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Old 03-05-2017, 09:40 AM   #1
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Building My First Deck - Am I Headed In The Right Direction?


Ok, firstly, this is all new to me. I'm reading books, forums, etc. but I'd like to figure out if I'm headed in the right direction at all. I'm removing an existing deck and redoing it because 1) It's old 2) It's not safe 3) I want to expand the size.

Most of the things I'm reading are telling you how to design and build a deck secured to the house, but as I've started looking at the existing structure and how I think I'll need to construct this, it's seeming more like I will need to do a freestanding deck.

Sorry for any incorrect terminology or lack if information. Please ask me any questions for clarification.

A few things to note first:
- The current deck appears to be laid on a CMU foundation and the blocks aren't filled.
- The current deck sits down about 6" from the house so there's a slight step out of the house onto the deck.
- There's going to be some overhang on the deck, but 60% of the deck will be resting on something and will only be a few feet off the ground at it's highest.

Alright, here are some terrible drawn pictures that aren't to scale.

This is the overall foot print of the current deck area and the location of the house.



The way the deck currently appears to be is that it's freestanding, resting directly onto the CMU foundation. In addition, there is an additional CMU wall running the length of the deck about 6/6.5 feet from the outside edge. The remaining 4 ft or so above that are overhanging and are not supported underneath, instead having 4 foot 2x6's nailed into the side of another 2x6.



The deck seems to be entirely made up of 2x6's of varying lengths and the whole frame appears to be a grid-like pattern vs a traditional beam/joist setup.




So this is where I come in. I want to pull everything up and expand the deck to be a full 50'x15' rectangle. I also plan on utilizing the existing CMU.

If I'm correct, I can't utilize a ledger on the house seeing as it would only support a portion of the deck and doing so would set me up to have my decking go in 50' runs, which I don't want. It looks as though I would need to put my ledger/beam either on top of the far left side CMU. Then I would run my joists down and finish out the deck. This presents another issue of my joists running for 50'. Obviously I'm not going to have a single, 50' joist, so this is what I've come up with. Keep in mind, it's not to scale, I haven't drawn in proper joist spacing or anything, this is just a quick sketch. I haven't laid out a step 1, 2, 3, just a basic overall idea.

Fill the CMU wall on the far left side and place anchors along the wall to anchor what will become my beam to. The reinforced CMU will now act as my footer and post. I will then use 2x10's as my joists, space them 16" and run them no more than 15' before doing one of two things: 1) Using a 2x10 as a header, effectively making a smaller fresstanding deck 2) make another 2x10 beam, secured to a filled portion of the CMU and connecting the joists to that.

I will then repeat the process again, securing 2x10 joists to a 2x10 beam/ledger, running them the proper length, then capping them with a 2x10 header or making another beam in the CMU.

All told, I would make a number of square freestanding decks and either secure the ledgers/headers together, or (adding beams into the CMU) secure the decks to those. The picture below is roughly what I'm thinking. The grayed area in the top right is overhang. Because the 2x10's will be supported by a 2x10 beam that has over 60% rested or secured to a filled CMU wall, I think the overhang would be within limits and not have any bounce considering the structural rigidity of the 2x10s. The vertical lines would either be the 2x10 header being secure to a 2x10 as a ledger, or 2x10's secured into the CMU and anchored together creating a beam. I would also pour footers for the new section of deck and secure the outside joist to it.



Because I'm using 2x10's that aren't exceeding their runs and because I will have the deck either screwed into the CMU or secured into the filled CMU block, I think it would all be structurally sound. For the heck of it I would secure my outside joist to the house on the one section.

I'll admit, as I've typed this all out I think this design won't work. However, with only having a small section of house to attach a ledger to, needing to run the joist top to bottom (in the picture) so as to not have 50' deck runs, and having the CMU wall exist, I'm not sure how else to do this. Like I said, the existing setup is a grid pattern, nailed into each other, and resting on the CMU wall, not resting on any other support. So portions of my deck have started to bow as the nails have let go and everything has settled.

Am I crazy? Is this way out of line? Do I need help?
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Old 03-05-2017, 09:55 AM   #2
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Re: Building My First Deck - Am I Headed In The Right Direction?


My recommendation is to start by talking to the local building inspector to figure out what the code requirements are for your area. If there is no code, my recommendation is to design according to the Prescriptive Residential Wood Deck Construction Guide, available here at no charge http://www.awc.org/codes-standards/publications/dca6

The guide provides an excellent description of every aspect of standard deck construction, including footers, joists, beams, railings, steps, decking. Pretty much everything you need, including nice diagrams with accompanying text. In my town, the Guide is code, your town may be different, but if there is no code, the Guide is a really good resource, and if you follow it, you will not go wrong in my experience.
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Old 03-05-2017, 04:19 PM   #3
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Re: Building My First Deck - Am I Headed In The Right Direction?


+1 on checking with your municipality and using The Guide. If you run your joists 'the other way', you will be able to run them the full 15' length (on top of the requisite beams). The permissible amount of cantilever (overhang) depends species and dimensions of the joist, and I believe this is in The Guide as well.
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Old 03-06-2017, 09:39 AM   #4
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Re: Building My First Deck - Am I Headed In The Right Direction?


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Originally Posted by lenaitch View Post
+1 on checking with your municipality and using The Guide. If you run your joists 'the other way', you will be able to run them the full 15' length (on top of the requisite beams). The permissible amount of cantilever (overhang) depends species and dimensions of the joist, and I believe this is in The Guide as well.
Thanks for the reply. I definitely plan on checking with the city for codes and other requirements. This was a "can I do this or do I need someone else to do it" sort of thing. Just my brain doing some planning.

Speaking to your statement about the joists running the other direction, I am aware of the guide indicating sizing and length for overhang and will consult that accordingly. However, running the joists the other way, wouldn't that result in my decking running 50' down the deck? I would have to use multiple boards per run, right? I'm not going to find 50' decking.
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Old 03-06-2017, 04:41 PM   #5
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Re: Building My First Deck - Am I Headed In The Right Direction?


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Originally Posted by minker17 View Post
However, running the joists the other way, wouldn't that result in my decking running 50' down the deck? I would have to use multiple boards per run, right? I'm not going to find 50' decking.
Yes. I just don't think building a deck frame as a series of adjoining square will be all that strong and your municipality might require footings under each joint even if they allow it. If you run your beams the length of the deck they will have to be from laminated lumber anyway and will probably have to be built in place because a 50' beam will be impossible to handle.
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Old 03-07-2017, 05:56 AM   #6
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Re: Building My First Deck - Am I Headed In The Right Direction?


I don't think you are ready for anything, and would recommend hiring a carpenter.
The least is your block piers. You can't know if you can use them. What you must have are footings, and piers are secondary. You must dig next to the block piers and confirm you have a footing, which must be at least 12". Not sure but maybe you can fill the blocks? And the footings must be every 8' apart, if you use double 2x10 for beams. Sorry didn't check your area but the footings also must be lower than the frost depth of the area.
And it will look best if the decking runs the longer way. As advised, use the beams and cantilever to put down 15' joists over the beams, then run the decking square to the joists. The decking usually does have joints.
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