I don't do much footing work and could use a few tips. I don't have any problem with the grade of the bottom, but the sides. I start with the outside perimeter but my sides still seem to slope in if I'm not careful and they just don't look clean when I'm done. I see guys come in and dig them and they look as if they where cut with a laser nice clean edges. I mean the GC is happy with them, but I'm not. I had to trim 3" off of one of them because the bar was burning the side, and that is a real PIA with my sloppy TBL. Also my boss got all pissed, because I was taking the nails out of the first one that the GC had set for the corners. That is the way I have always done it I mean you leave a little on the sides so the nail stays and have a little slope on the side = the bar burning. So how do you do it? Also tips with the tie-ins, the corners always chunk off. I know the soil leaves a lot to be desired and my labor doesn't have a clue, but I know I'm better than this. Thanks
When digging footings, I will lay out the house or building and paint lines for the outside walls. I will set up the machine so that I am digging on the outside of the line for my overdig. The trick to getting a nice straight wall is to dig a trench down to grade first, then take a pie shape out. Never take dirt out from the middle until you get your trench on the line down to grade first. When you come to a corner, dig your trench about 3ft past the corner. Then get set up on the other line and dig a trench down to grade then take out your pie shape and you should have a nice clean corner.
When you say nails are you talking about corner stakes? Explain burning? If nails are corner stakes than what I do is ask for 5' offsets when stakes are set. Than lay out my footing in paint either on both sides of trench or one line down center and dig same on both sides what ever width of trench has to be. As far as the sides go mine cave in all the time with sandy soil so I step sides back as I go. If soil is hard packed than I make sure sides are plum as I go, my bucket has side cutters so this makes it easier. If you do have a man checking grade in the trench with grade stick I also have him use same stick to check width of trench and that it is centered correctly. My new machine mount laser receiver works for grade and checks for plum of excavator stick while I am digging, real nice.
If the soil is dry and compacted, I will wet it first so it doesn't chunk out on the edges. The moisture allows the bucket to cut vs bust up the soil especially on the top edges. Also, I always take a shallow cut on the top because a deep cut (especially when a deep cut is breaking out at the surface) will chunk out the sides. This also helps with real nice square, clean corners. The water also helps out a lot with the sandy soils - helping to hold it together to give nice finished sides. Hope this makes sense.
I always paint out the footprint, then i set myself up so that i can dig a nice straight line, i usually take about a bucket width outside of my line. Like someone else said cut the sides first then start digging in the middle. Usually if you take shallow longer bites your corners and sides wont chunk out so much. i usually take and scratch the first foot or so of material off the top outside the cut, as its usually just loose topsoil. It keeps material from falling in my hole, its safer as the guys in the hole have less chance of crap falling on them, the concrete guys like it cause they can get around the outside easy, and it just looks good.
Offsets are very important when doing a basment on a slope, which is about 99% of out basement digs around here, there isn't a flat spot to build anywhere. I usually run a 3 foot offset at least, depending on the height of the wall. Some guys say 2:1 is a good toe to run at, I think it's too shallow and you'll end up overdigging too much and compacting too much by the time it's over. Just eyeball the slope, if it holds pretty well, leave it, but at least 3 feet around the outside of all walls. Gives the concrete guys some room to work and they won't be worrying about the toe sluffing on them. For an actual footing for a garage or something like that, the trick is to paint it all out and dig very straight. Other than that, there's nothing to it. I did an earthform or monopour, whatever you want to call it about 3 weeks ago. The grade inside the "box" has to be set at the required floor subgrade before you even start digging the footings. A bit of a pain, just be careful once you get grade set in there while digging the footings. In all, basements and footings are super easy, the only somewhat complicated part is comprehending the plans at times. Once you have a clear idea of what's going on, doing the work is the easy part. It's the setup and calculations that make or break the job.
There is no basement this is just a slab on grade so over digging for access isn't an issue. The nails are set by the GC are for the corners of the footings these are all just squares up to 20'x20' and as small as 5'x5' most 3' or so in depth one 9'. Bar Burning is when your rebar touches the side of the footing, because it wasn't dig big/straight enough. The reason my boss want the nails left is we will be back charged for the extra concrete, they don't want the footing over dug at all. I going to try some water if I can get any and I think part of the problem is that I'm taking the center down as I dig the perimeter not quite as fast but enough I think that is part of the problem.
When digging footings 9' deep, the problem can be whether or not you are using a level platform. To help me in these situations, I have a bubble level installed on the floor of the backhoe right between my feet and each time I set my stabilizers I make sure the bubble is centered. It is much easier to get straight walls all the way down this way. If the soil is rocky, it is hard to have good clean walls and not have some overpour on the concrete. The rocks always come out on the walls taking some dirt with them leaving voids filled by the concrete. As in any excavation, a "rock clause" is a good thing to have in the contract which spells out different scenarios depending upon the job. In California this time of year, the water can really help get a good clean start on the top portion of the footing because everything is so dry on top now it is real hard to keep it from chunking no matter what type of soil it is. Once you are down a few feet there is always some moisture in the ground.
Thanks you guy for the tips again between them and a little more practice this week they're looking good now. I'm almost not ashamed to call myself an operator, now only if I had a clean up bucket.:bouncegri
Yeah if you guys had thumbs down there in CA you could grab a grade beam, that's what I use to clean up basement floors. Get it close with the bucket then grab the beam and finish it off. I find having a cleanup is good for hogging light materials when truck loading, but having a beam is nice too. Each have their advantages and disadvantages. I had both :bouncegri
I would, but I don't have a thumb on my backhoe that is how I do clean up after a demo job. They didn't have a problem with me using the heel of my bucket, but my side looks like I had just finished off a 12 pack.
Using the heel of the bucket is a good skill to master. I've started using it a lot more than I have in the past.