With summer here, lots of do-it-yourselfers will be hunting for info on Decomposed Granite. I have many posts on ‘how-to’ and ‘how-not-to’, including my eBooklets with complete installation information.
I’ve found a few more photos from previous installations of mine in addition to those already on my website.
First some Decomposed Granite paths
I would be amiss if I did not show a photo of how you can mix different fines to achieve different Decomposed Granite colors. Areas of the country have different standard decomposed granite colors.
Here in the San Francisco area, most DG is gold fines, and occasionally like some of the photos above you can find grey. In the photo below we mixed in some black fines to obtain a darker color.
Elsewhere on my website, I have photos of a rock I used that was more pink. Rock can be used but it must have fines in it.
Decomposed Granite Stabilizer Crushed Stone are the most widely used natural alternatives to asphalt and concrete pathways. An expensive but new product is out on the market that creates a hard surface for Decomposed Granite pathways and patios.
This product, called TerraKoat, is sprayed on with the instructions below.
Decomposed Granite Stabilizer
One note: There are other liquid stabilizers out there that DO NOT work. This is because the solids content of these other products (like G3) is lower than the TerraKoat.
What that really means is the company that makes the G3 waters it down. Another difference is that the TerraKoat contains a proprietary admixture that increases the longevity of the surface. Wheeler Zamaroni has compared both products in real life applications and they found that with TerraKoat you end up with a stronger more durable surface.
Therefore, if you are NOT using TerreKoat, then use a powdered stabilizer. TerreKoat costs about $15 gallon. A gallon will do about 20 sq. ft.
1. AGGREGATE SELECTION FOR FINAL SURFACE: Select an aggregate that contains a variety of sizes. For instance, crushed stone mixes such as 3/8 minus, 1/4 minus or 3/16 minus work well with TERRAKOAT STABILIZER, where as single size aggregates like 3/8 rock or pea gravel are not suitable.
Screenings with extremely high fine content are not suitable either. To ensure compatibility of selected aggregate with TERRAKOAT STABILIZER, prepare a test area.
2. STRUCTURAL STONE BASE PREPARATION: Before starting the actual project, factors such as climate, native soil type, amount of use, should be taken into consideration. As a rule of thumb, “The better the base preparation, the better the results.”
For optimum performance, install 4 to 6 in. of 3/4 minus crushed stone, then compact using a vibratory plate compactor.In restricted areas where a compactor will not fit, use a hand tamper.
3. SURFACE AGGREGATE: Spread surface aggregate over the compacted structural stone base. Rake or screed to the desired level, and slope to allow water run off. Do not compact until after TERRAKOAT STABILIZER has been applied.
4. APPLY THE TERRAKOAT STABILIZER: Using a watering can or pump sprayer, apply the TERRAKOAT STABILIZER to the surface at the rate of 20 ft2 per gallon for residential pedestrian use, or 15 ft2 per gallon for commercial pedestrian use. Allow TERRAKOAT STABILIZER to fully penetrate through the material
5. COMPACTION: While surface is still damp but not saturated, compact the surface with a vibratory plate compactor; 2 or 3 passes are recommended. In restricted areas where a compactor will not fit, use a hand tamper. The better the compaction, the better the results.
6. Seal Coat: After compaction spray TERRAKOAT STABILIZER over the area at the rate of 60 sqft per gallon.
Additional instructions include repairing cracks or using this product on an existing surface that was ill-prepared. For the complete instructions and additional information on TerraKoat, see my updated eBook on Decomposed Granite.
I have many readers who tell me their installer did not apply the DG correctly. Depending upon the circumstance, this stabilizer might be very useful.
Instructions for rebuilding AN EXISTING SURFACE
1. Scarify or rototill 1 inch of the surface, break up any clumps, making any necessary repairs, and add new surface aggregate as needed.
2. Apply TERRAKOAT STABILIZER at the rate of 15 ft2 per gallon; allow liquid to penetrate.
3. Compact using a vibratory plate compactor. In restricted areas where a compactor will not fit, use a hand tamper.
Instructions for maintaining AN EXISTING SURFACE:
1. Apply TERRAKOAT STABILIZER at the rate of 20 to 45 ft2 per gallon. Some judgement will be needed, as consideration for absorption and desired results should be taken into account.
2. Compact any loose areas.
As in my eBook, TERRAKOAT recommends 3-6″ compacted Base Rock with a vibration compactor and a 2″ surface of DG. If you are using the Strybing Arboretum method because of poor drainage etc., then only 3/4″ of DG is needed.
I recently visited some old clients and got a chance to see how their gardens had filled in. I want to comment on just two gardens with interesting patios.
The first was an idea I cooked up. It involved using pavers set in concrete around the edges of the patio. Executing it was a contractors’ nightmare I suppose. I wanted the pavers to be included in the final pour so the patio flowed together. First we did a hand pour and set the pavers in around the edges. You’ll notice those white things in the photo. That’s where the planted edging around the lawn goes and we had to have a backstop for the concrete, so it wouldn’t pour into the dirt. We used some styrofoam that could later be taken out.
The boulders to the right of the above photo are set so no concrete flows beyond them. That area was a planted pocket.
As we poured the patio, we had to hand work the concrete into the spaces between the pavers and wipe the pavers off of the concrete. We had to work fast and it was tedious. Like I said, a contractors nightmare!
I didn’t want the concrete to butt up to the lawn. I wanted a softer edge so I used a mixed planting of grasses and Stachys ‘Hummelo’, a small flowering Stachys which isn’t flowering in this photo, but flowers all summer long. The lawn itself is Carex pansa. The owner has two children who were around 10 and 8 at the time. They were able to play ball on the lawn.
Originally I’d picked out a dark purple colored paver, but that was too wild for the client so we went with a more subdued look.
The client asked for a small patio/sitting area in the corner of her garden. Instead of using more concrete, I chose decomposed granite with the addition of a few pavers in it to match. A path of the same pavers set in soil with ground cover leads to the patio.
I say that a yard takes about 6 or 7 years to mature. This yard is about 4 years old, still growing in, but I was pleased at its progress.
I also visited a garden that used the DG dusting method described in a previous post. This garden was installed five years ago. The DG still looked excellent, but in a few spots you could see exposed baserock. After five years it’s time for another dusting of DG. In making a decomposed granite patio, the major expense in materials is the DG. At over $80/yard, doing a dusting instead of 2″ saves quite a bit of money.
The paver patio set in concrete looked good, although the client never had it sealed. Sealing is really not necessary with a hard stone, but it does bring out the wonderful colors of the stone. Here is a photo of some of the detail work we did with her patio. My client is an artist and fun to work with. She’s willing to take risks and stretch the boundaries. She wanted the edges to have a ‘river’ like look. She personally went and hand picked all the river cobbles as well as placed them herself.
And to leave all you readers with a final funny thought: While driving around nearby Belvedere, the most upscale and expensive neighborhood in Marin County, my son and I saw a police car parked at a prominent corner with a stop sign. When we looked inside, there was a dummy policeman, complete with a donut and coffee mug on the dash. I guess the wealthy citizens of Belvedere can’t afford a real policeman to deter criminals.
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 drier climates 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.
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. There are ways to minimize this. Refer to my DG Patio book for spacing on pavers and proper installation. You will have to convince your contractor to use my methods because it is more time intensive, but it works.
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.
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 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.
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 pictured below, you must have mortar showing in the joints.
As far as flagstones go, there are many types, some of which I do NOT recommend because you will develop moss in the wet season and you MUST seal these types every year to prevent mold. I discuss this more in depth in my eBook.
In general 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.
For a more in-depth discussion on these topics, see my DG patio book. In it I discuss all the pros and cons of different materials, as well as give exact instructions for the installation of the different mediums, whether your contractor installs it or you do.
I’ve tried to keep the price to a bare minimum and it includes all the tips I’ve learned from years of experience. Good luck and do it right from the beginning. Hardscape, unlike plant material, cannot be picked up and moved, and is expensive!
I’ve done 100’s of decomposed granite patios and walkways in northern California and learned a few things as I went along.
When I first began, the industry didn’t have a ‘hardener’ that you could add. That made for a semi-successful installation, because in the winter your walkway was mushy at best. With the advent of hardeners, the DG comes out quite nice, with minimal mush.
Get the DG pre-mixed with the hardener (some landscape outfits will deliver like this) or mix on your own in a wheelbarrow per the proportion instructions.
Prepare a bed that’s about 5″ deep. Use an attractive edging. I am totally committed to Ryerson header, which is a thin hard steel that’s bendable. That’s because it disappears. It is expensive though, comes in 16′ lengths with its own stake.
The other plastic headers are ugly. An alternative are the many colors and types of Trek, which is a recycled plastic material. Use the 1/2″ wide size. The advantage is that its more bendable than the steel, but it doesn’t disappear, so its part of your project design.
For complete instructions, advice, questions and answers, see my eBook on how to install decomposed pathways and patios.
How to Build a Decomposed Granite Patio
Lay down several inches of road base and use a compacter to compact it very hard and tight. Order enough DG to lay down 2″ on top, compacted. Then here’s the secret: apply the DG (with the hardener mixed in good) at the rate of 1/2″ at a time.
Then compact. If you apply too thickly, the stuff won’t harden well. The DG has to be moist when putting it down, but not sloppy. Compact 1/2″ at a time till you have your desired height. Sprinkle with water.
Another method I’ve used quite successfully was told to me by the contractor at Strybing Arboretum in San Francisco. All their paths are done this way, and they get tons of traffic.
For this method, DON’T use hardener. Apply a good road base foundation of several inches, maybe 3 or 4″. Then apply only 1/2″-3/4″ of compacted DG. Essentially this is a dusting.
You will have to reapply every few years depending on your traffic. I used this method for a patio over 4 years ago and still have not reapplied. I think this is a superior method because you completely eliminate any winter mushiness. Even with a hardener there will be some mushiness.
Some warnings: DO NOT try to apply a hardener after the fact. I once went to a potential job where the gardener had installed a walkway, then put the hardener in after he was done. Oh my God! What a mess. The whole thing had to be removed and redone.
Next warning:- Do not install DG directly next to an indoor situation. DG tracks. It’s granite and granite gets on your shoes and gets in the house. You need at least a few steps (not many) before you go inside.
My son’s elementary school built a new gym for millions of dollars. The landscape architect speced DG as the hardscape all around the gym. That was a disaster. All those kids tracked that DG into the new hardwood floor and ruined it! They finally installed concrete as a spacer.
Next, the materials. Of course, every area is different. DG in the Bay Area came in gray, gold, or dirt brown. I’ve mixed them for different colors. Don’t be afraid to experiment a bit.
A new rock came out on the market from a local quarry that was cheaper (DG is expensive. Last I looked it was around $80/yard!). I was able to get ‘fines’ and used that successfully with the hardener for a coral color.
For patios, (see my complete post on patios)I usually don’t like to have a visible drain, so I put the drain(s) on the outside in the shrub area. The exceptions are like the previous post with the photo of the sunken patio. Of course, I had no choice. But really, always remember your drainage.
One neat new alternative to DG is permeable concrete. Its more expensive than ordinary concrete, but it is nicer, much nicer, on the environment. Its fairly new and my understanding is that a good powerwash in the spring opens the pores and keeps it permeable.
If you found this short entry useful, but need more information, click on this link for my full downloadable eBook on patios and walkways, priced at only $2.99. I’ve collected hundreds of real-life questions from do-it-yourselfers and all those questions will be answered in this short pamphlet.
I’ve also included information on DG pricing, colors, how to customize colors, and drainage. If you are not sure if you should use DG or another material.
I discuss the advantages and disadvantages of concrete patios and their preparation, mortared flagstone, flagstone on sand vs. flagstone with DG, as well as how to prepare gravel paths and patios.
Chock full of information in just 46 pages with additional color photos. If you like the eBook, please comment in the Amazon section. I appreciate all my readers and thank you all very much.
The formality of 17th and 18th century European gardens is a reflection of people’s desire to control their environment and the natural forces around them. They were still surrounded by wildness. The comfort of a garden with lines, hedges, and geometric shapes was their safety.
Today people yearn for the natural. We are surrounded by non-nature, non-wildness. We all want contact with what we cannot control.
That is why my clients, as a general rule, all say they want a ‘natural’ looking garden.
Having lived in northern California for so long, gardening was my salvation. I spent my childhood summers in the San Bernadino mountains and backpacked the Sierras and Rockies in my teens. I always yearned for that feeling of being ‘lost in nature’. I understood my clients deepest longings.
This week visiting some clients and potential clients, I was pleasantly surprised with some of my installations from last spring. As a general rule, I need to wait at least 3 seasons to take photos. But here are a few photos from last years installations with comments below. Besides, I bought a Nikon P90 and I’m loving it and excited to post some of the photos. Its really lightweight too so I can carry it in my daypack.
For more information on how you can design your own dream garden see my ebook on Design.