tying re-bar

[Randyj]

I'm in the process of tying rebar for a slab floor and never even gave much thought to the spacing of the tie wire. I do know that ideally you would tie it together every where it crosses. The re-bar is spaced 12" apart on a 32 x 32 slab. I'm thinking that all the way around the perimeter, everywhere it is overlapped together and then every 4 or 5 feet should be adequate and that the idea is to keep it from shifting when concrete is poured... does anyone know of code or rule of thumb for where to tie rebar? This will be a 4" slab for a hydronic radiant heated floor

[Spaceman Spiff]

For strength you need to tie rebar everywhere it crosses another bar, or every 6" on an overlap. As far as where to tie your tube, every 2' should be fine. All you need for the tube is enough to keep it from shifting when the concrete guys walk all over it.

[Randyj]

For some reason that just doesn't sound right... that would be tying it in right at 1,000 places. Sounds like extreme overkill to me. That little piece of wire isn't going to hold anything once concrete is in place.

[hj]

Overkill is rebar spaced 12" apart in a garage floor. Is this a garage where you will be rebuilding army tanks? Even wire mesh is an upgrade for 99% of garages.

[Lakee911]

Rebar is cheap. More power to him.

[Randyj]

Rebar is cheap. More power to him.

Fortunately I was given about 3,000 ft of rebar for this project. With the concrete thickness I'm using, and it sitting on top of styrofoam I think it will do just fine. Major thing for me is to minimize cracking ...and at least for a time part of the floor will be used as a garage. My big boat weighs about 8,000 lbs. don't think I"ll be trying to put it on the concrete tho'... but definitely will be rebuilding motors and working on all kinds of things in there. Definitely would like to park my work van there too. Actually, I don't know how much that big boat weights but it takes two trucks to pull it out of the water and it's heavy as heck.

[Lakee911]

and it's much easier to put all that rebar in before it's poured than after it's poured!

[dgold]

The only reason to tie the rebar is to keep the pieces from moving relative to each other - prior to the concrete setting. I've always seen it tied wherever two pieces cross as previously noted. If it would be easier, you might consider buying 1,000 plastic cable ties. very strong, and may be much faster for someone who doesn't tie steel wire for a living.

[Randyj]

Anyone know of any kind of chart or specs that show load bearing capacity of concrete per inch of thickness or something like that. I'd like to know more about how thick concrete should be for various applications. I do know that there are different strengths of concrete, psi or whatever they call it. Most of the concrete people I know are not engineers and have little knowledge of it other than how to get it out of the truck and make it look pretty before they leave the job. I had one to only give me the guarantee that it will get hard and crack....

[PEW]

If you want it to cure to full strength, keep it covered with plastic and wet for at least 21 to 28 days after pouring. The difference in the strength of the concrete will be dramatic.

[Randyj]

This has been a drawn out, postponed project for quite a while. Kind of paying as I go to avoid financing. I must have done something right... 256 ft of continuous foundation and not a crack in it anywhere after 2 years.

[hj]

What you probably did right was not overdig the trench so you would have had to put some fill back into it. Your garage floor is going to be to Corps of Engineer's specifications by the time you get done with it.

[Randyj]

Definitely glad to hear all the opinions. The man who gave me the re-bar told me what to do, how he suggested spacing and all about putting piers in the filled areas. This is what I refer to as a floating slab, totally insulated from the footing, sitting on 2" styrofoam which actually does or will give good support for the slab. At the moment I'm simply trying to get all the styrofoam under the concrete to save it from the elements. It has been sitting in the sun/weather for about 4 years and is beginning to deteriorate. Unless I come up with some money or financing this may be all I get built on the house for quite some time. With fall approaching there will be very little work for me and this project is going to break me... just hope I can make it through the winter... may have to put in my application at Walmart just to be able to eat for the winter once I pay for two truck loads of concrete. Wish like heck I was joking about that one too!