Help needed with barn floor

I bought a property with a 70 x 80 pole barn built as a stable and arena. I have no horses and really no interest in keeping horses so I want to convert this to shop and equipment storage. This barn sits lower than some surrounding land so I know I have to do some grading before anything else.

What I don't know is how to prepare the interior for a concrete floor. Do I have to do anything special around the posts/poles? I'm probably going to only do a section of this at a time, the first one being 40' by 24' or maybe 40' by 36' to get an extra door included. I've never done anything like this before so I need all the help I can get (and maybe more [img]/forums/images/icons/smile.gif[/img] ).

I know I want to have at least one drain and want to go probably 6" thickness to accomodate cars, trucks and trailers in there. Beyond that, I'm open to suggestions.

More than one way to do this - here's my suggestions, since I'm getting ready to do this too.

Use some 1/2" isolation material at the posts to allow the posts and concrete slab to shift independently of each other.

Use a clean sand fill as a final topping/level for the existing dirt floor - seems to be easier to work with.

Use the interior of the barn framing as the form for the slab - just pour the concrete to the bottom framing member. You can staple some plastic sheeting to the inside of the framing first if you want.

Speaking of sheeting, use 6 mil plastic as a vapor barrier on top of the final sand fill to prevent moisture from coming up through the slab. Your pumbing will be covered by the plastic and will poke up through it at the drain stub-ups.

Use p-traps at the floor drains - these will be below the slab. You can also use a small plant bucket or similar to leave a void around the stub-up when the concrete is poured. Gives you space to install a floor drain grate if you prefer. After the grate is installed, just mortar in the remainder of the void. Floor drain slope is OK at 1/8" to 1/4" per foot. I'm running 2 floor drains to a french drain outside of the barn - they are just for wash down anyway. I'm also installing a bathroom with shower (connected to septic) while I'm at it for added convenience.

I am pouring a 6" slab of 5 1/2 sack mix - this gives you "about" 3000 psi concrete which is plenty for tractor weights. Rather than 6 x 6 mesh which usually winds up at the bottom since everyone steps on it, I use #4 (1/2") rebar spaced at 16" ea way set on plastic chairs (spacers) that keep it in the middle of the slab. The rebar is tied at the intersections with thin wire. All this is available from a local steel or rebar vendor - they deliver too! The rebar sits on top of the 6 mil plastic vapor barrier.

Thicken the slab at all doors to about a 12" depth and add some additional steel at the bottom of the beam. The beam width can be about 12", then tapered back up to the 6" slab thickness. The beam should extend past the door openings a foot or so on each side, then taper up.

Since the interior slab is not really holding the building up, you don't have to thicken it around the outside edge unless you want to.

I considered doing the slab (40x50) in sections, but decided it would cost more in the long run, so I will prepare the slab - including steel placement - then hire a local contractor to provide and finish the entire slab at one pour.

If you do it in sections, consider leaving the rebar sticking out about 8" from the common side. When you add concrete later, you can pour up against the first section and the rebar will help to tie it all together. You will have a crack at the joint, so either install isolation joint material before pouring or saw cut along the joint and pour some sealer in there.

Hope that helps [img]/forums/images/icons/cool.gif[/img]

Sure not much to add to what Chevdog said. I would double check what the interior posts are setting on, in case you should take this opportunity to add some better footings under them, or even replace posts that are not completely sound (beginning to decay). Just easier now than later.

In regards to the plastic vapor barrier, some concrete people do not like it because it causes a lot of work waiting for the concrete to dry enough to do the final finishing. Last fall I had a concrete contractor pour my garage floor, where I insisted it include the plastic barrier. What he did was to put it down, and then spread 1" of sand on top. That sand held the plastic in place, and helped take care of the water problem when finishing the concrete. I strongly recommend the plastic vapor barrier.