Pouring cement floor in tool shed questions

[BobinIL]

I just built a 30 X 40 Tool shed for my toys. This shed will be used for storage of boats, Compact tractor impliments and as a shop. I plan to pour a 4" thick floor with 6 bag concrete. Should I pour this in 2 pours??? If I do 2 pours I will divide it right down the middle and put rebar in the center forms. How often shoud I put a bar? every 18 inches, every 2 ft? Then I want to pour a lip in front of the door. I assume this needs to be considerably thicker than the floor, How thick should it be. Should I connect it to the floor with rebar or let it float separately?

 

[Highbeam]

We have buildings in my city being built out of concrete. The buildings are over 500,000 square feet. They pour floor slab at a rate of 50,000 square feet per day.

As long as you have good help and a good supply of concrete, I would do the pour all at once and get it over with. No rebar is needed. It will crack.

 

[dooleysm]

He didn't specify feet or inches, but he did say, "This shed will be used for storage of boats, Compact tractor impliments and as a shop."

Unless he's literally talking about children's toys, I'd guess feet.

We poured my 32'x40' barn in one pour. We used the wire concrete mesh instead of rebar. I cut it every 8 feet in each directions. It hasn't cracked yet.

 

[EddieWalker]

Bob,

From reading your questions, it's pretty obvious you don't have allot of experience with concrete. This is not a job for a do-it-yourselfer. Concrete needs to be worked quickly to spread it out and get it level, than you realy need to know what you're doing to get is smooth. This takes a crew who knows what they are doing. It's physical, backbreaking work and just asking a group of friends isn't enough. They need experience to know what they are doing.

If you know one person who really knows his stuff, he can direct a group of rookies, but your chances are still pretty good that the wont move fast enough and have the "eye" for what needs to be done.

If you want to save money, you can level the ground, dig the footings, set the forms and put in the rebar yourself. This is what I do when pouring pads greater than 3 yards. Even three yards is pushing it for me and I've done a fair amount of this.

Then you only have to pay for a crews time to work the mix and the concrete you use.

The only advantage to pouring concrete in seperate pads is for expansion. Cocrete that is outdoors expands and contracts with the elements. This movement leads to it's cracking if it can't move. The bigger the pad, the more movement you have and the more cracking you'll get. Pads poured that are indoors are protected by the building that's over it, reducing and in some cases, almost eliminated the amount of expansion of the concrete. Your demensions are well below the limits of a single pour. There is no advantage in your situation to pour you pad in two pours. Even if you tried to do it yourself, it's too big a job to do right.

Before you do anything, talk to several contractors. Don't just listen to one, be sure to get three to five to come look at your job. Tell them what you want and how to go about doing it. Some wont' let you do any prep work, others are real good about it. Some will tell you they do it one way, others will have another way to do it. Listen to all and decide which is best for your needs and area. Be sure to listen to what they say because they are familiar with your weather and dirt conditions. What it's like in other parts of the country have zero to do with what it's like in your area.

Good luck,
Eddie

 

[Little_Grizzly]

Bob,

Sounds like a great shed! I always have a laugh when anyone on this site says "shed". To me the 10' X 10' building I just did was a "shed" hahaha.

Anyway, 30' x 40' is a pretty big concrete pad to pour by hand! I doubt it's even possible! So I assume you are having the concrete delivered. In that case do it all in one shot. Google is your friend. Search around and learn about things like expansion joints and bull floats and magnesium floats etc etc etc. So much to learn!

My guess is that you're going to pour a footing first. That will take re-bar. Then when that is done you'll pour the slab. That will take wire mesh.

There is also some great debates about gravel vs sand as a base. Also whether to put the vapor barrier over the gravel or under it.

My suggestion is to google google google 'till you can't take it anymore. I also read two very good books:

Construction Manual: Concrete & Formwork by the Craftsman book company
and
Taunton's For Pros by Pros: Foundations and Concrete Work from Fine Homebuilding.

 

[eanjay]

I just built a 30 X 40 Tool shed for my toys. This shed will be used for storage of boats, Compact tractor impliments and as a shop. I plan to pour a 4" thick floor with 6 bag concrete.

I'm just finishing a 24' by 24' worshop/tractor storage. It's sitting on a concrete pad spec'd by the county engineer. The sides are 12" deep with rebar, 12" wide sloping in at 45 degrees to the floor which is 4" thick on compacted gravel. On top of the gravel is a plastic vapour barrier, then 1" of sand and then wire mesh. The sand is only to prevent the plastic getting punctured. The mesh sheets over-lap each other by 8" and also fold down over the edge at the footings. That's 12 yards of 4000lb concrete that took about 2 hours to pour and work-up, a then was mechanically troweled on and off for the rest of the day. This is a floating pad, intended to ride-out frost-heave. Minimum depth for footings here is 4 feet.

eanjay

 

[PineRidge]

Bob,

From reading your questions, it's pretty obvious you don't have allot of experience with concrete. This is not a job for a do-it-yourselfer. Concrete needs to be worked quickly to spread it out and get it level, than you realy need to know what you're doing to get is smooth. This takes a crew who knows what they are doing. It's physical, backbreaking work and just asking a group of friends isn't enough. They need experience to know what they are doing.

If you know one person who really knows his stuff, he can direct a group of rookies, but your chances are still pretty good that the wont move fast enough and have the "eye" for what needs to be done.

If you want to save money, you can level the ground, dig the footings, set the forms and put in the rebar yourself. This is what I do when pouring pads greater than 3 yards. Even three yards is pushing it for me and I've done a fair amount of this.

Then you only have to pay for a crews time to work the mix and the concrete you use.

The only advantage to pouring concrete in seperate pads is for expansion. Cocrete that is outdoors expands and contracts with the elements. This movement leads to it's cracking if it can't move. The bigger the pad, the more movement you have and the more cracking you'll get. Pads poured that are indoors are protected by the building that's over it, reducing and in some cases, almost eliminated the amount of expansion of the concrete. Your demensions are well below the limits of a single pour. There is no advantage in your situation to pour you pad in two pours. Even if you tried to do it yourself, it's too big a job to do right.

Before you do anything, talk to several contractors. Don't just listen to one, be sure to get three to five to come look at your job. Tell them what you want and how to go about doing it. Some wont' let you do any prep work, others are real good about it. Some will tell you they do it one way, others will have another way to do it. Listen to all and decide which is best for your needs and area. Be sure to listen to what they say because they are familiar with your weather and dirt conditions. What it's like in other parts of the country have zero to do with what it's like in your area.

Good luck,
Eddie

I really agree with Eddie here. That crete will be with you for a very long time. If it's done wrong you'll be the one who has to look at it and deal with it. Some things should be left to those with more experience.

 

[BobinIL]

I do have limited experience with concrete. I have poured several floating slabs for feeding livestock on. The main thing that concerns me is the floor at the entry door. I do not want it to give and crack when I drive on it. I talked to a guy that poured a 2 foot thick lip in front of his door but he is driving large farm machinery into his shed. I will set all the forms, dig the footings, level the fill and lay down the vapor barrier and wire mesh myself. I will hire someone to direct the pouring operations and then get a few buddies to help with the pour.

 

[Spark_man]

I have a 36 x 36 pole barn with a concrete floor and a driveway skirt that is about 18 x 20 that we finished last year. I paid a local guy who was recommended to my by my neighbor something like 70 cents a square foot to handle the pour and finish it. I had already installed the 2 drains (one in the middle and one under a hydrant I also installed in one of the corners. He recommended installing key lock joints to control cracking (even though we used wire mesh, had fiber added to the mix and used an 8000 lbs mix). I think the cost of the joint material was about 50 or 60 bucks and he didn't charge me anything to install it.

The day of the install, he showed up at 5:00 AM (in the dark) with a helper and the two of them laid, leveled, power troweled and hand troweled the pour till they were done at around 2:00 PM. He and his helper were both in their 60s and had been doing this kind of work for 40 years. There is no way I could have either kept up with them or done such a fine job. The floor surface in side you could play billiards on. It was easily the best money I ever spent. If you haven't done this kind of work before, pay somebody or it will come out looking like cr@p and that much concrete is too expensive to ruin.

 

[ovrszd]

I have a 36 x 36 pole barn with a concrete floor and a driveway skirt that is about 18 x 20 that we finished last year. I paid a local guy who was recommended to my by my neighbor something like 70 cents a square foot to handle the pour and finish it. I had already installed the 2 drains (one in the middle and one under a hydrant I also installed in one of the corners. He recommended installing key lock joints to control cracking (even though we used wire mesh, had fiber added to the mix and used an 8000 lbs mix). I think the cost of the joint material was about 50 or 60 bucks and he didn't charge me anything to install it.

The day of the install, he showed up at 5:00 AM (in the dark) with a helper and the two of them laid, leveled, power troweled and hand troweled the pour till they were done at around 2:00 PM. He and his helper were both in their 60s and had been doing this kind of work for 40 years. There is no way I could have either kept up with them or done such a fine job. The floor surface in side you could play billiards on. It was easily the best money I ever spent. If you haven't done this kind of work before, pay somebody or it will come out looking like cr@p and that much concrete is too expensive to ruin.

WOW, you paid $900 for two guys to do your pour. Things must be more expensive out East!!