DIY garage floor help

Old 07-26-06, 01:21 PM
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DIY garage floor help

Hello All,

I need some advice on pouring and working concrete for my garage floor. I am trying to cut some costs and do the work myself if it doesn't seem too overwhelming. Here's some background and any advice on this project would really be appreciated.

The garage is a 3 bay (2 in front for vehicles and 1 in the back for farm equipment) 30x40 with one mandoor. It is of a pole-barn type construction. Along with the floor, I hope to have a small pad outside the mandoor as well as a transition area with a slight slope from the 2 vehicle bay doors to the driveway area. I thought of doing the floor in at least two sections so I could handle the job a little easier b/c I don't have a lot of help available and to help offset costs since I can then save up more money.

I will pour 4000psi concrete, 5" thick. I need approximately 21 yards just for the floor itself. I would like to have one large drain between the two vehicle bays with of course a slight slope to keep the drainage working properly.

Now I need some help. Here are my various questions.
Do I need to have stone on the ground or can I pour the concrete on the ground without stone? (the structure has existed for about 3 years now with no floor, just dirt) If stone is needed, how much? I've been told both ways is ok but without stone the floor will crack more.

Do I need a vapor barrier between the ground/stone and the concrete?

What is best to use for mesh/rebar reinforcement and how much?

How do I work the concrete once the pouring starts? (I know I need to get in it to level it out and tamp it down. Then I would use a 2x4 as a screed and work my way across. After that, I'm blank. Where do I cut grooves, do I need to trowel the concrete, how do I know it's ready to begin to cure, etc?

Do I have to form anything up or can I simply use the 2x10 treated lumber already in place at the bottom of the posts on each wall?
The builders told me that this is usually what is used as the forms since it is already there and is part of the garage. I can also use it as a guide to be sure the floor is level.

How do I install the drain and how do I slope the concrete properly to the drain?

And most importantly, how do I make sure the floor is level and the desired depth of 5" across the whole thing? I think I need to run some string from one wall to the other at the 5" marker and bring the concrete up to the string. Will this work?

Advice please........I only have about $2500 to complete this project and I don't want to waste 1/2 of that on a big crew doing the job if it is something I can do myself. At 21 yards and about $82 a yard in my area, I'll have $1800 just in concrete for the floor only. I am pretty handy at most things but I just have basically zero experience with concrete.

This is my first post here so thanks very much for your time and help.

Old 07-26-06, 03:10 PM
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DIY garage floor help

You need some help EXPERIENCED in pouring, placing and finsihing concrete, based on your questions. It will pay to hire someone if you can find him to work when he is not working at his regular job when you and your friends are available.

You also need some friends to help in the "bull work". I have seen few concrete pours that had too much help.

You also need a few more bucks for the other items in addition to the tools and wheel barrows.

You will need compacted base material under the slab (4" to 6").

You should have poly under the slab as a vapor barrier.

You will need a curing compound or poly and water to keep the concrete moist as it cures.

You will need 2x4s or 2x6s for forming and bulkheads depending on the thickness and fllor latout.

If you are in a nothern climate, you may want air entrained concrete for durability in your free-standing garage.

You wil need fiber mesh concrete or wire reinforcement as a minimu, Many contractor use both.

The existing soil may heave or expand, but the compacted base will minimize the effects.

I am sure you will receive additional input and opinions.

Good luck!!

Old 07-26-06, 08:53 PM
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That is helpful information Concretemasonry.....some of it I've been told and it helps to get it confirmed. I hate to submit to it, but I think you are right about getting a concrete crew to do the job. I know I'd give it a good try but I for sure don't want to screw anything up. I want the job done right even if it takes a little longer to raise more money. I will be watching them like a hawk and that way I'll know a lot more for when the next job comes up and I can try that one on my own.

Thanks much.

More advice is welcomed.
Old 07-27-06, 02:56 AM
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Divide the floor up into sections and hire an experienced flatwork concrete crew. You may want to focus on the section of flooring you want pitched to a drain. For now, do as much floor surface as you can afford with the $2500 bucks you have available. The crew will undoubtedly call on usage of some expensive tools like power compactors, power trowels and transits.

Now you are the boss. Tell the crew you won't bother them but will be watching to gain experience. Maybe they can use you as a helper on the day the floor is poured.

Now,hopefully you have gained some experience and can start on the undone sections as funds become available. You will also have abetter working understanding of concrete flatwork.

Old 07-27-06, 09:04 AM
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Consider that your 21 yards of concrete is about 42.5 tons, and I think you can see that this is a job for pros.
Old 07-27-06, 01:44 PM
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21 yards is far from a DIY job. I poured a 5yard slab last year with 2.5 people helping (myself, someone else who has done concrete work and an anti-diy posterchild). It was a L shaped design against an outside wall, which made it a bit complicated. But my point being: The last thing you want to do is get concrete on the job and not have enough help to properly work it. Buying $1800 of lumber and not getting all the framing up is one thing. Having a 15yard concrete lump you didnt get worked is another.

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