Garage Concrete Slab - Rebar Schedule

[Pettrix]

One thing I'm suprised no one has commented on is the 4" thickness. I consider 4" to thin for anything except sidewalk. I'd go with 6" thick. It could be in your area 4" is the norm, you might not have to deal with the freeze thaw we do.

Out here 4" is standard. We have a shallow frost line, around 18", so freeze/thaw is not an issue out here.

 

[Pettrix]

One contractor said that #3 rebar at 3 feet on center is sufficient.

Rebar costs = $4.70 per 20' stick (#4) (21x35 pad)
So on a 3 feet on center pad = 19 sticks or $90
On a 1 foot on center pad = 56 sticks or $263

That's a $173 difference

Yet that one contractor said it will cost a "fortune" for the rebar at 1 foot on center. He wasn't talking about the labor but about the rebar. How is $260 vs $90 a "fortune" ?

I could lay rebar myself. It's not rocket science.

Some of these contractor are so full of hot air, it's unbelievable.

 

[roadhunter]

Yes about the contractors ^^^. They are like children and need a babysitter to make them do their job.

 

[Pettrix]

Yes about the contractors ^^^. They are like children and need a babysitter to make them do their job.

Plus they ALWAYS add their beliefs and bias into your design plan. Just do what I am paying you to do.

 

[farmer2009]

Just install the rebar yourself and use as much as you want. Then let them pour it.
9.25" pad with fiber, rebar is on a rough 12x12. I didn't fuss with exact measurements just got close. Besides I ended up short 10' so I just devided the remaining section into what I had left. ~15x12 grid. Just poured yesterday so will have to wait to see if it cracks.

 

[Pettrix]

Just install the rebar yourself and use as much as you want. Then let them pour it. View attachment 482938
9.25" pad with fiber, rebar is on a rough 12x12. I didn't fuss with exact measurements just got close. Besides I ended up short 10' so I just devided the remaining section into what I had left. ~15x12 grid. Just poured yesterday so will have to wait to see if it cracks.

What made you go the 12x12 route? Is that #4 or #3 rebar?

I am going to try this rebar chair instead of using blocks and wire to tie the rebar.

 

[farmer2009]

What made you go the 12x12 route? Is that #4 or #3 rebar?

I am going to try this rebar chair instead of using blocks and wire to tie the rebar.

View attachment 483029

Number 4.

That pad will be home to a feed bin. 7 tons sitting on 4 or 6 legs. I wanted strength. Also added fiber into the 4,000psi mix.

Couldn't find chairs locally to get me close to center of a 9" pour. So drove 24" rebar to 4 1/2-5" then tied to it. Didn't take long at all. Couple hours by myself and that included cutting the rebar.

 

[Streetcar]

Number 4.

That pad will be home to a feed bin. 7 tons sitting on 4 or 6 legs. I wanted strength. Also added fiber into the 4,000psi mix.

Couldn't find chairs locally to get me close to center of a 9" pour. So drove 24" rebar to 4 1/2-5" then tied to it. Didn't take long at all. Couple hours by myself and that included cutting the rebar.

For strength the rebar should be near the bottom of the slab. This is the tensile stress region of the slab
For crack control the closer the rebar spacing the better, concrete will continue to crack until the crack hits the rebar

 

[Pettrix]

For strength the rebar should be near the bottom of the slab. This is the tensile stress region of the slab
For crack control the closer the rebar spacing the better, concrete will continue to crack until the crack hits the rebar

The Hercules rebar chair keeps the rebar exactly 1.5" inches from the ground. They are made for 4" slabs. This keeps the rebar down low in the slab, where it needs to be.

Another thing a tighter rebar schedule does is that if the soil/AB underneath moves or sinks, the concrete will span this void without snapping/cracking because the rebar will hold it in tension. Without the rebar, the concrete would snap/crack in this void spot.