Deck design recomendation


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Old 04-17-16, 05:02 PM
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Deck design recomendation

I am in the process of removing a cantilevered deck due to rot & am considering converting to a post and beam design. The deck size is aprox 19'x4' & about 4' above ground. I am looking for a design that will not block the basement window below the deck. I feel a beam that is really wide might look crowded & block the window. I also need a configuration that will not put a post in front of the window. Any ideas would be great as I'm not sure what the best option is. (Pic of current deck) https://db.tt/EsEJ4XLV
 
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Old 04-17-16, 06:19 PM
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What's rotten?
Just the decking, floor joist, the wall?
No location in your profile so where all going to have to guess on what to do and how to do it.
How far is that deck below the door threshold?
 
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Old 04-17-16, 06:24 PM
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Your deck looks to be floating with no visible supports other than some cantilevered beams coming from outside the house. Give more information on the rot. But to change to a traditional deck, that needs support on the perimeter of the deck, you definitely will have supports and beams that obstruct your view from below. There just is no other way around that.
 
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Old 04-17-16, 07:14 PM
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I don't know that I would go for free standing in your case. Adding a new rim joist, then a properly flashed ledger with only a beam in front, along with 4 posts (spaced on either side of the window) would be fine, IMO.

If you go with a free standing deck, you still need a new rim joist and flashing there... and your posts in back would simply be to either side of the window and would match those in front. 8 posts total... with a beam sitting on each set of 4 posts, joists between the beams in joist hangers.

See http://www.awc.org/pdf/codes-standar...Guide-1405.pdf
 
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Old 04-17-16, 07:33 PM
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I would say the deck is about 2" below the threshold. I Live in Vancouver BC. The rot is on the ends of the joists with areas of rot on the surface, several joists have already been partially removed & replaced with sisters 2x10 nailed on. The deck itself was original construction & is an extension of the house floor joists.
 
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Old 04-17-16, 07:45 PM
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I have removed all the deck boards & cut back rotten joists (may have been a little over zealous with the saw but what is left is solid) I am considering cutting it back flush to the house & weatherproofing. If I do I will not have a house rim joist to attach the ledger to, just floor joists & blocking. Can I attach a ledger to the top plate to support that side of the deck? https://db.tt/0wezb9Pd
 
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Old 04-17-16, 08:34 PM
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To install a rim joist, you cut all the joists back an additional 1 1/2" beyond the exterior side of the sill plate, (a Fein Multimaster- or similar- is quite handy for this) and cap the cut ends with your continuous rim joist, which takes the place of all the individual pieces of blocking that are currently between your cantilevered joists. You then install flashing and bolt the new ledger to the new rim joist and use at least 2 lateral tension devices to connect the interior joists to the exterior joists. That is what I would suggest you do.
 
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Old 04-17-16, 09:01 PM
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Xsleeper - thank you for your suggestion. I had never heard of lateral tension devices, they look like an interesting solution. I'll have to look into that. Thank you.
 
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Old 04-18-16, 12:17 PM
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You do realize that even if you use "lateral tension devices" you're going to have to support the exterior side of the deck don't you? Xsleeper made some great suggestions and definitely give advice that you should follow. To support the exterior side of the deck you could put 4 posts in, one at each end and then 2 additional 1 spaced so they are outside of the window. You should still be able to use a beam on top of them not much taller if any then the present rim joist you have on the outside of the deck. You could then attach the new joists it using joist hangers.
 
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Old 04-18-16, 02:02 PM
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Could have sworn I said that.
 
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Old 04-18-16, 08:58 PM
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I realize I will have to use support posts in the front. Using a beam on top of the posts with joist hangers is a great idea. Any way I could use a beam that would allow for two support post. That way I would avoid a post in front of the window & keep things open. (Dimensions 19' x 4')
 
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Old 04-19-16, 04:00 AM
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The answer is no, post number 4 gives you the code book on decks and inside is the maximum beam span tables for various dimensional lumber. No where is there a span greater than 15 ft which would be a double 3x12. So, a single 19' long beam is not going to happen (at least not on a deck built to code).
 
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Old 04-19-16, 01:42 PM
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Is it true you can cantilever the beam 1/4 of its back span? Would I be able to do a 15' span with a tripple 2x12 & cantilever 2' onto each end for a total span of 19'?
 
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Old 04-19-16, 03:17 PM
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Yes, that is probably an option... *if* you use SYP 2x12s and your joists are only 6' long. Your posts could "probably" be 14' on center if your joists need to be 7' long. But as originally mentioned, you will have a stronger deck if you use 4 posts, and just space them far enough apart that they do not block the window. You would want to be sure you are using Simpson A6 post/beam connectors. And you will need to sandwich two layers of 1/2" treated plywood ripped 11" wide between your 2x12s, so that once your 2x12s are tripled, the beam will be exactly as wide as your 6x6 post is.

You will also want to get your plan approved by your local building department / inspector, if applicable. He, not anyone online, will have the final say.
 
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Old 04-20-16, 09:00 AM
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Xsleeper - thank you for all the input. I'll have to really evaluate my desire for two posts. At least now I have some options. Thank you to everyone for their suggestions.
 
 

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