Pouring footers without a form?

Discussion in 'Shop Talk' started by Ed Norman, Oct 29, 2005.

  1. Ed Norman

    Ed Norman Well-Known Member

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    We're making a sunroom and need to pour a little knee high wall before the glass starts. We want to have river rock that we've collected on the outside. I thought to pour a footer about a foot wide, then a wall about 4" thick, plus the rock and the concrete holding it. Could I dig the trench for the footer and dump the mud right in it without forms? Does dirt suck moisture out of the uncured concrete before it sets good?
     
  2. Cosmic

    Cosmic Well-Known Member

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    Normally you don't pour concrete in earth type forms. The one exception is if the earth is frozen. You never will avoid major contamination by crumbling earth walls. Basically asking for a mess. If the soil is frozen it can be done.

    One good method is just lay up the forms out of rock, if you got plenty. Can include rebar very easy. Make the footer wider by the amount of the rock forms. Just leave the rocks in place after the pour. Better, stronger, cheaper, smarter and quicker.

    You can do a form of rammed earth and leave the forms in place, similar to the rock walls. Lots of ways to skin a goat. Normally we never leave wood forms in the ground after a pour. Super termite bait, number of potential problems. If using the rammed earth method, line it with plastic.
     

  3. TnAndy

    TnAndy Well-Known Member Supporter

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    Hmmmm.....built quite a few houses and never done it any other way but dig a trench and pour the concrete directly in the trench unless the was no way to trench for some reason ( like bridging over rock )......this is the only way it's done here and meets all codes.....the inspectors DO want loose dirt shoveled out of the bottom, which we do with a square point shovel....but that's it. I can point to thousands of houses here that haven't fallen down ( or even cracked slightly ) as proof this works just fine in our soil.....which is hard clay.

    So I'd say the answer depends more on your soil type than a sweeping "can't do it "
     
  4. morrowsmowers

    morrowsmowers Well-Known Member

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    You can pour concrete directly into the trench. Be sure to use rebar to add strength. Make sure to go deeper than the frost line and thicker than the walls you will be building on top. If the ground is soft, sand, etc. then you will have to go wider and deeper than if you are building on rock.

    Ken & Sue in Glassboro, NJ :1pig:
     
  5. agmantoo

    agmantoo agmantoo Supporter

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    In the Carolina clay we pour in the trench. We only form for above ground.
     
  6. farmerjack68

    farmerjack68 Well-Known Member

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    Hey
    Thats the way we do it in central ohio too.
    Been doing it for about 12 years and no problems just make sure you footer is below frost line .
     
  7. Ed Norman

    Ed Norman Well-Known Member

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    Well, sorry Cosmic. The people have spoken. We have good hard soil, no rocks. The frost line is pretty deep here, would it work to hand dig the trench as deep as practical and then poke holes in the corners and a few places under the wall with a post hole digger?
     
  8. TNHermit

    TNHermit Well-Known Member Supporter

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    You can do it but the footer has got to be level to build a decent structure. ;) Use to do it all the time back in the 60's. Here's how. You form the top of it up with 2x4 on edge preferably. drive stakes on the outside every three ft or so. (you can use 1x4 if you stake it enough or don't mind a wavy edge (not to professional). After you get that form in then cut the stakes that stick up off level with the form so you can screed it off. Then you dig your footer out between the forms as deep as you need it from the top of the forms. Usually about 8-12 inches. Your wall and rock should set on the middle of the footer. the footer should be at least 2 and better 4 inches wider on each side. :rock:

    If it snows every year before it freezes you can put the footer right on the ground. Just ask anybody form northern Michigan. first time I built a house up there the piers were in the wrong place. The concrete guy said just "scoot" them over. Couldn't believe it. but he said it snows before it freezes and the ground never really freezes. But if it does freeze first the foundation had better be under the frost line. Mother nature will turn the place every way including loose..
     
  9. BobK

    BobK Well-Known Member

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    One thing to consider is how well the trench will dig.......if its in loose dirt/rock/soil and comes out too wide you pay for extra concrete...outside of that....pour away...but as mentioned have some way to screed the footing to a level surface....
     
  10. Beeman

    Beeman Well-Known Member

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    I have buildings built on footers poured directly into the ground with no form. As someone stated you might want the tops level especially if you are laying brick or block on top. Dig your trench and then drive a piece of rebar in the ground with the top of the rebar(or pipe) to the level you want the top of the footer. Once you have the first one set to the correct height just drive a piece every couple of feet and level to the previous piece. this will give you a level top to your footer, just darby or float the top to that level with a piece of wood. If you have access to a transit or a laser level it will make it easier, but a regular level or a line level will work.
    You mention 4 " pored concrete walls on top, that sounds narrow and it would take a lot of forming. I would probably go with 6" or 8" block instead.
     
  11. Ed Norman

    Ed Norman Well-Known Member

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  12. Beeman

    Beeman Well-Known Member

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    The rock sounds like more of a veneer and not a structural support. I would also believe that 8" block would probably be cheaper than poured concrete and the labor and price of the forms.
     
  13. TNHermit

    TNHermit Well-Known Member Supporter

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    I think laying a 6" block wall will be a lot cheaper both time and money wise than trying to put up a 4" wall. I've done a lot of forming for concrete and its not something to be tackled lightly. You can then put wall ties as you go to hold the rock against the stone. With concrete you have to drill and fasten them or ram set them on as you go. You can always pour the block full of concrete if you want to. If you have an average 5" rock and 6" block. You should make your footer 16 -20 inches wide.
    I would put bolts in the top of the 6" wall and use a double bottom plate. The first one being a 2x10 so it can be tied tto the block wall. Then a regular plate can set near flush with the outside of the stone. You'll need to put some flashing between the foundation wall and bottom plate to keep water from siphoning behind the stone. It helps with termites too :) Nobody does this anymore but its a mistake.
     
  14. Ed Norman

    Ed Norman Well-Known Member

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    The wall will only be 12-18" tall, then the glass starts. I could lay two courses of block then veneer the outside with the rock, if that would be cheaper. So what do I hang out of theblock to bind onto the rock veneer?
     
  15. Arborethic

    Arborethic Well-Known Member

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    Ed, your trench poured concrete is more likely to succeed if you line the sides and bottom of the trench with polyethylene sheeting. The plastic is pretty cheap. It helps avoid the soil pulling water out of the concrete too fast. In fact, I've been told that each 28 days you retard the final curing of concrete doubles its structural strength.
     
  16. Beeman

    Beeman Well-Known Member

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    Wall ties are what you want. They are laid in the joints of the block and stick out and are then laid in the joints of the stone. They are galvanized strips of metal that any building supply will have. I would lay 2 courses of block and a cap block on top of that with anchor bolts spaced where you need them if feasible. Are you putting a wood sill or is the aluminum frame of the sunroom sitting on the blocks.
     
  17. Ed Norman

    Ed Norman Well-Known Member

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    I'm putting a wood sill, then double wall lexan sheets over a wood framework.

    Are the anchor bolts set into the footers? How much luck do I need to get them to go thru the blocks in the right places?
     
  18. TnAndy

    TnAndy Well-Known Member Supporter

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    Anchor bolts are set in the block sticking thru the end joints ( on top ) of the cap course. You'll need about an 10-12" bolt to allow 4" for the cap thickness, about 2.5" above the cap for you wood ( 1.5 for the wood and 1/2-1" for the nut/washer ),and the rest down in the top course of block. Use rock or whatever for fill in the block webs where you put the bolts up to the level the bolt needs to start, then fill with mortar, doing this as you lay your cap course....probably only need 3-4 bolts for what you're doing.

    By the way, I no longer use bolts if I have a cap block course.....I simply use 3" masonary nails and fasten the sill board to the cap block. I think anchor bolts are a waste of time personally. Saw a news story of a tornado down in Texas once where it blew a whole subdivision of houses downrange....and there sat the block foundations with the sills anchor bolted to them as the camera panned the mess......ready to start work on again I guess ! .......if you're gonna nail the rest of the structure, why bother bolting the sill ?
     
  19. Cosmic

    Cosmic Well-Known Member

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    Still hard to visualize exactly what you are doing. Sounds like this is a smallish project. Normally you do not monkey around trying to pour concrete into any type of soil without forms. Sort of real Amateur City stuff. As mentioned you will have a very difficult screeding and get a decent level job. Plus where do you put your feet???? Will always be caving in parts of the trench just walking around and working.

    If using poured concrete always use some type of forms that allow for good dimensional stability and ease of work to get exactly the shape, depth and type finish required. Very poor to have a bad footing to then start to lay any type of unit masonary on, (Brick, block, rock, etc).

    You didn't say how much concrete is involved. In many areas difficult to get small deliveries, hand mixing is a bit of work. For a lot of those type jobs, can just make the footing out of block, rock or whatever using handmixed mortar / concrete. Depends a bit of how much volume you are talking. Many stone walls have laid up stone footings. May or may not have rebar depending on who did it and the age.

    Was pretty normal to make the footings for masonary steps out of cement blocks. They were turned sideways and buried as deep as required and a lot of extra mortar was used. Worked pretty well if the step's design did not require a pad type footing.

    Whatever the trick with most masonary projects is to have things straight, level and plumb. Without the proper starting work, footings and preperation and reference points / lines it is pretty well downhill from that point forward.
     
  20. rambler

    rambler Well-Known Member Supporter

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    NO! on that post hole idea.

    Foundations on this farm were poured in the dirt trench all the time, we are high-clay, trench can be 8 feet deep & won't cave in, holds it shape for months.

    You want a trench that is square sided, or tapered wider at the bottom than the top. You do _not_ want a V in the ground, the frost will pick up the sides & lift it. You want the sides pretty smooth, no it won't be perfect, but you know....

    Your post hole idea is a disaster. The frost will get below the shallow parts & lift them, while not lifiting the post hole corners. Will break up you foundation into crumbled landfill.

    If you want piers, then dig those, and build the sill part all above ground. Do not ever put in a 1/2 a footer to 1/2 the frost line!!!!!

    Frost moves things it can grab upward. If the frost can grab a wedge or V shape, or get under a portion of the foundation, it will lift that part up & not much you can do about it.

    The dirt trench will work, but you need to be smart about it - not any old sloppy trench, no shortcutting it. You need good vertical smoothish sides.

    The post hole idea means you'll be rebuilding in 2 years or less, total failure.

    I'm in Minnesota, so I know frost. :)

    --->Paul