I received a question from someone on using concrete pads underneath a DG patio, instead of prepping the subsurface with baserock material. That got me thinking about doing a post on patios in general and what, from a designer and installers perspective I know and understand.
First a few words in general regarding different types of patios. There are lots of different materials out there, some nice, some not, that can be used, and of course, different areas of the country will have different requirements. As far as California goes, here are the basics:
1. Use materials like DG (decomposed granite) or concrete pavers (set in sand) when you need a permeable surface. Many counties are now requiring with new installations a minimum of permeable surfaces to prevent massive run-off problems. DG is useful as a patio some distance from the house in order to wipe off small bits of granite attached to shoes. Concrete pavers are set on a sand base and come in all types, from ugly to handsome. I tend to like the Calstone ones. They are perfect for driveways since if an oil stain gets on a few, you can pop them out and replace them. Weeds are a very minor problem. Another alternative is permeable concrete. I haven’t used it personally, but understand that it needs power washing yearly to clean the pours out, plus its pricey.
Permeable concrete
- Calstone
2. For leisure patios with furniture lots of do-it-yourselfers or people on tight budgets like to put pavers and DG together. This works fine but keep in mind that high heels and furniture will get caught in the cracks of DG. To help this problem out, keep your cracks to 3/8″. Your contractor will balk and say he can’t do this. That’s because it takes more time and precision to fill those cracks. It can be done.
Arizona flagstone set in DG
3. For a long lasting patio that will have furniture on it, I prefer to pour a concrete base and put mortared pavers on. Another alternative is concrete. There have been lots of advances in concrete in the past few years. Meaning there are lots of types of decorative concrete looks, with stains and stamps and 2 or 3 dust on colors; finishes with broom, or salt pitting, or hard trowel. Just keep in mind that concrete is not a controllable substance and colors vary, fade, and cracks will develop no matter what. Also, on concrete OR pavers, always apply a sealer to bring out the color and protect the surface. I’ve had people spend thousands of dollars on an installation, only to balk at the $500 for the sealing. The color of the concrete never emerges correctly if you don’t seal it.
Indian pavers with decoative river rock
A WORD ABOUT PAVERS: If you decide to go for real stone pavers, I salute you. Although concrete is cheaper, stone is beautiful and will give you lasting pleasure. So how do you choose amongst all the choices at the yard. First, go to a large landscape supply yard and pick out the stones you like. Get samples and bring them home and live with the samples for a week or more.
You have two basic choices: regular or irregular. Irregular are pieces like the photo of flagstone above. Regular come in 1′x1′, 1′x2′, 2′x2′ and so on, like the Indian pavers in the above photo. So begin with that choice. Not all stones come in both. If you choose irregular, make sure to choose LARGE pieces, and I mean large. They don’t have to be thick as you are mortaring them. If you are setting them on sand, by all means choose thick pieces to prevent breakage. Remember that the thicker they are, you are paying by the tonnage.
If you go with regular, then unless all your pieces are uniform size, you must map out your design exactly. Usually the stone yard will have some basic design patterns for you to work with, or simply obtain some grid paper and go to work. Indian pavers have flooded the market in recent times. There are some incredibly beautiful stone and colors amongst the choices, but the stones are not all exactly to size. You’ll have to work with this when you or your contractor lays it down, which means some of the spacing will be off.
No joints in the perfect paver
Next you must decide on the size of your joints. Be exact in your communications to your contractor. If you have uniform stone, you can lay them down with no mortar in between. If you want joints, or if your stone isn’t perfect as in the Indian pavers, you must have mortar showing in the joints. Mortar is now no longer boring white only. It comes in various colors, so get a color chart. Have you or your contractor make up samples. The color is a powder and can be toned down so various samples with one color are useful. Obviously, or I think its obvious, don’t make the mortar color stand out more than the stone. I also think that choosing the same color as the stone looks odd. A few shades lighter works well, or a very light contrast.
DG under tree with Indian pavers on concrete patio
I DO NOT recommend Arizona Flagstone in general, unless you live in the desert. Arizona flagstone is always the cheapest and so pretty, but it is incredibly porous. You MUST seal it and seal it every year for at least the first 3 or 4 years. After that you can relax for a few years. When you seal it, you have to pressure wash it or apply a cleaning product made for stone BEFORE sealing. In Northern California where it rains a lot and is damp, Arizona flagstone, if not sealed, quickly becomes a magnet for black fungus spots. The beautiful colors quickly turn brown with black spots if not sealed, plus its slippery in the winter. Once that happens, it harder to clean.
That being said, choose flagstones that are hard with small pores. These would be stones that come from places like Montana. Flagstones come in many names, and what’s called one name in one yard will be named something else in another, even if its the same material. Just make sure the flagstone is dense.
Another thing you want to watch for in flagstone is how slick it is. Slate, though gorgeous, is really slippery when wet. I’ve heard that a little bit of sand in your sealer can help this problem. Better to avoid it from the start.
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- Calstone
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- No joints in the perfect paver
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- Permeable concrete
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- Concrete with pavers set inside
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- Broken up concrete planted inbetween
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- Arizona flagstone set in DG
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- Calstone pavers on sand
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- Calstone pavers with slate inserts
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- Mortared brick with stones
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- Pavers with ground cover
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- DG under tree with Indian pavers on concrete patio
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- Indian pavers with decoative river rock
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- calstone paver sample board
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- Colored concrete with broom finish
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- DG with pavers
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- Arizona flagstone set on concrete
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- Concrete with dust on finish
Filed under: Gardening Tagged: | Calstone, Concrete patio, DG Patios, Patios, Pavers
[...] Patios hard and soft [...]
I just installed DG base of about 4″ – 6″ thick for a pathway and patio. I plan to add about 2″ of stabilized DG, but have yet to do so. I used a vibrating plate to tamp down the DG base twice, once when half of it was in place, then again when the rest was laid down. It felt pretty solid once tamped. Yesterday it rained about 1″. Today the DG feels a bit soft and spongy. Should I tamp it again, or will it harden once it has dried?
Also, would a Jumping Jack (sounds like a jack hammer with a foot plate instead of a spike) be better to use than a vibrating plate to increase the compaction?
When you say DG base, do you mean base rock? If so, tamp it again. I always have my crew tamp it down every 1″ or so for the base rock too. I hope you didn’t install 6″ of DG. That just won’t work.
I am not familiar with a ‘Jumping Jack’. Usually the compactor works just fine.
Hello Leslie,
Oh my, thank you for your expertise!!!! This is amazing. I am a first time home buyer in the Sacramento area and am so inexperienced it is embarassing. Please forgive what you might think is a simplistic question, but what do you use as the base rock layer? Is it a bag of pre-mixed rock that constitutes base rock? Should I be looking for a specific type of rock? I really like the sound of the method used by Strybing Arboretum in San Francisco. My little section of patio will be a high traffic area and I really want it to be as little mess as possible.
THANKS AGAIN!!
Base rock is sometimes called road base. Just ask for it like that and they will know at your landscape yard what it is. It is rock of several sizes, from fines to larger that compacts well. You will need yards of it, not bags. You will need enough for 4″ at least of depth. Have it delivered as it is very heavy and a home truck can’t even fill itself up.
I recently visited one of the patios I did with the Strybing method. Its been at least 4 years and this house is located in Tiburon flats, which used to be part of the wetlands before they dredged it. The soil there is this disgusting black clay. That’s because it was marsh soil, no air. Anyways, given that it still gets lots of rain and poor drainage, this patio has held up extremely well. It just needs in some areas a bit of resurfacing with DG. I would suggest to that homeowner to put down another 1/2″ of DG compacted and should last for another 5 years. It is good method.
I have been following your posts for months now and am hoping you can help me. I live in Lincoln CA, in the greater Sacramento area. I installed DG throughout my backyard intending it to be a temporary fix to having no previous landscape. We built raised flower beds around the yard and laid the DG for the rest. We want an low maintenance yard. To install the DG we laid 2-3″ of gravel first then compacted the DG every 1/2″ or so. I am happy with the way it cam out but actually hate the DG in general. While watering I have to be careful not to get it too wet and it tracks into the house. It is also not so friendly on bare feet (all I was aware of before installing it). I have not decided weather I will do the permanent patio with pavers or cement. I like the artisan slate from basalite, but am considering buy a cement mixer and doing small patches (10×10) to build a cement patio. I would like something that is easy to walk on, easy to care for, and I can install with the help of my family.
So my question is, as I get ready to do something else with the patio is it best to lay on top of the DG or do I need to remove it all? I have read that pavers are not really stable on the DG from sinking or shifting. Also if I place pavers on top of the DG do I need to use a thin layer of sand still? I really like the look of the pavers, but think the cement will be less expensive, since we are doing it ourselves. I have been trying to research laying concrete on the DG but keep coming back to your site. I hoping you could tell me the best way to handle this, and how to install over DG. Thanks!
Thanks Suzanne for reading my blog. You have a few questions in there. First, you’ll need to get rid of the DG to install concrete, I’m sure. We always do a pour over something like a gravel base. I would guess that with a DG base, you will get tons more cracking than usual in your concrete.
I have installed pavers in DG as you can see on the photos on the site, but its not a pure patio of pavers, just a decorative look. I don’t really like pavers on sand patios in general as you’ll get tons of weeds no matter what you do. But for a few pavers to break up your patio, you can just dig into your existing DG and place them level. You will need several steps (feet) into any doorway area to get your shoes wiped off. Place them there for sure.
For a permanent patio with pavers, you will need again to remove the DG and maybe even some of the gravel. You need to pour a patio of concrete upon which your finished pavers will go. All the finished heights depend upon the thickness of the stone you chose. A slate is usually thin. That’s good because you are paying per ton so try not to buy thick material. You only need thick stone if there is not concrete base underneath. If you are going with stone, You probably can get away with pouring the base by yourself, although that’s usually only about $4/sq. ft. Your drainage needs to be taken into account as well before the pour.
Re: doing your own concrete patio. WOW, that’s quite an undertaking. Of course, you can rent a mixer and if you do your patio in stages its going to look like that, meaning you can’t get the same color or consistency in concrete after its weathered some. Really, just bit the bullet and do it all at once. Doing a concrete patio that’s large is something I really always leave to concrete professionals. We’ve done very small patios because its easy to control by hand, but a large area requires a know how about concrete.
You could save about $4/sq ft. on the demo and preparation yourself. You’ll have to make sure you have all your slopes for drainage proper. If you do the prep yourself, depending on what finish you use, it should come between $9 and $10 square foot for a professional to finish it off. You should consult with a professional all along while doing the prep as he might have some ideas particularly as to drainage. You will need to set your drains, if they are inside the pour, before the pour to finished height. That’s a trick as well. That goes for the same with pavers on concrete. Set the inside drains to finished height.
Good luck. Its hard to help from afar, and in addition, as a professional designer, I never consult with a homeowner who wants to install my designs. Remember, this will be your first time doing this vs. a person/company that does this for a living and has already made all those mistakes, as well as knows tricks of the trade.
Your posts have been unbelievably helpful. Not only to us, but also our neighbors who are installing DG paths. We did a test area and even with the rains we’ve had, it is holding up well.
We’re working on a Mediterranean/drought tolerant yard and trying to get that “European” look with the texture of gravel. Would it work to install DG as you outlined and sprinkle gravel on top? (The sharp-edged gravel, not the smooth pea gravel.)
We’ve been told that gravel will get stuck in the dog’s feet and isn’t as stable. However, it seems the best look for what we have done so far — lots of texture, minimal color, and repetition.
Thanks for any advice you can offer!
Why do both, the work and the expense of both. Just install your gravel alone. Here is how: You will of course need an edging. I like the Ryerson header but plastic will do. I don’t know where you live, but if it snows then you will need to dig a deeper base to account for heaving. Dig out 4-6″, then install your baserock as I outlined, tamping it down every 1″ or so very solidly, then install about 1″ of your decorative gravel. If you install too much gravel, or don’t have a good base, then your path will be very ‘squishy’ and you’ll be floating around your gravel when you walk.
Never heard the thing you say about your dog. I have a dog and have no trouble with his feet, but my dog is big.
Thank you for your prompt reply! Unrelated to gardening, but I keep thinking about your story of the buck… One wonders…
OK…one more question: Are there reasons your prefer DG for patios and paths? I’ve read complaints on a number of forums that people are unhappy with gravel. While they show the gravel a lot in landscaping magazines perhaps it’s not a good choice?
I do like the look of DG but for some reason, it isn’t working with our design. (We have a number of broken concrete/rock walls. Perhaps that is why the gravel “fits” better.)
However, we want our landscape to be practical, safe, and fairly low maintenance.
BTW: We live in Southern California. The DG or gravel patio and paths will go in on a dark, North facing.
I wouldn’t say I prefer it. I’d say most people I’ve designed for who install DG want a solid patio but don’t want to spend much money.
Frankly I think that a gravel patio is very Mediterranean and you can see lots of photos of Italian villas and gardens with gravel. I think gravel is very practical and easy to maintain, esp. where you live without much rain (excepting the last week of course!). Most of the time if I suggest a gravel patio, people balk. Go with what fits your design look and I think the gravel will look great. Good for cleaning up the dog poop too.
Hi there – thanks for the great information. I was hoping to get some advice on what to do with my current Arizona flagtone patio. We had our flagstone patio installed about two years ago and in order to save money, we set it on DG. Two years later, the DG has washed away (we live in Sacramento) and the flagstone is begining to break. We were considering having it set in cement or something similar that is more permanent. Is this a good way to go? Is it an expensive upgrade since the patio is already laid? Any suggestion would be appreciated.
Hi Frances, Well the answer to the $$ question is Yes. If your flagstone is breaking it is because the installer installed the WRONG type of Arizona flagstone. What I mean to say is that he picked out your color etc., but chose pieces that were too thin.
If you are laying on baserock (vs. concrete), then you must choose thick pieces. This is because you will always have some movement. If you are laying on Concrete, then thin pieces are just fine.
I am wondering if your contractor worked on a bid? I wonder this because he might have been cutting corners. You know that thicker pieces are heavier by the ton, and even though the sq. ft. would be the same as thin pieces, the tonnage is what is priced. So it would make his bid appear the cheapest. He’d be cutting costs in the materials, then he could make it up in the labor. Just a thought.
If done properly, there is no way in just two years the DG would wash away! I would call this guy back and make him do it right.
First, as you might know, my preference is for a DG/flagstone patio to be set as close as possible. Most of the base needs to be baserock with a thin layer of DG for some play for setting the stones. The stones must be thick and the spaces no more than about 1/8″.
Now, to change this to concrete. As you might also know, I strongly feel that if you are to use a patio frequently, it should be laid correctly and that would be with concrete. To do this, you would need to completely pull up these stones (which you can reuse so set them aside), and remove the base rock etc. so you can pour a 3-4″ patio base. Drainage would need to be installed and I like it installed, if possible, outside the patio in the landscape area. As you know, all your water will run-off, unlike the DG, so drainage is very important. Once your concrete base is installed, then you need to place your stones. Again, decide on the spacing of your joints–how much you care to see. When you mortar the joints you can choose a color. Have your contractor do samples and one color can be cut to darker and lighter tones. Don’t make the mortar color darker than your stone, obviously, but you can tone down from a white mortar to a grey or whatever.
Basically, besides your stone, its a completely new job.
I might call in the original contractor, as I said, and make him fix this. If you didn’t use a licensed contractor, then you just might be out of luck, but that is why I recommend that all hardscape be done by LICENSED (Ck. if their license is 1. on their card and 2. there is a website to check to see if it is an active license) contractor. Good luck.
Your site is beautiful! Pls advise. I just replaced my front yard in Van Nuys with flagstone (yes, I used Arizona) over a 2-3″ base of sand. Random thyme planting is going in BUT, for the most ~ should I broom in DG w or w/o stabilizer??
You should be fine with that flagstone in Van Nuys, as you have such little rainfall (in a normal year that is). So you are not putting in thyme between all the joints? With the thyme you need to put a sandy loam down inbetween the joints for the thyme to grow. The thyme won’t be happy in just sand. Frankly, I really don’t know for sure if you’ll have success with DG inbetween those vacant joints. That is because underneath there is a sand base and that is very porous. You can put the DG in but my suspicions are that you’ll be putting in DG every year. What you could do is mortar those joints and you can use a color in your mortar of your choice. For sure you’ll get cracks in the mortar and that is because of the shifting stones on the sand. But the mortar will keep out the weeds and you won’t have to replace it.
Hi Leslie– I really appreciate your detailed insight. I noticed the comments were closed on the DG Path thread… so feel free to delete this, but I was just wondering about a path + patio area. I am following your instructions for the “dusting method,” more or less — I was thinking of 3.5 inches of class 2 base rock, and then about 1 inch of DG, compacted. My problem, however, is choice of edging. Home Depot has 20 foot lengths of “wood flex,” which is nice and sturdy, almost like trex… however, it is only about 3.5″ tall…
My question is, can I dig a 5 inch trench, lay down 1.5 inches of base rock, compact it, and then install the edging by “resting” it on top of the layer of base, and using spikes, , then put down the remaining 2 inches of base rock, then the 1 inch of DG… thereby leaving roughly 0.5 inches of edging exposed. The idea is that the edging does not reach down and “seal” the entire bed of base rock…
Or is that not okay?
If not, there is a product called Ultra Edge which is thin (1/4 inch) but it is 5 inches tall which will work. However I don’t know how flimsy it is until I open the package.
Or, is there another way to make a nice, sturdy DG pathway leading to a small patio, using only a 3.5″ tall edging?
Thank you so much for your time,
Nate in Monterey CA
Make sure that you compact the base rock good. The edging isn’t for the base rock, its for the decorative part in this case the DG. Base rock compacts really well and that is why it is used for road work (sometimes called road base). It doesn’t need an edging, so you’ll be fine with the Home Depot trex. Put the trex almost flush with the DG, leaving the finished look just slightly elevated, very slightly. This will keep dirt from coming in as well as the DG flowing out. Make sure you aren’t making a trip zone though…only slightly elevated. If that trek is wide, say 1″, then flush is fine.
Thank you so much. I am very lucky to have found your website! Cheers, Nate
Can you explain what base rock or road base is?
Thanks for all the great tips. You helped me avaoid a near disaster.
Well, I think technically it might just be the left-overs fines, or screened materials, of gravel, I think. But if you ask for it at any landscape supply house, they will know what you are talking about.
For what it’s worth, my concrete guy said that it is basically old concrete, which has been recycled, along with gravel mixed in. I have 9 tons of it in my driveway right now ($9 a ton at our local dump). The consistency ranges from pure powder, like dry cement, to chunks of gravel and rocks 1″ thick.
I think in different parts of the country they might use different left-overs that are available. I found that what they call road base in WY is different stuff than what we use in Marin, but it works. In Marin, they sell it for $30/yard which is a lot more expensive than what you have.
1″ thick stuff might not compact too well. The idea is that it compacts into an extremely hard base surface which is used as the road base, or in this case, the patio or path base. But yes, there are fines, some stuff powdery, and some small rocks. You must use a compactor.
Thanks again. I saw that American Soil and Stone have both recycled base rock and virgin base rock both of which they note meets CalTrans standards for road base. The recycled is made from recycled concrete and asphalt. The virgin is rock crushed just to make base rock.
Leslie,
Thanks again for your helpful information. I’m also enjoying the rest of your blog.
I was wondering if you had any experience working with “DG” from Nun’s Canyon in Sonoma (Glen Ellen). I am using it for a path at my home in Mill Valley (Tam Valley). I put down two 1/2″ layers yesterday on top of compacted base rock. I moistened it slightly using the compactor to add a little moisture. In some places it got a bit muddy and sticky. Even after leaving it untouched today, which was fairly hot, it is still very moist. This rock seems a lot more porous than granite. Do you know of anything to watch out for when working with this Nun’s Cyn fines?
Tom
Sorry, not familiar with it.
Hi Leslie. I’m in a bit of a quandry and thought I’d seek your sagely advice . . . didn’t find a similar situation anywhere in your DG entry or this one (both awesome by the way!).
The corner of our San Diego backyard has an old, but well-framed, quarter-circle (~450 ft^2) “patio” comprised of ~5-6 inches of moderately-well-compacted gravel. This gravel looks very similar to the “3/4 gravel” sold by the local Home Depots, being highly angular and ranging from ~1 inch in maximum diameter to ~1/8th inch in minimum diameter. The stuff is clearly NOT road base and contains essentially no sand or finer grains. You can probably guess where this is going.
I’d like to cover this gravel with a couple inches of compacted DG (sufficient “headspace” exists), but minimize the possibility that the DG will erode down over time through the gravel’s pore space. One obvious strategy is to first compact the heck of the gravel to minimize its pore space, then compact 1 inch of DG at a time until things seem stable, ideally meaning that the gravel’s pore space is effectively filled to provide the moral equivalent of typical road base.
My concern is that the above approach WON’T sufficiently fill the gravel’s pore space and that the DG will weaken over time, creating micro-sinkholes and all kinds of related mayhem and additional work in the long run. Another possible strategy to “fake” a road base is to first compact in finer grain (maybe more uniform?) sediment until no more “disappears” into the gravel, then proceed with the DG compaction. Yet another strategy might be to (again) compact the gravel, spray-wash in either DG or finer grained material until the pore space appears filled, let things drain (note: drainage seems OK, but not great, based on a few laser level check of the base of the gravel), compact down this “road base”, and finally proceed with the DG part.
I’d really appreciate any suggestions from the voice of experience!
If anyone else has dealt successfully with a similar situation, I’d love to hear from you as well (montyschell@cox.net).
Hi Stephen, WIthout seeing it, I’m at a loss to give you good advice. You seem to have a good understanding of the processes involved. As you know, road base is really hard stuff. Renting a vibrating compacter and seeing what occurs will give you your first clues. I would say another possibility is to remove at least half of this material, compact it as much as possible, then buy a very finely sifted road base material. I did a driveway (not DG) in WY with a material they call ‘crushed fines’ which is essentially the left-overs of all their sifted materials–their junk. Its very small stuff. The natural base is a clay that turns into egregious mud in the spring. First I put a layer of sand to turn the mud into a more concrete mix. Over that I laid down this crushed fines. The result has been fantastic. Where last year the road was completely rutted and impassable, this year its hard and compacted where its been driven over. Most people were putting down gravel which just washes away, but this works in.
My point is that you might try something similar, with removing 1/2 of your material, then adding fines and vibrating. I would try this with about 1″ of fines and see what occurs. There are many ways to skin a cat as they say and I think as long as your result is a very hard stable base before you put the DG on, you’ll be ok. Also, you don’t tell me what your native soil underneath is. If it is more on the clay side, it will probably work. More sandy, then you might have a problem with the stability. Even when I do a crushed rock path, I put it on base rock, but if the native soil is hard, I can get away with a lot less base rock foundation.
One last thing, I would’t put ‘spray-wash’ DG as a pore filler. I don’t think that will work. I’ll be interested in what you do and your results.
Hi Leslie. Thanks for your time and thoughts.
The native soil is very clay-rich, so that is working in my favor.
Quick clarification: You suggested removing 1/2 of the gravel (in this case, ~2-3 inches) before “retrofitting” in the fines by compactor. Does this imply _not_ putting this gravel back in (with sufficient fines mixed/compacted in, of course!), and instead increasing the thickness of the compacted DG from the planned 2″ to more like 4-5″? In this case, seems like going with thicker DG might be better.
Finally, one minor error on my part, likely not relevant, the quarter circle is actually only 115 ft^2 . . . forgot to divide by 4 after doing the ole’ A = pi * r^2!
I hope to start on this beast this weekend and will let you know how things proceed.
Regards, Stephen
“Does this imply _not_ putting this gravel back in (with sufficient fines mixed/compacted in, of course!), and instead increasing the thickness of the compacted DG from the planned 2″ to more like 4-5″? In this case, seems like going with thicker DG might be better.”
No, not at all. What I’m suggesting is removing 1/2 of the existing gravel which may be just to large to compact tightly. Then putting down actual baserock and compact that sufficiently. Start with a little to see how it does. I suspect the baserock will help firm up the leftover existing rock. The problem with leaving all those 5-6″ is that you can’t use a compactor on that much thickness gravel at once. This method might help you cut down on buying baserock as well as compact the leftover 2″. You only need no more than 1-2″ of DG total.