Can old roofing river rock be used under pavers?

Player

*perhaps I should have titled it "should..." instead of "can..." lol*

Hi, I have some old river rock that was once on a tar & gravel roof (relatively small rock...not the large rock used on completely flat roofs). I was going to try and use it as a base under concrete but have decided to do pavers instead. I know many rocks should not be used under pavers as they don't compact as well and will cause your patio to shift around. I'm all about recycling and conservation where appropriate...but I want this patio to last without shifting. What category to these rocks fall under (for pavers or not)? And if not, is there any good use for them?

I'm hoping to start this project first thing in the spring and am trying to determine if I need to get rid of these rocks (which are in the patio space) before spring. And that task could take at least that long.

Thanks!

jasoninct

Would the river rock work? yes

Am I certain that the river rock will make a stable base that will not allow the pavers to rise, settle or move and interrupt the pattern over time? no

A concern I have about the river rock from a roof is that some of the stones may have some tar or other roofing materials on or mixed in with the stone that I would not be comfortable with buring into my lawn where people, children and pets go.

concretemasonry

If they are river rock with no other size materials (smaller rocks down to sand and some binding material), the could not be compacted enough for a normal paver base. They river rock can shift and the pavers willl rock (no pun intended).

What do you consider pavers? The larger sizes (over 10") are really not strong pavers. The strongest, most stable paver installations use interlocking concrete pavers that are about 4"x8" about 2" to 4" thick.

Dick

jlhaslip

Can you top them off with some sand?

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Player

I haven't decided on the size or kind of paver. If the river rock is used as a sub-base and sand is between that and the pavers, would that work (without shifting the pavers around, eventually)?

So you would recommend smaller pavers? Or any pavers that fit together? Any particular suggestions?

jasoninct

the river rock will not compact enough to form a solid base for pavers no matter what size they are.

Sand is used as a bedding layer between the pavers and the compacted gravel base. The standard thickness of the bedding layer is 1 inch thick.

Putting sand over the river rock, eventually the sand will settle between the rock and will not settle in evenly making the patio or walkway become uneven.

Use the river rock in flower beds instead of mulch, as fill when making a drywell, anything else other than a base for pavers no matter what size they are

jlhaslip

I meant that you should place some sand over the river rock and then compact the blend.

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Player

Thanks for the info. That makes sense.

What would you recommend instead of river rock (wondering if I have to purchase the bags of whatever expensive, compactable rock the local home improvement place tells me...or do I have other options)?

Could the river rock be used under concrete?

High Gear

Road Base gravel which is crushed limestone here in northern Il.

That would be 3/4 dia size down to fines (dust), the rock is angular and will

compact incredibly tight with enough compaction and water.

6" minimum base is the norm in my area.

Do a search on this site for more info, lots of past postings about this.

Gravel dump truck/tarp/front ditch/wheelbarrow/sweat equity ...don't listen to the box store hacks.