RV garage - Foundation recommendation

[dcg9381]

For those that have put up "RV storage" buildings or otherwise designed a structure to keep your RV:

What did you do in terms of foundation design? The cost of concrete these days is pretty high and throwing up a 6" slab will far exceed the cost of the building...

When I talk to contractors about it, none of them have designed for 5th wheels - I usually call it "heavier than a bobcat, but lighter than a backhoe".


Seeking foundation design recommendations...

[rzrbckr]

I don’t own a storage building, but the facility where I store just has gravel under the shed. If I were to build one, probably what I’d do also.

[dcg9381]

Gravel is great for a shed roof building or open ended building.. And you're right, it REALLY decreases the cost of construction. This is for an enclosed building (there will be other stuff in it besides an RV) - needs to have a foundation.

[fourfourto]

I have my 442 in a portable garage I have gravel but have a 1 foot square block for each wheel (dig them in flush to gravel.)

Im moving soon upstate the 442 got a garage and i will put the blocks on grass for rv.

[rzrbckr]

Originally Posted by dcg9381

Gravel is great for a shed roof building or open ended building.. And you're right, it REALLY decreases the cost of construction. This is for an enclosed building (there will be other stuff in it besides an RV) - needs to have a foundation.

Yea I understand. Concrete here in the Houston area is sky high due to all the new roads and other construction going on. I’m sure you’re not much better up there around the arklatex.

[JRTJH]

When we built our pole barn for the fifth wheel, a concrete floor would have made the cost about 2.5 times more. I used crushed limestone (called Afton #20 here) after the building was constructed. Even with concrete, around here they build the pole barn, then pour the foundation, so there's no significant difference in technique. I have a small diesel tractor with a front end loader, so I did the limestone myself. After laying it down and smoothing it out, I rented a soil compactor from the local "rent-it company" and went over it several times (so I could use the entire 4 hour minimum rental time). That was 5 years ago and the floor is still smooth, hard, no ruts and no settling.

Total cost for the limestone, delivered on site was $19 a yard. I got 30 yards and had enough to do the 24x32 building, a 2' apron around the outside and most of a 24x50' driveway. There are places where the subsoil wasn't level, so places have 3" of Afton and others may have 4 or 5", but the surface is smooth and level. I park three ATV's, the tractor, my boat trailer and the Cougar inside during the winter.

I'm not sure I'd want to spend the $10K for concrete unless I was going to use the building as a workshop where I'd be rolling "small wheel stuff" around. For general storage use, the Afton has been more than adequate.

[gearhead]

That TxDot road base will set up like concrete. I used a little of it to make the transition from my concrete driveway to my limestone RV parking pad.
If I were to do a dedicated RV storage I would probably use one of the "carport" companies. I thought about running a 24" wide perimeter "sidewalk" to set the building on and then TxDot road base on the parking area. I don't what is stronger...Hilti gun the frame to 6" deep concrete or mobile home anchors.
My son was just telling me that some barn contractors are now using concrete sono tubes and placing an "adapter?" on top for 6x6 posts. Water table around here is about 6" below grade so putting a 6x6 post in the ground gives me the heebie-jeebies.

[B-O-B'03]

Yes, concrete is not cheap.

We had a pad that we parked our popup on and when we bought the trailer, in early 2015, I had it enlarged and had a cover built over it.

You can see in this picture how much concrete we added and it was around $2K for it (I think 6 yards) and the slab is 4 inches thick, with re-bar reinforcing.



-Brian

[Frank G]

It's all about the compaction density of the undisturbed soil under the concrete. Every site is different. Do you experience Frost? Do you need a rat wall? Building Permits? Local Building codes?

There is not a simple answer to your question, only a qualified engineer can give you a definitive answer. Most concrete contractors, who warrantee there work, will give you a slightly over engineered answer and quotation.

[DocWMB]

3/4" minus, compacted gravel over 3" compacted pit-run to a depth of 12" total has done well for me for 10 years. Built a 12 x 40 foot 13' high sheet metal building on 2" metal frame right beside my pole barn. Didn't need permits for this "agricultural building."

[notanlines]

dcg, your local building department will give you the proper (and legal) guidelines needed in your particular situation. The slab description will depend totally on the definition of "permanent" for your structure. Cheap steel carport-like structures are not considered permanent in most locales. Heavy-beamed structures requiring footings are permanent. I might add that 4 inches of 3000-3500 pound concrete over properly compacted soil with 6x6 10-10 "hog wire" will be sufficient. The need for the footing will come from the building department.

[dcg9381]

Originally Posted by Frank G

It's all about the compaction density of the undisturbed soil under the concrete. Every site is different. Do you experience Frost? Do you need a rat wall? Building Permits? Local Building codes?

The soil here is basically some dirt (12-17") over large croppings of limestone. Getting into the limestone typically requires a rock saw or ram. Typical means of building a foundation is to scrape that limetsone or use road base fill (whatever is less expensive) until level.

Yes, we need a rat lip.

Outside the city limits. No inspections. Single "development" permit not associated with an inspection. Basically it's very easy to build where I am without jumping through hoops of jurisdictions and multiple engineers.

Engineered foundations - we go back and forth on this, but there is significant cost in that stamp that does absolutely nothing other than provide some liability. The money can be used for additional materials.. Or I can put it into that stamp.

Originally Posted by JRTJH

I'm not sure I'd want to spend the $10K for concrete unless I was going to use the building as a workshop where I'd be rolling "small wheel stuff" around. For general storage use, the Afton has been more than adequate.

Crushed granite is the available material here, which does well over limestone rock and a level pad site. However, the interior of this building will be space for tools and "rolling stuff around" - so it needs to be concrete.

Sounds like many people are doing 4" of reinforced rebar. May add some additional concrete on-center with the wheel tracks.

Cost of 40x60 concrete, fairly level site, about $25,000. I'd wait out the construction crazy if I could...

[xrated]

I already had a gravel pad for my 7' x 16' enclosed race trailer that I kept parked next to my detached back garage. When I bought the T.H., which is obviously a lot longer and needed a cover over it, this is what I ended up with. The gravel base was extended for the length that I needed and I added 4" x 6" x 8' long treated lumber posts around the edges to keep the surface gravel in place. Each one of those were drilled and I used 2' pieces of rebar to drive into the ground to "anchor" them so that they couldn't move at all. The carport was bought, and then erected by a carport company and when that was done, it was scooted over closer to the existing detached garage as all of this is getting pretty close to the right of way (gravel road) that runs past my property. The carport has rebar style anchors that are 30" long driven into the ground also and seems to make for a pretty secure setup. Here are a couple of pics of the finished unit....

[captcolour]

Here in Kentucky, in 2013, had a 50x60 pole barn with 14' walls and 4" reinforced concrete floor built for $47,500. Included 12' and 8' garage doors, a man door, 6 windows, 2 cupolas, and insulation.