Stone dust vs sand for laying pavers? Help!

orchid_ladycats(z7 MD)July 1, 2005

My husband and neighbor are putting in patios --starting this weekend. They are doing it themselves, with the help of some other friends and neigbors. They are both very handy and very strong guys. They've rented a backhoe and compactor. The neighbor is laying brick; we're doing pavers for a 12' by 20' patio. The neighbor has decided, and convinced my husband, that rather than using sand and gravel for the base, they can use a product called stone dust. The ground under the patio is clay -- no topsoil at all, so it is very firm.

Is this a wise way to be doing this? Please answer ASAP -- thank you!

Joan

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dontknow(z6 - Upstate NY)

Sounds like we have a similar yard and just had a patio installed last week. The person used various sizes of crusher run (gravel)at each level and then topped it off with stone dust. As it rains over the next month or so, the dust will slighty settle at which time I will apply Poly-Meric sand in between the joints.

Not sure if that helps.

    Bookmark   July 3, 2005 at 9:12AM
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artistone

stone dust is fine it acheives quite good compaction. when compacting it is best to do in 2 inch layers rather than filling an area and then compacting

    Bookmark   July 11, 2005 at 3:42AM
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orchid_ladycats(z7 MD)

Thanks so much for the responses. It's reassuring to know that the stone dust was a good choice!

Joan

    Bookmark   July 11, 2005 at 4:05PM
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jkbogle(5)

I would be concerned with what is under the stone dust. I recently completed a patio using stone dust, under the stone dust I had 2 inches of #1 stone. This was placed in an effort to promote drainage under the patio.

Think about this. Stone dust turns to a hard almost clay like material when wet. The stone dust was put on top of clay. Clay retains water and does not drain well, right. What happens to water when it freezes? It expands. I would think this would cause the stones to heave.

Hope this helps

    Bookmark   July 25, 2005 at 12:30PM
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camaro_2006

In the last 10 years my brick patio has sunk about 2 inches. It contains gravel, sand and some stone dust underneath it now. Would it be ok to bring up the level of patio 2 inches by just using stone dust?

    Bookmark   April 28, 2006 at 9:36PM
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danthelandscaper

I'm a landscaper of 10 years experience and still going. I always used to use stone dust as a base for paver walkways/patios. However last year I was talking with a employee of Grimm building supply (where we get all our paver materials) and I was told sand is the ONLY way to go for numerous reasons. To start stone dust does not have good drainage when packed down which causes water to build up under the patio/walkway. When old man winter comes along and freezes that water it expands and has nowhere to go but push your patio upward...also known as heaving. Clay also retains alot of water and will heave quite a bit come winter time. Stone dust also has a very acidic PH to it and will eventually breakdown your pavers causing them to crumble over time.
Now on the other hand we have sand (beach like sand). Sand packs down well, still provides drainage, and also has the ability to shift quite a bit. So without having the water built up under your walkway it is alot less likely to heave. Minimal heaving will still occur (exspecially with a clay base under the sand) but thats where sands ability to shift comes into play. When the ground under the sand heaves the sand will actually move with it giving the ground room to swell without pushing your walkway/patio up. It is important to have a MINIMAL of a 4 inch deep, packed sand base (recommend more if you have alot of clay in the area). That will allow you the room for movement and shifting. Sand also has a neutral PH which doesnt break down your pavers. Now that your sand base is laid and your pavers are down its time to sweep polymetric gelling sand into the cracks of the pavers than lightly water it in. Repeat the process until all cracks are completly full. The gelling sand prevents weeds from coming up out of the cracks and helps stop water from getting under the pavers. Once fully hardened the gelling sand will not sweep away, blow away, or wash away when cleaning your walk/patio. Good luck to you all. Hope this helps.

    Bookmark   May 20, 2006 at 9:28AM
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inkognito

I don't think the above has any basis in fact and should be viewed with caution. The real base for a patio is the compacted sub-surface and the sand or stone dust is used only for levelling and is therefore not compacted. Bricks or pavers are compacted into the stone dust. Anyone who has made a sand castle at the beach will know where this this statement leads when the tide comes in, "Sand packs down well, still provides drainage, and also has the ability to shift quite a bit." As for stone dust breaking down pavers that are made of concrete you might want to take that with a grain of salt.

    Bookmark   May 20, 2006 at 3:52PM
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danthelandscaper

I dont know how you build patios. I will say that ANY patio I have EVER seen built in my 10 years landscaping, built by me or others, was laid on a compacted layer of stone dust OR sand. COMPACTED being the key word. Look you even somewhat said it yourself, the bricks are COMPACTED into the sand. OK so whats the diffrence if you pack your sand or stone dust with a tamper first, or like you must do, beat your stones into the sand ?? YOUR STILL COMPACTING IT SMART GUY.......Ohh and has anyone ever clued you in that materials act diffrently when under pressure rather than in a free standing form as in a "sand castle". Take my advice how you want too. I didnt put it up here to be bashed by someone, I put it up for those of you who would like more info on patio's and sidewalks. Pavers made of concrete??? They are called cobble pavers for a reason. I guess the bottom line here stone dust and sand both work as a base for your patio it all depends on personal preferance. I personally found in my 10 years experiance I like sand 100% better over stone dust but to each is own.

    Bookmark   May 24, 2006 at 1:02PM
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inkognito

At least you are thinking enough to defend your position dan but I don't think we are talking about personal preference and if experience is a criterion mine doubles yours plus some. I appreciate that you put your advice up to be helpful and I am not knocking that intention, what I am questioning is the inaccuracy of the advice. I do not intend to educate as the correct way is documented elsewhere and is not personal preference but sound practice.

    Bookmark   May 24, 2006 at 8:46PM
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tonyd206

I like tohe original poster have a similar circumstance as to whether to use stone dust or sand as a bedding for my pavers. The company that makes the pavers said to use sand when I called them. The company that sells the pavers says to use stone dust and that is the preference of most of their commercial contractors and I have read a hundred different article that go back and forth. My question is has anyone had problems and with which bedding? Also, should you compact the sand or stone dust prior to setting you paver or should you set the paver and then compact with your rubber mallet? Any info is greatly appreciated!!

    Bookmark   September 5, 2006 at 3:36PM
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sandykk(z6 MD)

Thanks for your input Dan. We just finished a stone walkway and our stone supplier also recommended a base of 4" sand, then filling in cracks with the stone dust.

    Bookmark   September 12, 2006 at 9:28PM
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bobincampverde

How about using sand for a base and stone dust for the grout? I just completed a flagstone patio and used sand but I do not care for the trail of sand that goes to the porch and house.

    Bookmark   November 12, 2006 at 10:30AM
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mimireco2

I would like to improve a concret slab patio that is lower than I want due to water running on the concret from the higher grass. Is it possible to lay brick in top of the concret? Can I use sand stone or do I ust a mortor to lay bricks on top. I am a women trying to do it myself. Can someone give me some advice. I also want to extent the patio ares from the concret area.

    Bookmark   December 31, 2006 at 10:32AM
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roxy63

Where can I purchase polymeric gelling sand? I don't want sand being tracked into my house. Will this product wear out of the grout joints? Is there a type of mortor I could use instead?

    Bookmark   March 31, 2007 at 11:42PM
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macbirch(ACT Aust)

And to add to the above queries, is the advice in this thread relevant to small retaining walls built out of those blocks that you put together without mortar? Like Tonyd we've been told different things by different people.

    Bookmark   April 1, 2007 at 7:11AM
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WendyB(5A/MA)

I just received 3 estimates for installation of a paver walkway. 2 of them would use 1"-2" of stone dust over the gravel base. The third uses washed concrete sand as the bedding base rather than stone dust. They all described similar excavation and prep compacting in 2" increments. All 3 of them use polymeric sand for the finish sweep.

So I googled sand vs. stone dust and landed here. I still don't know for sure, but I think I am leaning towards the sand. In one of the paver catalogs (not the mfr I picked but a high end one), the warranty had an exclusion if stone dust was used for bedding layer. I believe the mfr I picked also recommended concrete sand for the bedding sand. I'll have to check again.

The guy who uses concrete sand offered a 5 year guarantee on his work.

My flagstone rear patio is set in stonedust and also in joints heaves during the winter and frequently needs sweeping in extra stonedust in the spring. All of the flagstones are no longer level to each other after 10 years of this.

    Bookmark   June 15, 2008 at 10:56PM
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mike_d30

You don't use stone dust for compacting, you have to lay at least four inches of compactable sub base like item 4. Item 4 is a mix of gravel rock from dust to 3/4 inch stone. The varying sizes makes it great for compaction. This is what you use to compact and build your base, heck the Roman used this to pave the known universe, some roads still stand today.

Four inches of item 4 will keep your patio from heaving in the freeze. After compacting the soil, then laying and compacting 4 inches of item 4 you lay one inch of stone dust, this is just for leveling the pavers not the foundation of the patio. If you lay a patio on only one inch of stone dust I don't think it would turn out well, especially if you live in cold climates with a winter freeze. One inch of sand or stone dust on top of soil will buckle and waver really easily.

    Bookmark   June 30, 2008 at 10:18AM
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morango(5a)

I'm in Wisconsin, where we have a lot of freezing weather, and what we use here sounds like mike d30's "Item 4." The local stone yard calles it "road base" among other things. Four to six inches of that stuff are compacted before the stone and levelling sand are laid. For filling in gaps, we have always used mason sand for pavers and bricks, and actually we just use the road base itself to fill in for a flagstone application. Just my 2 cents.

    Bookmark   July 11, 2008 at 4:34PM
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WendyB(5A/MA)

sorry, I guess I wasn't clear in my post/question. I was asking about the final "bedding layer" only. The total excavation is about 8-10".

Anyhow I went with the "washed concrete sand" bid over the stone dust. The installation is in progress now.

After a lot of research, and my own experience with my patio set on stone dust (yes, it is over compacted gravel base), I decided to skip the stone dust for this walkway.

    Bookmark   July 29, 2008 at 7:22PM
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engine7design

I'm laying a 12X14 patio right now. I've dug down roughly 8-9 inches. Part of it is into a hill that I expect a lot of water to come running down. I'm putting a wall around the patio and into the hill. (I'll set the wall about an inch or two lower than the patio floor) I'll be laying down about 2 inches of pea gravel, compacting it, then about 2 inches of leveling sand. My friend used stone dust and he found it hard to keep all his pavers level and the end result is a somewhat wavy floor. I figure the sand will be a lot easier to lay my pavers on because I can squish it around, add and take out material as I go along with a level.

Also, I'll back fill the wall with crusher stone then topsoil on top. Does anyone think I should use masonry adhesive between each brick in the wall? Also, I'm skipping laying down weed screen first because I figure weeds coming up through the gravel and sand will be minimal and easy to spot treat. Sound good? Any other advice?

    Bookmark   July 31, 2008 at 6:56AM
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grillboy

Dan made the key point: COMPACTED. Dig down 10" and tamper the bare dirt first. Tamper at every step in the process thereafter. I am not endorsing anyone's product, but my friends have recommended renting Wacker's compacter/tampering products from your nearest big box or tool rental place. See one in action at:

http://www.youtube.com/watch?v=EVWz67Sj4y8

The tool available for rental likely looks more like a lawn mower than the tool in the video (which is very expensive).

I recommend a three-layer fill procedure, tampering after the first two fill layers (don't tamper the sand).

I am using 4" stones and gravel as my base, placing pieces of old brick and broken terra cotta roof tiles that I had lying around on the very bottom. You want this layer to be uniform and compact, or everything else you do afterwards will suffer.

Then I will add a 3" layer of pea stones. I believe this is the crucial step that many miss (my Italian grandfather swore by this). The pea stones fill in the gaps in the base, and stop the final top sand layer from settling down into the gaps in the base over time.

Finally, add the 4" of top layer sand or stone dust (I'm leaning towards sand). Don't forget the polymeric gelling sand for the cracks, or else you will end up with grass and weeds growing up through the cracks.

Good luck!

    Bookmark   August 6, 2008 at 5:13PM
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randallpink

Having laid more pavers than I care to remember I would have to say the idea of 4' of sand under the pavers is a mistake I don't care how well it's compacted and I could show you patios laid that way to prove it. Also there is a BIG difference in "sands", it can make a huge difference as to the clay content of them, whether they are dug or crushed sand,washed or not,and particle sizes. For instance dug washed masons sand won't fully compact no matter what you do it will always shift because it has no fines and no angles to the particles to "lock up" to each other. As for the drainage aspect, any patio or walkway rgardless of the material should have at least a minimal slope to it. 1/2" in 10ft.can be sufficient, and this is in the base as well as the finish. A good base is the most important part,4"-8" for a patio or walk depending on the existing soil conditions,more for a driveway of very compactable material. Here we use a limestone "road pack" sometimes the bottom lift may be a screened 3/4' rock if drainage is a real concern. We lay a layer of loose sand screeded out using pipe about 1 1/4"in diameter as guides. Working off the finished area lay the pavers and when you run the compactor over the pavers they settle in and lock up. As to worrying about how acidic or alkaline a ,aterial is I can't imagine anything short of hazardous material being acidic enough to affect quality concrete pavers,and there is a big difference in concrete pavers,take pavers from different companies and wet them and see which ones are dry the soonest. The best ones will dry much quicker as they are made harder and don't absorb as much water. Well thatsenough rambling so good luck with your project and as long as yoy like it that's all that really matters anyway.:)

    Bookmark   October 1, 2008 at 10:50AM
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mvp15

I'm planning on doing a patio with pavers. One contractor does it with crushed stone and sand underneath the pavers. Another contractor does it with concrete base insteaed of stone and sand. My question is if anybody knows which is the best way to go? What are the benefits of doing it one way vs the other?

    Bookmark   May 22, 2009 at 9:39AM
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WendyB(5A/MA)

I had the same dilemna last year. see post above. I went with the 8-10" of gravel compacted in 2" increments, followed by a bedding layer of washed concrete sand (as recommended by the paver manufacturers), and polymeric sand for the finish sweep.

It went great. They did an awesome job and the walkway did not budge an inch during the winter (frost/thaw/heave).

After they put the gravel base in and compacted, that was the end of their day 1 on the job. As I walked over it, I couldn't believe how solid it felt. It was like walking on solid concrete. The compacting is critical.

    Bookmark   June 19, 2009 at 7:49PM
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johnthegreen_hotmail_com

I have a six inch base of compacted item 4. I want to put down an inch of stone dust and then my pavers and run the tamper over them. What can I expect the finished height to drop after that compaction run, maybe a quarter inch? Reason being, is I am trying to have the finished product level with concrete around a pool. Thanks, john

    Bookmark   June 23, 2009 at 1:20PM
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marys67

My husband installed a small walkway with pavers, the base is done with sand. His brother told him to use playsand as a final sweep which he did. He now thinks it was not the right sand and wants to use the polymeric sand. How should he go about this? Does all the play sand have to come out...vacum?? Or can we just sweep away as much as we can and add the polymeric sand on top?

    Bookmark   August 13, 2009 at 8:22AM
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haugenbp

I realize this is an old thread, but I have a question related to it that isn't quite answered here. I was at Home Depot yesterday looking into materials for a stone patio, and the associate told me I only needed 2" of their Paver Base (which it sounds like is the stone dust discussed above) followed by 1" of play sand. She gave me a brochure that shows this, but it doesn't seem specific to where I live, which is Minnesota where it obviously freezes a lot. Anyone in a cold climate have any experience with this, or can you advise me how many inches of gravel I should use? thanks.

    Bookmark   March 29, 2010 at 12:52PM
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njfitz

stone dust is an absolute problem. DO NOT USE IT!! I have been in the business 22 years and I see all the experts' jobs - they are terrible. The sand - "concrete sand" is where the interlock takes place - it comes up and fills the joints causing them to lock up. Stone dust will only get hard "under" the pavers and actually hold water, which is another issue. Use concrete sand and only 3/4" under the pavers. Just make sure the base is deep enough and compacted.

    Bookmark   April 16, 2010 at 3:45PM
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johnturner9

I just got through putting in 400sq ft. belgard pavers on #10 crusher run as my 5" base on east TN clay the a 1" screed layer of the same #10 crusher run. I put in a french drain to help with water drainage and it has worked great!

    Bookmark   July 2, 2010 at 2:09PM
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bnhbutts

Just layed the base for a sandstone patio using recycled 304. Compacted 3-5 inches of 304 in a 21 X 21 area over a couple of inches of stone and fabric to keep out growth. I have read over and over that the base is most important. It has held firmly and drained well. As soon as I finished a steady rain feel for the next day and there was no puddling anywhere on the surface. It is pitched slightly away from the house and deck. The next step is 1" of concrete sand used as bedding for the stones. We will then fill in cracks halfway with 304 and then polymeric sand to finish it off. I'll keep you informed, but the 304 has done its job quite well so far.

    Bookmark   August 24, 2010 at 10:13AM
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bnhbutts

Sorry - failed to mention that I live in Northeast Ohio if that proves helpful to someone based on the materials we've used.

    Bookmark   August 24, 2010 at 10:16AM
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patty_cakes

Is polymeric sand the stuff that hardens like concrete? Is it ok to use just sand, with a little top soil over it since I want to fill the cracks w/ground cover? Will this be a problem w/weeds? If so, how do I go about having the ground cover AND eliminating weeds? I've never done this sort of thing before~guess you can tell. ;o)

    Bookmark   September 2, 2010 at 2:02AM
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shudjean_yahoo_com

I have an overgrowth of bamboo in my backyard where the ground stays very moist and does not drain off good. Will sprinkling some stone dust in that area to soak up some of the moisture help keep the overgrowth down? I've already tried other methods to kill it, but nothing works!

    Bookmark   May 14, 2011 at 12:43PM
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EdwardZ

I have a slate stone front walkway laying on a mortar. That's an old house and so old walkway. I hired a Contractor to redo it. There is a procedure the job was done: removed the slate slabs, put a roll of sick plastic on a ground (to prevent a grass and weeds growing??? - but what about the water accumulation and lock of draining?),put a layer of a DUST STONE???, but not a Q-P stone as stated in a Contract, than pour a mortar and RIGHT AWAY placed a slate stones slabs without preparation a concrete base bed. Than filled the spaces between the slabs with the same mortar. The wood frame wasn't installed at all, as a result the edges are not straight and walkway itself not leveled and has wavy surface. All job was done in about a 4-5 hrs. In addition to that the finished walkway wasn't cover with a plastic to let the mortar to cure and newly done job stood unprotected from fallowed several-hours-in-a-raw shower. Do anybody have an opinion about the way the job was done? Will be very appreciated.

    Bookmark   May 22, 2011 at 9:18AM
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TerryInTosa

Am so glad I found this forum. To Dan the Landscaper I wish to send a special thanks. I am about to start a sidewalk paver rehab, was about to head out for materials when I read your posting. Hope nothing has changed since you wrote in way back in 2006. I am going to use sand. Thanks very much for taking the time to post.

    Bookmark   July 11, 2013 at 10:50AM
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andyokeefe

You've definitely made a good choice with the stone dust. The sand is not that good as it doesn't compact as well as the stone dust.

    Bookmark   July 13, 2013 at 8:54AM
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