Concrete Piers or Full Foundation for Firewood Storage

[BoylermanCT]

I am planning on building a car port on one side of my garage to store firewood. I store my firewood on pallets, and move them from their summer drying area to the winter storage area with my tractor. My plan is to pour a 10x22 concrete pad 6 inches thick. I want the option to store a car or my tractor there when it is not full of firewood pallets. The roof will be held up by 4 6"x6" posts supporting a 22' 6"x6" beam which will support the 2x6 rafters. I was planning on pouring 4 12"x48" concrete piers to support the 4 posts. My father-in-law thinks I will have problems with the pad staying level since there won't be a full foundation with frost walls around the pad, like there would be on a normal garage. If I do the piers, I can pour them myself with my mixer, but I will plan to have a contractor bring in a truck and pour the pad. If I need a full foundation, I could dig the trench with the backhoe, but I'd have to hire a contractor to do the forms and pour the foundation, so overall cost would be significantly higher with the full foundation. Any advice or recommendations?

 

[jack707]

Why not use road gravel?

 

[jack707]

IF it was me I would level a spot and use road gravel and compact it.

 

[s219]

Yeah, unless you need a flat floor, I'd just use gravel. Save a lot of hassle and money. I would have done gravel floor inside my barn if I didn't want to store implements on dollies.

 

[BoylermanCT]

Thanks for the suggestions. I was planning a concrete floor so I could position the pallets side by side, 6 deep for a total of 12 pallets or 4 cords. To get 12 pallets in this space would require use of my pallet jack, hence the concrete floor. The only access to the carport is on the 10' side, the long side is not accessible to the tractor. The carport is large enough to use the tractor to drop the pallet inside it, but not large enough to maneuver and get them in position to fit 12 pallets. Eventually I will enclose the carport, and have a 7x7 garage door for access. I can't do any wider door because of the slope of the roof.

 

[LD1]

Floors are poured inside polebarns all the time without issue and no full foundation. I don't foresee an issue unless you tie the piers to the slab. You don't want that. Use a foam membrane or expansion joint material around the piers so the slab don't adhear. The key is good compacted dirt under the slab.

And forget the 6x6 on top. I don't know what the ground snow load is in your area, but a pair of 2x12's will support a 50psf snow load and support a 16' roof with only 1 post midspan instead of 2 like you are planning. And Your roof is only 10', which means that header is only supporting 5' of food.

 

[Mysfyt]

Do you have issues with frost heaving in your area? I'm assuming your piers are going 4' down to get below the frost line. If you're in sand with good drainage the floating slab will be just fine.

 

[SPIKER]

I agree with others, and LD1 said about the header is correct, 2x12 is better than beam, sandwich two one inside and one outside on the 6x6 and use a few nails to hold level in place then thru bolt using large carriage bolts couple 1/2" will due.

For the poles you dont have to concrete but drill holes 36"+ dia and down 5' pour in 12~16" good mix & let set. Set poles on that and compact w crushed stone/soil mix. When concrete goes in wrap poles with either styro, plastic or felt paper to keep it from sticking to wood posts, (be sure to get good ground contact treated posts) or laminated treated ground contact posts.

Next is to keep the roof drainage away from slab when poured so moisture in soil around barn stays low good spouting and swales to keep water away from barn area...

 

[BoylermanCT]

Thanks LD1. I tend to go for overkill when building things! Code here is for 50psf snow load. Thanks for the info on not connecting the slab to the piers, I'll make sure they are separated with foam or similar. I was going with the 6x6 beam (3 2x6's bolted together) as it is cheaper than 2 2x12's. Plus it seemed to make sense putting a 6" beam on 6" posts. My plan is to get the posts, roof and floor done before the snow flies, and then next year add a 7800KW solar panel array on the roof of the garage / car port. So I wanted to plan for the extra weight of the solar panels, hence the extra post.

Mysfyt, like most northern places, we have frost heaves, my road becomes an obstacle course each winter! I'm planning this as a permanent addition to the garage, so I want to do it once and do it right. I don't want the posts heaving which would raise and lower the roof and solar panels.

How far down below the slab should I dig out for a gravel and sand base? How many inches of gravel and how many inches of sand? I have access to a small gas powered plate compactor. I'll talk to the concrete contractor as well, but want to go into that conversation with a basic idea of what I'll be doing.

 

[jack707]

I would put down a base of 4" road gravel and compact it tight put 3/4" plywood end to end and tape the seems then you wont have a problem rolling your pallets to the area.