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  1. #1
    Join Date
    May 2010
    Location
    IL
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    36

    Default Dug out crawl space

    I am looking for some guidance. I have run across this situation in older homes. The home was originally built on a crawlspace, footings in our area go down 42". A home owner at some point in time decided to dig out the crawl to make a basement. Typicaly I see approx 24" of soil left on the inside of the existing wall. Sometimes it is finished either poured or block and sometimes left exposed as in the photo.

    Does anyone know of any reference material as to what is considered a good or safe dug out?

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  2. #2
    Join Date
    Mar 2007
    Location
    Connecticut
    Posts
    1,828

    Default Re: Dug out crawl space

    Footings should not be exposed or undermined, as they appear to be in that photo, and ANY home that has had modifications to the sub structure needs to be checked and OK'd by a structural engineer.
    That foundation would have to be resupported from below to comply with today's standards now that they have bastardized it, and in the midst of trying to save it, the whole wall will end up being replaced.
    Why leave a loose stone wall above a nice new foundation


  3. #3
    Join Date
    Feb 2009
    Location
    Southern Vancouver Island
    Posts
    4,546

    Default Re: Dug out crawl space

    The "Angle of Repose" comes to mind for that. Try a Google search.

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

  4. #4
    Join Date
    Mar 2007
    Location
    NoCal
    Posts
    237

    Default Re: Dug out crawl space

    Sure looks like that foundation has been severely compromised.
    Recommend structural engineer for that one


  5. #5
    Join Date
    Oct 2010
    Location
    Tolland, CT
    Posts
    33

    Default Re: Dug out crawl space

    rule of thumb is for every foot down below the footing you need 1.5 ft horizontal. so for instance 4 feet below the footing you would need 6 feet away from the footing leaving that much fill to support the weight.
    Again this is a rule of thumb and anything that might change structural integrady should be done by qualified engineers.

    Mike

    Quote Originally Posted by Bill Penn View Post
    I am looking for some guidance. I have run across this situation in older homes. The home was originally built on a crawlspace, footings in our area go down 42". A home owner at some point in time decided to dig out the crawl to make a basement. Typicaly I see approx 24" of soil left on the inside of the existing wall. Sometimes it is finished either poured or block and sometimes left exposed as in the photo.

    Does anyone know of any reference material as to what is considered a good or safe dug out?



  6. #6
    Join Date
    Mar 2007
    Location
    Oregon
    Posts
    2,365

    Default Re: Dug out crawl space

    Different guidelines for different soil types - 45 degrees of undisturbed soil is the one I've seen most. Some say go laterally 1 foot then apply the 45 degrees. I've seen engineers bless much steeper angles but it's a case by case basis depending on the soil.

    Not much of a question for the one pictured - it needs support. Realistically, it's not any big mystery. There just needs to be a foundation poured to retain the soil cut.


  7. #7
    Join Date
    Mar 2007
    Location
    Ormond Beach, Florida
    Posts
    26,243

    Default Re: Dug out crawl space

    Quote Originally Posted by Matt Fellman View Post
    Different guidelines for different soil types - 45 degrees of undisturbed soil is the one I've seen most. Some say go laterally 1 foot then apply the 45 degrees. I've seen engineers bless much steeper angles but it's a case by case basis depending on the soil.

    Not much of a question for the one pictured - it needs support. Realistically, it's not any big mystery. There just needs to be a foundation poured to retain the soil cut.
    45 degrees, or 1/1 (one foot down, one foot out from footing) is a good rule of thumb.

    However, different soil types have different angles of repose, some are actually greater than 45 degrees (greater than 1/1, some types might be 1 foot down and 1-1/2 feet out, as stated above).

    For swimming pools, the typical design is 1/1+1, i.e., one foot out for every foot down, then one more foot out. That means if you go down 5 feet, you go out 6 feet (5 feet + 1 foot).

    If the pool is closer than that to the house footing, typically the steel is doubled both ways, i.e., instead of on a 12" x 12" grid, the steel is now on a 6" by 6" grid in the area of the pool which falls within that 1/1+1 area.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  8. #8
    Join Date
    Jun 2010
    Location
    West Chester PA
    Posts
    166

    Default Re: Dug out crawl space

    Quote Originally Posted by Jerry Peck View Post
    45 degrees, or 1/1 (one foot down, one foot out from footing) is a good rule of thumb.

    .
    For the Architect and Engineer that works with me, this is the general standard....

    Deviations, require review with additional recommendations...


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