RV Concrete Pad Questions

[bluwtr49]

I'm putting together a drawing package for the concrete pad in my upcoming garage and I would like some input.

Per the building drawing package the slab requirement is a 4" X 48'5" l X 20'3" with 12" X 12" footers. It also has a 1.5" X 1.5" sheeting edge. 2500 psi at 26 days. The slab is above grade.

I'm thinking about specifying a coach wt of 45,000 lbs and a max tire loading of 8,000 lbs to give the contractors and idea of what the point load will be.

Is that a good approach as opposed to simply specing the concrete type, thickness, and reinforcing?? After all they should be the experts.

Thanks again for all the valuable input on this project.

[kjburns]

A lot depends on the soils in your area and the subgrade you use. 2500 psi concrete is more appropriate for sidewalks. I would use 3000 psi concrete. In some areas with expansive clay soils, rebar and wire mesh may not be enough and post-tensioning works better.

When I built my RV garage, they used a 4" slab with #3 rebar at 24" each way, which is pretty minimal. It's fine for this area even with a heavy coach like mine. It might not be right for your area, so it's worth getting with a contractor who has some experience in this type of work.

I've been in the rebar business since 1980, doing everything from small residential projects to huge projects with thousands of tons of steel. I should clarify that 6 x 6 mesh doesn't mean anything. That's the wire spacing. There is also the wire size or gauge. For example, 6x6-W2.9/W2.9 is a six inch spacing each way with 6 ga wire each way...a common size.

[turnersteve]

PastorCharlie wrote:
When I poured my shop floor I poured 6" with three courses of 5/8 rebar around the edges and 4" with wire and 5/8 rebar crisscrossed in the floor.

I agree, I poured an extension to our utility driveway and is 6". The rest of the driveway is 4" and just driving the MH on it cracked it in several places but no cracks in the 6" slab.

[Pangaea_Ron]

Probably as important as the concrete slab on grade is the compacted base below. I would use 6" thick compacted granular fill, with 6" thick reinforced concrete slab over.

A quick calculation for weight per tire would be: ~9"x9" footprint, which increases to 21"x21" with a 6" thick slab = 3.06 SF "footing" per wheel. Assuming 2,500 PSF soil bearing pressure, that would support ~7,656 LBS., which is just about what you are hoping for.

Edit: Oops, math correction

[rgatijnet1]

The footers are great and they do give additional support.....for the building. The footer is only on the perimeter and does nothing to support the weight of your coach. I would go with a 6" slab, reinforced with 6x6 mesh and using 3000 pound fibermesh concrete.
By the time they cut expansion cuts in the slab, you will need the additional thickness to prevent settling of the slab.
I would also specify that the slab is poured LEVEL, rather than having a slope towards the door. Even here in Florida, where we get a lot of rain, the level slab is much easier/safer when dealing with vehicles that will be worked on and on jack stands. Before the garage is built, a level slab will allow any water to run off just fine.

[the_silverback]

If you intend to park it for a long time put something under the tires between them and the concrete pad. Both Michelin and Goodyear say this needs to be done. Maybe there is something on their web sites. I remember a engineer from Michelin saying a piece of plywood is OK. Please check it out.

[Big_Katuna]

I'd go 6" and get a higher PSI concrete.

[Executive45]

Labor is the biggest expense. Materials are cheap. PastorCharlie has the right idea. 6" is minimum I'd go....Dennis

[PastorCharlie]

When I poured my shop floor I poured 6" with three courses of 5/8 rebar around the edges and 4" with wire and 5/8 rebar crisscrossed in the floor.

[Skipg]

Here in Yuma Az. There are many RV ports and the standard is a 6 inch slab. I personally have had two RV slabs pored and both were 6inches deep. 4 is to thin go with 6 you won't regret it

[Steele_Grey]

When I had my pad put in, I told the contractor the weight I needed to place on the pad and he built accordingly. He did a great job and no problems in the 3 years I've had the pad.