10 Reasons why select Natural Stone Travertine, Limestone, or Marble Pavers vs Concrete Pavers.
#1 REAL natural stone travertine pavers are less expensive than faux-stone concrete look-alikes….and have a much better look and enduring life span. #2 ASTM* Tested – twice the strength of concrete. #3 Stays Cool Underfoot unlike man-made products or slate. #4 Great for all exterior (pools, patios, driveways) and interior spaces (kitchens, bathrooms, countertops, basements). Copings, treads, and wall caps are all readily available in various thicknesses. #5 ASTM* Tested – high co-efficient of friction for a non-slip surface. #6 No Maintenance – no need to seal or coat (especially, if dry-set pavers). #7 ASTM Tested for freeze/thaw compatibility in northern climates. #8 Retains its natural beauty forever! (They are over 50 million years old). #9 Does not scuff or degrade like patterned concrete or stamped asphalt surfaces (asphalt and concrete get extremely hot). #10 Fashion-forward look with timeless beauty.
LIMESTONE Pavers
Limestone is the youngest of all these natural stones, a sedimentary stone usually found in ocean beds. Typically, limestone is homogeneous in color and most of the buildings around the world (ie: The Parthenon, Empire State Building, Lincoln Memorial, Pyramids, The Great Sphinx) have been built with sedimentary limestone. It is the most common building material in the world. It is a great choice for a more contemporary or modern design. It has 5000+ compressive strength and is great for all applications, including driveways.
TRAVERTINE Pavers
Travertine is a type of “morphed” limestone, but it is created from Artesian wells which means lime has been deposited by water, which is why Travertine has such a varied movement in the stone. It is about 50 million years old. Travertine makes an excellent natural stone material choice for any indoor or outdoor area because it never gets hot (no metal content in the stone), it is twice the strength of concrete, and is non-slippery. Travertine (and limestone) are durable for any application both commercially and residential.
MARBLE Pavers
Marble, on the other hand, is about 100 million years old and is perfect for the same applications as travertine and limestone. Since marble is an older natural stone material, it typically will be “veinier” and less “wild” than the travertines. Like all stones, marble is used for interior flooring, wall veneer, pool decks, patios, driveways, and wall cladding in both commercial and residential applications.
Natural stone paver driveways are a thing of beauty, a real estate highlight, and a feat of engineering. They increase property values, up the curb appeal, and boost resale prices. So, what’s the best way to protect that investment and maintain its physical appeal? Let’s start at the basics, which means ensuring the natural stone driveway installation is done correctly.
There are two options for natural stone paver driveway installation.
‘Dry set’
‘Wet set’
And, at Gothicstone, we suggest all ‘dry set’ and ‘wet set’ installations include a cellular confinement system (CCS) underneath for maximum longevity and lifetime value.
Insider notes: ‘wet set’ driveway installation with natural stone pavers
An issue with ‘wet set’ (poured concrete slab substrate) particularly in climates that have a lot of freeze-thaw cycling, is that concrete slabs are used as the sub-base/substrate and often will crack. It’s often not a question of “if” the underlying concrete slab will crack, it’s “when” it will crack. And a cracked concrete slab will commonly transfer the crack(s) to the adhered surface stone or any material on top, such as concrete pavers, for that matter. The reality is very few contractors are willing to put the effort into making a slab that won’t crack because it takes extra work and expense. Utilizing rebar, a geo cellular confinement system, and a ‘separation membrane’ (such as Schluter®-DITRA & DITRA-XL) will mitigate the possibility of failure, as described below.
Geo Cellular Confinement System (CCS) to the rescue: Why implement in a ‘wet set’ driveway application?
Some people think the cellular confinement system isn’t needed under a large concrete slab. But we disagree. The fact is the minimal extra expense will all but guarantee that you will never have slab cracking. Water is going to get underneath the concrete slab and during freezing, it will expand. The cellular confinement system holds everything in place minimizing movement resulting from freezing and thawing environments.
Cell-Tek Geo Cellular Confinement System (CCS)Rutgard Roadway 4 Geo Cellular Confinement System
Steps to installing a ‘wet set’ long-lasting driveway with a cellular confinement system:
To recap, if you want your installation to last a long time, follow these 9 steps:
Excavation with appropriate drainage considerations to mitigate water pooling underneath.
Installation of geotextile to prevent gravel from sinking into the soil below it.
Installation of the cellular confinement system following manufacturer’s best practices.
Fill the confinement system utilizing only clean (washed and graded) gravel. We strongly advise against using ‘modified/unwashed’ gravel mix.
Installation of a top layer of geotextile on top of the gravel.
Installation of rebar grid on the top of the gravel (preferably epoxy coated or ‘high-tech steel alternative’ composite rebar to avoid the risk of rust-causing future failure).
Pour a fiber-reinforced concrete slab. It is imperative to follow the local code regarding the implementation of expansion joints.
To ensure longevity, an extra step we recommend is to install a separation membrane such as Schluter®-DITRA & DITRA-XL on top of the concrete slab to mitigate cracks transferring through to the surface stone.
Professionally install the appropriate natural stone including grout lines (and expansion joints where necessary) to enable expansion and contraction. This is imperative in extreme weather conditions. In a perfect world, ½” thin natural stone can be used when all the above steps are adhered to with precision. Otherwise, we would recommend the 1 ¼” standard thickness for exterior applications.
In conclusion, there are redundancies in the above best practices instructions. There is almost zero chance of failure if all these steps are completed, and the resulting driveway should last a lifetime.
Insider notes: ‘dry set’ driveway installation with natural stone pavers
‘Dry set’ installation is the ideal method for driveway stone pavers. It avoids excessive movement of the stone due to heaving in colder climates. Also, stress from an expansion of the stone in hot climates. These unwanted issues are inherent in poured concrete slab systems. ‘Dry set’ installation is an environmentally sustainable alternative that allows water to pass through it rather than create problematic water runoff.
For the safest approach, it’s best to select natural stone pavers of smaller sizes. When working with smaller pieces, such as 4”x4”, 4”x6”, or even 6”x6” cobblestones, use a ‘dry set’ application. But if your customer wants something different than the classic cobblestone 4”x4” granite, limestone, or porphyry block, the key is to consider the flexural stress on the stone. If the stone surface is longer than 6 inches in any one direction, then a strong (high ‘flexural strength’) material is optimal, particularly when considering a ‘dry set’ application. Avoid natural stones prone to having natural fissures or clefting.
Large format natural stone pavers in a driveway installation
Large format pavers can be successfully installed if the installation is done properly. You can install 12”x12”x1¼”, 16”x16”x1¼”, 8”x16”x1¼” or larger if it is installed correctly. But that’s a BIG “if”. Many contractors/masons rely too heavily on laborers to do the installations, emphasizing speed over quality. This isn’t a good idea. A small void or a “pea under the mattress” can cause failure.
Geo Cellular Confinement System (CCS) to the rescue
To mitigate shifting and cracking, install a cellular confinement system. Gothicstone recommends a cellular confinement system (CCS) under any base. With driveways, it’s almost imperative due to tire track “rutting” to use a CCS. For example, if you have a sand or dirt driveway, ruts inevitably occur over time. But it also happens with blacktop driveways or any driveway where you have constant stress and load on two narrow tire tracks. The vehicle load will compress the ‘track’ area, whereas a CCS can keep the substrate from spreading out. This method prevents stress on the tracks from making ruts in your installation, and thus pieces from failing. Because when the ruts happen, there’s uneven compression on the pieces. It’s the unevenness of the load where problems like this occur.
Small 4”x4”x4” cubes/pavers typically won’t break, which is why people typically use this size of material, but they will be susceptible to rutting and shifting. Often people want to use a larger format driveway stone. If so, a ‘dry set’ and a cellular confinement system are the approaches to use.
Ruts and cracks can be avoided
The larger pieces will help in that they won’t rut as readily, however, they may crack. Whereas small driveway stone pieces will allow the material to “sink down” into the ruts without breaking. But they’ll allow the ruts to occur more easily. Plus, more water is washing in between the joint areas because you have more joint areas.
If you have a 4”x4” compared to a 16”x16”, you’re going to have about 1000% more joint area with a 4”x4” installation. That’s an incredibly exponential amount of joint area because in a 16”x16” area, you will have 16 pieces of 4”x4” material (4 in one direction and 4 in the other direction) and then all those joint lines in between where the water will be entering and then allowing for either washout or heaving underneath it.
So, the smaller driveway stone pavers do allow for more movement to happen but, eventually, they may cause ruts unless you use a cellular confinement system to keep everything underneath in place.
Keep in mind that vehicular weight will be on the pathway of the vehicle tires; that is where the bulk of the load or stress will go.
Steps to installing a ‘dry set’ long-lasting driveway with a cellular confinement system:
To recap, if you want your installation to last a long time, follow these 8 steps:
Installation of geotextile to prevent gravel from sinking into the soil below it.
Installation of the cellular confinement system following manufacturer’s best practices.
Fill the confinement system utilizing only clean (washed and graded) gravel. We strongly advise against using ‘modified/unwashed’ gravel mix.
Follow local code requirements regarding the height/quantity of crushed stone/gravel required in your geographic area.
It’s considered best practice to compact every two inches of height when applying the gravel.
Installation of a top layer of geotextile on top of the gravel.
Installation and compaction of screenings/’fines’ (concrete dust, sand, or small/fine gravel)
Professionally install and compact the appropriate natural stone pavers. Where small grout lines are open between the pavers, sand or polymeric sand can be swept between the joints.
To retain the beauty of the stone, you should use an impregnating stone sealer using a color enhancing impregnating stone sealer, so it keeps the stone looking new. If you want the stone to age naturally, you don’t have to use any stone sealer at all. In any case, sealing in a ‘dry set’ application is not necessary. Never use a ‘topical’ stone sealer (non-impregnating).
5 design approaches using natural stone pavers:
Creating a “deco” look. Use smaller pieces that can manage the load in the heavy traffic areas and install the larger stone along the sides.
Placing smaller format material at apron entrances of driveways. The entrance apron, where vehicles turn in off the main road, typically takes an enormous impact as they swing into the driveway. In most of the United States, when you approach a driveway, there will be a bit of a bump or a swale causing impact. So, on the apron entrance, from the road to the driveway, consider using a smaller format stone. The smaller format driveway stone mitigates the impact of flexural stress, while at the same time smoothing the sloping transition to the street.
Mixing and matching alternating sizes to provide attractive applications. Smaller driveway stone pieces on the apron can be cut from the same blocks of stone as the rest of the project applications. Whether it’s a long driveway, walkway, or pathway leading up to a patio or pool, for example, the entire project stone can match no matter the size or thickness of the material.
Picking the appropriate material if you select larger format driveway stone pieces. Gothicstone™ SEAHAZEtm limestone is extremely strong, has high compressive strength, and high flexural strength.
Choosing 4”x4”x4” cubes is not necessary. It’s not necessary to go that thick, however, with carbon footprint, shipping costs, and other green initiatives being an increasingly important consideration, a 4”-thick paver is going to double the shipping cost of a 2”- thick paver. From both a cost-effective value engineering perspective and a carbon footprint perspective, a 2”-thick piece gives you a better value and is good for the earth!
Have questions on cellular confinement systems and selecting/specifying natural stone for driveway systems? Contact us.
Other resources that may be helpful in planning your driveway installation:
Yes, even for residential pool deck or patio pavers!
The need for stabilization grids (sometimes referred to as cellular confinement systems or load support grids) is something that is largely unrecognized throughout the construction industry in paver installation which sort of boggles the mind. I would say that the large-scale industrial masonry world understands because they have heavy-duty architects working on road projects, those that require forethought, and longevity. Unfortunately, on the mid-size to small scale projects ie: from parking lots to a driveway, backyard patio, or pool paver projects, it’s usually not a consideration for reasons that are not understood by me.
Stabilization equals Longevity of Paver Installations
Stabilization is at the heart of the project when it comes down to the longevity of the installation. Anybody can lay down some stone or pavers on soil or grass and they’ll stay there for a week, a month, or a year. If you want pavers to stay in place for 10, 20, 50 years, you need to have a stable substrate. As with interior tile projects and exterior paver projects, it’s all about the substrate. Without the proper substrate, nothing else matters because you will have failure – 100% guaranteed.
Courtesy CellTek
Recommended Use of Stabilization Grids
So, without the soil stabilization under a paver installation, you’re extremely likely, in almost every scenario, to have some movement. There are some very stable environmental situations that may not necessitate it. Climates that don’t have much temperature change, climates that don’t have a lot of rain, and have very compacted sandy soil, are where you will not get a lot of movement underneath. As you know, that is a small portion of the world we live in that has that kind of climate.
So, conversely, if you have a lot of rain, if you have a lot of temperature change, particularly if you have a lot of cycling in freeze/thaw, and that’s the real killer, you’re going to have movement in your substrate. When you have movement in your substrate, you are going to have movement above your substrate because the substrate is what is holding your stone or pavers. For that reason, stabilization grids are recommended.
Courtesy CellTek
Paver Installation on Concrete Slab with Stabilization Grids
When you have a concrete slab, it’s the adage, it’s not IF your slab will crack or fail, it’s WHEN. Concrete slabs are extremely prone to failure because they are asked to perform very unforgivingly and next to impossible tasks…to endure movement underneath them without cracking or failing. And, again, when you have movement underneath, you’re going to have the material on top crack and fail. Even the concrete itself is prone to failure without movement from underneath because of heat, especially in hot climates, and or cold or thermally cycling climates, where it gets cold then hot, cold then hot. The slabs will expand and contract according to the heat and cold they are exposed to and particularly, the cycling of heat & cold, heat & cold.
Small concrete slabs, for sidewalk sections 3’x3’ or 4’x4’ are not a big concern. Unfortunately, enough people do not put on expansion joints, they use control joints, which when it fails, fails along the control joint. A control joint is nothing more than a little line cut into the surface of the concrete making it a little bit weaker on that line so if it cracks, the crack goes along that line that was cut into it. So, it’s a prettier failure. The concrete slab is not the best solution.
If there are no elevation problems or choose to raise your elevation, it’s perfect to put a grid down on top of the existing concrete slab and put pavers on top of that.
Benefits of using STABILIZATION GRIDS
What happens when there is failure ie: wash out from too much rain underneath, and without a properly compacted substrate, you can have the substrate washing out from flooding, heavy floods, constant flow of water eventually eroding underneath, the stabilization grid will hold that substrate together so that it’s not possible to wash out. The gravel can’t go through the walls of the grid, so it holds it in place.
One of the bigger dangers is the freeze/thaw expansion and contraction issue that is extremely common in the climates of the upper forty-eight states in America and around the world. When you have snow and wintry weather, warm weather, then freezing weather, warm weather, and moisture-cycling, the moisture gets underneath the pavers and freezes. And, as we all know, when you look at ice cubes in your freezer, they all have a hump in them because when water freezes, it expands. So, you’re going to get the substrate holding water. If there is quick freezing overnight, the water will expand and therefore, your whole installation will heave up a little bit.
When it heaves down, when you use the grids, the grids will hold it in place instead of it shifting a little bit every time. When it shifts a little bit every time, from heaving then relaxing, heaving then relaxing, heaving then relaxing, you can imagine things will start to spread out over many cycles and next thing you know your pavers are 1/8” apart then ¼” apart, next thing you know, they have those openings and more water attacking it and now you have bigger gaps for the water to go in and turn to ice and more washout issues, etc. The whole thing kind of goes to hell without the use of a stabilization grid or cellular confinement system.
Are you looking for different exterior stone options? Gothicstone is here to help. Contact us today to find out more about our products so we can value-engineer your stone solution. We look forward to providing you with natural stone materials to help make your client’s outdoor area an exclusive living space.
Stone Cleaning and Sealing for Natural Stone Pavers, Tile, Coping, Step Treads.
Hardwood decks/patios, as well as wood on houses/buildings, need to be power-washed, cleaned, and sealed on a regular basis. Although you power wash and seal a hardwood deck every year, natural stone deck maintenance is much less frequent. Stone sealer and cleaner products are very high-tech and require minimal maintenance.
Stone Cleaner Maintenance for Natural Stone Pavers, Tile, Coping or Treads:
Regular, basic maintenance type cleaning: *
Use a stone cleaner that is easy to find at any hardware store or
Use any non-caustic degreasing agent (mild dish or hand soap) mixed in warm water.
Deep cleaning, minor restoration (mild etch) type cleaning:
Dilute muriatic acid ten parts water to 1-part store-bought muriatic acid.
Wet the entire stone surface.
Pour dilute mix and move it around with a sponge mop – consider doing in twenty square feet over lapping sections. Don’t let it sit in one place without moving and agitating it. Acid will neutralize after 10-15 seconds.
Finish by rinsing the surface with clean water.
Note: The acid should not be strong enough to do any damage to the ecology or be harmful to your flower beds next to the stone patio. Once the acid contacts the stone, there is a little bit of sizzle, a bit of chemical reaction that happens and then it should be neutralized.
Stone Sealer Maintenance for Natural Stone Pavers, Tile, Coping or Treads: **
With natural stone, you should never use a prophylactic coating type of sealer because the stone wants to breathe. Using a “breathable” stone sealer tends to last many years longer. When using a high-quality sealer, you will only have to seal every 5-15 years or longer. Some companies offer both a color-enhancing stone sealer and a “matte” finish stone sealer. Both types of sealers are impregnating sealers and penetrate the stone about a ¼”. The color-enhancing stone sealer will help the stone “pop” its deep rich darker color (like when it is wet but doesn’t add shine or sheen to the stone). The “matte” finish stone sealer leaves the stone the same color when it is dry. Gothicstone recommends Stain Proof, stone cleaner, and stone sealer products.
Considerations when applying stone sealer:
If grout was newly applied to the tile, pavers, coping or treads, you should wait at least 2 weeks for the outgassing to complete before using stone sealer.
If only stone cleaning was done, seal after the stone is thoroughly dry, typically a day or two.
Follow the directions on the bottle for the impregnating sealer.
* This does not apply to high polished marble – contact us for those details.
** We highly recommend purchasing sealer products from a tile showroom. We recommend Stain Proof by Dry-Treat.
Are you looking for different exterior stone options? Gothicstone is here to help. Contact us today to find out more about our products so we can value-engineer your stone solution. We look forward to providing you with natural stone materials to help make your client’s outdoor living space unique.
