Decks, Patios, Porches and Docks - Deck Footings

Hi,
I am intend to build 4X5 meter on ground deck, my garden is 20 cm lower then the balcon so it will be very low level deck

( the Deck will be extension of the balcon, the balcon width is 4 meter )

i am going to use 14cm beams for the construction ( of course i won't have Joists as i have not enough height )

my question is how many concrete footing i will need ( 30cm diameter ) and where to dig them ?

Thanks,

Welcome to the forums! By your measurements, I take it you aren't in the US. Generally you can build a low deck, but must keep in mind you need air circulation in order to lengthen the life of the deck materials.
As far as your footings go, you would contact your local building authority to determine your frost line and what they would require upon inspection, since we don't know where you live.

Hi,
I am living in Israel so the frost line is not an issue... :)

First, can you get Simpson or US Steel hardware in Israel?? If so, that will simplify the construction.

Your height (20cm) is roughly 8", if my metric conversion is correct. Your size (4 X 5 meters) is about 13' X 16', and your framing (14 cm) is roughly a 2X6, or possibly a 4X6.

If you have three 14cm beams parallel to the wall -- one at the wall, one at 2 meters and one at 4 meters from the wall, you could support those on footings. Then use joist hangers (Simpson LU26's) to hang the joists between the beams, flush at the top, spacing the joists as needed to support the deck boards.

You would need either 3 or 4 footings under each of the beams, depending on what size and species of wood you are using and how far it will span.

Yes i can get those simpson accessories and the wood type is finn pine. moreover i want the deck to be freestanding so the three 14cm beams will be vertical to the wall ( the balcon width is 4 meter )
is that mean that i will need 12 footings ? or 9 will be enough ?
thanks again.

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balcon wall --0-----0------0------0--


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just to make the sketch ( the -- refer to the 14cm beam ) and the balcon wall is on the left

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soory i have another thing that i am not sure about....
is the joists must be vertical to the beams ? becuase accoding to my plan the joists will be parallel to the three main beams ( the joists marked as "..." and the "|" refers to the connecting beams)


--0-----0------0------0--
|.......|........ |........|
|.......|........ |........|
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|.......|.........|........|
|.......|.........|........|
--0-----0------0------0--

If your joists are parallel to the beams, as shown, the deck boards will run in the short direction. If you install the joists between the beams (you "l" shown as connecting beams in your diagram), you deck boards will run in the long direction.

Whichever way you want it is fine.

Thank you i have better understanding now, is there a way to set the three beams parallel to the house so i will need only 9 footings ? since it's free standing deck in case the first beam will be centered along the three footings it will be around 8" from the patio sill, and then it will be problem to lay the first two deck boards.

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0 0 0
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0 0 0
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Of course it means also that the joists length will be around 7' is that ok ?

The only way to eliminate the 8" gap will be to run the beams as shown in post #7 -- perpendicular to the balcony.

The way that you have the framing diagramed in post #7 is fine if you want the boards to run parallel with the wall.

Hi lefty
Thank you very much. :)