Deck support posts


Old 07-25-09, 11:11 AM
TBramblett's Avatar
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Question Deck support posts

I want to add a small (10' by 10') deck in my very sloped back yard. I think I can do the decking and support members, but I am not sure I have the skill to set the posts in concrete and get them leveled. Would I contract with a regular deck building company and just have them do the post part of the job? Or what other kind of contractor would do that if not a decking outfit?

A related question is how long an unsupported span of top decking is OK? If I use 5/4 thick, 6" wide top planks, will a five foot span be OK, or would they flex under normal weight?

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Old 07-25-09, 11:33 AM
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The footings don't require any special skills, as long as you know how to use a shovel and can mix redi-mix concrete.
Figure out the location and size of the footings, dig them and pour the concrete. Sonotube up about 6" to a foot and set a post base or column base in the wet concrete, inside the sonotube.

After they have cured a day or two, you can attach your posts. Level isn't difficult -- get the 4 posts in place and use a level and long straight edge or a string level and cut them off even.

Span of the deck boards depends on what you are using. 5/4 decking spans 16" or less. 2X6 spans 24" or less. Composite -- follow what the mfgr. says.
Old 07-25-09, 11:42 AM
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The hardest thing about footings is getting them in the right spot and digging the holes. For a 10' x 10' you will likely only need 2 or 3 holes depending your beam. This deck is a good size to "get your feet wet". Do some research on line or book stores and I bet you can do the whole thing.

Like Lefty posted, 5/4 over 16"oc joists, 2x6 on 24" or less. I suggest 16"oc joists because it will give you a more solid feeling deck.
Old 07-25-09, 11:45 AM
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Received 2 Votes on 2 Posts shouldn't set deck posts IN concrete. You should pour concrete into a hole (expanded out at the bottom) below the frost line for your local area (check with your inspecters office), and put a standoff base into the concrete before it cures. Something like one of these.....

And I'm not being rude, ok, but if you have to ask about that kind of span for the deck may not really be ready for this project w/o some onsite guidance.
A 5/4 deck board is only 1" thick and will need support at least every 16", in some cases as little as 12". I've seen decks built with 24" spacing and they are like trampolines.

I'd suggest some of the basic softcover books on deck construction available almost anywhere, or a visit to the library.

Also, almost any home center or lumberyard has deck design software on a computer that can print out drawings, specs, and materials lists.

This site is very good for answering specific questions and troubleshooting problems. But a project from scratch like this may be a bit tough. If you are willing to wait a while, someone may have a saved primer on decks they can post.

Good luck!
Old 07-25-09, 01:51 PM
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I agree with Gunguy, read a lot, first. This should get you started, hit the ones with "Limited preview" under the title: deck building - Google Books

Do you know your frost depth?

Frost heaving sono tubes: Building a deck: expert advice from ... - Google Books

Be safe, G

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