I’m pouring a slab soon. I’d intended to put a couple #4 rebars in the bottom of the footing, but my finisher dropped by to check my forming progress and mentioned orienting the rebar vertically.
I’ve snooped the web and find both details, but no explanation for why either might be better or worse.
I can see the vertical placement to resist frost heave…good for Montana? But i can see the horizontal placement if one figures the weight of the building is keeping the bottom layer of concrete in tension.
Please help me think through this. I’m tying wire today…
Misc.: Footers are 16″ deep and 16″ wide. Slab is 4″, with rebar and fibermesh. Footings are on undisturbed clay and sand, and the slab area has been whacker-packed. I’m not sure if any of that is pertinent, but just in case…
Replies
Too many years since my structures classes.
Consider this a friendly bump
I just called the concrete company and talked to their "guy". He couldn't decide either.
Hey, BB, give a gal a piece of your mind??
2 #4 are all you need, just lay two in the footer on bricks(grey)
Thanks. Done.
Rebar in footer: two bars will do, but it would be nice if you can add a short piece between them at the dobies (gray bricks). This way you can use just 1/2 a brick per "chair", and the chair will keep the rebars in place a lot better. Just keep the chairs short enough that they won't stick into the sides of the trench, 16" wide trench, you can get by with ones about12" long. How's that?
Our slabs are engineered per building safety. We have an "L", 12" x 48" with the 12" leg pointing down into the footing (footings are 18" deep and poured at the same time as the slab). The "L's" are placed 4' oc. . We are not required to use rebar in the slab but we do any way since we can tie it to the "L" as these have a nasty habit of popping out of the slab at an inopportune moment. The footings have two number 5's top and bottom run continuous around the perimeter. We also use a little chunk of bar with a dobie or two under it as the previous poster mentioned. Don't skimp on the bar. Cheap insurance IMO.
I'm using #4 bar throughout, what was recommended to me. I'm also putting rebar in the slab area 4' o.c., with 12" legs turned down into the footing. I'll make sure my footing rebars are spaced appropriately. Looks like i'm making do with just the two in the footer, though. Argh...it's an hour each way to get more rebar. If i don't get my pour tomorrow as planned, then i get my pour on Wednesday, and i'll have time to do it.
You're going to laugh when you see my "chairs". Junkhound would be proud, though: i'm cutting up some old dishwasher racks.
Splintie,
Don't forget your ufer.
Jim x 3
I thought of the Ufer ground, but my trenches have gravel in the bottom and the slab in underlaid with plastic, so i'm thinking conventional ground is the way to go since the concrete won't actually be making contact with wet ground. The subpanel will also have a ground wire back to the main panel. I'm always delighted to have my notions overturned if my thinking left something out...?
Splintie,
Gravel is no problem for the ufer. My trenches wouldn't have plastic below the gravel, but even if yours do you will have good contact between the concrete footing exterior side and the soil (unless I misunderstand and your entire slab is electrically insulated from the ground).
I assume you mean driven ground rod or ground ring when you say "conventional ground". A ufer is better. Where I am in California, for new construction, a ufer is REQUIRED. Without one, sometimes 1 or 2 driven rods pass muster, and sometimes the inspector has required a new trench just outboard of the footing, 20' long, concrete filled, with the ufer.
Jim x 3
Yes, i lined the whole thing with plastic. We're mostly dry, dry, dry in MT, but a good rain on wet snow can make a slab wick a lot of moisture.I was thinking i'd get better contact with wet[ter] soil by smacking a ground rod deep into the earth. All the footing trenches that i dug were bone dry this time of year.
most houses dont weight enough to need rebar in a footing, but code requireds two # 4
The footing is a big water magnet... much better at grounding than a driven rod, or even two. Here, we can clamp to a 20' piece of rebar.And I wouldn't lose any sleep over the rebar placement for a one story shop. 10" ladder wire makes fine, inexpensive chairs.How are you going to insulate your slab edges?http://www.tvwsolar.com
We'll have a kid
Or maybe we'll rent one
He's got to be straight
We don't want a bent one
He'll drink his baby brew
From a big brass cup
Someday he may be president
If things loosen up
A footing might normally be a big water magnet, but i'm trying to prevent that, LOL! One side of the foundation will be bermed against a small rise, which is where i'll drive a rod. I guess i can actually do both, if my reading is correct.I'm not planning on heating the shop - i have my 'real' woodworking shop in the walk-out basement here, where all the stationary tools are...and the btus! I had to rein in my Garage-Mahal tendencies and resisted an urge to throw foamboard under the $$lab, too. This new bldg will mostly serve for storing all my hardwoods, lawn tractors, house parts, gardening stuff, and will let me mechanic indoors. Right now i have one of those god-awful plastic tents covering $10K worth of hardwoods; it's a race to see if that monstrosity disintegrates before i get this shop closed in.
On good soil probably adequate, but you are used to sand some clay and no frost heaving. Her man in the mountains knows his locale and that orientation vertically instead of side by side will give her far more strength against frost heaves.
Compression vvs tension
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Found you aphoto of the general ideas above. The L rebent and the vertical orientation.This is for a much larger structure, but worth the lookhttp://www.downing-planetarium.org/construction/May24/rebar.jpg
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Are those L's just stuck in the ground?
They sure do look like it, don't they?I chair the flat grid with the L's turned down off it without touching down. I like your chairing idea. One more thing that will not be safe from me when I go to the dump...
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Turned-down slab edge, correct?
4 #4 T&B (top and bottom)
Bend a #3 stirrup around those every 48"
Leave a leg extended on the stirrup so you won't need a separet bent bar to tie into the the rebar in the "field" of the slab.
Good grief, man! How big are the gophers in Texas?!?!LOL...I'm building a shop, not a place to store my D9.
Think of the two bars laid parallel and one above the other say 8-12' like the top and bottom chords in a floor truss, or an i-beam.
It resists vertical stresses better that way. Take a TJI laid on it's side and watch it flop and bounce, vs apply verticcal prssure to it when it is vertical.
Your foundation perimeter will be subject to vertical stresses of various kinds but almost not lateral stress that the crete couldn't handle without steel
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I've been fretting about this like mad. I thought of the I-joist analog too, but if that's true of concrete and steel as well as wood (and i'm not sure it is), then the same principle would hold true in the sunny south, that a concrete footer would be a better "beam" with iron low-and-high, instead of side by side.The only way i could see an advantage to a vertical orientation was in case of frost heave. For that i put a few inches of gravel under the footers, and will install a perimeter drain to daylight. Drat, i have it all tied together now, just came indoors to climb into the refrigerator for a spell. I'm going to cut my ersatz chairs and think some more.Thinking some more: If we pour tomorrow morning, it flies like it is. If we pour on Wednesday, i'll have time to lay a whole 'nuther round of rebar inm above the two rounds below. Edited 8/21/2009 4:41 pm by splintergroupie
Edited 8/21/2009 4:45 pm by splintergroupie
Don't fret over it kiddo.
I do plenty of monopours with just the side by side pairs or even sometimes a single tied with the central grid.it is when I am confident in the soils and drainage.My point with BB was that while his is OK, the verticle is BETTER.Reason you generally see side by side is that it's much easier and most footers are for taller re-inforced walls above that will have rebar also, so the vertical orientation in a footer for a wall when it is buried three to eight feet deep is of no benefit.But when doing a FPSF, every little bit helps.So my assumption is that since a local guy whop does this all the time recommended it, he may have likely seen a reason for it.Maybe not. He might be just like a lot of guys who just do something cause they've always done it... and granpappy before us...with no understanding why at all. So with a 12-16" depth of perimeter monopour on solid base with good drainage...The only thing you lack to make this a perfect FPSF is foam insulation perimeter shield.
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My finisher guy is a working fool, and his finishes are top notch, but i don't think he's big on theory. As you said, i think he does what he's observed others do, without really studying it. That said, i went out today and got another round of rebar for the footings just before the batch plant closed. I learned today at the concrete plant where i buy rebar that they automatically use air entrainment. I asked about having it added and they laughed, said i'd have to request they leave it OUT, for this climate. The dishwasher racks, cut apart with bolt cutters, are making splendid chairs! I've cut up three racks, one to go; i'll take pictures. I used the racks for drying my wood products like game boards and lazy susans, but they needed recycling, one way or another. They also work as mini-pallets. I could get all i wanted from appliance repair shops, from irreparable DWs. Another tip: oven racks make snazzy reinforcement mats for steps.
There IS a rebar made for those "verticals" ( used them, cussed them, buried them in 'crete) that have one "leg" horiz. ,then a short vertical, and then a long horizontal leg. Short horizontal is tied to the footer steel ( and tie it to the underside of the footer rebars), and the long "leg" goes into the slab. Some footers I've worked on ( actually in, that is) had 5 rebars, two at the bottom of the footer, with three more above them. We also tied "L" shaped corner pieces to connect the rebars in the footers corners. I was a commercial "rod-buster for over six years, and have a few scars to prove it.
<<and have a few scars to prove it.>>Yup. I'm supposed to donate blood on Monday, if there's any left. Between steel, ties, and the dishwasher racks...While i have you here...i read about those wire tie spinners. Do they work well? I tried lineman pliers, vise-grips, and a screwdriver shaft through the loops, settled on the vise-grips for the best control. I broke several ties, though; maybe 10% had to be redone. Do the spinners help with that?
I've used those spinners so much I had a caluse(sp) a blister and another caluse on top of that. These take a special tie called "bag ties". They have a "loop" at each end. Just wrap around the bars and twist away! I got to the point that I was as fast as the guys with the pliers and wire reels! Note: My shoulders still have a "groove" worn in them from packing those bars around. One "little scar" was where a #4 upright tried to go through my hand. About 1-1/2" long hole right by the thumb. Any other questions on rebar, feel free to ask.
You've got grooves, i've got burns. It was 97º today and i was working on black plastic. Oy! Yes, i have "bag ties". I just learned the name of those when i bought them. The savvy gal at the counter asked me how many i wanted. I said, "Oh, a hundred or so." She said, "About a foot, then." I said, "That seems a little long to tie two bars together." She chuckled and said a foot of the strip of bag ties works out to about a hundred. She had a guy go out to a building and pull the hardware while i was cutting and bending bar using their machine. He doubled the amount i'd paid for, which is GREAT bec i hadn't figured on tieing the bars to the chairs to keep them spread. Happily, i don't have any upright bars to work around, just J-bolts to get in the right spots. Which reminds me...i need to daub a bit of paint on the forms where those go so i don't have to make it up during the pour.
On some days, I'd go through a whole bag of those ties, oh me aching back! As for footers, I'd be chasing the backhoe down the trench, laying and tieing bar as I went along "crumbing". I alsp set short "pins" every 4-6', these were to set the grade of the top of the footer(TOF on the plans) and then painted a line on the bank to able to find those @#@# pins while pouring the footer. Biggest "footer" I worked on was for three silos INSIDE a building. It had a "mat" of #8 bars on the bottom, 24" tall standees holding up a second mat of the same bars. Around the edges were "U" shaped bars that connected the two mats. 25' wide by 100' long footer! Three people= 8 hours. Each place a bar crossed was "saddle tied" with four "bag-ties", and the other shaped bars had double wires at two locations along the bars. Was kind of a bear to pour and finish, but got it done nice and smooth AND level. Some jobs barely took a pick-up truck load of bars, one took 20 flat-bed SEMIS to bring in enough (barely) rebar.
I was watching some video of rebar tied together, then MOVED! I was thinking of how many ties i broke today and just shuddered. I also saw some cool looking plastic clips that seemed really fast. No doubt $$$ too. They were put on with hand-held installer, kinda like a figure 8 with the loops at 90º,open at top and bottom. #8 rebar...i never knew it came that large. Do you tie it with #3????? <G>
I'm not sure what those spinners look like that they are talking about but a pigtail is all I've ever used. probably cost $3 at Lowes. For a one shot deal like you are doing, pliers would be though... especially considering you are probably nearly done...
Yep, that's the critter. I'm all done with the ties in this pour, but it sure looks like a handy gadget to get to know. Needle-nose vise grips ended up being my tool of choice, but it was slow going.
I'm all done with the ties in this pour, but it sure looks like a handy gadget to get to know.
Not hard to learn.. ;-) The don't come with instructions though... hehehe
Nope, just wire-ties. I, ve worked with rebar from #3 up to # 18 size. A word about rebar size ( for the non-rod-busters out there) the # is in 1/8" , so a #4 rebar is about 1/2" diameter bar. So a #18 is about....2-1/4"!. Try lugging 20' sticks of that around all day!
I can't recall if i actually saw it on the Interwebs or merely imagined it, but somewherehow i got the idea that plastic zip ties could be used like wire ties. Do you know about this, O Wire Tie Guru? It seems brilliant, just in case i invented the idea. <G>
Plastic wire ties belong anywhere but in concrete. The heat inside concrete while it cures will MELT those plastic ties enough to make them useless in the slab. You want the rebar to stay together, even after it has cured. This is where it counts for strength.
>> The heat inside concrete while it cures will MELT those plastic ties enough to make them useless in the slab. <<
You really think concrete gets hot enough during the hydration process to melt plastic? Don't know, just asking.... If so, seems like it would melt ICFs also. What about the poly below the concrete? Plastic concrete chairs? My experience is that concrete gets warm during the hydration process - not really hot. Course, I've never been inside concrete when it was curing. It would be interesting to do an experiment with a thermometer....
"You want the rebar to stay together, even after it has cured. This is where it counts for strength."You're kidding, right?
nope
If that's the case, why isn't rebar tie wire specced in engineered drawings? If it's important for structure they should tell you the gauge, material, etc. All I have ever seen is the lap length. No mention of ties. Explain please.
Tie wire becomes a part OF the rebar. On the "steel prints" we are told how much wire to use, HOW it is supposed to be tied ( double wire,saddle tied, double saddle tied, etc) and some even tell you what wire to use. We were also taught NOT to weld rebars together, as this also weakens the rebar. Same with using a torch to bend a reabr into shape, the rebar will BREAK at that point. Another point about plastic wire ties, they will wear away and break in the concrete. A wire tie usually leaves wire ends sticking out into the concrete, concrete will adhere to these, concrete will not "stick" to the plastic wire ties. Of course, if one wants to do things on the cheap, well, that's up to them.
OK, you guys made me put on my librarian's hat. It seems i must have absorbed the idea from FHB magazine itself:
http://ths.gardenweb.com/forums/load/remodel/msg0514293325421.html
From that thread:
"Fine Homebuilding article mentioned, Issue 170, April/May 2005, page 83. Quote: "Plastic zip ties and internal webbing hold vertical and horozontal rebar in place." It's describing how to use interlocking foam forms for a foundation pour."
Here are some pics of the job the first day, ready to pour and some close-ups of my dishwasher-rack "chairs". The rebar got tied to the chairs, too, after those pics were taken. I chucked up an L-shaped hook in my cordless drill and went to town on the chair-ties. MAN, THAT WAS FAST! And no carpal tunnel. And the ties looked very crisp compared to mucking about with vise-grips. Thanks awfully for the tip, Marson. No pigtails for this gal!
How far apart are those kickers on your forms? I just had my first turn down slab poured. GC wanted kickers every 30"... every 15" would have been better. We didn't have enough staubs at the bottom of the form, either, and ended up pushing dirt against it with a bobcat... other than that, it went fine<G>http://www.tvwsolar.com
We'll have a kid
Or maybe we'll rent one
He's got to be straight
We don't want a bent one
He'll drink his baby brew
From a big brass cup
Someday he may be president
If things loosen up
I can step on the forms and they don't budge - i have string lines on them since i began digging the footings, to be sure they stayed put - but i'll take your advice and put more kickers in, definitely. Pour is scheduled for Wednesday and the last thing i want is complications...i got my J-bolts with locations marked on the forms, my trowels, my diamond blade at the ready... I read about spraying the surface with sugar water to retard drying, but i have loads of lumbers wraps, which is what i used under the reinforcement for waterproofing. They're loads sturdier than 6 mill, and it keeps one more thing out of the waste stream, so i guess i'll tarp and water it. I wanted to try the sugar water thing, but it seems like it'd be a sticky mess to wash off afterward. No, i can't bear the thought of buying anything ready-made. <G>
DO NOT USE SUGAR WATER!! (That is unless you want to have an exposed aggregate slab.)
That technique is used to retard the top surface so it can be washed off and expose the aggregate. Just cover it with any cover that will retard the moisture loss out the top of the slab. Keep the cover misted to prevent over heating of the top of the crete.
They can't get your Goat if you don't tell them where it is hidden.
Thanks for that clarification about the sugar water being for stripping the top layer of cement; definitely not what i'm aiming for. One of those instances where a little knowledge is dangerous, for sure!Dominic (finisher) prefers just to let the sprinklers take care of things. I suggested that lumber wrap with the white side out would counteract the plastic underneath not allowing evaporation, but he wasn't convinced it would make a better cure than just keeping it wet with a sprinkler. Would you care to vote on that?
It's amazing how much 16" of concrete weighs, and how hard it is to move it when it gets where it ain't supposed to be<G>If you can pour early, you can probably strip the forms in the afternoon... if you can have a bobcat with a toothed bucket there, makes that part go real easy... rip and strip.http://www.tvwsolar.com
We'll have a kid
Or maybe we'll rent one
He's got to be straight
We don't want a bent one
He'll drink his baby brew
From a big brass cup
Someday he may be president
If things loosen up
My finisher just stopped in and was most complimentary about my prep: "It's a shame to pour concrete on that!" I beamed. Then he said i should consider adding more kickers, lol.We're pouring bright 'n' early Wednesday morning. I'm ordering a yard extra and setting some sonotube footings for the shed roofs on either side to use up leftovers. More insurance: i'm also hiring his brother for the dump/screed part. I feel i'm wimping out a bit, but a whirlie truck costs $60/hour and screeding isn't my forté. Best part of all, though, is his power trowel!!!!I'm learning new terminology: "putting it to bed for an hour" = putting retarder in the mix; "concrete is just flying these days" = what happens when you don't put retarder in the mix when it's 90º.
No Bobcat here, but i have a 7' bar, and it should be easy since the forms are lined with plastic, and everything is screwed together. (Not Piffin screws. <g>)Now i gotta get a case of Gatorade and a couple pounds of gorp for my boys and get my sprinkler lined out.
90, ninety not hot, it been ninety for the past four months. we dont use retarder, never used retarder, but thats because we have afternoon showers so we want it hard quick. early first thing. early to us is 2 am. we poured 275 yards today at 2am and was done by 5:30. we added 70 more at 11 am, and fourteen more at three pm. Typical day. i got 45 tomorrow at 10:30 and 21 at 2:00. typical 16 hour day.
Hey, i missed this one yesterday.I'd be fine with pouring at 2 a.m., but i can't get the drivers and the finishers on my schedule!
What size are those form boards? 2x6? 2x10? 2x8? and I assume they don't actually go down into the ground? The reason I ask is that you don't need that many kickers unless you have 2x8s or 2x10s fully that are above grade.
I guess it is poured by now. Got a pic? How big is the whole thing? 20x20? less?
Form boards are 2x6, with the bulk of the footing below grade - 16" deep in total. I have stakes left, so i'll put more kickers anyway. Can't hurt and it won't take but a few minutes. Pour is tomorrow, 7:30. First thing today i ordered 10 yds. of 5-1/2 sack retarded concrete with neural tangles and extra oxygen. The slab is only 22 x 22, which translates to a little less than 9 yards, but the slab slopes a bit to the footing, so i'm again taking no chances. I'm digging post hole footings today for the shed roofs to either side, to take any excess there may be...as soon as i finish my second cup of coffee.
I have built a few different types of slab on grade foundations - all engineered - and none had foam insulation under the footing itself. Footings always go right on firm ground. foam under slab only. Maybe they do it differently in other parts of the country where soil types and frostlines are vastly different. BTW - we have virtually no frost line here, although code requires any footing in the state to be a minimum if 12" below grade.
BTW - was that you with the house owned by you and your siblings around Asheville? What ever happened with that?
Also BTW - I have a ~ 100+ yard slab pour starting on Monday.... I an gonna enjoy watching.
Edited 8/28/2009 7:04 am ET by Matt
I can remember doing 440 yard a day. We never put foam under a slab. We'd pour the footer/wall first, add foam "boards" against these and back fill to the grade under the slab, THEN pour the slab. Those foam boards had a bevel milled on one edge, this bevel would be towards the top of the wall. The bevel also acted as an expansion joint between the wall and the slab. I've also put down 6 mil. on the gravel "base" and then the rebar. On one job, we put down the 6 mil., then a layer of sand, then the wire mesh. This was for a basketball court/gym for a high school, and the slab needed to be flat within an 1/8" all the way around. Then a wood gym floor was laid down. That 440 yard pour? It was for a building up in Marion, Ohio. 9 pours, each about 440 yards @ 6" thick. 12 loading dock "pits", a retaining wall at each dock area, and a ramp to drive into the building. There was also a "thickened slab" in those floors to support concrete block walls for restrooms and such. Just a day at the office." Although I have the right to remain stupid, I try not to abuse that right"
I got eighty yards in a couple minute,waiting on trucks, just another day at the office
>> I've also put down 6 mil. on the gravel "base" and then the rebar. <<
That is the only way I've ever done it for house slabs, although often, we don't use rebar - it depends on what whoever engineered the plans specified. Always wire though. Rarely fiber mesh. To me having rebar and wire in a slab almost automatically says it needs to be 5" thick which is just a bunch more money... Slab houses are very popular down here. Personally, I wouldn't own a slab house - unless I moved to FLA or someplace and didn't really have much choice. Here the current crop of home buyers don't seem to know the difference. I've never had a perspective buyer or HO ask me about "cold hard concrete" or similar.
>> On one job, we put down the 6 mil., then a layer of sand, then the wire mesh. <<
Unless the sand was wetted down I'd be afraid that the sand would suck the moisture out of the concrete and weaken it. I would imagine it was engineered to the max though...
Sounds like you have about 100x more experience with tying rod than anyone else here... Maybe you could be called a "rod buster"? Always nice to have an expert on board. Welcome!!! It sounds like you have been doing some heavy commercial/industrial concrete. I'm guessing that in highrize construction, bridge building, etc, etc, the super structure that is created with the rebar is closely engineered and monitored because it is so structural, and those huge "cages" of rebar have to be done perfect just in order to support their own weight prior to the pour. Here, in residential construction, the only thing I ever see specified on plans with regard to rebar is the lap. Never anything about tying it etc. Course here, we rarely even build basements.
BTW What's it like in Marion Ohio? Is that where you live? I visited there back in the 70s/early 80s several times and the economy seemed quite depressed... I had never actually seen that "up close and personal".
Also BTW, since I'm just the guy who hires concrete subs so I'm mostly just watching and occasionally doing something obnoxious like saying "can we please add some more kickers here?", or "can you get your guys to stringline this thing so I can check the thickness"?. That last one happens after gravel but before poly, wire. etc...
OK stripper girl, let's see what you've got!
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
I was a "rod-buster" for about five years, before becoming a "concrete-carpenter" ( form man). I've led my share of rebar crews, even was "leadman" on tilt-up wall jobs. Marion< Ohio has changed a bit, Still some railroads in town, the Union Tank Car factory is in the area of the old Erie Lack of money yards. " Although I have the right to remain stupid, I try not to abuse that right"
Rod-busting is also a "mind-set" sort of thing. One has to be able to get in there and tie like crazy, even chase track-hoes along a footer trench. Crumb it out, check grade, lay and tie the rebar, and set the grade pins for "Top of Footer" so that it is ready to pour THAT day. The "highest" I've ever worked was a second floor pour and rode the pumper hose doing it. The "lowest" was in a "tunnel' under a factory, along with a new floor above it. That floor had double layers of #5 bar, 12" on center, with wire "chairs" inbetween each "mat". The company I worked for at that time was Ferguson Constuction Co. out of Sidney/ Dayton, Ohio. Some on here talk about 12-14" sonotubes, I worked with 18-30" diameter sonotubes. With upright rebars out of a pier footer, and round rebar "stirrups. Add in a "template" to hold four anchor bolts and have to pour 12 of these THAT day. Yep, FUN! And this was 12 months a year, the only time we didn't work was in the rain. I also learned all about "Rain-turtles". " Although I have the right to remain stupid, I try not to abuse that right"
got any pictures and the educational tales to go with them that relate to your CC and rod days? It's a large void in my personal experiece and probably more than a few others here. It would be a good thread if you had the interest.
I was to busy tying bars for pictures. Now, if someone has a question or two about these things, I'd be more than happy to help out. Some days it was just little 3' high frost walls (100' a day), others were 25' tall "piers" to hold a roof over a swimming pool ( Honda's Anna Engine plant, Anna, Ohio. They had a "wellness center" we were adding on to) Ever seen a 25' long vibrator, let alone used one 25' in the air?
Tying bar: Single tie wire, double tie wires, single saddle ties, double saddle ties. It all depended on the SIZE and location of the rebar. We used to tie up all the pier "mats" ahead of time, so these got saddle tied, that way we could hook on with some straps with the hoe bucket and lift and carry them to the holes.
Stirrups: These are rebars bent into a shape to go around a group of other rebars ( like in those rebar "cages", or just in an ordinary pier) that were 1) square, or rectangle in shape, or 2) round as in stirrups for sonotube piers. We'd take a level and go around the uprights and mark where the stirrups would be tied in, usually at 12" intervals. We also tried to be neat so they were where they needed to be in the pier. Another form of these was called a "standee", we used this toseperate mats form THICK piers an footers.
Finally, we had what was called a "steel print", seperate from the "blueprints" used on a job. These spelled out WHAT size went WHERE, How many went where, and even called out a special ties and stirrups. On that Anna job, 14 #6 uprights were cage at 12" intervals with a #4 rectangle stirrup AND a #4 "shepards hook" that ran through the pier from short face to short face. The "Hook" had a 90 bend on one end, and a round bend on the other. When we took down the scaffolding around this thing, the last guy down was able to climb down using just the rebar cage as a ladder.
So, anytime someone has a question about these things, just ask, I'll be around." Although I have the right to remain stupid, I try not to abuse that right"
Thanks very much for popping in here. I learned from you and others many times more than what i started with.
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I been there once, tain't no fun hanging around like that. There was a Grand father once that was working on a job like that, missed the connection while changing where his harnass went, and fell about 60' down onto more rebar, end of grandpa. If you look closely, you'll see the harnasses those guys are using. 100% tie-off is the RULE, not for the rebar, but the rebar tie-er. " Although I have the right to remain stupid, I try not to abuse that right"
I would never work at that height I am a chicken!!Back to welding rebar. Why can't you? I didn't know rebar had temper, I thought it was just plain iron with a grid pressed into it. can you help an old guy out on this one?
Might read this link for a quick primer.
http://en.wikipedia.org/wiki/Rebar http://www.rebar-info.com/rebar-info-welding.html
They can't get your Goat if you don't tell them where it is hidden.
Thanks
I checked the links. What I gather is the steel is so much of an unknowen material that welding is hit and miss? axle-steel ?? I thought axle steel was of a higher quality or am I miss reading this.?I have set up many ICF's and they stress the none tied lap joint D X 40 , i think I understand that concept. I can see if you are craning in big structures you don't want a snap, but if you are doing a garage slab a few hits with a MIG ? Please help this grey hair fiqure this out
Thanks
We didn't like to weld rebar because concrete will "flex" as the seasons change and this flexing will break the welds in the bars. The two common "grades" of bar I worked with was a #40 and #60. The #40 bar bends easy, making it easy to use in bent work. The #60 grade is a lot harder steel, and will snap if bent too sharply ( been there, done that) like for "L" shaped up-rights connecting footers to walls. A machine CAN bend these, but those are a little "pricey" for most people. Also, because of those "ridges" on rebar, it is a little hard to get a good weld joint. We've welded the ENDS of rebar to other metal forms, such as angle brackets and lintels. So if you need a metal angle iron edge on a slab, weld some short "L" shaped pieces of reabr to it to "lock" the angle iron to the concrete." Although I have the right to remain stupid, I try not to abuse that right"
<<was that you with the house owned by you and your siblings around Asheville?>>Not me. I nearly married a fellow with a farm near Tryon, but that one time i showed a little sense and fled the scene of the accident. ;^)100 yards....i'm just now surfacing after helping pour and finish only 10! Concrete finishing kicks my butt more than anything i've ever done. It makes roofing pale by comparison.
Pour started at 7:30, finisher left at 12:30. Both Florian brothers, Dom and Dean, worked on the pour, then Dom and i did the finishing. It got sprinkled/tarped for the rest of Wednesday, then i removed the forms and cut control kerfs yesterday, retarped and continue sprinkling. Other than burning up my Bosch sidewinder and having to borrow my buddy's PC worm drive to finish the control cracks, all went very well. Forms were rock solid throughout and i remembered to lift the top round of rebar as we poured.I'd measured the slab to need 9 yds., so i ordered 10 to be on the safe side. The slab took just 9 yds., so we used the extra to pour piers (black plastic pots that trees arrived in...perfect taper!) for the overhanging 8' roof on one side, and a rat slab (right term?) for the area underneath that i was just going to gravel for firewood storage. It'll still get more pea gravel, but my pallets won't sink in as they do on dirt now.Next up will be the retaining walls. I'm probably going to mix my own concrete for footers on the wing that goes on the right side of the shop, then i'm doing PWF for the first three feet above the footers, regular 2x6 above that. Drain, rock, 20 mill PVC billboard tarp for waterproofing...oops, i gotta go!
Edited 8/28/2009 2:33 pm by splintergroupie
It looks like a low damp spot. Hope you plan good grading fort drainage so you avoid frost heaves.Are you left handed?
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
The slab is nudged back into a slight rise next to my neighbor's fence, but from there it's all downhill; taking a drain to daylight will be a piece o' cake. The standing water you see is from freak rains a week or so ago. We got 2.2 inches in a month that previously set a record at .4 inches. We had flooding at a time when we often can't breathe for wildfire smoke. It's what Jesse and i were talking about in his "Bitterroot" thread, how lush everything looks now...very strange.Left-handed? Right is dominant, but i can do most things ambidextrously. Why do you ask?
Edited 8/24/2009 3:02 pm by splintergroupie
We just had over two inhes each night this past weekend.
Getting 2-3 inches in three hours can change the errain around sometimes.First look at the wire ties I thought they were twisted backwards from the way righties do, leaving me to think, Hmmm, She might be left handed.
but after posting that, I looked more and think they are twisted to the right.Now if we can just get you voting tht way
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Just thought i'd let you know what Dominic told me about rebar: the BI's themselves aren't in agreement on the pours he's done that require inspection. <shrug>I'm going to wire up the third line of bar tomorrow. I didn't know if he would just dump it in and push it down, or if i should suspend it somehow, but he said just to leave it lying wired up in the trench and we'll pull it up as we pour.And he reminded me about the Ufer ground. I'll bend a bar and wire it to extend above the slab, just cause, and put my aux ground at the eave edge as he suggested. I was already skeptical about copper wired to steel, inside concrete; then he said there are electricians here who have just refused to do it that way.
Ufer grounding is required in the jurisdiction where I build. Connection to the copper ground wire is above the top of the concrete. We have to leave 6"-8" of bar exposed for the connection.
I've got plastic all under my slab and footings, so i question how much good it would do to have a Ufer ground in this case, but the last electrical inspector i had for my house said to bond the copper wire to the rebar in the footer, which concurs with so many images i got off google, like this one:
http://www.ab7e.com/AB7E_Tower_ufer_welds_20Jan08.jpgAs i said, it makes less sense to me to bond inside the concrete where you can't see if the dissimilar materials are reacting compared to making the connection above ground, as you suggest. Then i saw this, but later read that copper doesn't have good conductivity in concrete because of concrete's above-neutral pH:
http://www.wiredogelectric.com/Previous_Jobs/830%20Jefferson%20Bl/Ufer%20ground%202.jpgIt's certainly not for lack of trying to find THE answer that i questioned the Ufer method and figured i should back it up with a ground rod. I'd be delighted to have this resolved to my satisfaction with any more information you can contribute to my minute store of electrical chops.
Our local AHJ only requires a Ufer ground if there is concrete in direct contact with earth, like in the bottom of a footing. If there is foam under the slab, then we don't put one in.
I don't see why foam under a slab makes any difference for putting in a Ufer ground, if the footing is still in direct contact..?
We put foam under the footing.
Foam under the footing...one more illusion shot to hell. I'd always assumed (don't say it...) footings had to go right over undisturbed or compacted soil.
If anyone asks about the racks, just tell them "it's those new white epoxy coated chairs".
Jon Blakemore RappahannockINC.com Fredericksburg, VA
The fellow who's doing my finishing for me is a scrounge like i am, did a lot of labor trades to get his house built. I'm pretty sure he'll get a chuckle out of my chairs.He refused to take any money for The slab he finished for me in the of the house i moved here, bec i was stretched thin at the time. I got him back by dropping off a sump pump in the middle of his basement foundation that i knew he was thinking he could put off until later. Through this recession, he's been constantly up to his eyeballs in work, he's that good and that nice of a guy to work with. I'm really looking forward to Wednesday. I know this isn't a big deal for you guys, but i've only remodeled stuff, never got to build a whole thing from scratch. Plumb, square, and level...oh, my!
Are they the ones from Kenmore, Indiana or the better ones from Maytagglesville, Illinois?
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Actually, I think it's Amana, IL.
Jon Blakemore RappahannockINC.com Fredericksburg, VA
I can only imagine something like that in a very large thick pour.Don't know about ens sticking up - we cut the spare ends off. Don't use for rebar, but we do tie Pex into place with plastic ties and nip off the extra.But you really have to stretch the imagination to get the core crete temp hot enough to melt the ties in typial residentiaal pours. Seems crete that gets that hot will have other structural issues from cracking and shrinking too.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Odd, because when they built the Titan missile bases, all rebar was required to be welded for the extra strength it lent to the concrete. I wonder if concrete science has changed significantly since the 1950s and this no longer a recommended practice in light of new research findings. (http://www.chromehooves.net/Ant%20Term.htm, scroll down to Construction: "*In typical construction, most steel reinforcement is constructed into a latticework using wire to tie the bars together. This is fine for most applications, but the specifications for the Titan I complex called for "continuous reinforcement" which meant that rebar was welded together instead of just tied with wire, adding a far greater strength to the concrete pours as a single large mass.")Z
That is because of the "couplers" used to join two lengths together and then welded. I wasn't even allowed to heat rebar up to bend it to the shape I needed ( did it anyway) because the heating took all the "temper" out of the rebar in that area. We even tried to weld snap ties with a rebar in-between two halves, broke right away, and had a "blow-out" to boot." Although I have the right to remain stupid, I try not to abuse that right"
Splintie,
There are 2 kinds of spinners. One type works like a rotary screwdriver. The other type works like a Yankee screwdriver, in reverse - it turns the hook when you pull the outer case away from the tie.
The yankee style is faster and more expensive. You need premade ties with end loops to use either type.
Jim x 3
I wish i'd thought to ask at the concrete plant today if they sold the spinners, but it was so late that i was rushing to get the bar and get the heck out of their hair.
I've been searching the net and haven't seem the Yankee-drill type, though i did see some rebar tying machines that had a cordless-drill configuration.
I don't suppose i'll use one enough to warrant the outlay for anything fancier than the deformed hook model, but i like knowing what's out there.
I saw galvanized bag ties while i was hunting for the drill-type spinner. Do you (or anyone else) know under what circumstances galv wire ties would be used?
I've tried a few of the spinners that are like a yankee screwdriver and didn't like them at all. I broke about half of the ties with the thing. You have to pull fairly hard to get it to spin, and they frequently break before they are cinched down. Maybe you have to get a heavier gauge tie. But that tool would be way down on my list of required toys. In a pinch I've bent a 16d nail, cut off the head, and chucked it in a cordless drill. It actually works quite well, though it is a bit cumbersome.
they make a cordless wire tier
<<In a pinch I've bent a 16d nail, cut off the head, and chucked it in a cordless drill.>>Ha! I love those sorts of solutions! I'll give that a try.
Roughly speaking. Concrete has a high compressive strength and a limited tensile strength.
Rebar running parallel at the bottom of the beam is to resist forces or load from above.
Rebar running parallel at the top of the beam resist forces from below such a expansive soils.
Rebar vertically and horizontally at right angles to the beam resist horizontally horizontal shear. These are often what is called stirrups.
Vertical rebar is often used just to support the horizontal rebar or to tie a wall etc. that is to be poured or layed (CMU) on top of the footing after the footing is poured and cured.
Like I say "Roughly Spealing"
What's kind of odd is that i used this same finisher in 2000 to do my walkout basement, formwork included, and watched him put the bars in the bottom on the footing. Not a monolithic slab - i did a pressure-treated wood foundation - but the house hasn't had a bit of movement.
I'm remodeling (re-building really) a small house here in north Texas and the pier and beam foundation was shot. The BI wanted an engineer to design the new foundation so I hired an engineer to take my concept and "engineer" it. He specified 5 #5 rebar for a 12 x 24 perimiter footing because of our heaving clay soil. That should be strong enough.
Jim
Good thing rebar's cheap! Just curious...why didn't you go with pier and beam again?
I did. We hand dug and poured a new perimiter beam inside the old one. Jacked each wall up and slid in new floor joists. The house is only 750 sq ft so it's not as bad as it sounds.
A better question would have been "Why didn't you push the house over into a pile and sell the lot?" Because SWIMBO says my son needs a place to live. What else would I do with all my fee time evenings and weekends?
Ah, that gave me a good chuckle! Thanks!