What is the best way to set a 4x4 post where I have existing concrete?

Question

I have to set a 4x4 post in my concrete patio in order to support a wooden gate. The hole needs to be dug adjacent to the corner of my garage. The gate will be 2 sections, each 4 feet wide and approx. 5 feet tall. I'm thinking that I can drill out the concrete with a mason bit and remove a circle of the concrete large enough to dig with a post hole digger. I would then set the post in new concrete. Is this logical thinking? Any suggestions?

Answer 1

Hi Rusty,
As usual Doc has some great ideas and suggestions. If, however, you are insistent on going the route you suggested, which is a sound one with one exception, here's what I suggest. Rent a portable jack hammer and hammer out the hole for the post. Trying to drill it out with a masonry bit will take until Christmas as well as go through a number of bits depending on how thick the crete is. Make sure you get the hole at least 2' deep and before you put the post in make sure to add some pea gravel for drainage. Also, treat the end of the post that will be in the ground with a wood preservative.
Good luck.

Answer 2

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Answer 3

Sounds smart to me, but there is an easier way to get the post in place. You will still have to drill into the concrete though. They sell brackets or supports that will hold a 4x4 post, and you anchor those into the concrete by Lag Bolts and concrete anchor Shields. Simpson Strong Tie makes them. The ones your hardware store carries might be of another name,but the same product idea. They are also made to be mounted in different ways. Some you put into wet concrete, some anchored directly onto the concrete with several mounting options.I think drilling ,then using the concrete anchoring shields and lag bolts along with washers would be the best way for you to go.

Answer 4

Hi,
First of all you'll likely get various answers here. If this was ME, after so many years at this, I'd forget the hole in the concrete.

Without knowing at all the substance of the gate...I want to assume something like Stockade fencing; I'd look for alternative methods. A gate that size of any substance will be "weighty" especially at the points of closing/meeting.

I'd also be interested in a wee bit more detail in how you define adjacent. If in fact the gate clould be aided in support by the structure of the garage; I'd work on that plan.

I'd probably consider a double 4 x 4 post tied into the garage CORNER, to help support. I might even use "pier blocks" with post brackets embedded, and take into account adjusting the CUT on the post. I might even do some sort of Ranch gate assembly using the 4 x 4's over, to aid in supporting the opposite gate. I might then consider turnbuckles and threaded rod for the gate structure itself; and I might consider Wheels on the gate centers.

Steven Wolf

Answer 5

Can't differ with the general contractors on this one...

4 feet wide and 5 feet tall...a lag bolt is not going to keep the fence from tipping over. You don't have enough tension in the lag bolt to support the lateral forces that are going to want to tip the fence over with the opening and closing of the gate, the winds blowing, the dog or kids leaning up against it, etc.

Embed that post at least 2' into the ground.

Answer 6

Most of these are great Ideas, here are 2 problems I see

1. You need some kind of bracing for each one of the posts for you gate hinges, I don't think that one little 4x4 will have enought *** in it to hold that kind of force for any length of time.

2 Treeted lumber will if set in concrete rot off after a couple of years, I promise..

From a scientific point of view to have enough support for the gate for every foot the post is out of the ground you need to have 2 feet in the ground. (i.e. post is sticking up 4' then 8' needs to be in the ground for proper support meaning you need a 12' post)

I know this is not what you wanted to here but good luck

Answer 7

Jackhammer the whole thing - take out all the gravel - put in and set the post - refill with concrete - don't try to do it without takin all the concrete out.

Answer 8

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Truth is, I've been a carpenter for almost 36 years, and I haven't found anything like this for less than 10's of thousands of dollars.