Home Forums Hunting & Shooting Hunter's Campfire Question for you concrete/bricklayer guys.

I've got a fence project fixing to start at the house.......

I'm going to build a few brick columns about 5 ft high/12 in square. I'm going to put a piece of rebar inside the column, buried in the footing with the idea of filling the center of the column with concrete when finished. Question #1-how deep/big does my footing for the columns need to be? Does there need to be more rebar/screen, etc down in the footing for strength?

Next, I'm going to have a app 2ft high wall in between the columns connecting them together. I was going to stack 2 4"w x 8"t x16"l hollow concrete blocks on top of each other in between the columns. Next I am going to use some leftover rock veneer to plaster in place along this 16" high wall. Qestion #2-what size footing needed for this? Does it need rebar/steel screen, etc for strength?

Thanks for the help.

Is it a fence or retaining wall?

Footings depend on soil type, and frost lines (but that isn't likely a problem for your app)

If I was doing this in my yard I would make the footings for the columns about 18-24" square, a foot or so deep. One 1/2" vertical rebar is probably plenty but two won't hurt, put a bend in the down end. I would also run rebar in my footer between the columns, make that footer about 8" deep and a foot wide. poured as so columns and wall steel are connected and ends overlap a foot at least.

It is a fence. The soil is a sandy loam type I believe, but must have enough clay in it where as it gets very, very hard when dry. Do I need any reinforcement for the column footings?

I would check with the civil engineer in your area and see if there are any building code that pertain to this, as I am from Montana and the rules vary from state to state. If there is no code I would pour a footing 2' wide and 1' thick for the length of the whole structure and dig 4' deep post holes under each column to make sure it won't tip over. And yes I would put rebar in it.

Just do your vertical with a hook/bend under the horizontal. Have the horizontal rod run from one end to end, so it is all like one piece when your finished.

A good rule of thumb on your footings is at least twice as wide/square as the column. Depth and shape have a lot to do with soil conditions. Hard pan/clay you can go around 8 inches or more deep, with a flat bottom. If you have loose sandy type soil, then you should go a little deeper with a rounded bottom. Everthing that 700LH has said, too! The only other thing I can think of is make sure that your brick mortar has fully set before you fill the column with concrete, and when the time comes, slop it in as gently as you can. I have seen many a brick column come undone from pouring the concrete in too soon, and too fast. Good luck with your project.

R.

You need to PM Jacques Laramie!

Sorry I was gone a few days.

Anyways it sounds like you have had some good advice -- One thing that I would keep in mind though, is that other than for expense, you cant have too much footer for a colomn. IMHO 12" posts look pretty cheezy and spindly when done -- I think you would be happier with 16" or larger columns. with 12" columns you end up with a 4" x 4" hole in the center and it takes four brick per course, but by going to 16" you get and 8" x 8" hole down the center which is four times better than the 4" x 4" one for only two more brick a course.

As I said before you want as big a footer as you can afford -- your gonna be putting a lot more money above the ground than under it so don't scimp here.

I would go at least twice as big for the footer too, and at least a foot deep. and have at least four pieces of #4 bar laid out in there like tic tac toe spread a little more to the outsides but still in from edges too half way down in the mud. Any additional size or thickness will be to your advantage too. I would then have a piece or two of #5 bar sticking up out of footer at least 32" for lap high in the center ( spread a little) and more bar to drop in the hole when you are done with the columns that reaches from the top of the footer to a few inches from the top (one or two of these should do) of the column.

Then I would pour them solid full of grout ( wet concrete) when joints were all set and take the additional bar that you are going to stab in the grout and pump them up and down several times to settle grout.

Brick are not strong for fence structures and neither is the mortar between then -- 95% of your strength should come from the reinforced concrete inside of them -- and any kind of anchor attachment should reach well into that as well.

With 12" columns or posts you get so little of that that it hardly counts. Wind is hard on fences, and even if you have one that doesn't catch wind, like wroght iron, it will look better and last much longer with beefy columns.

Don't be surprised though if you can go out in several years and see some settling has taken place -- it shouldn't be too bad, but you will probably be able to sight down the fence and not see a perfectly straight line at the tops of columns anymore -- they all do that sooner or later, depending on soil and grade situations (geomorphology). None of us live or build on hard solid ground, it is more like building on a raft -- in your case several rafts tethered together , so a little movement will come along, just make them as strong of individual rafts as you can.

Oh BTW I didn't understand what you were going to do with the 4"s (4"x8"x16") but you don't want to use two of those if you can use one 8" (8"x 8" x 16") you want the big holes in 8"s for the same reason -- the strength does not come from the mortar between blocks -- it comes from the reinforced concrete in the holes -- Block are just pieces of form that doesn't need taken down, 95% of the strength is what goes in those holes.

I hope that helps and gives you some things to think about.

Jacques

Thanks a million Jacques. I think you're spot on on the size of the columns. I think 16" will be much better. How deep, in your opinion, should the footer for the columns be? Stacking two 4x8x16 hcb was my way of making a 16" tall wall (something decent) to plaster the mfg stone to in between the columns. If the 8x8x16's are much stronger I can use that. Thanks again.

You've got all the engineering for construction, now how 'bout a mix-design for your concrete?

If you do not have freeze/thaw issues I'd go with non air-entrained, 3,000 psi mix, 8" slump for the pillars, 4"-5" slump for the footings, and 'bout a .45 water/cement ratio. 25% pozzolins to reduce cost, and help workability.

If you do have freeze/thaw issues, go with an air-entrained 3,500 PSI, with the same characteristics as above.

My two-cents.

Sorry Mako, I don't savvy slump, pozzolins, or air entrained. I was going to buy some 80lb sacks of Quikrete and get after it. Educate me, please.

Do you have freeze/thaw cycles?

No need to apologize, I'd just hate to see the engineering done correctly, only to have the product fail.

I've never really worried about freeze/thaw to be honest with you. I know my sprinkler system is buried 10-12" deep and its never froze. Does that help? I live in Midland, TX.

Quikrete is fine. W Tex, like Lower Az has minimal ground movement

Make your pier ftgs 6" bigger than your columns, 16" column = 28" sq footing, 12" thick concrete. Rebar, use #4 (1/2") 2 ea way as stated before as a mat in the ftg and 2 #4 verticals coming out. Pre wire your mats and after pouring concrete center them on top and take a shovel or stick and push them down about half way, 3" min from the bottom is code, measure and jab the verts, don't make it too hard by pre installing them since you will not have an inspection, at least here in Az nonstructural/nonbearing walls don't.

As far as your 16" tall panel between columns to apply the rock, there is almost no weight per sq inch so you only need an area a little wider than 4" and 4 to 6 in thick, no rebar, basically a landscape curb size.

Sounds like a cool project.

Kent

Oh so you've got some stone to lay in a band or something around the columns I take it -- if so you want the block to be an inch or so smaller each way so that the transition happens in an inside corner -- fours will work fine for that and still give you the solid grout concrete center it's a little harder to lay a four and keep it plumb -- I think I'd still go with eight by sixteens (actually 7 5/8"s x 15 5/8" and lay then with no joint between them to make them as small as possible, then dry lay whatever brick you are using and open the joints a hair to -- if you can even get 1/2 inset, you will hide the back of the stone on an inside corner -- if you cant get enough like that you probably would be happier with the fours and trimming a little off of them to get the desired inset