Just wanted to double check before laying out a deck saturday – I’ve looked at the tables already. 14′ x 22′ deck, second story, 2×8 joists. I plan on having two beams going across – one at 4′ from the house, one at 8- and having a 2 foot cantilever at all sides. I’d like to go with three posts on each beam, having a 9ft unsupported span. I was thinking a tripled up 2×12 beam would be way more than enough. Maybe even a triple 2×10? This is my first second story deck, and I want it *strong* (but not “clunky”)!
Oh yeah, and while I’m thinking- for any of you deck experts- do you put tar paper over the tops of built up beams for moisture protection, or leave as is? I’m in the mid atlantic.
Thanks all!
Replies
Is there some reason you can't attatch the deck to the house with a ledger and use just one beam?
Al Mollitor, Sharon MA
Yup - the house jogs out 2 ft in one section (1/3 of the length) as an overhang. I'm leery to put a load on something that is already cantilevered (plus the code doesn't allow it, as I understand it). I figured I would just continue the beam, which would permit me to use 2x8 joists rather than 2x10 for the 12 foot span I would have with only one beam.
Check out http://handymanusa.com/articles/tables.html Good reference for post, beam and joist spacing.
regards
Maybe I`m doing the math wrong.....I`m assuming the 14' measurement is off the house. If the second beam is 8' off of house, you`ve got a 6' cantilever.
J. D. Reynolds
Home Improvements
"DO IT RIGHT, DO IT ONCE"
My bad- should be another 8 ft- so a beam at 4 ft, and a beam at 12 feet from house . . .
I'm in the land of 4x beams but if you have to use 2x's I would triple a 2x12 because if you are going to have a 2' cantilever on a 14'x24' deck your beams will span 10' not 9'. (24'- 4'=20' divided by 2 = 10')
Putting 15# felt on top of your tripled up 2 x12 will definitely help detour trapping water between the joists.
Bob
"Rather be a hammer than a nail"
I was hoping I would get a response from you! This is my first "real" deck - and I want it done right, especially since I am doing it for a friend. The deck is actually 16x22- looked at the site today, minus 2 ft here, add 2 ft there. So 9ft spans . . . but I might still go with the triple 2x12. What is your feeling on a beam with spacers in between? I looked at a deck that was done by the man they were going to hire ("professional") that was roughly the same size, but used 2 2x12 with a 2x4 spacer for the two beams parallel to the house. . .is that even kosher??
Thanks!
A double 2x12 at 9' span should be plenty. Your "professional probably used 2x4 spacers because they were treated and much less expensive than treated 1/2" plywood spacers. Two 2x's and 1/2" plywood = 3 1/2" which gives you a beam that is easy to gusset while sitting on top of a post.
If you don't have to span 10' and only span 9' you should be alright using this method.
Bob
"Rather be a hammer than a nail"