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  1. #1
    Tristan Maire's Avatar
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    Default DIY pier foundation questions

    Hello all, I am glad to have found this board. The husband and I are in serious need of help. We're putting in a small cabin in central NY, which we will be finishing to use as a permanent residence. To save money, as we're on a very tight budget, we need to build the foundation ourselves. According to local code, the foundation must be below the frost line, or "frost protected". Our only reasonable options are tie-downs (which I'd prefer not to use) or to build concrete piers. We've decided to go with the second option.

    The cabin will be a single story 14x26 with a 14x6 porch. We're planning to build twelve piers, three lines of four down the length of the house. The building site if fairly level, and the soil is gravely, not clay. It's also on top of a small hill, so drainage should be good and it will not sit in water.

    We plan to dig the 12 holes, each 4 1/2 feet deep. We'll tamp 6 inches of gravel in the bottom of each hole. Then we'll pour in 4 inches of type S cement, add an X of rebar, the 4 more inches of cement. Before the cement has completely set, we'll raise a 6x6 post of foundation grade lumber in each hole, set into a bracket (of some kind, I need to research) to connect it to the concrete. Then we'll backfill and level the posts, no high than 18" at any point. I'm praying we'll be able to rent a gas powered auger to help us dig, as we'll have no power on the site and I am very pregnant. :-)

    Does this sound like a reasonable, legal, and study foundation for a small cabin? Do we have to worry about the wood rotting and needing to be replaced in a few years? Of course we want to foundation to be sturdy, but we also want to save labor and money if we can. I'd love to hear everyone's thoughts, and if anyone has a better idea I'd like to hear that too.

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  2. #2
    Join Date
    Feb 2009
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    Southern Vancouver Island
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    Default Re: DIY pier foundation questions

    You want concrete for the full depth, then the bracket for the wood post should be 6" above the soil level.
    Nowadays, everybody uses these concrete forms. It doesn't take that much concrete to fill a tube, so you could mix it in a tub by hand, or rent a mixer.

    Sonotube Concrete Forms - Sonoco Construction Products

    Wood buried in soil is just asking for trouble down the road. If you can't get a good concrete foundation in, build the cabin on concrete pier blocks and call it a temporary structure.

    John Kogel, RHI, BC HI Lic #47455
    www.allsafehome.ca

  3. #3
    Tristan Maire's Avatar
    Tristan Maire Guest

    Default Re: DIY pier foundation questions

    I'm talking about foundation grade lumber, which is specially treated to be used below grade. Having done more research after posting my original question, it appears that foundation grade lumber holds up as well as cement piers in the long term.

    As for the original questions, materials aside, does this sound like a setup that will be likely to pass inspection (I know only the local inspector can tell me for sure), and to support a house of the size we're building?


  4. #4
    Join Date
    Mar 2007
    Location
    Knoxville, TN
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    2,446

    Default Re: DIY pier foundation questions

    Why not just ask the local code guy, instead of a bunch of home inspectors that may or may not give you the right answer?

    I can see how this could come out...
    Local AHJ.. "You can't do it this way".
    You.."But I got it approved by these guys on the internet".
    Local AHJ... "You still can't do it this way".


  5. #5
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    Default Re: DIY pier foundation questions

    Quote Originally Posted by Tristan Maire View Post
    Hello all, I am glad to have found this board. The husband and I are in serious need of help. We're putting in a small cabin in central NY, which we will be finishing to use as a permanent residence. To save money, as we're on a very tight budget, we need to build the foundation ourselves. According to local code, the foundation must be below the frost line, or "frost protected". Our only reasonable options are tie-downs (which I'd prefer not to use) or to build concrete piers. We've decided to go with the second option.

    The cabin will be a single story 14x26 with a 14x6 porch. We're planning to build twelve piers, three lines of four down the length of the house. The building site if fairly level, and the soil is gravely, not clay. It's also on top of a small hill, so drainage should be good and it will not sit in water.

    We plan to dig the 12 holes, each 4 1/2 feet deep. We'll tamp 6 inches of gravel in the bottom of each hole. Then we'll pour in 4 inches of type S cement, add an X of rebar, the 4 more inches of cement. Before the cement has completely set, we'll raise a 6x6 post of foundation grade lumber in each hole, set into a bracket (of some kind, I need to research) to connect it to the concrete. Then we'll backfill and level the posts, no high than 18" at any point. I'm praying we'll be able to rent a gas powered auger to help us dig, as we'll have no power on the site and I am very pregnant. :-)

    Does this sound like a reasonable, legal, and study foundation for a small cabin? Do we have to worry about the wood rotting and needing to be replaced in a few years? Of course we want to foundation to be sturdy, but we also want to save labor and money if we can. I'd love to hear everyone's thoughts, and if anyone has a better idea I'd like to hear that too.
    This is not an accessory structure.


    No. The IRC does not prescribe this method of construction (RCNYS), envokes engineered design meeting BCNYS requirements. Certainly not within the BCNYS prescriptives as you've described, and certainly not without an engineer's stamp, IF anything remotely similar were to be allowed.

    You won't find this foundation in the prescriptive codes, properly it is an engineered design. Some jurisdictions allow it, others require a sealed design. The closest minimal prescriptive foundation you'll find in the generic IRC is a pier and curtain wall. It contains the required continuous footing and lateral bracing for the structure above.

    Proximity to wetlands? Flood zones? Wind zone? 30, 35, or 40 lb/ft snow zones?

    Last edited by H.G. Watson, Sr.; 05-15-2012 at 01:30 PM.

  6. #6
    Join Date
    Jul 2008
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    Snowbird (this means I'm retired and migrate between locations), FL/MI
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    Default Re: DIY pier foundation questions

    Quote Originally Posted by Tristan Maire View Post
    I'm talking about foundation grade lumber, which is specially treated to be used below grade. Having done more research after posting my original question, it appears that foundation grade lumber holds up as well as cement piers in the long term.

    As for the original questions, materials aside, does this sound like a setup that will be likely to pass inspection (I know only the local inspector can tell me for sure), and to support a house of the size we're building?
    Nope.

    It requires a design professional to deviate from the Residential Code, State of New York's, prescriptives. Energy compliance and frost/freeze protection issues for plumbing need to be addressed as well.

    Perhaps a wood foundation would be more acceptable to your budget, manual labor DIY and remote site plans.

    The following link (code) will bring you to the Residential Code for New York State, navigated to Chapter 4, Section 403, Footings, General (scope):

    Chapter 4 - Foundations

    Last edited by H.G. Watson, Sr.; 05-15-2012 at 02:01 PM.

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