footings/piers in sandy soil

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Old 08-02-10, 05:39 PM
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footings/piers in sandy soil

hello, I have begun excavating to pour footings for a deck which will support a hottub. I have done my calculations correctly and have enough footings planned, etc. to carry the load. What I was not planning on is the fact that I have very, very sandy soil where I have excavated. It is almost as if the sand was brought in when the house was built. I have two questions about this and I was hoping someone might help.

1) is it safe to put footings in sand? Will the weight of the tub setting the deck even more since it is sand instead of clay or loamy soil? It is hard to imagine the cold months causing any type of heave here, but I am going to try to get as close to 48 inches as possible (the required footing depth in Michigan).

2) does anyone have any thoughts on how to remove sand from the footing hole? I know it seems like a silly question, but I did rent the auger which dug very nice holes all over, but did not pick up the soil and remove it from the hole very well. When I went back with the hand post hole digger, even this is tough to remove sand with. Most of the grains just drain out the sides of the tool. I have actually resorted to using a wet/dry vac and sucking the sand out of the holes. Am I crazy on this? Is this a sign that I should not build the deck here?

Never have I wished for clay so much!

Thanks
 
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Old 08-04-10, 06:04 PM
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Don't use that type of footing. Use a "ribbon" footing. \_____________/
 
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Old 08-09-10, 05:20 PM
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any chance you could point me to a place to get more info on ribbon footings? Also, I was hoping to put a hot tub on this deck, so I dug a ton of footings (21 to be exact).

Is a hot tub not a good idea of the deck is built in sandy soil and requires ribbon footings?
 
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Old 08-09-10, 06:33 PM
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If you already have the footings installed, leave them. As far as I know, hot tub supports & the hot tub should be installed first, then the deck gets built around it.

Call the manufacturer of the hot tub & ask what's needed to support it.
 
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Old 08-10-10, 11:15 AM
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Well, I already have the footings (piers) dug- or at least most of the way. My original post asked if anyone had advice about removing sand from post holes, since it does not hold together well. I have since found that running some water in the hole makes the sand clump up a bit and makes it easier to remove.

So- my current state is that I have these pier footing holes dug, and have enough dug to install enough posts to support a hot-tub on top of my deck. I plan on building the deck first, and maybe putting a hot-tub on top of it in a couple of years. Cannot afford it all now. But, in order to be forward thinking I need to build the deck with enough posts to support the weight of the hot tub. Does that make sense?

Which brings me all back around to the questions. Will pier footings (deep cylindrical footings with posts mounted on top of concrete) work to support a hot tub in sand. Or do I need to further explore this ribbon footing idea? I have no idea what a ribbon footing is for the record, or if it used in my part of the country- Michigan.

Thanks for your help
 
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Old 08-10-10, 06:27 PM
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Picture a 3 or 4 ft deep wall underground, as long as you need it to be. That's a ribbon footing. I guess my diagram didn't work. \__________/

The ends are on an angle to create a friction footing. I still say that the supports for the tub & the tub itself should be installed first & the deck built around it but do it any way you want.
 
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