How to Level a Concrete Floor in old Barn

[bobm6996]

We have an old small (20 x 26) barn on the place we bought a couple years ago. Structurally very solid, so last year put a new roof on and tore off the old metal siding and replaced with OSB then Tyvek. Plan to finish when the weather warms up. This is going to be workshop (primarily woodworking), but the concrete floor is not very level. Years ago they probably poured it by hand or in multiple pours whenever they could get the concrete for free. It is thick, but has some cracking and just not level or smooth finish. Afraid it will not be good for setting saws etc. on because will be to challenging to level.

Any ideas on the most economical way to level this floor?

 

[mjcountrybumpkin]

Have a 2" cap poured on top of existing floor. I worked for a company that specialized in concrete leveling and repair and that was always our cheapest option if you could stand to lose 2". Otherwise the self leveling bag mixes became an alternative , rather expensive though.

The 2" cap should be poured from a 4000 psi grout mix for a good quality floor. With a max 3/8 ths inch aggregate.

 

[Looking4new]

IF you have exposed footings (like I had in my pony barn) then just use a laser level and add about 3" to the floor after you clean it real good and wet it down before you pour. I used the quick crete bagged concrete mix you buy in the hardware store. Mixed it in a power mixer and laid it. Troweled it off and voila I have a new floor.

 

[mjcountrybumpkin]

Just figured it up and with the going rate here you would be at: $450 for concrete and at $0.55 a square foot to finish $286 for labor. I have no idea what prices are where you are at but that should give you a rough guess at what it would cost.

 

[bobm6996]

Thanks for the quick responses. Thanks mj for figuring an estimated cost, I can handle that amount. Will get my son, 3 SILs, beer and food and we can handle the labor part. I have the room in height to add 2-3" and still able to pull the tractor in w/o having to drop ROPS. Did not realize you could pour concrete on top of old. Do I have to add rebar or wire or anything before I pour?

 

[Looking4new]

It would make the new floor stronger if you did. But it is not a must. Just clean the floor good and any oily/grease spots clean with TSP and dampen it down before you pour. On the size you state, I would do it in 5' to 8' sections to make it easier to trowel.
After you pour and float it to get rid of any air pockets dampen it again and run your float (steel trowel) over it for a smooth finish or power trowel it. I did mine by hand. Mine isn't the smoothest in the world, but it was for a hen house so I didn't care.

 

[Stimw]

X-2 on the cleaning, it should be VERY clean and you need to look into Bonding Agents.
They help concrete stick to concrete. They are thin and watery and easy to apply.

 

[jrpat]

I poured a floor in my shop a few years ago (not on top of an old one though), and used 3/8 inch rebar instead of the wire mesh. I had the concrete delivered by truck and had them add fiberglass to the mix instead of using the wire mesh. I spaced the rebar about every 3 feet, criss-crossing it. It was a four inch pour. I poured it in the spring of 2009 and have yet to have a crack in the floor. I personally am sold on the use of fiberglass in the concrete mix. You have to put up with a little bit of fuzz on the top for a while until you wear it off, but I am very happy with it. JP

 

[Fifelaker]

I would look into fibermesh mixed in with the slump. It will keep cracks from growing. Last I bought it was an extra $7 per yard.

 

[jel1988]

Do you really want a level floor? When I build garages we slope the floor out the overhead door.We would put 2" of slope on a 24' garage floor so water would run out the door instead of puddling. If you do want a dead level floor place a board or tentest expansion joint materials around the perimeter, lay in you welded wire mesh. When you order your concrete ask for 3/8 pea stone aggregate and superplastizer. The superplastizer makes the concrete free flowing similar to pancake batter. This will only add $10-15 a yard to the price of the concrete. Get the ready mix truck to deliver as quickly as possible roughly spread it out and take a concrete tamp and tamp your way out the door vibrating the mix like jello. It will set up fairly quick, trowel it if you want, we use this mix in basements we don't trowel it at all!