So undecided about placement of control cuts

[Bottlecapdigger]

Ok, I have a poured floor of 36x44 with 3 openings of 12' 2 on the side and one off set on the end. Knee wall, infloor radiant heat, 3 inches of insulation under neath, fibre cement, rebar around outside perimeter about 16" in from the wall.
The floor has be poured since about July , it's looks great, a small crack at the walkin door way. Other wise no cracks. My question is do I NEED to saw cut it at all?
If I need to I should probably do it before winter, if so how deep should it be cut?? the floor is about 5-5-1/2 " thick, Pex at the bottom of course. I was thinking cut it into 12 squares some will be a little over 10 wide or long. I would think that the cuts should not be near the edge of the 12' door but rather come out from the centre. Another thing , I plan to get a car hoist and don't want the cuts to interfere with the placement of it. I have never come across yet on how deep the cuts should be, 10,20, 30% of the thickness? This is why I keep putting this off. What do you members suggest I do?

 

[Jo Diesel]

I would cut it into 6 sections. Down the middle and divide 2 sides into 3 pieces. Pretty sure you need like 2" deep cuts.
I did not cut mine and I have a few cracks but they do not bother me.

 

[groovyjay]

Was the fiber used steel or plastic? What was the fiber ratio used in a cubic feet?

 

[bowhuntr311]

I would think if your gonna have issues with cracking its gonna be in the winter/spring when your ground freezes/thaws. Any contraction/expansion cracking related to the concrete curing would have happened by now. With rebar and fiber a person would hope it will not crack but I'd rather cut it than have it crack.

 

[Wesley J]

This is a good reference for a lot of things slab related:

http://www.concretenetwork.com/concrete/slabs/controljoints.htm

 

[Bottlecapdigger]

This is a good reference for a lot of things slab related:

http://www.concretenetwork.com/concrete/slabs/controljoints.htm

thanks. That's a great web site, answered a few questions for me. Thanks

 

[Dick in Wisconsin]

My concrete guy did the saw cuts the morning after the pour. I have a pex, insulation, etc probably just like you did.

After the race shop was finished and I started to use it, I realized I should have dictated where the saw cuts were. I back a trailer up to one of the doors to load a race car. The driveway should have had saw cuts just outside of where the trailer tires needed to be so I had something to guide the trailer in with.

Inside I should have had the saw cuts make a rectangle where I would park the race cars so it would be very easy to get the cars located in the middle of their respective stalls.

I also would have like to have had a saw cut in the shop at the center of each opening.

Hindsight is always 20/20. Maybe you can benefit from some of mine.