jwortley

All,

Some time ago I posted the fact that I needed a new garage floor (much to my dismay). I bit the bullet and shelled about 5k to break and replace my floor. It's been down a few days now and is curing. Now, I have a question for the group..... The contractor wants to cut the new floor into quarters. He says the choice is mine but he would recommend it to reduce pressure and control any cracking. My preference is to not do it and I am skeptical that he is just trying to avoid issues. I paid a premium for this contractor. Has anyone had any experience with this and could second the recomendation or offer an opinion?

DHI

What strength concrete was used?

You should wet cure that floor in order to minimize cracking. Cure wet for up to 7 days to minimize shrinkage.

Saw cutting will control cracking from shrinkage.

Is there any Rebar or wire mesh in the slab?

pontifex4

I'm tuning in for this, too -- I have a fresh floor for my new garage that's been under snow all winter but I don't have any cuts in mine, yet (5" deep of 3600PSI, mesh in the middle and rebar around the edges).

DHI

I forgot to ask how big the floor plate measures and do you have a drain or catch bassin within the pour?

jwortley

DHI/Ponitfex4 - wow, lots a quick feedback - thx! Here are some additional details. Its a standard 2 car garage, 5" thick (actually I think it might be closer to 6"), 6 gage wire mess and rebar on the edges into the house foundation. The concrete quoted was 32c2, 6% Air/340kg concrete 4641 PSI. There was no centre drain installed

The old floor appeared thick with mess as well but it was really a prep issue as it sank all around but far more so in the center.

JDSStudios

My house was 2 years old, garage floor was not cut and it cracked.

DHI

The fact that you do not have a drain somewhere in the middle is a good thing. Intrusions and protrusions in a concrete pour is where all cracks usually emanate.

For the bad.... if the wiremesh has been tied into the perimeter/foundation, this will cause the concrete to pull as it shrinks slightly in its curing process. This pulling will increase chances of cracking. If it wasnt tied in, you can imagine how the slab can "shrivel" onto itself towards the middle without restriction and so with less chance of cracking.

More good.... the slab is relatively square in configuration reducing chances of cracking. rectangular and slender pours will shrink more in one direction.

Tough call.

Keep it wet !!

ZR8ED

My garage has the cuts, but the back half of the garage is one piece, and front half (at the door) is two pieces. (entire floor is three pieces) No drain. Looks original to the house circa 1970. Sorry but I just don't know enough about concrete to advise if you should or shouldn't. Will the contractor guarantee his work with/without the cuts? That would be my deciding factor. I would hope he know's best as he is the one that did the work.

Goodluck!

petee_c

Just a question as to how deep do the cuts go? I have a 3 bay garage, and there is a cut between each bay, and one across all 3 bays (in the middle) - so it's divided into 6 relatively even pieces.

Looking at putting a MaxJak in the middle bay.

P

JimV8

Cutting is good followed by a fill with something pliable like urethane.

Turbodan

I have a double car garage with some cracks and want to put in a hoist so I may have to do the same; curious what type of cost is involved?

jwortley

The mesh was not tied in and the rebar was put in independently (about 3 ft long). My contractor mentioned nothing about keeping it wet which has me curious.

jwortley

My contractor indicated the cuts would go about 1.5" deep.

jwortley

TurboDan,

Happy to share costs. I went and got 3 quotes and tried my best to get them to be comparable. I found each of the contractors (perhaps deliberately) positioned themselves differently. Initial quotes were approx $4,200, $4,600 and $5,800. Of course the highest price contract came across as the most competent. In the end all of the guarantees were the same 1 yr and given about 40% of the cost was removal I wanted to get the best value not necessarily the cheapest. I called up the highest price guy and indicated he was way out and I wanted to know why (just in case they were doing something the others weren't). In the end the initial quoter went nuts with extra rebar across the slab which drive the price way up. In the end he ended up coming in at about 5K.

Bob D..

A slab about 20' square will almost certainly crack as the concrete sets.
The saw cut controls where it will crack, and the saw cuts can easily be filled with a variety of compounds, and finished.
I'd do the saw cuts.
It is a good idea to keep the surface moist for a few days - concrete doesn't dry, it cues, and the curing action is impeded if it gets dry. Likely it won't be a big effect but there is a risk that the surface will not be as durable as it would otherwise.
Just mist it with a hose.