Pouring a Concrete Garage Floor

Pouring a concrete garage floor takes a lot of work. If you aren’t particularly handy, either get an experienced person to help you or hire a professional. A garage floor should be solid and stable because it’s the foundation of your garage. Make sure your garage floor pouring thickness meets the load it has to hold — more depth is needed for bigger vehicles or equipment.

If you’re faced with the prospect of pouring a concrete garage floor, is it really going to be as hard as it sounds? It depends on your skill

You aren’t alone in feeling apprehensive. Here are some reasons you might be nervous, things you don’t know:

  • what preparation the ground needs
  • what tools you need
  • what materials you need to use
  • about forming or pouring
  • about the finish work

And these are all valid concerns when you’re committed to doing a good job with pouring a concrete garage floor.
In terms of tools, you’re going to need quite a few items. If you already have experience with home construction or repair, then you may be in luck because you’ll likely already have many of the tools you’ll need. Start with some basic carpentry tools (hammer, saw and nails, for starters) and a level to construct the forms correctly. You will also need tools, like a wheel barrow and shovel to process and pour the concrete. If you don’t own these, you can rent them in most areas. You will also need concrete finishing tools, like trowels and a finishing broom to make sure that your surface is clean, level and the texture you want.
Of course you’ll need concrete. The amount you will need depend son the thickness and square footage you require. The average garage floor pouring thickness is between four and six inches. You also will need either rebar or mesh for reinforcing the concrete.
Before you get started forming your garage floor, make sure you have a solid ground surface. If the ground is untouched, has never been dug in, you are good to go. If you are pouring the floor on ground that’s previously been dug in, you want to compact the soil and top that with fines for a stable surface. If you are pouring your garage floor on Bentonite-like soils, you may want to make footers into the ground before pouring the slab.
A garage floor consists of first a footer that runs the permitter of the garage. Next you pour a stem-wall onto the cured footer; make sure you have rebar spaced along the top of the stem wall so you can attach your garage frame to it. Once those pieces are cured you can start pouring your garage floor.
Forming for concrete involves creating a mold, or shape, that you will pour the concrete into. By using wooden boards (footers and stem wall forms are typically are 2″x12″, while floor forms will be 2″x4″ or 2″x6″), a hammer, and nails, you can build your form, or mold, that will hold the concrete until it’s nearly dry. Make sure your corners are square. Measure and measure to ensure you have the correct size and shape for the garage floor.
Pouring is an altogether different matter. Most laborers try to not to pour concrete on hot, dry days because the concrete sets too fast, making for a less sturdy floor. Pouring concrete on cold days takes special attention and preparation as well. You also want to overfill the forms slightly to ensure that any excess water in the forms rises to the top. The concrete should be mixed thoroughly enough that it pours easily and evenly.
You then want to “float” the surface with a magnesium or wooden float. This is the tool used to level and smooth the top of the concrete. This is simple when you have a small area, but it can be done in larger areas with careful planning. You need to have a way to get to the middle of the newly filled area. You may want to consult a concrete professional about other special tools that are available for this project.
You’ll also want to score the garage floor so that you have expansion and movement space. This helps to keep the concrete from cracking as it expands and contracts with the climate conditions.
In the end, pouring a concrete garage floor is all about rounding the edges of the drying concrete and removing the wooden forms from around the area. Of course, these garage floors aren’t ready to be used until the floor is completely dried.
Pouring a concrete garage floors will take a lot of time and a lot of equipment to do, but if you’re interested in doing the job yourself, it’s possible even for a beginner. So no more worries.


26 thoughts on “Pouring a Concrete Garage Floor

  1. Im pretty handy with a hammer but Im not so sure footed around concrete.
    My question is this, my driveway was graveled about 13 years ago and we have been driving on it ever since. Do I need to dig it up, rent a roller and tamp it down, or can I just pour on it?
    Thanks

  2. Hi Kennedy,
    It probably isn’t going to make much of a difference, but if it were me, I’d go with the 1/2 inch. I presume you plan on crossing the rebar as well? You can also use some fiber mesh added to the concrete for some added strength.

  3. After moving into our new construction house, we find the garage is 18 inches below grade (per site plan). The builder wants to pour 18 inches of new concrete on top of the existing floor. Can this be done? Please help!!

  4. Hi Sara,
    This is more of a construction question than a flooring question. But, my hunch is there could be a problem with that. I don’t think the two
    layers would adhere and that could cause problems. I would suggest calling your local building department to ask about how that would work, and if it’s an appropriate fix.
    So….if the concrete was poured that way ‘per site plan’, then why does the builder want to pour another 18 inches of new concrete on top of that now?
    You may have to take the original out and pour a new, appropriate one. For your sake I really hope not. I just can’t help but wonder if your builder has messed something up and trying to cover it up or just wants to get more money. If it was ‘per site plan’, then it shouldn’t be an error, right? Unless the whole ‘site plan’ was in error. Just thinking that the builder should be responsible if it was an error. Anyhoo, I really think your local building office would be a great help and help guide you on what you can do if something is amiss with what the builder has done and wants to do.

  5. I am pouring a garage floor and not sure how to space my rebar for the floor. I live in Montana and not sure that would make a difference. Thanks for your help.
    Bill

  6. Hi Bill,
    That’s really more of a construction question, I don’t pour concrete or prepare the area before it’s poured. You could probably find an answer by doing a search at your favorite search engine. Something along the lines of rebar spacing concrete garage and/or floor should work.

  7. I am getting ready to pour a garage floor…28×38, 6″ thick. How is the best way to go about keeping the concrete level when pouring? I thought about nailing some thin plywood, 6″ high around the walls, then putting a piece down the entire center of the garage, and using them to slide a 14′ 2×4 down keeping the concrete level with the top of the plywood boards. Would this work? If so, what happens if I leave the plywood strips nailed to the wall, and that one down the center? Will that cause a void for ground water (i have water puddling on top of footer when it rains) to come up? Where on the net can I find more detailed info on pouring a floor like this?

  8. Hi Mike,
    The questions you’re asking are construction issues. I’m sure though, that if you went to your favorite search engine (mine’s Google) and typed in forum concrete floor you’d find some good places to ask your questions.

  9. Dear Flooring Lady,
    Your site is the closest I have found to our situation…15 yr old house with poured concrete footer all around but dirt floor within footers (not level, slightly sloped). Moisture collects up from the dirt floor, so we want to add a poured concrete floor. Where can I find a step by step guide to doing this job ourselves. We are very handy with tools and can rent things like a small cement mixer, etc… but I need instructions on forms, rebar type and attachment, need for gravel or drain or sump pit before pouring concrete, type of concrete, sealing after cured, etc. Can you recommend a site or a manual? I have already searched under poured concrete basements etc and yours was the first site with any real info, just not detailed enough. Thanks!

  10. Hi Kathleen,
    The best thing I can recommend is hitting a search engine again. Try doing a search for …. concrete floor how …..something along those lines. A DIY (do-it-yourself) type site would help too. I know there are lots of forums where folks ask questions about construction issues and get help. Good luck!

  11. This is crap, your article give just enough detail to get people into trouble. Why do you have a page about pouring concrete and then when people ask question you cant answer them.

  12. Hello David,
    I’m sorry you feel that way. This site is designed so that others can explore different options for their flooring needs & problems and to ask questions to try to get some help or more insight. I’m not super-knowledgeable in every single subject, but I also think that it would be a disservice to not include flooring options that I’m not greatly familiar with. If I don’t know what would be the best solution – I thell them — plain and simple, and encourage them to do more research, ask professionals, talk to manufacturers (if applicable), etc. I’m not going to pretend that I know something when I don’t – I think that would be wrong – and way more misleading/dishonest than the view you have and that you’ve already expressed.

  13. hello i would like to know how thick should the concret be for the garage floor, driveway and the pitch for the driveway.
    thank you.

  14. I, want to put a new concrete floor over an existing concrete floor in a 16×24 garage the existing floor has been painted with concrete paint wats the procedure of preparing the existing floor

  15. Hi Rod,
    What’s going on with the present floor that makes you think you want to lay down a new layer of concrete? Is it just that you don’t like the paint? What do you want the end result to be?

  16. Hi Chris,
    The article is designed to give basic info. This is a flooring site, not a construction site – you might have better luck at a construction type site. This article gives a good basic overview of what you will be doing.

  17. My garage floor is all broken up with dirt and stones coming out from everywhere. Thanks to the previous owner and the salt from the winter weather. It’s uneven eveywhere and had pot holes that I filled with concrete couple years ago for a temp fix. In a case like this where the floor is broken up and is not leveled anywhere, can we still pour concrete on top or would we need to do further demolishen first to level it and than pour concrete ? Thanks

  18. Hello Adil,
    It’s my experience that you need to demolish the old floor before pouring new concrete. You just don’t get good adherence of the old and new surfaces. The best results are to start fresh.

  19. i am buying a new construction house . I noticed the garage floor (cement) has hair line cracks like the shape of a + almost end to end and almost side to side of the floor.
    did they mess up? I dont like the though of having hair line cracks that get bigger and bigger every year. would love your thoughts on this. the floor was poured in September cool summer in alaska.

  20. Hi Jean,
    Concrete can crack for many reasons, not just because it was messed up. You may want to have a concrete mason in your area inspect the cracks and offer their suggestions.
    Also, if it’s not too late, maybe you could get something in your purchase contract to make sure this is taken care of, if it is a problem.

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