How thick a slab for a bus?

[John Z]

Along with the base prep and rebar - if you know where the bus will be parked, could you not just pour 6" - 7" footings beneath that spot, and leave the rest of the floor at 4". I don't think i would put 6" in an entire building of that size. Up here with the cold winters, it seems that they all will crack eventually, so just design it with the relief joints so the cracks will show up where you want them.

[JackConrad]

Just our way.  We poured a 28' X 58' slab for our shop.  We knew where the bus would be parked, so we poured that part 6" thick with 6" wire mesh and 5/8" rebar. The rest of the floor was poured 4". We also poured the 4'  X 14' approach to the bus door 8" thick. All concrete had the fiberglass mesh added when mixed and we used 3000# mix.  We have had no problems so far. Of course living in SW Florida, we do not have freezing and thawing to deal with. Our driveway is 2" asphalt. We have no had no problem driving the bus over the driveway, but I would not consider parking the bus on the asphalt for extended periods of time.  Jack

[Stan]

Brian: Before you discard the idea of thicker concrete, calculate the additional cost of the concrete as a percentage of the total cost  of the building. If you are going to have an insulated heated shop, an extra 2" of concrete will be a small percentage of the overall cost. On the driveway, the pecentage increase will depend on the amount of money spent on the base, rebar, forming, placing and finishing.  These costs are fixed and the additional cost is only the cost of the concrete.

[kyle4501]

If you plan on installing a car lift in your shop, 6" concrete makes the install a simple bolt in.

Seems like things never go according to plan anyway. Is it possible to install the garage concrete later & just use gravel until then? While not ideal, this worked out OK for me in the past.

If the neighboorhood requires a paved driveway, there will be more restrictions forthcoming. Me thinks you will be ahead if you can find a suitable spot with fewer requirements.

Building ain't getting any cheaper. 

[belfert]

Seems like things never go according to plan anyway. Is it possible to install the garage concrete later & just use gravel until then? While not ideal, this worked out OK for me in the past.

If the neighboorhood requires a paved driveway, there will be more restrictions forthcoming. Me thinks you will be ahead if you can find a suitable spot with fewer requirements.

The type of building I am having put up requires a floating slab or other type of footing.

The restrictions are by the city, not the neighborhood.  There is no HOA or any covanents.  I've decided I probably won't build in that city because meeting the requirements increases the cost too high.

It is next to impossible to find a lot around here that will allow a large outbuilding and not be 60 miles out.  The cities even 30 to 40 miles out all have pretty restrictive rules on building.

Brian Elfert

[Ace]

Brian I have never heard of a "floating slab"! Can you please explain?

Thanks

Ace

[HighTechRedneck]

Brian I have never heard of a "floating slab"! Can you please explain?

Thanks

Ace

Here are a couple of explanations I found via googling.

"floating slab" -- it "floats" on the soil, with the deeper concrete around the edge holding it in place. In northern climates, the concrete around the edge has to extend deep enough to remain below the frost line in winter.

Floating Slab
A floating slab is a reinforced slab placed between walls or footing. The footing poured for a floating slab is allowed to set and the forms are removed. The slab floor is poured inside the footing and is separated from it by an expansion joint. This process of pouring the slab separately allows the slab to rise or fall without causing cracks at the footing edges.

[belfert]

A floating slab is simply a slab of concrete that rests on the earth with no frost footings.  It floats above the frost during the winter months.  The edges are thickened to support the weight of the walls.  The edges are also insulated in an attempt to keep the ground underneath from freezing.

Brian Ellfert

[dwbruner]

My shop is 40'x60'.  The slab is 7" thick with a 12" wide x 24" deep perimeter beam.  There are also 2 lateral beams (40' length) on 20' centers and 1 longitudinal beam (60' length) right down the center....all are 12" wide x 24" deep.  All on top of a nice pad of select-fill soil.  I have not had any slab problems while parking my '85 Eagle, tractor and 1,000's of pounds of other junk. 

Darrin