HELP!!!! building a pole barn

[mopower440]

hello,
I live in middle tennessee, i mess with cars a lot and need a garage to work on them, dont have a lot of money so i figured i would build a pole barn type garage, decided on a 24x30, i staked out the spot i want to build it on, i started to dig for my posts and ran into the biggest rock ive see on the place, it goes all the way down one whole side of where i need to dig post holes and about 1/4 of the way of the front of where the barn will be, people are telling me to just dig the holes for the posts on the 2 sides i can and cement the poles in as normal, and for the other 2 sides that have the rock in the way, to just set the posts on top of the rock and brace them up with 2x4's and build to them just like i would normally do if they were in the ground, then when the building was up, they would be secure, ok, but keep in mind, the rock is only 3-4 inches under the dirt, so thats pretty much like setting the posts on top of the ground, ok, i always thought that the whole reason for digging 3-4 ft. holes and cementing the posts in the holes was to anchor the building to the ground so high winds wont take it down, so if i do it the way im being told, whats going to hold the place to the ground? I know some of the poles will indeed be in the ground, but will that be enough to keep the building secured in a high wind? Also, i dont know if we have codes here or not, but if so, will they allow this? I also plan on pouring a concrete floor after the building is complete, so i figured that would help hold things down but at the same time, if i have a bunch of poles just sitting on top of the ground, when i pour the concrete, wont that push these poles out since the concrete is so heavey?
HELP!!
thanks

 

[MossRoad]

So is this one big rock under most of the barn? Could you use post anchors and bolt them to the giant rock maybe, then bolt the posts to the anchors? Seems like they do that for a deck when you build on concrete piers. Why wouldn't it work for solid rock?

 

[markct]

my fathers pole barn, as well as a few others around here are made with the poles sitting ontop of concrete piers, the poles dont actualy go into the ground, i dont see why yea would have a problem with setting them on the rock, sounds like a good foundation to me as long as its secure and wont move.

 

[snooks]

As long as you can get the post anchored to the rock and your sure it is a very large rock, you should be ok. A local guy I know had a huge machine shed built for his combine and tractors. The outfit that built the shed failed to set the post in concrete and a big wind picked up the barn and landed it on a nearby highway (up side down). Thank god it didn't hit anybody /forums/images/graemlins/blush.gif. Wish now I had taken pictures. His was much larger than what your talking and the wind threw it like it was nothing.

 

[bebster]

Might be a way to drill down into the rock far enough to bolt on a post bracket (the kind they use on top of concrete piers to fasten deck posts to). An expansion bolt (sort of like a lag bolt but used for masonry) would help secure the bracket; also set the bracket in some cement.

Another thought would be to scrape down to the rock on that side, and pour a 12" wide footing with rebar. Then attach the posts to that footing. If you can get some holes drilled at different angles into the rock and slip rebar into those holes and into the footing, you can in effect "toe-nail" the footing to the rock.

Not perfect, but the extra support from meaures like these will help keep that side from being a problem.

Then take extra steps to anchor that side to the two adjacent sides. Simson-Strong Ties has plenty of galvanized steel brackets to help make this possible. Or you might even consider having a few long 6' straps fashioned that wrap from the anchored side all the way around to the rock side, and screw these on.

 

[mopower440]

So actually, im not supposed to cement the poles in the ground anyway, im supposed to dig the hole, pour a footer and rest the poles on top of the poured cement footers and anchor the poles to the footers somehow, right? ok, if i just set the poles on the rock and anchor them to it somehow, how do i get that past the codes or whatever? I will be upset if i get the thing up and they make me tear it down..

 

[RedDog]

Mopower440,

First off, I can understand why you want a barn to work on cars. By your name I can tell you will be working a lot! /forums/images/graemlins/wink.gif


Dig the hole, pour concrete in the bottom, set the pole on top and fill the hole back in with what came out of it. This will not work in your case with the rock.

I would do as someone else suggested,,, put your post on top of the ground. We have buildings around here that way.

I'm glad we don't have "code people" looking over our shoulders here. /forums/images/graemlins/grin.gif

Good luck and don't get discouraged!! RedDog <font color="orange"> Kioti DK65 </font>

 

[Inspector507]

mopower440,
You've mentioned "codes" a couple of times now. You need to check to see if you have a governmental agency that enforces codes before you go too much further. They can be your best friend sometimes when you run into constuction troubles. Or they can be your worst enemy if you build it without proper permits/plans.
Just my .02

 

[bebster]

At 24' x 30' you might need a building permit (probably too big to be called a shed). Easiest way is to visit the building inspector and tell him what you want to do. But he might insist on certain things just because that's his job -- to enforce the building by-laws, etc. He'll worry about the wind blowing the building off its footings, or the frost heaving the foundation (if that's an issue where you are).

But I've found that if I think it through in advance and show him that I too share his concerns, but I've come up with practical solutions that may not be typical residential home construction but accomplish the task, there's a chance he'll feel comfortable and say ok.

 

[mopower440]

ok all, you are right about finding out about codes and all, so i will do that first thing in the morning, BUT, I dont have a clue where to start..who do i call and what do i say?