Post frame building slab.....

[Kenfyoozed]

I am building a post frame metal building.30'x40' with a 10' leanto off the back. This will make the slab part 40'x40'. I have only had one estimate and waiting to get more. But not sure what to look for or what i need. I live in South Alabama. The concrete guy said 4" thick slab with 6" footers, using fiber mesh and no rebar. I will use this as a work shop and to house my "toys" ie; lawn mower, tractor, 4 wheelers etc....

Would you guys mind pointing me in the right direction?

Thanks in advance.

[rasimmo]

That is what I did on my barn (4", fiber, no wire, footers). I have not had any cracks from tractors, trucks, loaded trailers or anything else. The only crack that happenned was in the tack room with nothing heavier than me going in there. I guess it must have settled there or somehting.

[DutchHenryBrown]

I have had 2 30x40 pole barns built 1 w/fiber no footings 1 w/rebar no footings and a 20x20 garage w/wire and footings. They all cracked but using stress cuts or what ever they are called help to control that some what. The only thing with the fiber and not sure if it was not finished right but the fibers came to the surface in some spots? Seems like all concrete cracks some time or other in its life or I just was not lucky enough to get it done right? Oh and all were in the 4" range of thickness. Good luck.

[Stimw]

I graded formed and had a 40' X 65' slab poured. I got the "With fiber you don't need rebar" sales pitch.
WELL obviously they never go back and look at the slab 11 years later!
I've got areas that have heaved up or dropped an inch and cracks! And these are areas that I scraped down to level, no fill what so ever!
I think fiber is BS just so the concrete co can get $4. more a yard and the drop and finish crew doesn't have to work around rebar or wire! With rebar and or mesh there is no guessing if will it crack and lift later.

[Kenfyoozed]

Talked with the concrete guy again. He does use wire mesh. So will thise be adequate? And the footers are 8 inches deep.

[ustmd]

Where I live (Central TX), every reputable concrete guy will say you need wire mesh, rebar, grade beams and you can add the fiber if you want to avoid hireline cracks.

Now, I also live on the Blackland Prarrie and the soild has a very high plasticity rating--it moves a loT. During the high summer, we have crack open up that you cannot see the bottom of.

[familyman]

The ground beneath the slab must be adequately compacted. If it's undisturbed soil, running a heavy piece of machinery back and forth over the area should do it. Just don't tear it up.

3" of clean, washed 3/4" gravel should be next, followed by a layer of 6 mil. poly sheeting.

Mesh is good, don't omit it no matter what concrete you use. Be sure the mesh is supported on wire or brick "chairs", to keep it suspended in the concrete. It does no good down at the bottom.

Wet concrete is weak concrete. Be sure that the compressive strength is what you want (3,500lb?) and that they don't add water to make it easier to spread. You would need special tools to check the slump; the concrete should appear fairly stiff and not at all soupy. Plenty of aggregate (gravel) is good.

Be sure that they provide relief cuts every 10 feet. This will help reduce cracking.

Several hours after the pour, cover the slab with 6 mil. poly. Staring the following day, each morning lift the plastic and sprinkle lightly with water. Keep covered for 3 days.

Use a good sealer, and you're done.

Best of luck!

[cattoon]

I live North of you in Alabama, I had a 30x50 slab poured in a pole barn. The fella that poured mine didn't recommend fiber his response was,"we all thought it was a great idea, but since I've been using it I've decided that it doesn't replace the wire or rebar". My floor has mesh and rebar. I think the rebar was only on 24" center. In the doorway where I pull my tractor and other equipment in, the slab is a full 6" thick 10ft wide and about 24ft long, was very easy to reinforce that area prior to the pour. During the pour, Steve(contracted with crew to pour and finish) said that "it's probably the strongest floor in the county". My advise is to make sure it's a little overbuilt because it would be a sad sick day to have it done and then a crack across the floor. I have crack control joints sawcut and thus far after about 5 years no visible cracks.