Hello Everyone,
I have a footing that is about 3′ deep that need 4 pieces of #4 rebar ran in it. I would like to drive rebar in the ground instead of using chairs to hold it up. How do you conform to code when doing this since code will not allow steel to touch earth? Do I put some type of insulater around the rebar drove in the ground or is there a product made for this?
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Replies
A footer that deep must be for a commercial building, right?
Seems to me that any struycture needing this kind of sized footer should have some very detailed specs to begin with.
but for the specific Q - epoxy coated might satisfy the BI but I would be asking him that Q first to save a lot of grief.
BTW - just curious - how wide and do you mean opnly three rebars or three levels of laddered rebar?
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Yes its for a commercial building and I have Engineering specs on the foundation, but it does not show how to support the bars. I was thinking about putting cheap pipe insulation around the rebar that is drove in the ground then tying my steel to it.
I wouldn't consider that.The reason for no ground contact is to keep it from rusting. The material you mention is not waterproof, and it would store oxygen close to the steel, increasing the odds of rusting faster. As that rust gets started, it will eventually travel to the main bars.If chairing is not in the cards, think about suspending with wire from above
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I was told by my building inspector that I would have to put a sleeve around the rebar that is drove in the ground. Does anybody know what type of sleeve one would use.
Go to a farm supply outfit and get some fiberglass electric fence posts. Drive them into the ground instead of rebar.
If ignorance is bliss why aren't more people
happy?
I have been trying to think of a item to solve my problem and you just figured it out for me.
Thank you
I actually used to be an inspector on Commercial buildings and like Piffin said it is all to keep the rust from following the the steel up into the footer expanding on the rebar and causing the concrete to spall and crack. If your inspector wants a sleeve on the rebar you drive in the ground I'm guessing any PVC pipe would do. I can't say I've ever seen that done however on the jobs I inspected.What might work better for you and I've seen it done on numerous occasions is build the rebar mat and suspend it from the tops of the forms with some tie wire.
Edited 2/28/2006 1:30 pm ET by Ribs
If you inspector wants a sleeve on the rebar you drive in the ground . Even if he wants a sleeve on it, it would not be legal. No rebar can touch the ground no matter what. tie a bottom bar and set it on bricks or chairs or hang the rebar from top of form.. 2+3=7
Edited 2/28/2006 2:16 pm by brownbagg
What if he got a gallon of that liquid rubber tool coating stuff? He could dip ends in and let them dry. The steel would not be "in contact" iof he didn't drive any deeper than that 6-8", right?Or he could get epoxy coated...
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I think the fiberglass fence post idea would work great for my application as they are 3/8x48" and cost $.99. If I was using a chair it would have to be 12" tall and they are not sold in that height in my area. There are no form board to hang the rebar from as the soil is the form.
run a 2x across the soil. 2+3=7
suspend would be my choice typicaly
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Sounds like a King Kong Condom to me
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Don't drive the rebar into the soil. First, lay in a pair of #4 bars at the bottom of the footing. 3" from the outside on each side. Run them continuous and support them on dobie blocks. Then, order hooks from a rebar supplier. They bend stuff all the time and will save you the trouble. Tie those in on top of your first pair of bars, and then tie another pair of continuous bars above the first. The hooks will probably extend up into your stemwall and support another pair of bars (or more. You can also use tie wire to hang or otherwise support rebar inside forms.
Why not use concrete bricks, this is done all the time when chairs are not practical.
mike
like david said the bottom bars are the way to go, in fact i would be highly suspect if they are not required for an engineered footing for a commercial building, even if it isn't in an earthquake zone.
then again like david says you build on top of the bottom bars, the slang word dobie comes from the word adobe meaning brick or block of concrete or any kind of rubble or rock if it is flat enough.
word adobe meaning brick. FYI clay base bricks cannot be used as concrete chairs, only concrete base bricks.. 2+3=7
Brownbagg, DanH and David are all giving you good advice.
The key consideration here that Brownbagg addresses indirectly but otherwise has not been identified clearly for you is the isolation of the rebar mat from earth contact for the reason of electrical continuity.
Strange but true.
This is not about water following the rebar. Concrete is permeable.
The reason why you cannot drive rebar into the earth and tie your mat to it is that you may get galvanic corrosion, particularly if you have chemically aggressive soils. This will be greatly accelerated if you use the rebar as your ground.
I got dinged on this by a particularly astute and intelligent inspector who took the time to explain it to me. He allowed me to use the installation I had completed if I insulated all of the vertical supports that I had driven into the ground from the rest of the mat. He said I could just cut the tie wire, tape all of the supports up real good with duct tape, re-tie everything, and he'd let me go, just don't do it again.
He explained the concept of electrical isolation of the rebar mat from the earth, so I would not make that mistake again.
Chairs are your best bet, you could probably order them from Whitecap. Dobies are OK, but as Brownbagg pointed out, no clay-based materials are permissible. Hanging the rebar is OK, too.
Power always thinks it has a great soul and vast views beyond the
comprehension of the weak; and that it is doing God's service when it is
violating all his laws. -John Adams, 2nd US president (1735-1826)
This is an interesting subject as it may also relate to the "ufer" ground that the new electrical code is pushing.
They want you to have 20' of rebar in the footings (or copper wire) and use that as one of your main grounding connections. When you hook this to the other ground ( water pipe ), electrode, whatever..you have set up a perfect path from the soil to the re-bar.
Where do you think the average contractor will be tempted to connect the copper grounding wire going up to the service panel??
I would bet there will be a lot of these connected to the re-bar system!
I think you are right.Power always thinks it has a great soul and vast views beyond the
comprehension of the weak; and that it is doing God's service when it is
violating all his laws. -John Adams, 2nd US president (1735-1826)
I would bet there will be a lot of these connected to the re-bar system!
We use the uffer as part of the re-bar system and simply angle it up as a verticle footer-to-wall tie. The upper end is angled out of the foundation for an ICF wall or simply embedded in a foam block to the outside of the form if a traditional concrete wall and pried out after the forms are stripped.
Maybe, technically, we're not embedding the entire 20' length in the footer and that's not meeting code? That just occured to me. Hmm.
Just make yourself a batch of Dados......aka concrete bricks
We did that on a similar 3 foot commercial footer once. just put a piece of plastic of two sheets of plywood, make 3 inch forms around it....pour mix without rocks and slice it up like a sheet cake..... problem solved