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brian
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# Posted: 10 Apr 2013 10:29pm
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My home/cabin is on the very edge of a wetland in Michigan, soil stabilaztion membrane was used under the lot, clay back filled for home foundation, I would like to put a deck off the back of home, but punching through the membrane only 18 inches down at footing location is not an option. there could be destabilaztion problems or pressure under membrane, so,I cant do 42" depth pier for city code,what type of surface type spread footing could i use & the city inspector approve? 12x20 10' high-attached to home
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johng
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# Posted: 10 Apr 2013 10:49pm
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Not knowing what you have to work with, but could you cantilever out using the floor joist for support?
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brian
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# Posted: 11 Apr 2013 12:01am
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Well, the ground is good and solid above membrane, home is stable on it, I just dont want to dig more than 10" down, I have considered a Diamond pin pier, Great invention! but even that goes down about 30" ,,,,it will punch through membrane. IMO, this is to large/heavy a deck to cantilever all the way back to home foundation, would have serious pull on ledger, also, I really need that space under the deck for shed space.
I am thinking a large thick surface pad 5ft x 24ft-10"thick/rebar reinforced, just wonder how that pad would behave in Michigan winters, would inspector even allow it.
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ICC
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# Posted: 11 Apr 2013 12:57am - Edited by: ICC
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Quoting: brian what type of surface type spread footing could i use & the city inspector approve? 12x20 10' high-attached to home
1. ask inspector what he would pass. he's the one who has final word, none of us. even though his job is to inspect and not design he may be helpful and it will not cost like an engineer
2. do i read that right? 10 feet is the deck height above ground? ??? Way too high. 10 inches is more like it on clay without the option of deep posts.
3. if it can not use the same type of foundation as the home, depth etc, do NOT attach to home. Differential movement is a guarantee if you do. Build as stand alone deck. But no more than 30 inches ground to deck floor upper surface, and brace as if your life depends on it. i guess it does actually.
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TheCabinCalls
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# Posted: 11 Apr 2013 08:45am - Edited by: TheCabinCalls
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When I hear "WETLAND" in MN, WI or MI it makes me wary. Check with your Wildlife group and inspector both. They could make you undo anything that compromises the wetland or watershed. And these days with the Clean Water act and education they will likely make sure you do it right. Check first.
As for a foundation that seems strong: is pier set by heavy equipment to drive them as far as they'll go down. In MI aren't you supposed to be 36"-42" deep?
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brian
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# Posted: 11 Apr 2013 12:22pm
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Deck must be 10' above ground/attached, door is already up there on home, no heavy equipment will get to back of house for pier/pile driving, City has approved deck, but suggested a soil engineer, i did consult, they said do not punch through membrane do to hydralic pressure created by membrane fabric, I could have a gysure in my backyard and severely undermine entire home foundation/soil stabilazation, yes, code is 42" but they will approve something else do to soil conditions.
Im off to the city to find the Geo-tech who designed the home in 2005/forclosure/2008 unfinished, im sure they had a design for upper deck since door is already there!
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