# bluestone patio



## sergdman (Dec 20, 2010)

Hello

I installed a bluestone patio over the summer here in NJ. The bluestone is sinking in some areas now that the winter is here. Can anyone help me to correct the problem. 

Thanks


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## Daniel Holzman (Mar 10, 2009)

Settlement of stone is a good indication of improper foundation preparation. The foundation should consist of a minimum of 4-6 inches of crushed stone or masons sand, compacted. Compaction is typically done with a plate whacker, although it can be done with other tools. My guess is you have either insufficient base, the wrong type of base, or you did not compact adequately.

If any of these apply, the solution is to remove the stone, and prepare the base properly. This may require removal of some base, or compaction of the base.


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## ClassicLighting (Nov 26, 2010)

I agree with the above response. Proper base prep is the most important aspect of the patio. Dig a six inch footing below grade,3-4 inches of crusher run compacted, 1" of mason sand, then stone. 
In order to fix it right, the base has to be redone.


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## sergdman (Dec 20, 2010)

The problem is not happening along the 300sq ft walkway or on half of the patio. The problem I guess lies where I did not use gravel or crushed stone. Half of the patio was place on an existing slap of concrete. I just placed the bluestone on top of stone dust, maybe two or three inches if that. I did not use the gravel because it would make my bed to high. I am not sure how i could correct it now as the concrete slab is over a foot thick. Any way I can maybe compact the stone dust better again and lay the stone in the spring in that section that is sinking (on top of the slab) I can not lift the patio anymore as I already have a four foot retaining wall on the other end of the patio where the gravel and crushed stone was used. It appears to be no movement at this time. I also have the steps to the patio completed. Everything was fine until now, freezing outside. This is bad! Please any suggestions again.


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## GardenConcepts (Jan 21, 2010)

Very unusual to have settling over top of the concrete slab- but yes, you could re-compact the screenings. Are you sure the area around the slab (stone base area) has not heaved up?


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## Kurtzilla (Jul 12, 2010)

sergdman, quick question for you. Did you go tight joint with the bluestone or did you leave spacing in-between the peices? It also sounds as though your stone dust may have a moiture content to it, which in return will make the bluestone shift during freeze thaw cycles.


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## jasoninct (Oct 10, 2010)

my thoughts, wait till spring then pull up the affected bluestone, screed away the top inch or so if stonedust, run a vibratory compactor, put the removed stone dust back down and compact that again. Level the surface and replace the bluestone.

As for the reason, I'm going to agree with the frost heaving theory. If the base or subsoil has been heaved by freezing then by the end of the winter the problem may be worse.


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## prosa (Dec 27, 2010)

I would take photos and measurments of the effected area, Wait till the spring and remove and excavate to the proper install height. Reinstall And enjoy after Mud season.
Also agree with chris the the area were the slab is did not move but the arear oppsite of it heaved.


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## sergdman (Dec 20, 2010)

Hello everyone. So I don't think that the patio was sinking. I think that possibly it was as stated by Garden Concepts, it heaved up. Could it be that the water has no runoff since it is on top of the slab and it is causing it to freeze and push the stone up. I noticed that when the temp. went back up they all kind of evened out again. Here are some pictures that I took before the first snow storm in December. With all the snow I have not seen it since. The first one is before the winter came. As you can see they shifted once the freezing temps arrives.


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## sergdman (Dec 20, 2010)

anyone?


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## Bondo (Dec 8, 2007)

> Could it be that the water has no runoff since it is on top of the slab and it is causing it to freeze and push the stone up. I noticed that when the temp. went back up they all kind of evened out again.


Ayuh,... It's No Doubt from frost heaving...

It'll lay back down, come spring...


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## sergdman (Dec 20, 2010)

Bondo said:


> Ayuh,... It's No Doubt from frost heaving...
> 
> It'll lay back down, come spring...


Thanks for your response. Is it normal? The walkway never did.


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## Bondo (Dec 8, 2007)

sergdman said:


> Thanks for your response. Is it normal? The walkway never did.


Ayuh,... If there's Water under it, it'll Heave...
If there Ain't, it Can't...

Sounds like yer walkway is Better drained...


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