I am planning to install a wooden fence from the corner of my house to a
neighbors fence, a distance of 28.5'. From the corner of the house I have
to cross about 15' of a concrete apron. There will be a ten foot gated
opening about 5' from the corner of the house.
My question is: what is the best way to set the 4x4 posts in (or on) the
concrete. I would prefer not to have to punch holes in the concrete for the
uprights but could anchor them with steel plates and use gussets to
reinforce the base of the uprights. What do you suggest? Thanking you in
Derek in south Florida
I don't see a bolted plate holding up long term. Perhaps it would if you
ran a support cable from the post to the wall of the house, but it would
look terrible. There is going to be a lot of lateral stress on the post.
One thing that would help, assuming the concrete is flat and level, is to
put a wheel on the end of the gate so it takes the weight.
A five foot wooden gate will have significant weight, and it will need
a sturdy post to avoid sagging. A standard six foot fence needs a 4x4
post with at least three feet in the ground--more if possible. The rule
of thumb is one third of the post underground for gates, corners, and
ends. You can get by with less for the line posts if you don't have
lots of side loading from wind or climbing people.
You can brace the load parallel to the fence with diagonal bracing back
to the next post, but when you open the gate, the load changes to
perpendicular to the fence, and braces don't help.
You _might_ be able to get by with a steel post, welded to a, say, 18"
flange at the bottom, with hefty bolts sunk into the concrete; but it
won't be very attractive.
Put wheels on your gates. The posts won't have to be as sturdy.
You have a less than ideal situation. You would have to put very large
plates on the concrete to get them to be solid, and then the mounting of the
wood to the plates would be difficult to get that joint strong, too.
Probably weld pipes onto the plates, then drill huge holes into the posts.
I was a steel erection contractor for nine years. Here's my take on it.
IF YOU CAN, drill and set the heaviest posts that you can. Something
similar to telephone posts about 8" in diameter. If not, something like 3"
x 3" x .250" wall steel tube set three feet into Sonotube. An alternative
is to have diagonal supports, or right angle ones that look like framing
squares coming out from the posts and anchored in the concrete, or in a post
hole with concrete.
Your main problems will be: natural sag due to the wood aging, kids swinging
on them, hanging hardware wandering south after a few months of rain/sun
cycles, wind catching them and testing the whole assembly, and the inherent
instability of the rest of the fence to act like a wet noodle when magnified
What you want is not just a plain little fence. Wood is heavy, and you go
to another order of magnitude from say, chain link. What you want to do can
be done, but to do it right, you will have to overengineer it.
Underengineer it, and you'll wake up to a pile of junk one morning, or
someone getting hurt. A ten foot opening in a wooden gate with one or two
pieces is a lot of wood to mount, keep straight, and swing open and closed a
lot. Wood is not the best choice because if gets loose too much. A better
alternative that looks as good is making a metal frame, then bolting wood to
it. Easy to change out if it rots, warps, or gets busted. Put diagonal
cables in there with turnbuckles so you can adjust it when needed.
Probably not what you wanted to hear, but this thing is big enough to hurt
someone, or be a disastrous failure. Do it right from the start, and it
will be safer and cheaper. You'll be thanking yourself the first good storm
My girlfriends Mom and Stepdad hired a similar job done (6ft around yard and
a 10ft gate opening (2 - 5 ft gates). The wind caught one gate and twisted
the 4x4 so bad it was a wonder it did not break off. They called back the
handyman, he screwed/bolted up the 4x4 so it barely holds. They asked me to
look at it, I told them I can't fix it, it should never have been installed
like that in the first place. I had them add a wheel to the gate.
You need to plant the posts in the ground (cut concrete with a saw,
break,dig, and cemet). Use 6x6 wooden or 4x4 steel posts. For the gate
look for a heavy steel gate that you can mount fence boards to or build with
wood using metal corners supports/bracing etc. Cedar fence boards are much
lighter but costs more. Use a spring loaded wheel on the gates.
Another idea is using standard gates with those plastic sleeves that slide
into the fencing to create a covered look. This way you would not need such
heavy posts, but you still might use the wheels.
Visit/call your local fence company and see what they say.
wheels on for support. I had also thought of making a sliding gate on
wheels. I might check with fence companies but I will still do this myself
with a burly friend who just lost his construction job helping me. To get
the permit I will have to show the details of construction to the city
building dept and have it inspected.
Best wishes to y'all, Derek
rent a cement hammer from the hardware store and make 2 holes for your
posts and forget about it. Do it right and stop worrying about the
drilling, good luck, henry
Lemmeesee ....... South Florida ............. don't they have humid
conditions there? Yeah. Just stick wood posts in the ground. It SHOULD be
okay. What could happen? The worst is that you have to redo the whole job
in a couple of years, but at least you won't be worrying about it in the
Hint: Do it once, do it right.
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