Deck post footing question

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Old 05-13-09, 08:07 PM
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Deck post footing question

The code I'm building under in my city require the following - "deck footings closer than 5 foot to an existing exterior house wall must bear at the same elevation as the footing of the existing house foundation"

My question is, does "must bear at the same elevation" mean the bottom of the deck footing has to be the same depth as the one for the house?
 
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Old 05-13-09, 08:27 PM
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The way you are spelling it out means the "top" of the footing of the deck must be no higher or lower than the footing of the house if within 5' of the house. The deck footing will probably be deeper than the foundation footing. Not sure which location you are in (no profile filled out), but it may help.
 
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Old 05-13-09, 08:29 PM
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Deck post footing question

Yes, that is what it appears to mean.

It is good assuming the house foundation was built at the minimum frost depth. If the house footings were deeper than the minimum, an inspector may give you a go ahead to put the bottoms for concrete piers at just the frost level.

This will insure that your deck does not heave up and create problems at doors, etc.

Is there anything required about the piers further away than 5'? It could be bad if they were not deep enough and heaved upward, causing the deck drainage to go back toward the house instead of away from the house, which is normally desired. - That could create problems with the house foundation.

Dick
 
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Old 05-13-09, 08:33 PM
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Originally Posted by tenn1 View Post
The code I'm building under in my city require the following - "deck footings closer than 5 foot to an existing exterior house wall must bear at the same elevation as the footing of the existing house foundation"

My question is, does "must bear at the same elevation" mean the bottom of the deck footing has to be the same depth as the one for the house?
As a builder this is why I HATE how codes are written. Ought take someone out back and flog them.....

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I would get back to the inspector. If that code is taken literally that would mean a full basement is 8' and the deck footers would be 8'+ If we go the other direction and the deck is on sloped ground 5' away from house then the footings would be up in the air a piece to match the house if the top of that footer is to be at the same elevation as the houses.

Let me really mess everybody up here. If we pour a footer and laid block for a house to sit on, that block is now the foundation. But if it is hollow between those walls its a "basement"

Now dig down 3' and pour a footer 3' high/thick then what is it . A large footer? its not a block foundation in the sense.. When does a continuous pouring of a concrete footer turn into a wall??? Especially if its buried.

Building over 30 years and still think humans are a different stupid in to many things and it really shows up how codes are written...

My interpretation of this is the footings must be no less

The other mind bender is I have been asking inspectors does the mortar between the foundation block separate the block form each other or does it hold them together???

Enjoy....
 
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Old 05-13-09, 08:37 PM
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Deck post footing

I'm in eastern virginia and the footing thickness requirement is only 6" for the deck I'm building. So it would seem I would make the deck footing equal to the top of the house footing but only 6" deep whereas the house footing may be 8-10" or so.
 
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Old 05-13-09, 09:04 PM
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Sounds correct.

A 1 story house has footings 6" thick, 2 st. - 7", 3 st. - 8".

Usually you can call the building department for info, ask for an inspector or a plan check engineer. Be safe, G
 
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Old 05-14-09, 08:12 AM
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This code seems to be coming from the line of influence of a loaded footing on the soil below. The house foundation is designed one way. When you add a deck, or whatever, you are potentially adding pressure to the exist. structure. This line of influence acts at a 1:2 slope away from the new load. At 5' (60") from the exist. wall, you are potentially adding lateral soil pressure to the exist. structure at a minimum depth of 30" from the bottom of new footing. This would likely only effect a basment. And it turns out in the case of an average size deck what would that be...700-900 #'s 'ish' per footing. Not very substantial. To me this code is a 'just in case' it happens to turn out to be something substantial.
 
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Old 05-14-09, 08:29 PM
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tenn1,

I'm with 21boat -- that statement is about as clear as mud, and whoever wrote it SHOULD BE flogged!!

The way I read it, the BOTTOM of those footings need to be as deep as the foundation of the house. (Footings bear at the bottom of the hole, not the top.)

Check with your local bldg. dept. who are the ones that enforce such an ambiguous code and get THEIR interpretation, so you'll be on the same page that they are the first time around and won't have any problems.
 
 

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