept, won't do the job unless you go a ways up the post
Simpson has no catalog items to do the job either .....BTDT
Connecting a wooden fence post to a concrete embed is not the same as connecting a metal flag pole, traffic signal pole, etc to its foundation.
The wood to metal load transfer will be the weak link.
What is the moment capacity of 4x4 fence post? What is the moment capacity of your metal embed? What is he moment capacity of your proposed metal to wood fastener pattern?
KInda hard to fully develop 4x4 moment capacity with through bolts plus cross grain tension will bite you. Not to mention the inevitable sloppiness in the connection. You'll have better luck with lags. Out of plane strength will be decent but in plane (all the fence) will be rather low unless you have straps on all four faces.
cheers Bob
The Simpson post / column bases are not designed nor meant for free standing (ie fence post) applications......read the catalog notes.
cheers Bob
======================================= You're preaching to the choir.......
and your design, though sound in concept, won't do the job unless you go a ways up the post ======================================= You don't like a 12" strap then make it 18".
The bending load is handled by the metal, the wood is just along for the ride. ====================================== Simpson has no catalog items to do the job either .....BTDT ====================================== That was my reaction to Tom V's post. ====================================== Connecting a wooden fence post to a concrete embed is not the same as connecting a metal flag pole, traffic signal pole, etc to its foundation.
The wood to metal load transfer will be the weak link. ====================================
Not sure I follow you. ======================================
Could care less.
The metal is not imbeded.
You can calculate the section modulus based on a 3-1/2 square with 10 GA walls on the two (2) opposite sides and none on the other, if you like.
proposed metal to wood fastener pattern?
None required, the wood is trapped by 3" wide straps and thru bolts. The bending load is handled strictly by the metal.
plus cross grain tension will bite you. Not to mention the inevitable sloppiness in the connection
You lost me.
Lags are guaranteed to mess up. Much prefer metal plates thru bolts with ESNA (Aircraft) stop nuts.
be rather low unless you have straps on all four faces.
Straps must face fore and aft to handle the wind, snow, etc load.
The lateral sides of the post do not require straps since the fence will serve as diagonal bracing.
Lew
Agreed! 8 or 9 inches is not going to cut it unless the fence is inside a building where no one or wind will come in contact with it.
Lew-
Your concept is good but the devil is in the details.
NONE of the Simpson post bases / column bases are designed / meant to be used in free standing post configuration (ie a fence post or flag pole) Read the catalog notes.
Totally agree, IMHO they need to be a heavier material, aproaching 1/4" thick and extend up the pole at least 24".
A 4x4 post embedded in concrete in the ground has a decent "moment capacity". To get a fence post connected to a "concrete chunk" via a metal connector to perform the same as an embedded post requires a bit of design; especially the fastener size and pattern.
Its not as simple as it appears ....... a moment capable connection; wood to concrete via metal connector winds up being a pretty hefty piece of hardware
Gotta agree there too, there comes a point where digging a hole large enough to handle a large enough diameter cylinder, positioning the bracket and handling the extra concrete becomes a much more labor intensive job than probably replacing the fence again. For longevity I still believe a galvanized steel pipe is going to be the simplest and best bet.
I missed the beginning of this thread. I would just note that in my experience in the mid-atlantic area, a CCA pressure treated SYP post will last at least 25 years buried directly in the ground. I have PT posts that have outlasted 2 generations of cedar pickets and are now holding up their third. I cannot say if the newer PT chemicals will hold up as well as the old CCA formula, but it seems that all that concrete and metal is overkill .
Leon-
I've designed & built moment resistant post bases where there was NO wood to concrete or wood to soil contact. They are HEFTY pieces of hardware and look like crap, only suitable for "hidden locations"
I agree that a galv pipe into concrete is the strongest, simplest way to go. But the pipe has to be pretty large & the pipe to post connection is hard (imo) to make decent looking. Simpson makes some pipe to wood connectors (like large pipe straps) but one still winds up with the pipe showing unless you "box out" the pipe.
I've yet to see or develop a concrete / connector / post solution that reduces rot / termite issues AND looks good enough to satisfy the customer. :(
I think the best looking, quickest, easiest, cheapest solution is a treated 4x4 in concrete over gravel using the heavy treatment (not the home depot stuff).
cheers Bib
Leon-
I've designed & built moment resistant post bases where there was NO wood to concrete or wood to soil contact. They are HEFTY pieces of hardware and look like crap, only suitable for "hidden locations"
I agree that a galv pipe into concrete is the strongest, simplest way to go. But the pipe has to be pretty large & the pipe to post connection is hard (imo) to make decent looking. Simpson makes some pipe to wood connectors (like large pipe straps) but one still winds up with the pipe showing unless you "box out" the pipe.
Actually it is not uncommon to see a fence, along the coastal areas, with chain link "terminal" posts for the regular posts. There are wrap around brackets that allow the attachment of wooden 2x4 rails readily available at most home centers. You certainly want the termanal posts as they are approximately 2.5-3" in diameter. The normal smaller posts would not be suitable. If you really wanted to strengthen the post you could fill it with concrete also. Actually these also look pretty decent .
I've yet to see or develop a concrete / connector / post solution that reduces rot / termite issues AND looks good enough to satisfy the customer. :(
I think the best looking, quickest, easiest, cheapest solution is a treated 4x4 in concrete over gravel using the heavy treatment (not the home depot stuff).
cheers Bib
and 4x4 or 4x6 PT posts using 1/2" bolts).
scott
Another Solution:
Plastic electrical conduit is Sch 40, gray PVC, 10 ft sections, and is suitable for above or below grade installation.
Install 3" conduit with gravel surround about 24" below grade then fill with sand to about 12" above grade.
Cap top of pipe is optional.
Attach fench with wrap around clamps not thru bolts.
If you don't mind gray color, you will be happy with longevity.
If you do mind gray color, it will be like ugly on an ape.
Have fun.
Lew
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