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Building a 20'x14' deck and would like some expert opinions

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Forum topic by JMG posted 07-03-2009 11:32 PM 2773 views 0 times favorited 18 replies Add to Favorites Watch
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JMG

45 posts in 2003 days


07-03-2009 11:32 PM

Topic tags/keywords: deck tips framing outdoor

I am building a 20’x14’ deck and would like some expert opinions. The deck will be attached to the back of the house. The deck will be 9’-10’ off the ground and the homeowner dosen’t want any posts under the deck, only around the edges. I’ve decided to use 2”x12”x14’ for my joists on a 16” center. Will this carry the load?

-- -Jon


18 replies so far

View Dick, & Barb Cain's profile

Dick, & Barb Cain

8693 posts in 3053 days


#1 posted 07-03-2009 11:49 PM

I searched for a chart, here’s a PDF that may help you.

-- -** You are never to old to set another goal or to dream a new dream ****************** Dick, & Barb Cain, Hibbing, MN. http://www.woodcarvingillustrated.com/gallery/member.php?uid=3627&protype=1

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pommy

1697 posts in 2445 days


#2 posted 07-03-2009 11:50 PM

JMG

2×12’s are fine i would like to know how your thinking to fix to the house if your not using posts and is the area under the decking is this open to be seen as i would look at that sort of area as great storage space and if so the post round the edge would be fine also…...

Andy

-- cut it saw it scrap it SKPE: ANDREW.CARTER69

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patron

13182 posts in 2094 days


#3 posted 07-04-2009 12:05 AM

some were in the middle of the span ,
i would put a row of blocks ,
under a plank for the 20 ’ run .
to keep the joists from ” flipping ” or twisting under any party weight .
i make a story board , about 6’ long ,and use it to mark my loist tops with ,
checking against a string ocasionaly for straight , as planking is not all even .
and start it out side edge with any overhang you want on decking .
and work back t bldg. last plank against bldg. can be scribed or next size up to fit to bldg.

-- david - only thru kindness can this world be whole . If we don't succeed we run the risk of failure. Dan Quayle

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James

162 posts in 2034 days


#4 posted 07-04-2009 12:07 AM

it will carry easily jon. be sure you get that ledger board good and secure against the house, and also be sure to get everything watertight after you are done ripping off siding and reinstalling.

-- James, Bluffton, IN

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JMG

45 posts in 2003 days


#5 posted 07-04-2009 12:08 AM

Thanks for the reply Andy. I am attaching the deck to the house with 3-3/4” tapcon concrete screws paired with posts on both ends of the deck. The homeowner wants the space underneath the deck for a patio and access to the finished basement.

-- -Jon

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JMG

45 posts in 2003 days


#6 posted 07-04-2009 12:10 AM

James, I wish I was ripping off siding, but I’m attaching to brick. Anyone have any better suggestions than 3-3/4” tapcon concrete screws with posts on each end?

-- -Jon

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pommy

1697 posts in 2445 days


#7 posted 07-04-2009 12:12 AM

Dick i just looked at the PDF and wow your building codes are so different over there we still use 4×4’s up to 12’ so i think i will not say to much from now on lol….......

Andy

-- cut it saw it scrap it SKPE: ANDREW.CARTER69

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JMG

45 posts in 2003 days


#8 posted 07-04-2009 12:13 AM

Thanks for the tip David, we’re on the same page with the blocking. Do you think one row will be sufficient, or should I go with 2?

-- -Jon

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JMG

45 posts in 2003 days


#9 posted 07-04-2009 12:20 AM

Thanks for the PDF Dick, I agree with Andy, very different from the way we do it here in SC.

-- -Jon

View ahock's profile

ahock

102 posts in 2077 days


#10 posted 07-04-2009 01:10 AM

The 12’s are fine for the joists…even a little on the strong side (which is good). For the attachment to the house I would use some expansion bolts (it’s basically a threaded rod, with a wedge on the end, some shims in the middle and a nut on the other end. when you tighten the nut it pulls the wedge into the shims and makes it’s own anchor; these are MUCH stronger than tapcons, which aren’t really structural at all). You’ll want to put two anchors a foot in from each end, and then stagger one every two feet (3 inches from top, 3 inches from bottom etc). To clear span the 20’ on the outer edge you’ll have to use a treated glu-lam beam, at least a 6.75” x 16.5” beam (this is the minimum, number from Boise lumber). One each end you’ll probably want to use 8×8’s with a slight taper two feet from the top, then the top foot plumb again at 6.75”, you can get a special metal connector from USP that is a post to beam in galvanized steel to connect the two. OR you can use 8×10 posts with 6.5” cut out of the top to make a ledge for the beam and through bolt the beam and post with 1/2” carriage bolts. You could get away with 6×6’s and a 3.5” thick mortise and tenon into the beam as long as it is 6” long. To make everything cleaner looking, use hangers on the outside as well and hang the joists from the side of the beam. I would encourage you to place rubber on top of the glulam to help prevent water from sitting there and promoting decay. I’d encourage you to put 1/4” spacers between your ledger board and the brick to let water drain through and not decay the ledger board. If you have any other questions feel free to ask! (I’ve done this for awhile…)

-- Andy, PA ~Finding satisfaction in creation

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patron

13182 posts in 2094 days


#11 posted 07-04-2009 01:21 AM

with 2×12 , 1 row should do o/k.

-- david - only thru kindness can this world be whole . If we don't succeed we run the risk of failure. Dan Quayle

View a1Jim's profile

a1Jim

112938 posts in 2330 days


#12 posted 07-04-2009 01:29 AM

Hey Jon
It sounds like you have most of info you need about the only alternative I could think to suggest is depending on what space you have inside the brick wall you could bolt all the way through the wall and have a board inside to have large washers and nuts going through to the outside ledger. In any and all suggestions I would check on your local codes to make sure they conform to your codes.

-- http://artisticwoodstudio.com Custom furniture

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JMG

45 posts in 2003 days


#13 posted 07-04-2009 01:39 AM

Wow, thanks for the info ahock. I didn’t have a good feeling about the tapcons anyway. I have convinced the homeowner to let me use 4 posts across the front of the deck instead of spanning 20 ft but good suggestion on the treated lam beam. I was unaware that they were available treated. I’ve used them quite often in subfloors of FROGs . I will be using 6×6 posts on the four corners, 2 more spaced out on the front, and one in the middle of each side.

-- -Jon

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JMG

45 posts in 2003 days


#14 posted 07-04-2009 01:42 AM

Thanks Jim, I definitely need to refresh myself on those codes

-- -Jon

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jeffthewoodwacker

603 posts in 2557 days


#15 posted 07-04-2009 01:46 AM

I would also recommend what a1Jim did and bolt clear through the brick if at all possible. That is a long span for just one row of posts. Treated lam beam is a good idea and you could consider a 2 foot cantilever.

-- Those that say it can't be done should not interrupt those who are doing it.

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