Pole Building footings

[DiskDoctr]

I never heard of anyone using a bracket to secure a post to a concrete pad with polebarn construction? I have seen "L" shaped brackets holding post frames to concrete foundations.

Being steel, it was easier for me as the brackets just bolted to the steel posts, then the long anchor bolts into the concrete. Not sure of the distinction you seem to be making between the term "bracket" and "L shaped brackets" ? Maybe I just missed something

We floated our slab on top of plastic, then 4-6" gravel, but the footers for the posts all had to extend below frost level. I think ours are all 48" plus. Some were 6' (where most of the fill was).

I see the OP is in Michigan, also a cold state (sometimes )

Hopefully a few building contractors/experts will chime in.

Rimshot- if you are going to put just a gravel floor in the building, you may want to put down fabric first, to keep the gravel from making its way to China We use plastic when under concrete- keeps it drier and warmer, but not sure how that would be for gravel...?

-JC

 

[DiskDoctr]

Here's a link with some pole to foundation options:

Perma-Column | Permanent Foundation Systems
Foundations - National Frame Building Association
http://postframeadvantage.com/i4a/forms/form.cfm?id=29&pageid=3931&showTitle=1

And I read some places using a type of coating (pvc or others) on the bottom of posts to prevent rot.

Hope this helps!

- JC

 

[rimshot]

I see what you are talking about now DiskDctr. That is one fine foundation system. I really like those tubes for the vertical stuff. The fabric or visquine is a good suggestion also. I don't believe thee 22A gravel will migrate too far as the grade will all be very nice native gravel (coarse)

I just got off the phone with the Bldg. Inspector and he wants trusses w/combined load of 70lbs/ft. Footings must be 42" deep from grade to bottom of concrete. There is no requirement concerning mechanical fastening of post to footing. I am in a very protected area of woods and the East side of a steep hill so high winds are not a problem. I understand the nature of the extra resistance for any wind lift.

Being that gravel is very coarse I would expect needing 20-30 yards for a 6 or 8" base of 22A crushed gravel. I could very easily provide a layer of 6 mil between the native gravel and the layer of 22A. With no floor and a steel roof I would sweat the sweat that forms under steel roof panels Spring and Fall. Creating ones own rain storm is the type of thing I am hoping to eliminate.

Qrtrhrs; Do you mean attach blocks of 2 X 6 perhaps of 8" length on four side of bottom of a 6 X6" post.. I'm not quite clear on your method. I believe you are trying to create an 1 1/2 surface to fight this wind lift.

rimshot

 

[Eagleview]

Why not just dig the holes and sit the poles in the holes with a punching plate at the bottom and back fill ? A bit of cross bracing in the walls and it will stand for a lifetime . Punching plates can be flat rocks , broken concrete etc . I used old truck rims filled with concrete and lowered into the holes when I built my house . The local concrete plant filled them for a carton of beer when they had left overs from jobs .

 

[DiskDoctr]

Footings must be 42" deep from grade to bottom of concrete. There is no requirement concerning mechanical fastening of post to footing.

A true "pole building" has the poles buried in the ground and wouldn't necessarily need any anchoring other than the concrete or whatever you used to fill around the poles.

But a lot of folks are putting in buildings without the buried poles, instead setting posts on top of footings (like my steel building).

If you're going to bury the poles (including within the sonotubes), you may want to consider putting tar and/or something to protect the wood below grade. One place mentions using tar, then a heavy kind of shrink wrap or other coating...some options there.

If you're going to set the posts on top of the footings, I would fasten the posts with anchors.

I'm not sure of your conversation with the inspector, but you might want to be sure he knows which method you are using. May not matter, but you don't want any surprises after it's built and to be inspected.

Sorry if it sounds like I'm being **** about this, but asking a few questions, maybe more than once to be absolutely clear, is better than remediating a misunderstanding later

You may want to ask for more info about the plastic under the gravel due to humidity. Fabric would allow water to pass through (both ways), plastic may hold humidity in the building due to exposed steel surfaces. Might want some opinions on that. Maybe tyvec has something that passes moisture one direction (out)...?

My steel building is fully insulated, but I recall the mfgr asking if it would be insulated. If not, he was recommending ventilation fans to manage humidity. Wouldn't be a bad idea either way.

Hope this helps out a bit.

- JC

 

[QRTRHRS]

Qrtrhrs; Do you mean attach blocks of 2 X 6 perhaps of 8" length on four side of bottom of a 6 X6" post.. I'm not quite clear on your method. I believe you are trying to create an 1 1/2 surface to fight this wind lift.
rimshot

Yes, that is what I am saying but keep the blocks up a bit from the concrete pad, perhaps six inches. You don't want to increase the surface area where you may have moisture.

What you are doing is making a rough "bell" shape.

 

[rimshot]

Thanks to DiskDoctr and QtrHrs. I appreciate your excellent observations and sharing of experience.

This building site is blessed with excellent natural gravel plowed in here by the glaciers they tell me. It's the same thing practically as placing a building over a never used drainfield only I am fortunate to have about 50' of natural God Given nearly pure stone.

You both have pointed out that it would be best if the post end grain is prohibited from wicking up any water. It would do exactly this if it were unsealed and rested on concrete directly. I don't recall if those sleeves on DiskDoctr's foundation are encased on the bottom or not. You built a Cadilac of a fine foundation. I'm probably going to have to do something a little more like a Chevrolet. I just don't need a Toyota. I would prefer the Cadilac of course but I want enough money in my budget to complete the steel roof

I talked to Lowe's and HD today and will be getting quotes of a 28 X 32 X 10' building. I did manage to upgrade the post material from the 4X6 posts to the newer laminated versions that resist twisting. Seriously, I have seen some regular wood version that looked like corkscrews.

One more quick question. What did you guys use for the load bearing connection at the point where the double 2 X 12 truss carrier's cross with the top of the 4 X 6 posts. I have seen guys simply nail those and I just cringe t the thought. Seems like they need more than nails can offer like possibly a couple of 1/2 " carriage bolts at the very least.

Again, special thanks to DiskDoctr and QRTRHRS for helping

rimshot

 

[bill in ny]

on my new pole barn i nailed the 2x12 truss carrier's to the poles. under each joint there is a 2x8x3' piece nailed for more support. the pole barn i built 28 years ago, using the same method is like the day it was built. i also nail a 2x8x4' piece between the carrier and the poles.

 

[DiskDoctr]

On my metal building, I don't have regular trusses, rather clear span beams. It's open to nearly 16' in the center.

That's the nice thing about forums. Lots of different advice from different people. :licking: (<-- Okay, just wanted to try this guy out!)

- JC

 

[dodge85rc]

Well on my pole shed and the addition that was put on, they used an auger to drill the hole 5 ft. down, below frost level, threw in a round concrete block and set the post in and back filled and tamped it in. This is how it is normally done around here. They used treated 6x6's on the posts, 8 ft. center. The posts are notched on top and the truss's are set in the notch. I think you guys are over analyzing it. Keep it simple. Don't laminate posts or wrap them in anything. If you buy a quality treated post of the appropriate size, rotting, water and structural integrity will not be issues.