footing for pole barn posts

[mopower440]

I got the 'how to build a pole building' book by Mthew Logan, he says for the pole footings to either pour concrete in the holes or pour a 45 pound bag of gravel in the holes for the post footing, i figure the gravel would be easier than fooling with cement, but where do you buy bags of gravel?

 

[cowboydoc]

You can buy bags of gravel at any home supply store like Menards, Lowe's, Home Depot. The cheapest way would be to go to your local quarry and get a pickup load of it. The easiest way is just to get some oval concrete footings. They are usually 12-14" in diameter and 4" thick. You just drop them in the bottom of the hole and put your post on top of them. No fuss and no mess.

 

[CTyler]

Thats what a lot of pole building companies do. Drop a round, octagon, etc.. patio block down the hole.

 

[Molerj]

Or you can buy the bags of sakrete & just empty the bag in the hole, dry.

 

[yellowdog99502]

Be sure to check with your local building department. Some get rather tough on footings for post type construction. Depending on your soil conditions, gravel may not be the best choice.

In a worst case situation, a 30' wide building with posts at 8' on center and a 30# snow load gives a load of 3600 lbs at the footing (no dead load included). For a 4 x 6 post the equals 150 psi or 21,600 psf. Not very many soils will support that load. By using a 16" diameter footing that load is reduced to 2,580 psf. The footing depth (thickness) must be 1/2 the diameter of the pad.

There are several companies that supply the pole barn industry throughout the country and carry a precast 'cookie' just for this use.

Secondly, if you go with the dry pre-mix, be sure to add water and mix it in the hole and let it set before placing the posts. We have seen several structural failures caused by simply pouring the dry mix in the hole and expecting the available ground water to permeate into the mix. It just doesn't happen all that easily. I know there are a ton of buildings that have been done this way with no problem, but, I have never felt that lucky.

Concrete is cheap insurance compared to a building that decides to sink.

Enjoy the project,

Don

 

[mopower440]

I like the idea of patio blocks, but wouldnt i need to double stack them to make them strong enough?
also, i like the idea of pouring the dry premix into the hole and adding water, then mixing and letting it harden, but wouldnt i still have to mix sand in with it to make it right?

 

[gerard]

My contractor used solid 3 x 6x16 blocks, put them in the bottom of the hole, dump in a bag of sakrete dry which fills in around the block (he used an 18 or 20 inch auger so the holes were pretty big), place the 6x6 post and dump in another bag of sakrete dry, then backfill the entire hole with running crush and tamp. No need to water, the concrete will absorb moisture from the soil and cure just fine. (Remember with concrete the less water in the mix the stronger the concrete, just may take a little longer to set up if you dump it in dry.) Using two blocks wouldn't hurt but the blocks are pretty strong in compressive strength as long as they sit on a solid base. All the block is doing is spreading the weight of the post over a bigger footprint so you'll get less settling. Anything that accomplishes that same goal will work just as well. (You can use big flat rocks if you have some handy)

 

[jmc]

Yellowdog,

I felt the way you do about leaving dry sakcrete hydration to chance but I just had Morton put up a barn for me and they put it in dry. When I asked them about it you could tell that a lot of their other customers had probably questioned them on it and I think they would have mixed it if I had pressed them. In the end, I relied on their reputation and experience of 100 years in this business.

This is my second Morton building and they don't skimp on anything- material quality, structural, or skilled labor. I'm kind of picky about construction details and watched their progress closely. When they were done with it I couldn't help but congratulate each one for doing such a careful job. Anyway, it could be that they knew that this southern Indiana clay would provide the water the sakcrete needed and they may not leave it to chance in other types of soil.

As an aside, their opinion on concrete "cookies" was that the bottom of the holes are not clean and flat. The cookie may rest on the temporary high points of the bottom and settle later.


John

 

[mopower440]

what about this guys, i ahve used this premix from lowes before, you dont need to add sand to it, just water, i did it for my mailbox post, directions said to pour the dry mix into the hole, then add 1 gallon of water and stir it and let it set, no sand mixing involved, would this be sturdy enough? i could just dump the bag in the hole, add the water, mix it up and let it harden, instant footing, then i can set the poles on top of it..?

 

[Molerj]

Just to add my .02 worth. If you are going to add water to it, it would be easier to mix it in a wheelbarrow than trying to mix it in the hole. Then when you dump it in the hole, you would be sure that it would level out because it would be thoroughly mixed up.

 

[EddieWalker]

If you decide to use pre-mixed sacks of concrete for the footings I'd suggest using the higher qualitiy stuff. One of the reasons for the price diference is the use of lesser quality material.

You are going to have tens of thousands of dollars of tools, equipment, vehicles and family momentos in this building over time.

The very most important thing to consider is the foundation. This is not the place to cut corners. Don't build it like a fence post!

Fence post sacks of concrete have small rocks and not much else. It's a cheap mix and does a fine job holding a post straight in a hole. It's not designed for structural loads and cracks fairly easy.

You need strength. Use the high grade stuff. Overall it's only going to be a few doller more per sack and probably only $100 more overall.

Mix it before pouring into the hole. You can get away with dry spots on fence posts, but dont risk your whole building on 5 minutes extra work.

You also want as dry a mix as you can get. The dryer the mix the stronger it will set!

Good Luck,
Eddie

 

[bebster]

I agree that these footings should be solid. Afterall, they will support the entire building. If it leans think of all the expense and problems downstream.

My barn has 24" square and 12" deep foundation pads where my posts rest. The pads are deep enough to be below the frost line (depends on where you are). The concrete is the real stuff, the kind you'd use in a house foundation. That means the right mix of water, concrete and stones for that purpose.

Prepare the hole like you would a foundation footing. That means dig it out, but don't dig out the dirt at the bottom -- leave it untouched. If you loosen it, it will have to be compacted before pouring the concrete, or else it will settle on you later.

Then mix the concrete in a wheelbarrow and pour into the hole to 12" depth. If you can set in a couple of pieces of 12" #3 rebar (3/8" diameter) criss-crossed and at least 2" below the top it will add more strength. You can buy short pieces of rebar at Home Depot for example, and it's cheap.

Make sure the top of the pour is level, and let it cure a week. Then you'll have a solid base for your posts.

Of course then you have to decide what to put around the post. There are several threads on this subject, but the concensus I've come away with is to either use gravel/sand or a post-protector set in concrete for more strength and wind protection.

 

[RedDog]

</font><font color="blue" class="small">( Just to add my .02 worth. If you are going to add water to it, it would be easier to mix it in a wheelbarrow than trying to mix it in the hole. Then when you dump it in the hole, you would be sure that it would level out because it would be thoroughly mixed up. )</font>


Exactly!!
That is how I did mine. When you use the round stones you are hoping that your hole is exactly right. Some holes you have to egg shape to make them the right distance to the other post.

Forget the stones, use the mix in a wheelbarrow.

RedDog <font color="orange"> Kioti DK65 </font>

 

[mopower440]

Guys, i can mix it in a wheelbarrow, but the part i dont want to do is mix in sand to the concrete, trying to get it just right and all that, im asking if there is a type of premix in a bag where all i have to do is add water and mix it without having to buy bags of sand to mix with it? If i remember right, when you buy the bags of dry quickrete and stuff like that, you have to pour it in a wheelbarrow, then add sand, then water, im looking for a bagged dry mix that already has the sand or whatever so all i have to do is add water and mix it till its right, then pour it in the holes, is there such a stuff?

 

[gerard]

There are all kinds of bagged pre mixes you can buy and just add water that will work for your purpose. Read the bag and just get a around a 4000psi or more mix. Thats how much weight it will take in compression without crumbling. The way you're going to do it is way overkill but then there's nothing wrong with that! Just takes more time which is why you won't find even the best builder doing it that way. Concrete takes 28 days to cure to 90% strength so take that into account if you plan on putting the post on top of the concrete prior to that. Thats why a lot of contractors just use block and dump in the mix dry. The block takes all the weight while the concrete sets up.

 

[Bird]

mopower440, if you buy cement you have to add sand and gravel and water, but almost any of our lumber yards, Home Depot, Lowe's, etc. sell the bags of mix to which you add nothing but water.

 

[mopower440]

Thanks guys!! yes, my dad told me that you can buy the bags that only need water mixed with it, and i looked at lowes and saw plenty like that, now the question is, how much for each hole? The holes will probably be 12" wide and 3-4 feet deep depending on if i hit solid rock, they had 40 pound bags, 60 pound bags and 80 pound bags, how much per hole though?

 

[Junkman]

depending on how many holes you have, it might be faster and easier on you to have a cement truck come in and pour them all. Call the local cement plant and ask the minimum quantity and cost. It might be less expensive than the bag method.

 

[hockeyhead]

forget the cement truck, cost, damage to grade and cost, this is a 24' by 30' in TN. if I recall correctly. Any and all methods decribed here will anchor those poles in decent ground. Me, my question is how is the ground, high and dry? wet? clay, sand? loom? what? What kind of floor is the final product going to have dirt, cement, gravel? drainage is everthing in building pole barn, water is your enemy, the softer your ground the more support required to limit heaving and settling. I want to say based on your posts dirt or gravel flooring, mine is gravel. does the site hold water? any? even after ten days of rain? then fill, fill is cheap, just pay for hauling, have it dozed pretty level, let it settle, and drill your 14 holes, throw a block(blocks are cheap) in the bottom of the hole, set your poles, and mix 40lb bags of ready mix( at $6 per bag) in a wheelbarrow and pour it, in, but keep those poles square and true to your outside lines and she will go up well. keep your bottom skirt level, complete building, fill ground again to level using bottem skirt as your guide, with dirt or gravel to finish floor. I used sceenings from gravel quarry for my floor (cheap) and water, a hand tamper , a compactor from a rental yard and some sprinkled ready mix completed my floor, she is solid as a rock, will outlive me and I am down right proud of her. Now I am on clay ground farmed for atleast 50 years before I showed up and low,I hauled in 600 tons of fill to build the site up 2'. I built with help from family and friends a 40'x60'x 14' good luck in your project /forums/images/graemlins/cool.gif /forums/images/graemlins/wink.gif

 

[cowboydoc]

I really can't understand why everyone wants to make this difficult. Maybe there is something I'm missing. But why would a person want to go to all the trouble of mixing concrete, spending all the money for concrete, all the time to put it in, wait for it to dry, etc. etc. when all you have to do is buy the 14"x4" cookies drop them in, tamp them down flat and put your post in. We've put in alot of pole buildings and all the contractors I know do it the same way. Just can't see why it's necessary to make something so simple complicated.