Deck posts

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Apache53
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Joined: Wed Apr 03, 2019 1:41 am

Deck posts

Post by Apache53 » Fri May 24, 2019 10:40 am

I am adding a deck to my home, Deck size is 8'x 16' & want to use 4x6x10' posts on 4' centers that will also support roof at later date I live in Aberdeen WA & a wet climate will be using post & pier, Ea. pier block has a 16x16x2 concrete paver underneath.
My question is can post (4x6 X 10') not PT, sit on pier block W/bracket attacked Posts will sit in bracket, & have 2 2x6 PT at approx 40" tall bolted to bottom of post or sister-ed they will sit on the concrete pier block, To support the beam 2-2x8 PT that will support the joists ?

PT = Pressure Treated

DanM
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Re: Deck posts

Post by DanM » Fri May 24, 2019 2:12 pm

If you're planning on supporting a roof pier blocks are not good enough, you need to dig down and pour proper footings in the ground. The blocks can't support much weight, and they really don't offer much stability for a deck + roof. Also, spend the extra money to make your posts PT lumber. You live in the pacific northwest and get loads of rain which can very quickly start to rot untreated wood. Those posts are going to be supporting a roof and I'm going to go out on a limb and guess that you'd rather the roof doesn't collapse a couple of years after you build it.

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A. Spruce
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Re: Deck posts

Post by A. Spruce » Fri May 24, 2019 9:52 pm

In addition to what Dan offered, how you do your supports will dictate how the structure is built. Building on top of the ground, via piers, you do not get any structural stability from the ground, other than dead weight support. This means that the roof will have to have knee braces between posts and header to prevent racking. Not a big deal, but something that must be done if you want the roof to stay where you build it.

The alternative to knee bracing would be to set the posts in the ground, encased in concrete. In this scenario you are getting structural stability from the ground, so you won't need the knee bracing. The downside is, buried posts eventually rot, regardless of being pressure treated or whatever else one might do to try to mitigate the eventuality of rot. Because of this, I'm not a fan of buried posts for structures. If you're willing to work with an engineer or architect, they can probably design something less obtrusive than knee braces, but this does add expense.
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gcytryn
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Joined: Fri May 31, 2019 6:39 pm

Re: Deck posts

Post by gcytryn » Fri May 31, 2019 6:51 pm

I saw your video "How to build a deck" beam/posts/ledger. I would like to build a deck that is 24 feet wide and 14 feet deep. I am attaching it to the house using ledger board and want to minimize the number of posts, since due to the winter freeze, they need to be dug 6 or 7 feet into the ground. My question is: What size boards should I use for the beam (2X8 or 2X10) if I want to do it the way you show in your video having only one beam..... and what size the deck joists be (Will 2X8 be enough?) Thanks, Glen

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Shannon
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Re: Deck posts

Post by Shannon » Sat Jun 01, 2019 8:17 am

You should be able to do 2x8 joists 16' O.C and a span between house and beam of 12'.
if you only want 3 posts you could go 3 ply 2x10 with a max span between centre of posts of 10'.
The beam would cantilever past the outer posts a max or 24"
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