pouring concrete in pole building

bebster · Mar 16, 2004

I'm anchored to concrete footings that go down 4' below the grade, not to a slab. So the uplift would have to lift up a 4' deep wall of concrete that is tied to a 2' wide footing below it -- that's tons of weight.

I thought your posts were just sitting on the bedrock that was pretty near the surface. So a small collar of concrete won't weigh much I would think. If you can pour concrete 2' down that might be a different approach -- can you? 1' of concrete isn't going to anchor it, just provide a little extra weight.

It sure can't hurt to anchor your posts to your slab, and that might buy you some time to anchor it correctly to the rock before you get a good wind and it cracks your slab. If you do that, you'll want to put in plenty of rebar up to the post so that the slab doesn't crack off as easily.

Still the best would be to drill into the rock, epoxy a threaded steel rod into the rock and then run that rod up through one of the tie down brackets, and then bolt the bracket to the post. With the right epoxy, your literally as solid a rock for a relatively small expense.

GerardC · Mar 16, 2004

My posts are just setting on concrete pads, though they are 6 feet in the ground. Anyways, when the skelton was done and roof was only half on, a newbe on the job ran a bobcat into it at a pretty good pace. I was shocked that the structure didn't budge! I have NO poles in the middle for support either. I guess what I'm trying to say is that if 3 sides are solid, I really don't think that the 4th side being a little weaker will make the building unstable. When the building is "whole" it should be fine. Remember the Oklahoma bombing? The building still stood after the explosion. Maybe comparing apples and oranges?? Just my opinion.

bebster · Mar 16, 2004

I think you've got a point. If it were me, I'd charge ahead with the rest of the structure, and along the way find a method to anchor the weak side bdggdf, but not worry about it on the critical path to completing the barn.

mopower440 · Mar 16, 2004

too late to not be worried..lol.. after reading some of the posts, i thought that running the rebar from the floor into those few posts would definately be good enough, but im hearing otherwise, so im worried..lol..another thing is that 2 of these posts are corner posts..the building is pretty sturdy right now, its justthe whole wind thing, since its only going to be metal, wich is liteweight, im just afraid of the possibility of the wind getting under that roof and picking that one side up, thats why i wanted to do the rebar through the post and into the concrete deal, to hold that one side down., but..?

SPIKER · Mar 16, 2004

MOPO:

ever see some of thos hurricane anchors used for tieing the roof joists to the upper header? those work well to hold each16"~ 24" roof joinst inplkace. you're POSTs are not that close they are 8' appart or so correct!? then for that distance you NEED to anchor the posts no if's ands or butts. esp since by the looks of the photos posted before you have some hills & vallys and that means wind is expected and happens there often correct?

I would worry more about getting the posts anchored correcly NOW and then get the roof on, hardest part will be digging out around the post enough to get to the bottom of each one that is less than 24"underground. and personally I'd want them to be more like 36" of good back fill and the concrete would be poured lossely arround the posts.

the threaded rod and epoxy would work too, (I feel better with the hammer in type of anchor which is set as soon as you turn the locking nut down) but the threaded rod and epoxy works (long term I'd go for the lead hammer type as I'm not 100% sure the epoxy stuff will hold up with the freeze thaw that will happen at those depths.)

then use the Stainless Steel Lag bolts into the posts through the upright side of the 6x6 and personally I probably would make the angle LONGER than 6" and place them with 3 or 4 anchors into the rock and let the excess stick out each side of the barn. Once the sides are up the wind loading can be tremendous! more so pushing the walls sideways IN or OUT than LIFTING the building. Wood framed barns have enough weight to hold them in-plase better than metal ones. and the metal sides do not reinforce the walls much at all.

as for roofing the barn and leaving it with out walls. that is OK but metal roofs have a habbit of turning into SAILS or WINGS when there are no sides to keep the wind from blowing under the roof and lifting it. it will loosen the nails all over the roof if you get a gusty up down type wind. I have a free standing flat lean too type roof which was built in 1999 and it is almost dead and has about 1/3 of the nials 3/4" out. It was there when I bought the place. The old guy was verry happy to BRAG about his buildings but I didn't have the heart to tell him they will all be torn down shortly. there was a 4/12 pavilion type metal roofed one back farther built the year before it was gone in the wind I had the first winter! the wind lifted one corner and broke the 4x4 off at the top then probably beat up and down for a few min and eventually ended up about 45 feet away all torn up... My oldest brother told me they would be gone the first high wind. well the one is still standing but this summer I'm hopping to have the one gone, as I had to FIX it 3 times now. only reason I'm still fixing it is the backhoe attachment is at least under a rain cover now... soon the back hoe will be in a fully covered barn by fall...

MarkM

rambler · Mar 17, 2004

You are trying to mix 2 different foundation systems on one building. Bad idea.

You are not pouring a 1' thick slab - you will have a 4-6" slab floor. Your mh has a slab with a thicker footing around the edge, and the mh is anchored to the whole slab. That's fine. Works well. Your whole slab & mh act like a boat, floating up & down & shifting a bit on the soil, but it all is held together as one unit with lots of rebar & the concrete. The weight of the concrete, & properly placed rebar & anchors, make it act as one large unit.

A pole barn has poles anchored 4' or more into the soil (or a 4' concrete foundation with the posts bolted to the foundation = same thing), below the frost line into undisturbed hard subsoil. This is fine. It works real well, as the posts are very solidly anchored and do not move. As the soil surface moves, the poles will not because they are set deep & solid. As the wind lifts up, the poles have enough friction in the soil to not move. As the wind pushed in or out on the wall, the deep poles resist the side forces braced deep into the hard subsoil. All is well.

Now, you have maybe 2/3 of your poles set deep, a few set marginally shallow, and 5 or so set way too shallow.

If you anchor the shallow ones to the slab floor while the deep ones are anchored to the sub-soil, you create a situation where your building will tear itself apart over the years with no wind at all. Your climate is not as severe as mine, but floating slabs 'here' can rise & fall 4-6" every winter, and a soft spring will let them move a bit laterally. So you will have 5 posts moving around on your building, and the rest ridgidly anchored.

This doesn't work.

You could have built a floating slab with a stronger concrete rim, just as your mobil home, and anchor your posts to this slab _all the way around_ and it would be fine.

The problem is, you are stuck with the deep anchored posts now. You just can't let some posts free-float while others are solidly anchored. The building will flex itself apart over a decade, as well as overly stress the thin slab floor & crack the heck out of it.

You need to go with one plan - either deep anchored into the subsoil or a designed slab that free-floats & has strong outside anchor points for all the posts.

You are locked into the deep anchor posts at this point in time. too hard to go back to a floating design now. so you need to go ahead with a good anchoring system for all the posts to reduce your risk to something acceptable.

Any kind of shallow collar is about the same as trying to tie into the slab - it's a small band-aid that is mixing 2 different fondation types. I'd just as soon leave it as it is then waste time on that.

Of course, you can just leave it as is & you might never get a big wind. You can anchor several posts into the concrete with rebar & the building might hold up just fine in you climate, never notice any problems in 20 years.

This is like going to Las Vegas. You are putting quarters into your building & pulling a handle. The amount of risk you take is totally up to you, and any of your or our plans can work out just fine - or any & all could fail. This is your call to make - it's your building. What level of risk do you want?

Me, I'd want the posts physically held on to the bedrock. So will your insurance company if they have to investigate storm damage. If this were just 1 post, I wouldn't be quite so worried about it. but 3-5 posts, no wonder that building is a little wobbley.

While the roof picking up is a valid concern, my bigger fear on your building is a wall pushing in or out on a strong wind. You can't imagine the side-stress of a 30' wall having 50 mph winds pushing on it. If you leave the doors open & the wind pushes into the building, it will push both up & out on your completed building, really weakening a shallow post.

But, it's up to you. Seems you have all the info you would need to take your plan of action on this issue, whatever plan you use. Good luck with it. And thanks for sharing this project with us. /forums/images/graemlins/smile.gif I look forward to the next challenge it presents you. /forums/images/graemlins/smile.gif

Your building, your call. /forums/images/graemlins/smile.gif Time to pick a plan & go with it, don't look back. We'll all know if it was right or not in 25 years. /forums/images/graemlins/smile.gif

--->Paul

chucko · Mar 17, 2004

Well sure you can....Pour the conc like you would with a house making sure you have a correct footer and it goes well below the freeze line and you have all the correct re-bar in the footer and it ties in the wire in the slab….but if you have a rock down there the size of a house why not just hook to it and know it will never move.
With all the time you have been taking about how to fasten this down I could have drove up there and dug the two foot hole my self popped in the anchors and been back home. You are acting like your being asked to tunnel half way to china to do this……

It is a little late now because you started out saying you were building a pole barn and it is turning into a closed shop now. If I were doing it to close in with conc I would have built it more like a house would be it this order

1. conc floor with good footer
2. 2x4 (many 2x6 stud walls with a dub top plate and a few windows to let in air
3. Trusses toped with tin or what ever
4. sheet the outside of the walls hang the doors and windows.

Frankly and please don’t take any of this the wrong way but you are scaring me with some of the questions you have asked about building this barn/shop whatever it is being called now. If I were anywhere near you I would come by and show you what and how to do it but I am not.

mopower440 · Mar 17, 2004

well, you got to understand a few things, first, i ahve never built anything besides an 8x10 covered deck before, next, i have talked to many many people on this subject, including the man who wrote the pole building book i am going by, some are telling me if i blow hard it will blow away without those 5 out of 14 posts being anchored down, some are saying that the other 9 posts being 4' in the ground is enough, the guy i got the book from says and actually show pictures in his book of the posts ALL being set on top of the ground in a non- feeze zone and says the thing aint going anywhere, so im getting just as many 'its not going anywhere's' as i am 'its going to blow down', and me not knowing much about this stuff, i dont know..lol..even though i dont have a lot of experience with building, im not dumb and what i have so far is very good and built strictly to the pole barn book i have, ok, then, in a previous post i mentioned the frame of it wobbles slightly, not a lot, but slightly, ok, 90% of you said that it WILL do this until sheathed, thats normal, and that it didnt matter if all the posts were 10' in the ground or set on top of the ground, it would still wobble until sheathed, now, you are saying no wonder it wobbles just because a few posts arent deep..so, you have to understand why i am confused at this point..lol..personally, i really dont know, i do know that bad luck seems to follow me around and it would be my luck for the thing to get ruined..now, i also do NOT expect it to stand up to a full fledged tornado or hurricane or monsoon or anything like that, what would be the point if the house gets destroyed and the stupid barn still stood..lol..? all i want it to do is be able to stand up to 'normal' conditions, wich sometimes include fairly strong winds from a thunderstorm or if a tornado is in a nearby are and we get the outside stuff from it. Now, i wouldnt mind drilling the rock and anchor it but im not so sure its going to be too easy to drill through rock..? and next, i dont see how epoxy type glue is going to be strong enough to hold this rod in the hole in the rock, it would be one thing if you could thread the rock and screw the rod into the rock..lol..but thats not the case. How about some more details on this hammer drilling, does it take 2 hours to drill 2" through the rock or is it a fairly easy deal? next, i need to know exactly what size and all that of rod to get and what type of 'L' brackets to get, remember, i dont know a lot about building supply's and from what ive seen at the store, theres lots of brackets and such, so please understand where im coming from and that you guys help is greatly appreciated!
also, what about those hammer in anchors that spiker is talking about?

GerardC · Mar 17, 2004

( -now wait a minute, .. )

Don't you need a building permit? Where we live we MUST get and have a building permit in the window for all to see. I thought that it would be a pain in the @$& to go through all the so called "red tape" but actually it is real easy. Basically it's just a phone call and your on your way. AND the BEST part of this is that you are dealing with the building inspector!
They know the LAWS and BUILDING CODES in your area. That is their job.
Our neighbors wanted to put up a garage, (which they had already ordered), next to the other neighbors property line and were told they couldn't because if it were to fall down, it would fall OVER Marks property line. And when Mark wanted to put in a built in pool he was told he could BUT not where he wanted it. To close to underground wires and pipes. WE don't think of these things.
I guess that's why we have building inspectors. Get the picture.
They will go to your house and evaluate the site. At that point they will tell you if you CAN or CAN'T. Plus, when they give the final OK on your project, you are sure to be covered by insurance. /forums/images/graemlins/smile.gif

chucko · Mar 17, 2004

( the guy i got the book from says and actually show pictures in his book of the posts ALL being set on top of the ground )

I have be in trusses for 20 years (god I am getting old) if this guy told me this I would hand him his book back and asked for a refund....Just because someone has half built something and it did not fall does not me it is right! I have seen more bad stuff than I care to share or remember. Just because someone wrote a book does not make him right. I surely would not put anything in his pole on top of the ground building that I cared about

Knowing as little as you seem to know about building you should have never attemted this without a builder at least stopping by and saying now do this and do that.

Yea maybe you will be ok without anchor those post but how will you feel if you don't and something happens?