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second story deck support

Started by Wood Toucher, August 21, 2014, 08:29:55 AM

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Wood Toucher

I've been looking for plans for wood support brackets for a second story balcony.  The house is a raised 1.5 story with full foundation out of the ground.  Dirt to deck is over 18 feet and we don't want to use posts.  Are there drawings for an L shaped support with 45 degree brace someone has for this purpose?  Deck will be small 4' x 8' or so.  I've been a lurker for a few years and finally had a question worth asking.  Thanks.

jueston

if you put some kind of 4 foot bracket under the deck, you would certainly need to reinforce the wall in which you are attaching that brace....

and if your going to open up the walls for that, then you might consider what has became all the rage in new construction decks lately, removing the rim joist, and sistering the floor joists with PT 2X's and then cantalevering those 2X's out of the side of the house.

random internet picture of what i'm talking about:

Wood Toucher

Thanks Jueston, we would normally go that route except the second floor joists run the wrong way.  We would be providing vertical wood framing members in the wall to support the bracing and loads from the balcony, too.  We envision bolting the supports thru the board and batten siding and thru the wood framing in the wall to support this load.

Wood Toucher

We have another deck on the adjacent side of the house which we would like to sister the 2 x 8 joints for a 4 foot wide balcony.  What's the rule for the distance the joist has to be sistered for each foot of cantilever?

beenthere

Any local building code you have to follow?
That would be one minimum if so.

Don't know of a "rule" for cantilever when sistering on to joists.  Are they 2 x 8 joists now? As well, a 2 x 8 rim board?

Your location in your bio (profile) would help a lot. ;)

south central Wisconsin
It may be that my sole purpose in life is simply to serve as a warning to others

jueston

from 2012 IRC:

Quote
ABLE R502.3.3(2) CANTILEVER SPANS FOR FLOOR JOISTS SUPPORTING EXTERIOR BALCONYa, b, e, f

Member Size   Spacing   Maximum Cantilever Span
(Uplift Force at Backspan Support in lb)c, d
Ground Snow Load
                        ≤ 30 psf   50 psf   70 psf
2 × 8         12″   42″ (139)   39″ (156)   34″ (165)
2 × 8         16″   36″ (151)   34″ (171)   29″ (180)
2 × 10   12″   61″ (164)   57″ (189)   49″ (201)
2 × 10   16″   53″ (180)   49″ (208)   42″ (220)
2 × 10   24″   43″ (212)   40″ (241)   34″ (255)
2 × 12   16″   72″ (228)   67″ (260)   57″ (268)
2 × 12   24″   58″ (279)   54″ (319)   47″ (330)

For SI: 1 inch = 25.4 mm, 1 pound per square foot = 0.0479 kPa.
a. Spans are based on No. 2 Grade lumber of Douglas fir-larch, hem-fir, southern pine and spruce-pine-fir for repetitive (three or more) members.
b. Ratio of backspan to cantilever span shall be at least 2:1.
c. Connections capable of resisting the indicated uplift force shall be provided at the backspan support.
d. Uplift force is for a backspan to cantilever span ratio of 2:1. Tabulated uplift values are permitted to be reduced by multiplying by a factor equal to 2 divided by the actual backspan ratio provided (2/backspan ratio).
e. A full-depth rim joist shall be provided at the unsupported end of the cantilever joists. Solid blocking shall be provided at the supported end.
f. Linear interpolation shall be permitted for ground snow loads other than shown.

the formatting didn't work out that good, i got it from:
http://publicecodes.cyberregs.com/icod/irc/2012/icod_irc_2012_5_par017.htm

Wood Toucher

2 x 8's are the floor joists in the house at 16" o.c.
The house is my daughter and son-in-law's in rural Ohio with no codes except for the bank's "inspection".
They are finishing a shell house on the inside and wanted to put decks where they have french doors.

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