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Forming Foootings

Discussion in 'Residential Foundation Codes' started by snowroski, Jul 30, 2010.

  1. snowroski

    snowroski Sawhorse

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    Do footings have to be formed?

    I have in most cases required footings to be formed; recently I was questioned regarding the requirement because another inspector said that footings don't need to be formed.

    What are your thoughts?
     
  2. docgj

    docgj Silver Member

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    We require them to be formed. How will they install foundation drain at the proper location without forming?

    docgj
     
  3. Bootleg

    Bootleg Silver Member

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    The trench can be used as the form for the footing.
     
  4. texas transplant

    texas transplant Silver Member

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    I agree with Bootleg. Clean well formed trench at the proper depth works fine.
     
  5. mtlogcabin

    mtlogcabin Sawhorse

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    109.3.1 Footing and foundation inspection.

    Footing and foundation inspections shall be made after excavations for footings are complete and any required reinforcing steel is in place. For concrete foundations, any required forms shall be in place prior to inspection.

    What makes it a required form I am not sure for foundations. My thought would be depending on the soils you have. For engineered pad footings if the sizes are not kept consistant by forms then there may be possible differential settlements between the pads.
     
  6. docgj

    docgj Silver Member

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    How does one install the foundation drain below the top of the footing with a "trench pour"?

    docgj
     
  7. texas transplant

    texas transplant Silver Member

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    After the pour, the area to the outside of the footing is excavated, drain installed and backfilled.
     
  8. docgj

    docgj Silver Member

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    TT,

    That will work. Just seems like a lot more work then forming it to begin with.

    docgj
     
  9. Mark K

    Mark K Platinum Member

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    The soil can be used as forms as long as the loose soil will not slough into the concrete. When concrete is cast directly against the soil the IBC and I would assume the IRC requires a greater concrete cover.

    I would not worry about the slight differences in footing size resulting in differential settlement. There are so many more significant issues.

    Formed footings below grade would be required when required for waterproofing and where needed to maintain profile necessary to install other featurtes such as drainage. If there is a design professional involved he has a say in the discussion.
     
  10. Yankee

    Yankee Sawhorse

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    Drain not required if AHJ deems not required
     
  11. FredK

    FredK Gold Member

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    Guess it would depend on the soil in your area.

    Here it's 12" deep and no forms needed. Other contractors will use forms. And a lot are simple mono footing (12' deep) with a 6" board on top of the ground for outbuilding buildings (sheds/garages).

    Always with a clean trench.
     
  12. peach

    peach Sawhorse

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    almost always soil here too.
     
  13. Daddy-0-

    Daddy-0- Moderator

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    All of our footings for SFD are inspected by 3rd party. We receive a report from the engineer before foundation and projection which we do inspect. Weird huh.
     
  14. peach

    peach Sawhorse

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    funny how we think structural engineers necessarily know more about footings than building inspectors do... I happen to have a relationship with the best lab/structural inspectors in the area.
     
  15. Daddy-0-

    Daddy-0- Moderator

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    Peach,

    We have a lot shrink/swell clay soil and the county just doesn't want the liability. All footings here have to be engineered design, continuous and third party inspected unless it is a deck, small addition or detached structure.
     
  16. Paul Sweet

    Paul Sweet Sawhorse

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    A foundation drain just has to be below the slab or crawl space. It doesn't have to be below the bottom of the footing.

    Footings don't necessarily have to be formed in shrink-swell soils as long as the soil is stiff enough to stand before and during the pour. Having the footings below the level of seasonal moisture change is the critical thing.

    Minor differences of a couple inches in footing width don't cause differential settlement under typical light residential loads.
     
  17. TimNY

    TimNY Platinum Member

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    Contractors always form them here; we have sandy soil so a trench wouldn't work.

    Footings have to be level-- I suppose it's possible, but can you really get a level footing (across the width as well as the length) in a trench pour? Do they screed it?
     
  18. Paul Sweet

    Paul Sweet Sawhorse

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    I've seen rebars pounded into the ground used as reference points.

    Several years ago I built a garage and tried it, except I used 1/2" round plastic plant stakes instead of rebar, because I was too lazy to buy a long rebar and cut it into pieces. The concrete was thick enough to bend the stakes as it flowed into the trench, so the top of the footing elevation varied by 2 - 3"! I had a lot of fun making up the difference in only 4 courses of block. That garage was quite an educational experience. I found that it's a whole lot easier to draw buuildings than to build them.
     
  19. Kearney.200

    Kearney.200 Silver Member

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    we allow bank pouring here for frost footers all others are formed with 2x material
     
  20. Alias

    Alias Sawhorse

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    Almost always soil here. Depth here is 18", not 12" as the CBC calls for due to the frostline. I check trench for depth, reinforcement, and cleanliness before pour.

    Sue, in sunny CA
     

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