24x48 pole barn, need to pour slab first. 6x6's on top of slab?

[ShowroomShine]

I'm building a 24x48 truss kit pole barn in my pasture. I'm also finishing up the construction of my new house, and once the yard gets landscaped concrete trucks cant get back to the barn area. Soo....

I want to pour the pad first. I'm only concreting half the barn for a shop, other half is a horse barn. Problem is I dont know how to pour the slab first then attach the 6x6 posts. Do I make an extra footing under the posts, then anchor the 6x6's on top of the slab, or do I cut the slab out when I get ready to dig the holes?

 

[sd455dan]

I'm building a 24x48 truss kit pole barn in my pasture. I'm also finishing up the construction of my new house, and once the yard gets landscaped concrete trucks cant get back to the barn area. Soo....

I want to pour the pad first. I'm only concreting half the barn for a shop, other half is a horse barn. Problem is I dont know how to pour the slab first then attach the 6x6 posts. Do I make an extra footing under the posts, then anchor the 6x6's on top of the slab, or do I cut the slab out when I get ready to dig the holes?

Wouldn't that defeat the purpose of using a pole building?
By setting the posts first the 6x6s are stable and rigid after the concrete sets so that you have a strong skeleton to attach the trusses and the girts and everything else to.
If we had gone with pouring a slab 1st (30 x 48 building) i would have just gone with stick construction and bolted plates to the concrete. My builder buddy with all the experience actually suggested the slab and more conventional build. I believe the slab and plate construction has some long term advantages - like not worrying about the 6x6s rotting or cracking the concrete around them .

If you already have a kit - not sure how you pour the slab 1 st -pretty sure the 6xs need to at least be set in holes with concrete before the slab is poured... Maybe they can do both at once- fill in around the 6x 6's and also poor the slab to ?

Hopefully a TBN builder that has done pole barns will chime in on this

 

[zzvyb6]

You don't need to have the concrete truck go back there. There are concrete 'buggys' which are well suited to carrying a yard of concrete at a time back to your new barn while driving over a driveway, etc.

I just had a 175' by 11' driveway extension done and my neighbor just added a slab floor to his 50 x 80 pole barn. The truck stayed on the public road and my concrete guy rode his buggies back and forth. One fills while the other runs and dumps. They have dual tires and go pretty fast. You could hardly tell where they ran. In a few places, he put plywood sheets down to keep the lawn from rutting. Usually where a sharp turn had to be made. His finishing crew was able to keep up with his delivery rate in a well orchestrated manner.

 

[Aquamoose]

Never seen a pole barn built on top of the pads. Drive around the country and look at those old barns, especially really weathered & unused ones. The fact that they're still standing should be enough convincing for you especially how we've come a long way with the introduction of specially treated 6x6 made for in-ground applications. Raise the pole building and pour the slab afterwards. I used expansion joints around each uprights.

 

[teejk]

Wouldn't that defeat the purpose of using a pole building?
By setting the posts first the 6x6s are stable and rigid after the concrete sets so that you have a strong skeleton to attach the trusses and the girts and everything else to.
If we had gone with pouring a slab 1st (30 x 48 building) i would have just gone with stick construction and bolted plates to the concrete. My builder buddy with all the experience actually suggested the slab and more conventional build. I believe the slab and plate construction has some long term advantages - like not worrying about the 6x6s rotting or cracking the concrete around them .

If you already have a kit - not sure how you pour the slab 1 st -pretty sure the 6xs need to at least be set in holes with concrete before the slab is poured... Maybe they can do both at once- fill in around the 6x 6's and also poor the slab to ?

Hopefully a TBN builder that has done pole barns will chime in on this

My shop building was constructed on top of the poured slab. Concrete guy installed "j-bolts" during the pour. The builder built the walls in 8' sections (treated bottom plate, double top plate and horizontal members 2' O.C. from top to bottom which were then secured to the slab using the j-bolts. The horizontal members add some stiffness to the panels and also served to attach the steel. The slab sits high so there is no ground contact of wood. Trusses are 8' O.C. and rest on the wall sections where they are joined together (so essentially a 3" vertical support). A little more expensive than conventional pole barn construction it does have some advantages I think. No need to add nailers and they make insulation in 24" widths. The building went up pretty quickly. Anybody looking at doing this should plan it out to know where to place the j-bolts. And if steel is the final skin, remember that it covers 3'.

 

[prichard]

I can't imagine building a barn that I could not get to with a large truck, but that's besides the point.

You could pour slab but frame forms around where your posts will go then come back and drill for posts later, or drill now but don't pour the holes. Or you could use sonotubes for the holes.

There's also the concrete buggies as mentioned or a concrete pump for pouring later.

 

[Larry Caldwell]

Yes, each post needs a footing, which can be monolithic with the slab. Set post base anchors in the concrete. Those are heavy, welded steel strap anchors, not the sheet metal stamped anchors they use for porches. Check with your local lumber yard to see what they can dig out of their catalogs. If you give it a stand-off so it's not in contact with the concrete, you don't even have to use treated lumber, which can save you some bucks. You have to brace the posts pretty good while you build the building. Don't let the posts wobble around on green concrete or you might crack it. Once the building skin is on it's rigid enough that there is no problem.

After the poles are in the ground for a few decades they will rot, so we would just stiffleg the post, chainsaw the bottom off, bolt a post base anchor to the post and pour concrete around the anchor. 10 days later we would pull the stifflegs and bingo, a repaired building.

 

[Larry Caldwell]

Hmm. After doing a google search for a decent post base anchor, I couldn't find one. Simpson has a 12 gauge galv that is pretty heavy, so that might serve, depending on its bearing strength. Otherwise, you could have a local shop bend and weld one from steel strap. The ones I used to use had about a foot of heavy iron pipe sticking down, with holes drilled for rebar, so it had huge uplift strength as well as bearing strength. It strapped either two sides of the post or all 4 sides, with two or three 1/2" or 5/8" lag bolts on each side.

 

[Deere Dude]

I was at a pole building place the other day and noticed some heavy duty steel 6x6 post holders. They basically look like a U shape as the saddle and a plate on the bottom for big bolts or anchors of some sort to bolt to the concrete. If I had a slab already I would use them. They looked like about 5/16 to 3/8" thick metal.

 

[teejk]

Yes, each post needs a footing, which can be monolithic with the slab. Set post base anchors in the concrete. Those are heavy, welded steel strap anchors, not the sheet metal stamped anchors they use for porches. Check with your local lumber yard to see what they can dig out of their catalogs. If you give it a stand-off so it's not in contact with the concrete, you don't even have to use treated lumber, which can save you some bucks. You have to brace the posts pretty good while you build the building. Don't let the posts wobble around on green concrete or you might crack it. Once the building skin is on it's rigid enough that there is no problem.

After the poles are in the ground for a few decades they will rot, so we would just stiffleg the post, chainsaw the bottom off, bolt a post base anchor to the post and pour concrete around the anchor. 10 days later we would pull the stifflegs and bingo, a repaired building.

I think you have exposed the problem with traditional pole-barn construction, that being ground contact with wood. I think the old CCA wood was supposed to be good for 40 years but that is no longer an option around here and depending on soil I don't know if the 40 year thing worked anyway. I guess if one were to be able to sink posts deep enough and shield them from moisture top/bottom and all around they should last forever. Perhaps a concrete cookie on the bottom and the posts surrounded by large diameter pvc? Personally I'm glad I built on slab...I don't have to worry about ground contact of wood...a lot of lumber involved but it is all "high and dry". Will see if I can find the pix from the build.