FMDC’s Lisa Nunn on the importance of choosing the right natural stone for your project
When selecting a material for interior use, natural stone remains a popular choice, from high-end hotels to private homes. Designing with stone gives a unique and prestigious aspect to any application and with such a rich variety, there are many options to choose from.
With such an abundance of choice, it is vital the correct stone is selected, and that the design considers the technical properties of the material with respect to the intended use, for example as lobby flooring, kitchen worktops, or shower walls and floors.
As a Senior Geologist at FMDC and a member of the Interiors and Surfaces Focus Group of the Stone Federation, I have worked on many projects using stone for a wide range of applications in the interior environment. Part of my role is to advise members of a project design team as to the suitability of their stone selection – does the stone selected (e.g. marble, natural quartzite, travertine or granite etc.) possess the physical properties that will allow the stone to maintain a high-quality appearance and a durable performance throughout its service.
Interior applications using stone often involve complex design features, choosing the correct stone lies at the heart of any design. With this in mind – how do you determine what stone could be considered for your next interior stone project? Stones that have previously been used as say a lobby wall might be inappropriate for use in a shower for example.
Popular locations for interior stone are typically in the kitchen and bathroom as flooring, walling and countertops/vanity units. Other popular areas include fireplaces and communal spaces such as hotel lobbies, swimming pools, saunas and lift floors. Consideration must be given to each individual environment to assess which stone you may possibly use, for example for flooring – is it a frequently used area with lots of people or a private space with minimal foot traffic and will it be wet or mostly dry?
As an example, should stone be used in a hotel lobby, this would most likely be a dry environment with heavy foot traffic. The stone selected (including any treatments to the stone surface) for this area would need to withstand this level of use, not only in terms of strength but also, in particular, having a suitable resistance to abrasion and slip resistance noting the potential impact on appearance. Stone of lower porosity and water absorption may also provide added benefits to the daily maintenance regime as they generally assist with preventing dirt build-up as opposed to stone with a high porosity where dirt can gather more readily in open pore spaces.
Stone to be used as walling or tiling in dry internal areas will have less exposure to potential wear, however the risk of impact should be considered. Stone thickness and the method of fixing is important in the design to ensure that the stone is safely fixed and not at risk of falling.
In a wet internal environment such as shower floors and walls or around a sink area or bath top, the stone used will typically be exposed to cyclical wetting and drying, shampoos, soaps and potentially acidic cleaning materials. This is a process which may lead to deterioration should the wrong stone be selected. There are many stones that are widely and successfully used in wet areas and it is good practice to review successful precedents to aid in the selection process. Should a lesser-known stone be considered, low water absorption is vital as a start however the mineral composition and stone structure must also be considered. Further analysis into the mineralogy can highlight the presence of potentially deleterious minerals such as pyrite and some clays within features known as stylolites that may react with the water and break down over time.
Other popular areas for stone in interior design are kitchen countertops and vanity units, locations likely exposed to potentially acidic products such as carbonated drinks, lemon juice, certain cleaning agents and some cosmetics. The composition and colour of the stone used can aid in the longevity of the surface appearance. Carbonate rich stone can be susceptible to etching marks from such products and can increase maintenance requirements. In addition to selecting an appropriate stone it is also important that the correct cleaning products are used according to the stone composition and that this is recorded in a good O&M manual to avoid such issues from occurring.
This article highlights some key considerations for stone in the interior environment, however, following all available guidance, seeking expert advice and understanding the technical data are imperative in selecting the correct stone.
