What did I do wrong with my flag stone path install?

[EddieWalker]

I don't think compaction is the issue. Anything granular is going to hold water. When it gets cold out, water freezes and expands. This causes movement.

 

[jyoutz]

I don't think compaction is the issue. Anything granular is going to hold water. When it gets cold out, water freezes and expands. This causes movement.

I have had flagstones set on crusher fines for decades. We get snow and ice every winter but they still are rock solid and haven’t moved. Sand will always move.

 

[tradosaurus]

We set flagstones a year ago with the same type of base. But our flagstone was 2" thick. Maybe the weight helps?

 

[jonsstihl]

I don't think weight is the issue freezing water is an incredibly powerful force it will burst pipes. I did 15 ft by 8 ft with large thin rocks and planted thyme in between. yes they move a little but I can live with that. this is to go between my deck and the SPA.

the thyme has done remarkably well and is filling in all the gaps in the stones. we shovel part of the path off to use the SPA in winter so we have to be careful to not rip out the thyme.

 

[Egon]

If you have true frost heave there is a lot of work ahead for you. Look up Frost Heaves and you will get lots of useful information.

If it’s just a freezing wet area Insure the whole area has drainage and use crusher fines for about two inches of base. Do not pack. Work your paving stones into the crusher fines and then overfill and sweep the fines around. Leave excess in place for a few months and then sweep off.

Bedding your pavers in one inch of concrete will look good for one year. Then the concrete breaks up and looks ugly.

 

[nyone]

Move south until you don't have to deal with frost heaves

Then you have to deal with swamp ass for 12 months though.

In all seriousness you may be holding water under/in your base of stone. Drainage is key in any outdoor project.

 

[jim_wilson]

I dug down 7 inches, put in a base of 6 inches 3/4 minus, then 1 inch of sharp sand and then compacted with a vibration compactor.
Then laid out the flag stones. And ran the compactor again with cardboard to protect the stone. But these there not very thick. At best, 2 inches thick, but most 1 to 1-1/2. We filled the gaps with what locally is called "fractured granite," that was supposed to harden over time, and then set everything in place...... according to the landscape place we buy stuff from.
It has not worked out. The winters just pop all the flags up with hoarfrost. We have no issues with 2 inch thick pavers or brick, which was used in other areas with the same base.
I really don't want to pull all these out and reset them. I've bought a whole lot of Ez-Sand.
But right now I really don't have a clue as to if this will work.
Any and all suggestions, are welcome. Even ones that say I'm an idiot.

Based on your description - a few things come to mind: 1) You didn't go down far enough - and 2) you left some sort of "organic" soil under the area you dug down and 3) you're not getting good drainage and the soil has a high moisture content under your walkway when the freeze comes.

Hate to say it, but you're not going to fix it without digging it out and doing it "right" .

One of the "tricks " I noticed the local DPW doing around here when they were putting brick-paved sidewalks in the center of town a number of years back - was they dug down quite a ways - like 2ft or so - filled and compacted in "lifts" with a good base , then they poured like 6-8 inches of concrete , on top of the concrete went around 4-5 inches of stone dust - and then the brick pavers were laid on top of that.

Those sidewalks have been there now for at least 15 years and they're still in as-laid condition.

I live in MA - stuff freezes around here. On all the stuff I've done I try never let myself get into a "good enough" mentality - overbuilt it and it will be good for a long time.

 

[jim_wilson]

Since you already have a base of gravel, I would remove the sand and build up the gravel. I'm not sure what one inch of concrete would do under the flagstones. It might work better, but it's expensive.

In my *opinion* one inch of concrete isn't going to accomplish much. I can take my foot and put a piece of 1" concrete slab with one side on a rock - and break it with a good kick.

The freeze is going to do the same.

 

[tradosaurus]

Then you have to deal with swamp ass for 12 months though.

In all seriousness you may be holding water under/in your base of stone. Drainage is key in any outdoor project.

As long as you change your undies on at least a daily basis you are good.

 

[tradosaurus]

I don't think weight is the issue freezing water is an incredibly powerful force it will burst pipes. I did 15 ft by 8 ft with large thin rocks and planted thyme in between. yes they move a little but I can live with that. this is to go between my deck and the SPA.

the thyme has done remarkably well and is filling in all the gaps in the stones. we shovel part of the path off to use the SPA in winter so we have to be careful to not rip out the thyme.

In the OP posts he does state:

It has not worked out. The winters just pop all the flags up with hoarfrost. We have no issues with 2 inch thick pavers or brick, which was used in other areas with the same base.