Do-It-Yourself Concrete Floor?

[ChevetteRacer92]

Hello all,

I'm in the beginning stages of planning a shop layout to be built within the next year. Most of the work will be done by myself with the help of some experienced friends. Im not set on the size yet, possibly a 32 x 40' or something close. I'm not looking to cut corners by no means, but i am looking for ways to build a shop on a budget. Starting with the floor: concrete runs around $100 / cu yard in this area for someone to come out and pour it. My questions are...

Has anyone successfully poured their own floor? How much did it end up costing you per cubic yard? Was it worth the savings? How did you reinforce it? What kind of mix ratios did you use (sand, gravel, etc). Any pictures of the finished product?

Thanks for any advice / suggestions!

 

[fflintstone]

http://www.garagejournal.com/forum/showthread.php?t=78806&highlight=priceless

I did mine 2 months ago. Went with the fiber reinforcement in the mix. It was cheaper and I didn’t have to lay out and prop up the mesh. Rent a power screed at all costs. It made a job the normally wears out two people a bearable job for one person. With the commercial fiber and tax it came to $110 a yard

 

[garage_man]

I have done quite few pours for me and buddies, you can do it, make sure you prep it well, get in some sand and a walk behind tamper and get the sand to slope well, i sloped my house garage 1/8" per foot which should have been fine to drain, but i had a few low spots that now hold water, drives me crazy, when i go into buddies garages i notice the concrete guys are sloping the stuff for a 22' deep garage about 8-10 inches, i would definately recommend that, get the mix from your local supplier and tell them you want 3000 pound mix with fibers. i would still recommend putting in rebar in at least 4'x4' squares, you can just pull it up as you go.

as far as a power screed, i would disagree, i would get a couple sheets of rigid foam, cut them into 2x2 squares to kneel on, and do it by hand, if you use a power screed you will be there all day and night because it brings up so much water to the top, you can get a nicer finish in half the time with a mag and hand trowel.

it is a lot of work, but is fairly forgiving.

also, snap lines on exterior block to give you guides and pound wood stakes in the sand at the height of the lines in the middle in a bunch of spots, that way you can use the wood stakes as height guides, then just pound them below the surface with a hammer as you finish that area.

also, dont try to put joints in it as you go. just come back after 24 hours and use a saw and cut them in

 

[ChevetteRacer92]

Thanks for the advice guys! fflintstone, looks like you did a great job on your floor. For a slab that would be approx 32 x 40 how many expansion joints would be needed? This shop will be built to fabricate and maintain our race cars. I plan on dividing it up, one half being chassis / engine tear down, fab, paint, etc. (DIRTY SIDE) The other half will be for engine assembly, chassis assembly, and setup. (CLEAN SIDE) I want to section off a 8 x 10 engine assembly "operating" room in the back of the "clean side ". My buddies gave me the nickname of "Doc" because im extremely meticulous when im building engines. The assembly area has to be sterile and my OCD goes into overdrive... lol I go as far as not using Fast Orange or any hand cleaner with grit or sand in it.

The floor on the dirty side will be sloped, but i want to keep the floor as level as possible on the clean side for chassis setup and scaling. Im thinking about installing those long - grid type drains on the inside of the garage door and in front of the eng. assembly room on the clean side.

 

[ronstory]

Here is one of the best articles I've seen on the web for how to do "gold star" amatuer pour.

http://www.familyhandyman.com/DIY-Projects/Concrete---Brick/Concrete/form-and-pour-a-concrete-slab

YMMV,
Ron

 

[garage_man]

i would try to divide it up with joints every 10'x10' or so, or as close as you can get to that with being even.

 

[fflintstone]

If you are building it as a pole barn then you need to cut the joints inline with the upright posts. They tend to be stress points in the concrete, I went all the way around the sill plates and posts with ½” closed cell foam board (far cheaper than expansion joint material) If You are building it framed like a garage, then the 10’ grid is good. Some go 12’ x 12’ but I don’t recommend it.
You want AT LEAST 3,500 PSI mix.
Good luck.
You can see my shop progress here.

http://www.garagejournal.com/forum/showthread.php?t=80852

 

[garage_man]

good point on the joints fflinstone, if there are any outside corners in your garage you usually want to come off of those somehow to make a cut, concrete will typically crack at those locations, if it is the typical square, just divide it evenly

 

[WVBrady]

i would try to divide it up with joints every 10'x10' or so, or as close as you can get to that with being even.

If you ever plan to put in a lift, keep in mind that the requirements for the lift may require you to keep a specified distance away from any joint. This is especially important if ceiling height requirements prevent a connection between the tops of the columns. This consideration might affect the location of your joints.

 

[garage_man]

i have to assume you will need footings also for a lift. is that correct? or can you just set it on a 4" slab?

typically around posts or lifts, we cut a diamond that ties into the squared off expansion joints

 

[WVBrady]

i have to assume you will need footings also for a lift. is that correct? or can you just set it on a 4" slab?

typically around posts or lifts, we cut a diamond that ties into the squared off expansion joints

You would need to contact the specific manufacturer of the lift to be sure. I am going to install the MaxJax. They say it will work with 4 inches of concrete if it is in good shape. They also give a distance to the edge and probably to a joint; I don't remember right now. There is a long thread on it in GJ.

 

[Daniel Dudley]

If you have never done it, and are unfamiliar with screeding and finishing, I suggest you get at least one experienced helper. You have to live with concrete a long time.

Had a buddy and his know it all friend turn down my offer of free help on his garage / basement floor. Talk about screwed up.

 

[edsollen]

"as far as a power screed, i would disagree, i would get a couple sheets of rigid foam, cut them into 2x2 squares to kneel on, and do it by hand, if you use a power screed you will be there all day and night because it brings up so much water to the top, you can get a nicer finish in half the time with a mag and hand trowel."

I believe you are mistaking a power trowel for a power screed. The screed levels the concrete to the desired grade, the trowel produces the finish.

 

[Garage_man1]

you can get a power screed that will work and fit into a garage? i guess i just thought those were for the road crews.

 

[edsollen]

Our local contractor rental place has power screeds in various lengths. Basically a hand held vibrating screed.

 

[RealmSteel]

I would definitely get a copy of your local building code.
There are normally special requirements for drains inside a garage.
I'm sure there are other things in the code you will need to abide by.

 

[Falcon67]

FWIW - my friend that is a contractor and has done a ton of slabs, including his own big shop says screw the fiber, use two runs of 1/2" rebar around the perimeter and 3/8 across the slab on 18" centers. Very similar to the Family Handyman article notes.

I personally don't slope anything, my current shop was poured flat as possible. The next one will be as flat as I can make it. But that's just me.

 

[Mr.N]

Here is one of the best articles I've seen on the web for how to do "gold star" amatuer pour.

http://www.familyhandyman.com/DIY-Projects/Concrete---Brick/Concrete/form-and-pour-a-concrete-slab

YMMV,
Ron

Good read, funny I missed that before.

 

[Flange]

I am in the UK but I have in the past laid and finished many thousands of square yards of concrete in all types of situations.

I suggest you get at least one experienced helper

Good advice, use it.

Poweer screed. If you can, use it, they save a lot of work and they also help vibrate the concrete. Get a poker also and use it to get rid of the voids.

as far as a power screed, i would disagree, i would get a couple sheets of rigid foam, cut them into 2x2 squares to kneel on, and do it by hand

Each to their own I guess but i would strongly disagree. A power trowel will always give a better finish if you know what you are doing. However a hand trowel can give a good finish but it is back breaking if you do it right. You choose but ask a local experienced concrete guy for his opinion.

 

[nehog]

I did my garage. Did the site work. Cut the trees. Did the loader/backhoe work. Built the building. Wired it. I can do (almost) anything.

I contracted out the floor... The floor was so critical that I wanted it done right, and that's what I got. I don't regret any of the money I spent on it, using a subcontractor for the concrete work was the very best move possible.

 

[larry_g]

I personally don't slope anything, my current shop was poured flat as possible. The next one will be as flat as I can make it. But that's just me.

Don't confuse the difference between flat and level. I'm with you though I want my floor level and flat. I also consider my building a shop and not a parking garage. On the ocassion that I have to bring in a wet rig I will squeege the water out if necessary. Look at my build and you can see my seperate 'clean' room.

lg
no neat sig line

 

[NUTTSGT]

I did mine with the help of some family members that do construction work for a living.