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

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

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.

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

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

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!!!!!!!!

Originally Posted by Jerry Peck

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.

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).