How far can a double 2x10 beam cantilever over the cement footing

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  #1  
Old 04-04-06, 08:15 AM
deckgrasshopper
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How far can a double 2x10 beam cantilever over the cement footing

Timely question as I am having my holes dug this weekend!

The plans I submitted (and were approved) show that my cement footings will be 2 feet in from the edge of my main beam. The beam will be 2 - 2x10's nailed together with 1/2 inch spacers to make the width exactly the same as the 4x4's they will stand on.

I read in my book this morning that one shouldn't cantilever a beam more than its width (9.5 inches) over the end of the cement footings.

Can someone help me here? I have to flag my footing holes this week so that the guy can drill this weekend....its a pretty easy fix to do now...not so easy later.


(an example)

I have a 12 foot beam. I have it permitted as 2 footings - one at 2 feet and one at 10 feet. The 8 foot span in the middle is the maximum permitted for 2- 2x10's.

If I have to move my footers to 1 foot and 11 feet, I will need to add a third hole in the middle (at 6 feet) to keep the spans <=8feet.

Thanks very much!



(Project update: Flashing and ledger on, stringers are up)
 
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Old 04-04-06, 08:39 AM
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Where did you read that about the cantilever??

You're fine at 2', but don't go anymore than that.
 
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Old 04-04-06, 08:54 AM
deckgrasshopper
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book

Lefty -

Thanks for your quick reply. I read elsewhere that 2' is OK....but, thus far - this book has been my bible (and its where I read about cantilever for beam = width of beam):

Building a Deck (Build Like A Pro) (Paperback)
by Scott Schuttner

Its an awesome book and I would highly recommend to any inexperienced DIY'er like myself.

That and a computer to access this message forum.

Thanks again Lefty!


PS - Just to be sure Lefty - I'm NOT talking about the standard 2' cantilever of JOISTS over the beam..that I know is ok. I'm specifically talking about the beam over the ends of the foundations. Let me know if I miscommunicated in the first email.

Hopper
 
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Old 04-04-06, 09:04 AM
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You're fine -- you can cantilever the JOISTS 2' and the BEAM 2'. I do it all the time. I don't go any farther than that, but some builders do. I've done hundreds of deck repairs with longer cantilevers -- some as far as 4'. Not the way I build a deck, but ...
 
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Old 04-04-06, 09:37 PM
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IHI
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Also, save yourself the time and trouble building the beam that way if using 4x4's. upgrade your posts to 4x6's and then notch the 4x6 post so the 2x10's can be fastened to each other with no spacer and then they will sit on top of the notched section of 4x6. Run your 1/2" x7" stainless steel carriage bolts through the piece of remaining 4x6 and both 2x10's.

It's save alot of hassle and be just as if not stronger.
 
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