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  1. #1
    Brian E Kelly's Avatar
    Brian E Kelly Guest

    Default Length of Deck Joyces

    I did an inspection last night and there was a back deck with 2 x 8 pressure treated joyce that were only supported by end supports one bolted to the house and the other to a concreted cemented post cross beam. The length of the joyce's was 14' 4" and my question is is this enough proper support. I was taught along time ago if it looks strange it primely is wrong. Any input would be appreciated.

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  2. #2
    Join Date
    Apr 2007
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    gainesville fl
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    122

    Default Re: Length of Deck Joyces

    Brain,
    That seems like a pretty far stretch for any woman.

    That does sound like a bad example of what a deck should be.


  3. #3
    Join Date
    Mar 2007
    Location
    Colorado Springs, CO
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    Default Re: Length of Deck Joyces

    I think you mean "joist". Joyce is a woman's name.

    The allowable span for a 2X8 depends on the design loads, OC (on center) spacing between joists and the species and grade of the wood. The 2003 IRC Table R502.3.1(1) gives the following Maximum Spans for 2X8 joists (assuming DL (dead load) = 20 psf & LL (live load) = 40 psf):

    Species Grade Joist Spacing Max Span
    Doug Fir -Larch
    #1 12" 14'-2"
    #2 12" 13'-3"
    #3 12" 10'-0"
    #1 16" 12'-4"
    #2 16" 11'-6"
    #3 16" 8'-8"
    Hem-Fir
    #1 12" 13'-10"
    #2 12" 13'-1"
    #3 12" 10'-0"
    #1 16" 12'-0"
    #2 16" 11'-4"
    #3 16" 8'-8"
    Southern Pine
    #1 12" 14'-5"
    #2 12" 14'-2"
    #3 12" 10'-10"
    #1 16" 13'-1"
    #2 16" 12'-4"
    #3 16" 9'-5"
    Spruce-Pine-Fir
    #1 12" 13'-3"
    #2 12" 13'-3"
    #3 12" 10'-0"
    #1 16" 11'-6"
    #2 16" 11'-6"
    #3 16" 8'-8"

    The only case where a 14'-4" span is allowed for a 2X8 joist is using Southern Pine #1 at 12" OC.

    Hope this helps.

    (Does anybody know how to make a table here where the columns line up under their heading?)

    EDIT

    These maximum spans assume the joists are in "perfect" condition. As we all know, deck joists are prone to rotting along their top edges. As soon as these joists start to deteriorate their allow spans go WAY down.

    Last edited by Bruce Breedlove; 08-16-2007 at 02:39 PM.
    "Baseball is like church. Many attend but few understand." Leo Durocher
    Bruce Breedlove
    www.avaloninspection.com

  4. #4
    Join Date
    Mar 2007
    Location
    Knoxville, TN
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    2,332

    Default Re: Length of Deck JOISTS

    OMG .......... Joyce's?????


  5. #5
    Join Date
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    Ormond Beach, Florida
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    25,314

    Default Re: Length of Deck Joyces

    We used to live across the street from a Joyce, she was the typical "dumb blonde" if ever there was one.

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

  6. #6
    Richard Rushing's Avatar
    Richard Rushing Guest

    Default Re: Length of Deck Joyces

    Yep... there 'ever was' some blonde jokes:

    Blonde Joke

    A young blonde from Louisiana was on vacation and driving through the
    Florida Everglades. She wanted to take home a pair of genuine alligator
    shoes in the worst way, but was very reluctant to pay the high prices
    the local vendors were asking.

    After becoming very frustrated with the "no haggle on prices" attitude
    of one of the shopkeepers, the blonde shouted, "Well then, maybe I'll
    just have to go out and catch my own alligator, so I can get a pair of
    shoes for free!" The shopkeeper said with a sly, knowing smile, "Little
    lady, go give it a shot!"

    The blonde headed out toward the swamps, determined to catch her an
    alligator.

    Later in the day, as the shopkeeper was driving home, he pulled over to
    the side of the levee where he spots that same young woman standing
    waist deep in the murky bayou water, shotgun in hand. Just then, he
    spots a huge 9 foot gator swimming rapidly toward her. With lightning
    speed, she takes aim, and nails it right between the eyes and hauls it
    onto the slimy bank of the swamp. Lying nearby were 7 more carcasses,
    all lying on their backs.

    The shopkeeper stood on the bank, watching in silent amazement. The
    blonde struggled and flipped the gator onto it's back. Rolling her eyes
    heaven-ward and screaming in great frus! tration, she shouts
    out............................................... ......................
    ......................
    .................................................. ......................
    .......................

    "****...THIS ONE'S BAREFOOT TOO!!!!!!!!



  7. #7
    Join Date
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    Oregon
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    2,365

    Default Re: Length of Deck Joyces

    Quote Originally Posted by Jerry Peck View Post
    We used to live across the street from a Joyce, she was the typical "dumb blonde" if ever there was one.
    Dumb blond might almost infer cute.... whenever I hear about Joyces I always think about two women on their way to bingo on a Friday night in a Monte Carlo, smoking long brown cigarettes with all of the windows rolled up.


  8. #8
    arthur yates's Avatar
    arthur yates Guest

    Default Re: Length of Deck Joyces

    Bruce: I thought it would be a simple as preparing a "Word" Table; going to the "Tables & Properties" and then to "Borders and Shading" and then "Setting":... Select "None". Boy! was I wrong. When I went to paste this document in this posting, I lost most all of the formatting I had accomplished

    2x8 Deck Floor Joists with 10 psf Dead load and
    40 psf Live load; Allowable deflection = L/360

    Joist Spacing Specie Grade Allowable Span
    12 Douglas fir-larch #1 14-5
    do. do. #2 14-2
    do. do. #3 11-0

    16 Douglas fir-larch #1 13-1
    do. do. #2 12-7
    do. do. #3 9-6
    Joist Spacing Specie Grade Allowable Span
    12 Hem-fir #1 13-10
    do. do. #2 13-2
    do. do. #3 11-0

    16 Hem-fir #1 12-7
    do. do. #2 12-0
    do. do. #3 9-6
    Joist Spacing Specie Grade Allowable Span
    12 Southern Pine #1 14-5
    do. do. #2 14-2
    do. do. #3 11-11

    16 Southern Pine #1 13-1
    do. do. #2 12-10
    do. do. #3 10-3
    Joist Spacing Specie Grade Allowable Span
    12 Spruce-pine-fir #1 13-6
    do. do. #2 13-6
    do. do. #3 11-0

    16 Spruce-pine-fir #1 12-31
    do. do. #2 12-3
    do. do. #3 9-6

    Just a few observations:
    1. The typical dead load for wood decks is 10 psf, not 20 psf.
    2. Don't forget the adjustment factors when using code span tables. These tables don't take into consideration incising factors applicable to the western woods (all of the above except for Southern Pine). That factor reduces the allowable stress 20% to an effective stress of 80%.
    3. Another adjustment factor critical to wood deck joist is the "Wet Service Factor -Cm". In general that factor reduces the allowable stress still further by another 15%.

    Since allowable stress and allowable span are not one in the same, Use the following rule for taking into consideration the wet service factor:
    Length(wet) = 0.92 Length(dry).


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