Natural Stone: Designing For Longevity

When used properly, a stone’s surface should last +100 years. In this article we will explore some of the critical factors to designing stone surfaces for longevity. However, it should be noted that the easiest way is to design for longevity is to engage a professional supplier who cares about your project.

Often in design we look for a stone based on colour and texture. However, we should also consider; the technical requirements of the application, the maintenance requirements, the user type, and the desired aesthetic. Below we will cover off some critical technical aspects of both the residential and commercial applications such as:

  • Tiling low traffic
  • Tiling high traffic
  • Pool surrounds
  • Kitchen benchtops
  • Wall coverings and claddings
  • Driveways and roads
  • Commercial footpaths
  • Pod based tiling

Natural stone gives the designer an unmatched ability to create and customise the finished product, so having a clear view of the overall feel of the project is critical. Projects with a more provincial feel will lend themselves to tumbled edges, free form shapes, and textured surfaces. Projects with a more modern aesthetic will lend themselves to gloss and semi-gloss finishes for bulk areas with features of texture and vibrant colour.

Beginning the selection process for each area of a project starts with the following questions.

  1. Do I want my material to be uniform throughout the project? If yes, we are guided to materials that can be worked and finished in a variety of sizes and textures, as well as suitable for all the applications across the project.
  2. What is the general style of the project? Are we looking for plenty of variation or no variation? Are we looking for a rustic or modern finish? Are we wanting the project to age or be maintained as close to new as possible? What other materials are dominant in the project?
  3. What is the colour pallet we are working with? Based on the colour requirements many materials will offer the desired colour, but which material used will be driven by the requirements of the first two questions and the application.

The above give us a good jumping off point. From here we can look at the more technical aspects of the application. The ones to look out for are as follows:

  • Tiling Low Traffic- These are commonly residential flooring and walling including bathrooms, residential outdoor areas, within hotel rooms, and non-trafficked aesthetic features.

The requirements of low traffic areas are minimal for internal use- the major consideration is to expansion, contraction, and maintenance. External tiling should make sure the stone can handle weathering. Wetting and drying can damage unsuitable stone over time. Some surfaces can be adversely affected by sunlight.

Soft limestones and marbles with compromised vein structures, and travertines with high clay contents should be avoided. Abrasion resistance and compressive strength are good guides when picking stone for low traffic areas.

When designing for low traffic areas thickness can be as low as 10mm dependant on the stone. Internal finishes should be polished, honed, brushed or sandblast and brushed to reduce the build-up of soil and chemical during cleaning. The less texture on the stone the better the wear-resistance over time. The larger the tile in open areas the better. Limiting grout allows for easier maintenance and reduced bioburden across the work.

For slip resistance information please see “a guide to slip resistance”.

  • Tiling High Traffic- Hight Traffic Tiled areas are commonly found in lobbies and foyers, restaurants and bars, elevators, shopping centres, and shops.

The critical requirement of natural stone for high traffic areas are: flexural strength, abrasion resistance, structure, resistance to breaking load and the finish. 30mm thick stone is recommended for all areas with heavy cleaning equipment in use, and 20mm thick for all other areas.

Marbles and Limestones have been used in the highest traffic environments for thousands of years. The secret to longevity in high traffic areas incorporates more than just the stone but the installation as well. Large format tiling with epoxy grouting and post grout honing or polishing is the most effective installation of natural stone for high traffic areas. Second to this epoxy or polymer standard grouting. Expansion joints to Australian standards are critical for longevity and the correct treatment of control joints in slabs are a must.

Surprisingly one of the biggest issues for high traffic areas is post installation. Correct cleaning and cleaning equipment greatly impacts the long-term aesthetic of the stone. Ph neutral nonresidue spot cleaning is recommended with sweeping. Build-up of chemistry and wear from cleaning machines is often the reason behind avoidable refinishing requirements. Please see our How To Clean Natural Stone or Understanding Slip Resistance for more detailed information regarding these points.

  • Pool surrounds- Pool surrounds have a highly technical requirement. This requirement is often ignored.

Slip resistance, salt resistance, thermal proerties and structure are the more critical aspects when designing pool surrounds. Many stones give a beautiful finish when initially installed but rapidly deteriorate due to wet dry, salt attack and abrasion. Soft sandblasted stone will give a great slip resistance initially but will polish off under foot resulting in a very low slip resistance. Whereas a salt resistant softer stone can give and maintain a higher finish and slip resistance over time than soft and sandblast.

Low clay content travertine, dense hard sandblasted marbles, dense / dolomitic limestones and basalts are the go to for around pool surrounds. The Lithic Australia paving range has been selected to be suitable for pool surrounds as a bare minimum. All Lithic pavers are pool safe.

Add out examples.

  • Kitchen Benchtops- Selecting natural materials for kitchen benchtops is one of the trickier requirements of designers working with natural stone. The material needs to be able to span the distances required with unsightly joining, be structural to handle the cutting requirements of fabrication including- unique sink and stove top inserts, and be able to take the variety of chemical, temperature, and soiling of a working kitchen.

To select the right stone for kitchen benchtops it is advisable to look for a marble or dolomitic limestone with a MPA of over 130 and an abrasion resistance of less than 15. You will find these details in our technical documentation on each individual product page.

The other critical point is material structure. Some marbles and limestones can be beautiful as tile because you can avoid the veining and faults that occur throughout the large block. With slabs you can’t do this- therefore we look for stone that can give the 2.5-3m span without spider veining, soft spots, or major density changes. These stone are not easy to spot just by looking at the material. The advantage of Lithic’s slab range is that it has already been selected to take all of this into account, so you don’t have to.

Wall Covering and Claddings- Wall claddings can be mistaken as the simplest to work with regarding material type as they have low abrasion and strength requirements. Understanding rules regarding weight and height limitations are important, however. Type of fixing is also critical, for example a pinned external ventilated cladding is a very different set of requirements to a kitchen splash back.

External claddings: with an external cladding you want to ensure little thermal or moisture expansion / contraction, or deflection. Exposure to direct sunlight and other weather create increased load and sheer on fixings. Igneous and metamorphic stones like marble, basalt and granite are best in this application. Reduced veining and fissures are also desired. At no point should moisture sensitive stone be used in external claddings. Dependant on climate consideration is to be given to the effect of freeze thaw on the stone as well. When designing for external cladding it is best to give a preferred surface and colour and then let the team at Lithic propose suitable options.

Internal Cladding- Internal cladding allows more flexibility. There isn’t a product in the Lithic range that isn’t suitable for internal walling, so the opportunities are many.

Driveways and Roads- when designing for driveways and roads there are several considerations. For residential surfaces, consideration should be given to the type of traffic. General rule of thumb is to allow for a 5T vehicle. This covers off small trucks and maintenance vehicles. For commercial roads and driveways consideration should be given to local government specifications and standards. Based on size roadway applications will require a minimum 50-60mm thickness dependant on beading and surface dimensions.

So, when we are working with trafficable surfaces, we want to use stone that will not lose slip resistance as they wear. Stones with a high polished aggregate friction value are desired. Reducing sizes to 100×100 cobbles or 230×115 bricks overcomes many issues when designing for traffic. If a larger size is desired high MPA stones, with high flexural strength and high abrasion resistance, are desired. Basalts, some limestones, marble, and granites are preferred for larger size applications.

Commercial Footpaths- Like commercial roadway there will be a local government specification covering slip, strength, and size. However, generally of thumb, P4-P5 slip resistance, high abrasion resistance, high MPA, and high flexural strength are desired. Consideration is to be given to worse case scenarios for commercial walkways. Maintenance vehicles up to 10T must be allowed for.

So, when we are working with commercial walkways, we want to use stone that will not lose slip resistance as they wear. Stones with a high polished aggregate friction value are desired. Reducing sizes to 100×100 cobbles or 230×115 bricks overcomes many issues when designing for traffic. If a larger size is desired high MPA stones, with high flexural strength and high abrasion resistance, are desired. Basalts, some limestones, marble, and granites are preferred for larger size applications.

Pod Installation- A continually growing trend is the use of elevated paving systems or POD systems. These systems are being used to create usable or low installation-cost spaces in commercial and residential applications. Often on balconies and rooftops.

For these applications the stone must be able to withstand 4.5kn of force centre load with supports of 2cm2 no more than 2cm2 from the furthest corner. This is easy to achieve for stone from a testing point of view. 406x406x30mm, 610x406x30mm, 600x600x40mm, 800x400x40mm stone in the Lithic range will meet these requirements. Larger sizes will require an extra centre support. The challenge in designing these surfaces is to ensure we use a stone that is free of common fissures and veins that may weaken over time with weathering.

The world of stone is vast and beautiful. There are stones of every colour suitable for every application. The most critical aspect when designing for longevity is to work with a supplier who intimately understands the requirements of the application and the capabilities of the material. This is what we do at Lithic Australia everyday; we are passionate about bringing natural stone to the forefront of sustainable design.

Contact us today to see how we can help.

Working with the Lithic team can ensure you achieve the finish and longevity these systems require.