Deck blocks


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Old 10-25-16, 10:09 AM
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Deck blocks

Hi I am going back and forth between building a deck or a patio. I have been researching deck blocks keep coming up. I was wondering why they recommend at least 12 inches in the ground for the blocks. If I am building a floating deck and code does not require them to be Underground is there any advantage to putting them under ground if it is a floating deck?

If it's not attached to the house, if there is Frost in the whole deck will go up and down and should not affect anything as far as I can tell. Any suggestions?
 
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Old 10-25-16, 11:24 AM
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Not what you asked but how high would the deck be off the ground? If less than 18", I would go patio, as wood needs air circulating around/underneath it and will prematurely rot if too close to the ground and not allowed that airflow.
 
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Old 10-25-16, 12:28 PM
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The problem with frost heave is that it pushes in only one direction, up. If the frost/freezing gets below your blocks it will lift them up. When it thaws the blocks will tend to stay "up" where they were raised. The weight of the deck will push them back down some but it's not as far as the original, firmly compacted virgin ground.
 
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Old 10-25-16, 03:04 PM
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So if I dig out a couple inches of ground and put in some type of stone or gravel and set the blocks on top of that would that fix the frost heave problem? I was driving by a house today and saw a deck on the blocks sitting on top of a bed of stone. That's why I gave this a thought
 
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Old 10-25-16, 03:14 PM
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Oh yeah, I forgot to say that the deck is going to be on grade on the one end of the 20 foot Span in about two and a half to 3 feet above grade on the opposite corner
 
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Old 10-25-16, 03:39 PM
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Is it feasible to lower the grade on the end where the deck is close to the ground? The better air can circulate under the deck the longer it will last.
 
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Old 10-25-16, 04:22 PM
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Yes. I can lower the grade some so it's not ground level . As far as putting stone under the blocks, do you think it will help with frost heave?
 
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Old 10-25-16, 04:30 PM
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Deck blocks should be against the law to even be sold.
In your area the frost level is likely about 3', what good is a little stone under the block going to do?.
Want to build this deck one time and always have it level you need to go with sono tubes set below the frost line.
 
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Old 10-25-16, 04:35 PM
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What Joe said x 10.

If you don't mind having wavy deck boards do it the way you want to. If you want it to be as straight as possible for years and years put it on sonotubes.
 
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Old 10-25-16, 04:53 PM
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xsleeper I tried to send you a PM and your box is full.
 
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Old 10-25-16, 04:58 PM
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I'm not disagreeing with you guys, but I'm just wondering how sheds don't need to be sunk into the ground and they seem to withstand the winters. I appreciate your feedback
 
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Old 10-25-16, 05:22 PM
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Thx for the heads up joe.

Small garden style sheds have walls and sheathing that keep them square, and level isn't usually of primary concern on a shed. Believe me shed doors rarely work correctly for long on a shed that is sitting on blocks. Drive on any farm and look at the shape those old sheds are in, with crooked walls and broken concrete floors. That's what frost does. Its why almost all sidewalks will eventually break and heave where they crack. If you have something you want to be level, and built to last, you put it below frost, period. If you don't care how long your unattached deck stays level, put it on deck blocks. Putting it on rock might help some. But it's not a cure all.
 
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Old 10-26-16, 05:09 PM
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If your talking about sheds mounted on skids it floats on the surface and once assembled become a solid unit.
A skid also has a lot more surface area unlike just a single post.
 
 

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