Another pier question

Started by MushCreek, August 12, 2012, 02:59:22 PM

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MushCreek

Although our house is on a full basement, I am thinking about building a free-standing screened porch out back. Free-standing, because there isn't an easy way to tie it into my roof design. It will connect to the house with a deck walkway. The thing is that with the slope of our land, the entire structure will be 8-10' off of the ground. Kind of a cross between a gazebo and a treehouse, I guess. What kind of piers would I need for a 16 X 16 porch at that height? I can do all sorts of cross-bracing, as the area underneath will probably just be storage for yard furniture or the like. I'm in SC, so frost heave isn't an issue, and we're in a 90 MPH wind rating zone. What would be best- telephone poles? Concrete columns? A bunch of 6X6's? Thanks!
Jay

I'm not poor- I'm financially underpowered.

optionguru

I have a house built on a steep slope and I recently built a 15x15 deck on the back.  Because the site slopes down and to the right my outer right leg of the deck is about 14 feet high and my inner left leg is about 5 feet.  I used 10" sonatubes with rebar tied into a 18" square concrete pad at the bottom.  I used 8x8 rough cut posts with 2x12s lagged into each side of the 8x8.   They are spaced 7 feet apart tied into a ledger on the house and with a 1' cantilever.   and then I ran 2x10 joists on 2' centers over the "beams".  I used PT 2x6 decking.  A year after building the deck we decided to put a hot tub out there so we added additional footings and framing.  send me your cell number and I can text you pics.  Wetownh@gmail.com or 603-616-9292  Pete


MushCreek

Is your deck attached to the house? That makes a big difference. My proposed porch would be free-standing, as I wouldn't try to depend upon the connecting deck (more of a walkway) for any support. I just want to be sure it doesn't rack and wiggle in the wind.
Jay

I'm not poor- I'm financially underpowered.

Don_P

If I were building this.
I would pour footings below grade, low and wide, thick enough not to worry about punch through, wide enough compared to height that tipover is not a consideration. Attach the well braced legs to the footings.

MushCreek

Being from FL, I'm as worried about uplift as anything else. Do you have an idea of scale for footings. Would reverse flare footings, such as Bigfoot work OK? If I divide things up evenly, there would be 9 footings, one every 8'. In reality, it would be hard for really high wind to effect the structure, being behind the house, and having big trees all around. I've noticed that high winds here are up in the tree tops, not reaching the ground. If the trees come down, the structure is already flattened! I'll do some drawings......
Jay

I'm not poor- I'm financially underpowered.


MountainDon

Personally I believe the correct answer to this most likely requires an engineer. Every active member here would most likely be guessing.   ???  \
Just because something has been done and has not failed, doesn't mean it is good design.