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Stone Flooring

September 18, 2013

Marble Porcelain Tile

Stone is extremely durable and attractive but it can be costly and noisy. Stone for internal flooring is typically 15-20mm thick but the thickness is ultimately dependent on the inherent strength of the material you are dealing with and also the size of slab you require.

Stone can have its surface finished in a variety of ways including; polished, honed (by hand or machine), brushed, flamed, tumbled, flamed, riven, tooled, tumbled, or diamond cut. Stone can also be matched in a number of ways. They can be blended, side-slipped or book-matched.

With stone being a natural product made of the earth it does not come with the same warranty that a manufactured products might have. Its naturalness also makes it is impossible to ensure continuity of pattern or colour, but for most people that is what makes stone so intriguing and so beautiful.

Natural Stone
Natural stone will belong to one of three families of stone depending on how it was formed. Sedimentary stone is formed through the compression of plants and animals while igneous stone is formed from lava. Metamorphic stone is stone that started life as either igneous or sedimentary but was transformed by extreme heat and pressure, as in the way marble is metamorphosed limestone.

Sandstone and Limestone are examples of sedimentary stone. York Stone is a type of sandstone while portland stone and travertine are types of limestone. Although most commonly associated with beige and cream sedimentary stones can come in a range of colours. Both of these stones are porous and require sealing.

Tip: Because of its mottled surface travertine is good at hiding dirt.

Slate is an example of a metamorphic stone. This dense, waterproof, inert stone is frost and chemical resistant but can be affected by oily compounds. It’s generally resistant to scratching but darker versions of the stone may show up scratches. It can be finished in five ways; riven – hand split to even thickness, flame-textured – machine cut to even thickness, sanded – flat but not finished, honed – smooth and silky but matt, or polished – smooth and shiny.

Tip: Due to slates propensity to spilt the edges of slate should be well protected to prevent flaking.

Marble is limestone that has metamorphosed. It is a durable stone but it can be stained and corroded by acids. It can be polished, honed or tumbled. If chipped or stained it can be repaired.

Granite is the most commonly know of igneous rocks. It is extremely hard and impervious to almost everything, meaning that some granites don’t need to be sealed. It can be can be honed, polished, etched or flamed and it is often laid with narrow joints for a sleek finish.

Onyx is another form of igneous rock made from quartz crystals. It is naturally brittle but can be strengthened with resins. It is most commonly used for counters nowadays and looks stunning backlit.

Terrazzo is a durable substitute for marble or granite. It consists of a wet mixture of marble or other stone chippings in a cement or cement-epoxy base. It can be formed into tiles, which are pre-ground and do not need finishing after laying or laid wet in situ and then ground and polished with special machinery. Terrazzo floors are typically 15-20mm thick, require expansion joints are regular intervals and can be slippery when wet. In most countries Terrazzo is dubbed the poor mans marble but due to a shortage of skilled layers in Ireland it can be more expensive than most natural stones when labour costs are factored in.

Krokalia is the term given to the greek tradition of geometric mosaics made up of black and white beachstones.

Composite Stone
Composite stone is more uniform and shallower than natural stone and has become increasingly popular in recent years. As it’s a manufactured material composite stone typically undergoes testing and generally come with a warranty. It is composed of ground and chipped stone with a bonding agent, which is then cast into tiles or slabs. Composite stone can be cut into thinner tiles than real stone making it lighter and less expensive than real stone. Quartztile is an example of a composite stone and is made from recrystallized sandstone. It is very dense and durable but hard to form an edge on. It is also easily split.

Finishing Stone
Polishing stone intensifies its colour and pattern but it can make some stone slippery when wet. Honing stone gives a satin finish with good slip resistance but it makes it can make some stones more liable to staining. Sandblasting can be fine, medium or coarse and it can offer good slip resistance, depending on the stone, but will wear down to a honed finish over time. Acid washing is particularly good for calcium based stone, such as marble or limestone. Flaming is achieved by applying a flame to the surface of the stone and is often used on granite. Granite that has been flamed has a dull appearance because the quartzite on the surface of the stone has been burnt off. Riven stone has texture of unfinished slate while Tooled Stone is simply stone that has the imprint of stone tools left on it. Bush-hammered is an example of a tooled finish. Tumbled stone is stone that has being ‘tumbled’ in an industrial drum to give slightly softer edges and the impression of age. All finishes will be worn off over time but the original surface can be reinstated by refinishing the stone. Stone can also be stencilled with patterns.

Sealing Stone
Stone can be sealed with coatings or impregnators. Coatings place a thin layer of material on the surface of the tile and can be wax or acrylic based. If you want to a highly polished surface on your stone, waxes, acrylics, or any other so-called sacrificial-coatings are not recommended. Also certain coatings will not adhere to polished stone or porcelain. For the most part, sacrificial coatings increase the required maintenance of most stones.

Impregnators are designed to penetrate below the surface of the stone and either deposit solid particles in the pores of the stone or to coat the individual minerals below the surface of the stone. This restricts water, oil and dirt from entering the stone and staining the stone. Impregnators can be solvent or water based and usually contain silicone, siloxane, silane, methyl silicate or other similar silicon derivatives. Impregnators are classified into two types: Hydrophobic Impregnators, which are designed to repel only water and waterbased chemicals (fruit drinks, coffee, tea, soda, etc, would be repelled by an hydrophobic impregnator) and Oilophobic Impregnators, which reply both waterbased and oil-based stains. Some impregnators are listed as oil resistant. Oil resistant and oil repellent are entirely different. Oil-resistant products will only slow down the absorbtion of oil into the stone whereas oil-repellent products will prevent oil from entering the stone. Resin based sealants are more durable than coatings but they do not allow the floor to age and can be slippery when wet.

Slip Resistant Treatments for Stone
There are many treatments that can be purchased and applied to a stone surface to make it slip resistant. Some physically alter the surface of the tile while others alter the surface chemically. Chemical treatments are primarily hydrofluoric-acid based and work by attacking the surface of the tile to create microscopic holes, which inevitably decreases the service life of the stone

Tip: The rougher the surface of stone the more difficult it will be to clean.

Laying Stone
It’s very important that you get an experienced stone installer to lay stone. Not every tiling contactor will be good at laying stone. Typically the cost of laying stone is twice the cost of tiling due to the fact that cutting takes much longer and requires specialised machinery. Stone can be laid in a variety of patterns including diagonal, herringbone, offset, and tumbleblock but anything other than a standard brick or grid format will cost more to lay.

When selecting stone you should …

  • Check if the material has been used before in a similar application and if possible, visit a project to view it in service.
  • Consider the final finish and it’s suitability to the location. Polished stone can be a slip hazard and honed stone can be prone to staining.
  • Consider the maintenance requirements of the stone.
  • Consider the slip resistance that you require.
  • Get independent advice.
  • Check if the quantity that you require is available before making a final selection.
  • Ask for a comparison sample.
  • Find out the lead in time of the material
  • Find out how easy it will be to get replacements in the future.
  • Try to have a choice, it leaves you room to negotiate if the cost of one is too expensive.

When specifying stone remember to state …….

  • supplier
  • lead-in time
  • stone name including region, i.e. Kilkenny limestone
  • slab/tile size
  • thickness
  • finish
  • profile
  • laying pattern
  • treatment required, i.e. coating, impregnator, slip resistance treatment

Thank you to www.stone-federationgb.org.uk where is sourced some of this information from.

Also ….. Technical Information on Tile Flooring

 

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