Who has poured their own garage floor before?

[chrisp]

I am relocating my garage (back 15 feet) and will need to have a 40" frost wall/foundation built and the main slab poured. As with anything else I always have to investigate the DIY option so I know what I am getting and to see if it makes sense to do myself.

It's a 20' x 20' square garage. I don't want radiant heat or any other options, just a basic garage floor.

[KTL]

If you know a fella who does this type of work and has the proper tools and equipment (floats, trowels, contraction joint float, a machine to dig, good forms, and level, laser, stringline works too ........ etc.) it can save you a good bit of money to do the digging and prep work yourself. Also helps to know someone with an account at the concrete supplier. Those who use large amounts of ready-mix usually get a sizeable discount.

You'll also want to consider if you can put a drain in the floor. Some areas don't allow this, but it's a handy thing to have if you can do it.

As far as the floor itself, don't skimp on the concrete thickness. 5 in. is fair. 6 in. is good. More is better.

Be sure to reinforce it with fiber mesh within the concrete or use welded wire "fabric" rolls to add strength to the concrete.

Make sure you put contraction joints in the floor. Years ago, floors would be placed without dummy/contraction joints. Inevitably the floor would crack uncontrollably. That's what the joints are for. Since the floor will inevitably crack, the joints control this occurrence. Cracking is not necessarily due to loading. Shrinkage and expansion contribute to this as well.

Use a good strength concrete as well. In IL, the standard strength concrete is 6 bag mix ( 6 sacks of Portland Cement per yard of concrete) and 4000 psi compressive strength for flatwork. Flatwork being , sidewalks, curbs, patios or residential driveways.

[avi8torny]

You don't pour concrete.....you place it.

[chrisp]

Thanks.

[ruf-porsche]

Originally posted by avi8torny
You don't pour concrete.....you place it.

That's right and if they are pouring the concrete into the forms, than the concrete has too much water.

The stiffer the concrete mix the stronger the concrete will be , however, the stiffer the concrete, the harder it is to work into the form.

Also too much water in the concrete will cause cracking down the road.

Don't forget the rebars and control joints.

[tops911]

If you do a 40" foundation you'll need 1/2" rebar in the wall and footing. You'll need to rent some forms to pour the wall. What I get from my father (who did this work over 20 some years) is to use a key type joint and keep the slab 10'x10' and you should have no problems with cracking. There is a metal key joint made to use in slabs, you could pour the entire slab at one time but you'll need to use the metal key joint and trowel flush with the joint. A couple of other things to consider is the slab going to sit on the foundation or is the slab going to be inside the foundation walls. If the slab is inside the foundation the floor can have a slope twards the garage door for drainage. You dont need much something like 1" per 10'. A draw back is you'll have a ledge that sticks up an inch or so. Normaly the foundation walls are 8" thick. So you'd about a 4" ledge that would not be even with the floor. I used to do this kind of work 17 years ago, But now I shoot howitzers. Cement work is hard on the knees, artillery is hard on the ears.

[juanbenae]

3-4-5,, you may be asking what the hell is 3-4-5, use multiples of 3-4-5 to check to see that your corners are square. measure say 9 feet one way, 12 feet the other on a corner, the hypotinuse (sp?) will be 15 feet. a corner to corner diagnal should be the same didtance.

if you have expansive soil in the area you will want to cushion the slab with some compacted base rock. this will also help minimize cracking. an expansion joint along the slab where it meets the foundation is advised. 40" footing for frost? i thought building in california was bad with the earthquake requirements.

last hint,, find some guys that can finish concrete on pour day and pay the going rate. unless you want a nonskid rake finish you need to have at least one guy skilled at concrete finishing. a 20x20 slab can get away real quick in warm or windy weather.. keep it moist during cure in hot weather.

[BGCarrera32]

When I poured my large sidewalk and patio area, I spritzed it with the garden hose that night after it had flashed over (or whatever term the concrete guys use) and covered it with poly sheeting. Helps the slab to retain moisture so it doesn't all float to the top during hot weather (hence the concrete that flakes apart in a few months time). I kept it covered for a few days, and am pleased with the results.

Be well rested the night before cuz its hard work...

[Hetmann]

I had a concrete guy come in and do it for me when building my shop which is about 20' by 22'. We opted for a terra cotta color for the floor. It only cost a few more dollars to toss a couple of bags of pigment into the truck that delivered our concrete.

Our guy had an excellent finisher who stayed for hours smoothing the top. I'm sure I could never have done as good a job. After the floor had set he came back and scored it with a saw into 2' by 2' squares. The floor looks like Mexican tile and all my stress cracks (so far) fall between the squares.

[ruf-porsche]

Originally posted by chrisp
I am relocating my garage (back 15 feet) and will need to have a 40" frost wall/foundation built and the main slab poured. As with anything else I always have to investigate the DIY option so I know what I am getting and to see if it makes sense to do myself.

It's a 20' x 20' square garage. I don't want radiant heat or any other options, just a basic garage floor.

Is this garage attached to your house or is it free standing? If it is free standing you don't need to have a foundation wall (at least per B.O.C.A. and UBC. All you need is a thicken slab apound the perimeter of the garage. Check with your local building code before you build to determine what is required. You may have to check with zoning to see the requirements for setbacks.

[Zeke]

Originally posted by avi8torny
You don't pour concrete.....you place it.

Picky, picky. I've been in construction for 35 years and I've heard very few actually say that, even though it's technically correct. There is a difference between cement and concrete as well. Cement goes into concrete, concrete builds things. If a well meaning (and good paying) customer wants to "pour cement," I'm sure as hell not gonna stand there and correct his use of words. All of the above advice is good. Especially the advice to get a good finisher. Save your money somewhere else.

[avi8torny]

Originally posted by Zeke
Picky, picky. I've been in construction for 35 years and I've heard very few actually say that, even though it's technically correct. There is a difference between cement and concrete as well. Cement goes into concrete, concrete builds things. If a well meaning (and good paying) customer wants to "pour cement," I'm sure as hell not gonna stand there and correct his use of words. All of the above advice is good. Especially the advice to get a good finisher. Save your money somewhere else.

Just trying to get everyone on the same page...it's my nature to bust balls......usually always in jest.

[RickM]

Quote: "When I poured my large sidewalk and patio area, I spritzed it with the garden hose that night after it had flashed over (or whatever term the concrete guys use) and covered it with poly sheeting. Helps the slab to retain moisture"

The longer concrete cures the stronger it becomes. Wetting it and using plastic to retain moisture prolongs the curing process.

[47silver]

you should keep the top of the concrete covered with burlap and keep it wet for a week or so as it will get very hot as it cures. a 20x20 slab needs 4 people when the truck comes. if i remember at 6 inches this should be about 8 yards of concrete. some trucks can haul 10 yards. that is about 30000#? be ready to be exhausted and retain some energy to clean the tools. it is very hard work if you have never done it before and like someone posted above once the concrete begins to set, you will begin to realize that oh, oh maybe i bit off more than i can chew. nothing worse than a poor pour.
do a small sidewalk slab about 8 x 4 or go help a friend that is doing some concrete work to get some experience.
better yet. i think the going rate is about 4 to 5 bucks a square foot to have someone do the whole thing. in my opinion that is the way to go.
you also need a very good finisher.

[poobala]

cement is like flour is to cake, have you considered metal fibres in your mix or I hear now that a poly-propelene is used, this acts like a matrix and makes the concrete much less likely to crack, I hate cracks. fly ash, silica fume and other products can be added to raise your MPa or PSI. My 2 cents.

[jbryant]

Make sure the concrete is not to stiff when it comes out. I made the mistake of not knowing the concrete should have been sent back...it was too hard to work with...Call a pro....or have someone on site that knows the deal.

[JEB]

Hire a professional. It will be worth it in the end. Both from the amount of work it takes to pour that much concrete - and the finish you will get on it.

Not that it is rocket science - but it is hard work - and there are tricks to the trade.

[chrisp]

I had a guy come this morning to quote. I think you are all right to get a pro to come do it. Like anything else, there's no option to redo it (without big money being spent) once I am half way through.

The code is supposedly four 12" footings on the corners, a 42" frost wall and 6-8" above grade. I don't know the thickness of the slab he is quoting yet but I'll make sure he doesn't short change me on the thickness.

Thanks for all of the input and help. Glad to hear you can pour or place it.

[KTL]

Chrisp,

Don't forget to use a curing compound or sealer on your concrete. Using a sealer protects the surface from salt damage and makes garage spills (like oil and paint) much easier to clean up

The brand I used, sold by Home Depot, is made by Jasco. It comes in 5 gal. containers and is very easy to apply. Get your garden pump sprayer out and fill it with the sealer. Don't worry about boogering the sprayer as the sealer is water soluble. Spray on a nice even coat until the surface has a bluish-milky haze. You can apply this stuff while the concrete is still curing (right after the concrete has been placed and finished) or you can wait a few days until you can walk on it and apply it more uniformly. Either way is fine. I apply the stuff once a year and my driveway still looks like new whitish concrete after three years. I think it's time and money well spent.

I know there's other heavier-duty products out there. But for home use, this stuff is plenty durable. Plus, being water soluble it's much easier to use and clean up when you're done. Some of the solvent-based stuff gives off really strong fumes. Additionally, when using the solvent-based sealers the cleanup of the application equipment is usually futile so the stuff ends up being garbage.

Like you said. You want to do this right the first time. I think with the great advice everybody's given so far, you'll have a good idea how to get the job done right.

[Dantilla]

It's not rocket science, but you cannot stop and think for a while if something is not going right. Once the mud leaves the chute, you are working for as long as it takes, non stop. At least one person on the site who has some experience is important.