Deck footing question

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Old 01-19-07, 12:11 PM
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Lightbulb Deck footing question

OK, all decks talk about being put on a footing. I will be using 6x6 posts, the deck is on a hill, back side 1 foot up, front side ( 14 feet out) about 6 feet up. Stand alone deck. PT wood.

So, why can't I just cement the posts into the ground like you do a fence? If I do a 8" cement pillar ( 4 feet in the ground) and put the beam on that, whats stopping the beam from falling over? ( that bracket which you put on top of the pillar to attach the post does not appear to have much lateral stability, especially if the deck is going to be 6 feet up!.

I figured if I cement 4 feet of a 10 foot 6x6 into the ground, that thing will not have any tendency to sway! Otherwise it sounds like I would want to put cross braces on the posts!
 
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Old 01-19-07, 02:41 PM
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Deck footing question

A deck is not like a fence. The fence separates Iowans from intermingling unintentionally. A deck supports Iowans during social and recreational events.

If a fence moves, it is no big deal. If a deck foundation moves, there are big problems to the people on it and the house (if you make the mistake of attaching it).

Your deck footings should go below your local frost level - available from your local building official.

The piers should be concrete, preferably in a Sonotube-type carboard form projecting about 6" above grade. Insert a vertical rebar or two in the form and embed a galvanized piece of hardware to attach a post to. If you do not, your posts will rot out (or collapse) far too soon.

You correctly noted that the steel to concrete connection will not resist rotation, so you will need some lateral bracing for the deck. The amount and placement can be up to designer. You will probably need drawings to get a permit anyway.

Many people have been killed because of poorly designed or constructed decks, so it is foolish to waste your free labor on doing it wrong. A deck 6' high that is 14' out may have many people on it depending on the length along the house. I think the record for injuries on a residential deck is about 30.

Dick
 
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Old 01-19-07, 08:24 PM
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CanadianInIowa,

Like Dick said, a deck is a deck, and a fence is a fence. (He'll forgive me if the quote wasn't perfect!!) There's NO WAY that you build them the same!! Fences support the birds that land on them -- decks have to support the PEOPLE that walk on them.

First, you don't bury the posts in concrete. You pour the footings and embed POST BASES in the concrete. Then the posts are set in the bases.

Iowa -- you are probably dealing with frost. The footings have to be deeper than the frost line in your area.

6 feet up -- you HAVE to have railings, and a permit to construct it is going to be a must. Draw a plan; get it approved and pull the permit; build it according to the plan; the inspector passes the work and you are home free.
 
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Old 01-22-07, 07:28 AM
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thanks Concretemasonry and Lefty:

I'm use to fences only having to keep out the bears!

I thought I'd ask because the home-depot's deck S/W program provided that option. I was going to use the cement forms, but did not think of putting re-bar in them!

and yup, it will be going 4 feet down and of course the deck will have a railing ( I think it had to be 4 feet high, as it it so high off the ground!). I'm not in a city (where it is being built), and there are no permits needed in my area ( except for septic and wells). But I still will do it correctly, being a big deck, I dont want to have issues.

I'm reading my deck books and ensuring that I design it correctly. Just asking questions where things dont make sense. I have until the spring to get the plans correct (And safe).

I find this forum very helpful in answering questions/ learning other peoples mistakes, and other helpful stuff.

Till my next question.
 
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Old 01-22-07, 07:30 AM
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thanks Concretemasonry and Lefty:

I'm use to fences only having to keep out the bears!

I thought I'd ask because the home-depot's deck S/W program provided that option. I was going to use the cement forms, but did not think of putting re-bar in them!

and yup, it will be going 4 feet down and of course the deck will have a railing ( I think it had to be 4 feet high, as it it so high off the ground!). I'm not in a city (where it is being built), and there are no permits needed in the area ( except for septic and wells). But I still will do it correctly, being a big deck, I dont want to have issues.

I'm reading my deck books and ensuring that I design it correctly. Just asking questions where things dont make sense. I have until the spring to get the plans correct (And safe).

I find this forum very helpful in answering questions/ learning other peoples mistakes, and other helpful stuff.

Till my next question.
 
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Old 01-23-07, 07:23 PM
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I'm confused:


I came across a reply that Lefty made to a TooTall regarding Deck Sturdiness back in '06: he was taking about a deck, which wobbled.

He stated:"The deck is about 8.5 ft off the ground. I went with the 6x6 posts and I didn't cement them into the ground wich I'm regretting. I used steel feet on them and bolted the feet into about a 3ft deep auged hole filled with cement. "

Which is what I think Lefty is now suggesting, but then Lefty added:



".....Your post or column bases should have been EMBEDDED in the footing, not bolted to it. (That requires a different base than what you used.)"


This leads me to think ( at least at the time) it was OK to put the posts in to the cement ( perhaps not to the bottom like a fence post).

Just want to clarify, because I went to two different lumber yards and both said that placing the post into the cement is OK. Since where I am putting the deck up needs no permits, not sure were to go to get answers.
 
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Old 01-24-07, 03:03 AM
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Nothing to be confused about -- Too Tall used the wrong post bases. He used something like an ABU, which is bolted to the top of a footing after it has cured. I told him that he should have used something like a CB or CBSQ, which is embedded in the wet concrete.

I don't bury wood in concrete. Once it starts to rot and loosens up, you have no way to replace it.
 
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Old 01-24-07, 06:01 PM
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Thanks, Sounds like I have to get up on deck lingo ;-)
 
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Old 01-24-07, 06:19 PM
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CDN in IA,

There's a WHOLE lot more to a deck that just slammin' boards together!!

Do you see the difference in the footings that Too Tall was talking about and what I'm talking about? If so, fine. If not -- keep picking my brain!

Mike
 
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