Slab questions

[creep]

Just had my 32x40x12' shop from Adams Truss delivered yesterday and now I need to get my slab figured out so I can start putting the building up. The shop is home for my truck pictured below. Not sure how much it weighs, but I'm guessing 7k. No lift or heavy duty tools/machinery inside, just the truck and my tools.

With all that in mind, will a 4" slab get the job done or do I need to go thicker? Will 3500 PSI be sufficient? Do I need to have fiber in my mix? Will mesh get it done or do I need to go with rebar?

I know that's a lot of newb questions, but the bids I have gotten have been all over the place because of differing opinions by contractors on what I need. The last guy said I needed a 6" slab with #4 rebar on 12" centers.

Here is the truck that will be sitting on this slab:

 

[ConCretin]

A 4" slab is more than adequate for most applications including light trucks. Make sure you have a properly compacted gravel sub base 12" or so thick. I would excavate around the perimeter to create an 8" to 12" haunch to provide some additional support where the walls bear and you drive in and out. I would go with wire mesh on continuous slab bolster across the 4" slab with a couple #4 bars in the bottom of the haunch. Fibermesh is helpful for reducing plastic shrinkage cracks but is not a replacement for properly positioned wire mesh or rebar.
If you are thinking about an epoxy or other floor covering, install a good vapor barrier underneath the concrete. Saw cut 1" deep control joints immediately after finishing to create square panels no larger than 20' across. Keep the concrete in a continuously moist condition for at least seven days. You will have yourself a crack free and durable slab that will last you a life time.

 

[brownbagg]

4 is fine but if you want a lift later five or six, see how much more it cost for the extra thickness and see if its in your budget

 

[creep]

If we ever do a lift it will be outside. This truck will be the only thing inside and there isn't enough headroom for a lift.

The soil we have on the lot is pretty sandy. I have no idea if that is good or bad with regards to putting a slab on.

 

[bczygan]

Three things.
Remove all organic and loose material.
Place a well compacted base material to a level high enough that you get positive drainage to surrounding areas.
Provide additional drainage as required.

Decide now if future lift or underground plumbing (Water and waste) or electrical, phone, cable, computer or gas will be needed. Install or sleeve for it now. Think about heating system (In slab?) and insulation (Under slab?).

 

[creep]

Decide now if future lift or underground plumbing (Water and waste) or electrical, phone, cable, computer or gas will be needed. Install or sleeve for it now. Think about heating system (In slab?) and insulation (Under slab?).

No lift. We will have whoever does the concrete stub the electrical and plumbing. This isn't a palace like some of the shops I have seen on here, so no need for gas, phone. Heat will be provided by Carhartt and we plan to insulate down the road as funds allow.

 

[Charles (in GA)]

You are not planning ahead at all. I didn't think I'd ever have a lift. After a few years, I realized I am not getting any younger, and a lift would be nice. Surely that truck is not the only thing you own mechanical that needs to be worked on. Heat, we all yearn for a warm shop in the winter. I've spend way too much time in insulated coveralls working in a cold shop, what a pain. You may think its OK now, but wait a year or two down the road.

Plan ahead for things you think you will never need or want or use, and you will be much happier later on, or at least, you have good selling points for the next owner.

Concrete crews are not electricians or plumbers, you need to get them involved first, right after the forms are set, so they can set conduit and pipes that will go in the slab. Don't expect the "concrete man" to do that job. His job is to show up and pour concrete and finish it, not mess with plumbing.

Charles

 

[mdbeck1]

It would help if we had an idea of your physical location. Building codes vary from location to location.

The local inspectors will know what you are really supposed to have versus what the contractors are trying to talk you into. Most of the residental garages that I have seen use a 4" slab unless they are planning on something special like a lift or a much heavier load. In fact most of the automotive garages I've been in also have a 4" slab. You will start to see thicker slabs when you get into heavy equipment shops or shops with lots of heavy equipment.

 

[creep]

You are not planning ahead at all. I didn't think I'd ever have a lift. After a few years, I realized I am not getting any younger, and a lift would be nice. Surely that truck is not the only thing you own mechanical that needs to be worked on. Heat, we all yearn for a warm shop in the winter. I've spend way too much time in insulated coveralls working in a cold shop, what a pain. You may think its OK now, but wait a year or two down the road.

Plan ahead for things you think you will never need or want or use, and you will be much happier later on, or at least, you have good selling points for the next owner.

Concrete crews are not electricians or plumbers, you need to get them involved first, right after the forms are set, so they can set conduit and pipes that will go in the slab. Don't expect the "concrete man" to do that job. His job is to show up and pour concrete and finish it, not mess with plumbing.

Charles

I appreciate your suggestions, but you should probably know more about the situation before jumping to conclusions about what we have planned. The shop is being built on my parents land, which is also home to the house they just built. Attached to that house is their garage, which is where we work on our other vehicles.

This shop is being built for the sole purpose of housing a truck that is over 10 feet tall. I am a firefighter, as was my dad, and we are used to being soaking wet in freezing cold doing harder work than turning wrenches. For you, having a heated shop may be a necessity, but for us it is a luxury that we simply don't care that much about. We plan to insulate the shop later down the road, but for now our priority is getting the building up to house the truck so we don't have to roll around in the dirt to work on it like we have for years.

As I said in a previous post, if we ever decide we want a lift, we will be more than happy to put one outside on another pad, just like the one you see in the picture. As far as the stubs for electrical and plumbing, I haven't had a concrete guy yet who said he couldn't or wouldn't put stubs in for electrical and plumbing.

mdbeck1, the shop is outside the city limits, so there are no codes for buildings.

I appreciate everybody's helpful suggestions so far. It sounds like I will be looking for a pretty simple 4" slab. Is 3500 psi about right for this application or is that too high/low? Sounds like I need to put rebar in my footers and mesh in the slab itself. Correct?

 

[50cal]

Sounds like you have it pretty well covered. Your not going to put in a vapor barrier so your slab will be damp. Your not going to use insulation so your floor will be cold. You probably wont compact or put in a base so your concrete will crack severely. If I were you I wouldnt waist my money on rebar or mesh you obviously dont know how to place it and a chessey contractor will just walk on it driving it to the bottom of your pour serving no purpose at all. You are a unscrupulous contractors delight you have no idea what you want yet know everything.
The ideal foor six inches of base material compacted. Heavy duty vapor barrier bought from a builders supply house tape the seams. two inches of blue foam board #3 at least rebar on 1 foot centers on chairs remesh layed over the top of this to stop spider cracks, 4 to 6 inches thick 6 sack limestone mix no flyash. Power troweled watch them closely and tell them no poking holes in the vapor barrier to get rid of water

 

[Daniel Dudley]

Are you erecting a metal building on this slab ? Because if you do, it needs to be thicker at the edges and have rebar well placed. you should ask the people you got the kit from what they recommend, because they have been to this rodeo before.

 

[brownbagg]

just because you outside the city limit doesnt mean there is no code. there might not be any code enforcement in your area, but every building in United states must be build to code

 

[wuck]

A 4" slab is more than adequate for most applications including light trucks. Make sure you have a properly compacted gravel sub base 12" or so thick. I would excavate around the perimeter to create an 8" to 12" haunch to provide some additional support where the walls bear and you drive in and out. I would go with wire mesh on continuous slab bolster across the 4" slab with a couple #4 bars in the bottom of the haunch. Fibermesh is helpful for reducing plastic shrinkage cracks but is not a replacement for properly positioned wire mesh or rebar.
If you are thinking about an epoxy or other floor covering, install a good vapor barrier underneath the concrete. Saw cut 1" deep control joints immediately after finishing to create square panels no larger than 20' across. Keep the concrete in a continuously moist condition for at least seven days. You will have yourself a crack free and durable slab that will last you a life time.

+1 - Yeah,what he said. I'm sure the building manufacturer would give you the best answer though.

I've been looking at lifts since registering here, it seems like 4" of 3500 psi concrete is adequate for most. But, it looks like you can stand under your truck anyway ;-)

Enjoy your new shop!

Pat

 

[creep]

Are you erecting a metal building on this slab ? Because if you do, it needs to be thicker at the edges and have rebar well placed. you should ask the people you got the kit from what they recommend, because they have been to this rodeo before.

Metal trusses, wood purlins. The footers will likely be 16x16" with #4 rebar. The truss guy deferred to the concrete contractor because he isn't familiar with the soil conditions in my part of the state and they are much different than his region.

 

[creep]

just because you outside the city limit doesnt mean there is no code. there might not be any code enforcement in your area, but every building in United states must be build to code

I apologize, I misspoke. No permits are required since it is outside the city limits.

The building is professionally made and the slab will be done by a professional, I just wanted some advice so I could get an accurate bid instead of the inaccurate ones I had been getting.

 

[richj11]

This shop is being built for the sole purpose of housing a truck that is over 10 feet tall.

Does that truck have portal axles?

 

[DCarr]

I have a 4" slab with fiberglass that I drove a 21,000 lb. reach lift on and around w/o issues. Never parked it for longer than a few minutes. But what I did do caused no problems.

 

[chief ben]

I had my shop floor put down17 years ago and it is 26 X 50 6 inch with wire and Fiber I had the ground packed with a big roller, NO Cracks, and I have had some BIG heavy Equipment in the shop over all the years,
4 inch with Wire and Fiber will hold your truck with no problems, Oh and I had
4 inches of city pit packed and rolled before we pured the concret,
Do it Right the first time, Because there is no second time, Cracks ****.

 

[creep]

Does that truck have portal axles?

No sir, 2 1/2 ton Rockwell axles.

 

[richj11]

No sir, 2 1/2 ton Rockwell axles.

Nice

Yeah, they are portals. Rockwell is who makes your particular axles....

 

[creep]

Nice

Yeah, they are portals. Rockwell is who makes your particular axles....

I'm well aware they are made by Rockwell, but they are not portal axles. Portals are typically found under Unimogs. These axles came from US Military M35 6x6 trucks. These are top loader axles, but not portals.

 

[nissan_crawler]

Nice

Yeah, they are portals. Rockwell is who makes your particular axles....

Umm...no. Pinzgauers, unimog's, etc., have portals. Deuce and a half's did NOT come with portals.

 

[richj11]

Thanks. I always fit Rockwell's into my crude definition of a "portal" axle. You still read it that way on a lot of forums. Now I know better

 

[captnrbrt]

I know that concrete, especially higher psi concrete ain't cheap. I did my slab 6" with extra fiber and rebar placed. The cement truck guys wanted to know what I was going be working on with such a strong slab, I told them "anything I want or need to!". I tend to overbuild stuff if at all possible.