Converting an existing pole barn to a shop.

[ac777]

I am toying with the idea of converting a pole barn to an insulated shop. Heres the catch. It will be a wood shop for my side business, and I do not want cement. It also has to be done on a budget as I like to run my side business debt free. Anyways, the idea I currently have is to build the current dirt floor up about 6-8 inches with some type of crushed rock or pea rock. I would pack and level. I would then put a layer of 1 inch foam across it. then layer 3/4 inch plywood and seal. This shop wouldn't be supporting a lot of weight. The max would be occasionally a bobcat or pick up truck. Now i know this is not a popular idea, as I have never seen it done on a shop floor, but my uncle used packed pea rock/crushed rock for the foundation of his house, and just laid a 2x8 down on it and built up from there. So i think it would have a good possibility of working, but the only potential problem I see would be settling over time in areas, but if its packed tight and the ground beneath is packed tight, it should work. What say you?

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[CAMAN]

I don't know if it would be able to support a bobcat. Other than that the issue I see is how are you going to get the gravel perfectly flat? If there is just a slight variance, that will transmit through the foam and plywood causing either a spongy floor or a high spot. I've done a few block patios and compacting the base layer with a plate compactor doesn't magically make everything flat and level. It takes A LOT of time just to get it flat enough to screed sand.

How big is this barn?

[ac777]

i realize that by just packing it it wont be level, I would have to use leveling strings and keep working it level kind of like screeding concrete.

[kerryd15]

With just plywood and foam, I don't think the foam would handle the weight of a pickup either. How are you going to hold the plywood from moving around? It definitely would not hold up to a bobcat, especially if turning on it. you could use 2x6 or 2x8's treated laid on end and build the floor on that. Would save having to be perfectly level all the way across- kind of like a deck thats sitting on the ground. Not sure but you might need post in concrete to keep it level. I think with 2 layers of plywood on top- possibly one you could put a bobcat on it. I used to work in a double decker turkey barn that we could run a bobcat in to clean out. I think there were 1x12 and 1/2 plywood over. I remember one of the guys catching the plywood when scraping the floor. All 4 tires were dangling between the stringers, nine feet up!!

[Tom7227]

I don't know the terminology but there are types of insulation that don't compress much. A friend has a roofing company and he showed me some of the stuff that is about 2 inches thick and it doesn't compress at all when you walk on it. But I don't think you can just lay plywood over it as it would require something to attach both to do they stay in place.

I wonder about the cost though. By the time you bought this stuff and then plywood over it you may find it comes awfully close to the price of concrete.

How about splitting the difference - build a wooden floor for the actual shop area and just compressed gravel or crushed concrete where you're going to put vehicles?

[cavalierowner]

I think by changing things up a bit, you could get the right kind of Styrofoam to work. Although you might not like the price, I think your only chance of getting rigid insulation to work is to use Styrofoam Highload 100 and place your rock over that. The Highload 100 has a compressive strength of 100 psi compared to 25 psi of conventional Styrofoam and placing the rock over the insulation will help spread a wheel load out. That's what's done in commercial work quite a bit, for example, when a road has to go over a shallow water pipe that can't freeze.

As for the plywood, I just don't know for sure. I believe that you would absolutely have to get the rock well compacted and flat so there are no voids under the plywood. The only thing I could suggest is to buy a couple pieces of plywood and some rock and build a mockup. A few dollars spent on a mockup could save you a lot of money later.

[K_Josh87]

how about this, lay down .60 treated 2x4 or 6 flat on your screeded rock, then another 2x on edge nailed on top of the flat 2x to make an upside down T. I would do this 16" OC, and then foam in between (if you enen wanted to, Could possibly just do a frost barrier around the edge just as a concrete floor, your air space will help tremendously already. Then, a treated 3/4 ply, with possibly a second layer of 1/2-3/4 ACX to make a nice smooth thick floor...

I'm not sure there is a HUGE advantage to insulating the whole thing, if you have a frost barrier, and the rest of the building is heated and insulated, I don't see that floor getting THAT cold...

Just a thought on how I have seen it done for basement floors...

[Surface Tension]

Your going to need a frame to screw the plywood down to.

Otherwise you'll be tripping on joints from settlement and warping plywood.

Eventually you'll be tearing this out because it either rotted, delaminated, warped, or your just plain old tired of it.

Why don't you want cement? If its cost you might be surprised once you price it out and the alternatives plus keeping in mind some of those are not permanent or maintenance free.

Recycled conveyer belt used as a mat.

Something like crushed limestone would pack in well and I'd imagine a sealer would help it hold up to sweeping. Forget about insulating the ground because it won't hold up with any of those alternatives.

[reddog]

Your uncle used a pea rock footing for a Wood foundation wall. Perfectly acceptable, and meets code. The difference between what he did, and what you are wanting to do, isnt all that much different.. Pea rocks soil classification is "non compressive soil", meaning that if you can contain it, it will stay in place when sandwiched and be strucuturally stable. Actually, pea rock doesnt even need compaction, although in your situation, it certainly wouldnt hurt..

As far as the foam, you will need 2 lb density foam... With that said, it doesnt matter if it EPS, or XPS, as long as it is 2 lb density or denser for structural loading.. XPS foam, (Dow, Certifoam etc) typically is available locally at any box store, but not in 2lb density, unless they stock Dow Blue. Dow Grey board, certifoam yellow, and the pink foam is all 1.5 density and will not stand up to structural loading of any kind.

As far as just putting plywood down over top of the foam and expecting it to perform, it wont... not for very long anyway.. If you do a sleeper system on top of the foam, then you will need at least 2 layers of 3/4 inch foam to support a vehicle, and possible 3 or more to suppport a skidloader, for the reason mentioned by others.. By the time you do the sleepers and the plywood, you could have easily poured 4 inches of 4000 psi concrete and have a lifetime surface..

Capturing the pea rock at the door openings will be a challenge without a concrete apron of sorts outside the building..

Pea rock runs like water when it is not captured or contained..

[CAMAN]

I can see where he might see concrete as cost prohibitive, especially considering the time and cost involved in pouring/troweling it.

Now my question for those that have experience with it, would this be a good application to use a self leveling concrete? I have a very limited knowledge of the product, so no idea if it's strong enough for this application, and if the cost is higher or lower than traditional concrete. I can see the installation costs be quite a bit lower though, not having to wheelbarrow it or trowel level. Just an idea...

[reddog]

I dont think this application would be advisable for self leveling, unless you had some kind of mixer to DIY. USG Levelrock is a very good product, but it should be poured in layers, not bulk .

There are additives for regular concrete to make it more fluid, but wont affect the slump content. Adding water to make it flow better is not a good option, unless you want a weakened slab.

[ac777]

some good discussion here guys. I may just end up going with concrete anyways, but I wanted to look at my other options, since I didnt NEED concrete for load bearing. Going to keep looking at my options and pricing. Any other suggetions are greatly appreciated. I won't be starting the project until next summer any ways so Ive got some time.

[buckeyes08]

As a builder I'm thinking that by the time one buys the 2x's and insulation and fill (pea rock) may have the same expanse as concrete. In my opinion I would concrete the floor it would last for a long time.

[JohnMickish]

One major advantage to concrete in a wood shop is you can heat the floor, thus eliminating the air/dust movement created by a forced air system.

[PurpleFloyd]

Your going to need a frame to screw the plywood down to.

Otherwise you'll be tripping on joints from settlement and warping plywood.

Eventually you'll be tearing this out because it either rotted, delaminated, warped, or your just plain old tired of it.

Why don't you want cement? If its cost you might be surprised once you price it out and the alternatives plus keeping in mind some of those are not permanent or maintenance free.

Recycled conveyer belt used as a mat.

Something like crushed limestone would pack in well and I'd imagine a sealer would help it hold up to sweeping. Forget about insulating the ground because it won't hold up with any of those alternatives.

Pretty much sums up my thoughts.

I would do concrete for sure. The only way I would consider doi g plywood is to frame a 2x floor with a vapor barrier under it and the. Insulate between the joists and put on the plywood but the floor height would end up higher, you still could t use a skid loader and it still might have moisture problems down the road.

If the business grows and you get bigger equipment the concrete will be better too. My previous cabinet shop had a wood floor and for some things it was nice but it had a basement and not on grade. It was certainly easier on the feet than the one I have now with concrete floors.