We have created a page with the most frequent asked questions we received over the past years trading and these are the most common question also in the trade according to a research we made.
Limestone is a sedimentary rock found in abundance around the world which has been used in construction for millennia. Limestone forms when shells, sand, and mud are deposited at the bottom of oceans and lakes and over time solidify into rock. There are many different types of limestone, varying in colour, strength and porosity, amongst other things.
Travertine is also a sedimentary rock but its characteristic holes are formed when bubbles of carbon dioxide are trapped in the formation process.
Marble forms when sedimentary limestone is heated and squeezed by natural rock-forming processes so that the grains recrystallize.
Granite is formed deep in the earth’s mantle at extremely high temperatures, and is a very hard, resistant stone made of crystallized minerals.
Onyx is formed in limestone caves by drip water, as stalagmites and stalactites. It is a very soft stone, and somewhat brittle. This beautiful stone is characterized by its translucence, and can actually be backlit for striking, dramatic effects.
For a limestone to be suitable for building purposes it must allow the quarrying of large ‘blocks’ which when cut up yield ‘slabs’ with few imperfections and reasonable consistency of colour and markings. The colour and markings of a stone will vary in different parts of a quarry, most noticeably at different depths or ‘banks’. It is essential to understand how these vary in different quarries to be able to offer a consistent product. It must be noticed, however, that every batch of stone is different and that it is virtually impossible to precisely match a sample of a floor. At Limestone Gallery we periodically visit the quarries we purchase stone from to ensure the greatest degree of consistency.
In addition to these characteristics, to be used as flooring a limestone must be able to resist the surface wear it will be subjected to. There are various ways of determining a limestone’s hardness but as there are no British Standards governing the suitability of a particular limestone for use as flooring we at Limestone Gallery follow French recommendations, which are much more strict in this respect. As a general rule the lower the porosity and the greater the ease with which it will take a polish (or whether it will take one at all), then the harder the stone.
Being porous it is best to seal limestone, particularly when it is to be used indoors. There are numerous types of sealant available; at Limestone Gallery we prefer to use a non-filming forming sealant, which impregnates the stone and protects it against dirt and water.
When used outdoors it is necessary to determine the degree of frost-resistance of the stone to be used. A minimum of 30mm thickness of tile is usually recommended. Frost-resistance can be improved by sealing but it is always essential to provide an adequate fall to ensure proper drainage and avoid pooling of water on the surface.
All stones have characteristics, which are peculiar to them, and it is always worthwhile understanding them before deciding on which one to use. As our collection includes over 150 stones we can supply specific information or technical data upon request.
The laying of stone floors is always best left to a professional stone contractor. The following are simply general guidelines; for specific advice please call us, we will be glad to help. We carry out a limited number of installation projects and can also recommend experienced fitters
As with all rigid tiles a firm sub-floor is needed for the laying of limestone tiles. An even and level sand and cement screed is the ideal but suspended wooden floors need not be a problem as long as they are strengthened. Normally waterproof plywood screwed down to existing floorboards at 200mm centres is enough, but if in doubt it is best to get professional advice. If levels are a problem 1″ ply can be screwed straight to joists if the joints between the sheets are supported by noggins (wooden supports screwed between the joists) at 250mm intervals.
Thin bed: Tiles are laid with an adhesive. The bed should average +/- 5mm in thickness, but should never exceed 10mm. When laying on a suspended wooden floor a proprietary flexible additive must be used with the adhesive and the grout and the sub-strate thoroughly primed.
Thick bed: The bed used is a 20 to 30mm thick sharp sand and cement mix, fairly dry. When laying onto a suspended wooden floor expanded metal should be stapled to the floor first.
In all instances the back of the stone should be ‘buttered’ before fixing to provide a key. If the tile is too dry it must first be wet with water to improve adhesion. When laying light coloured or thin limestone white adhesive or white cement slurry with sand/cement semidry must be used. The former for thin and the latter for thick beds
It is worth noting that old limestone floors were never sealed and yet look wonderful today. It is only the first year, before an even look is achieved that new floors can look dirty. To improve stain resistance most stones should be sealed. There are various different types of sealants. For simplicity they can be divided into film-forming and non-film-forming. The first will leave a slightly ‘plastic’ look in the surface and will wear off with time, they do however provide a better seal. At Limestone Gallery we prefer the latter as they do not affect the look of the stone, do not wear away (a new coat can easily be applied every three to four years) and allow the stone to ‘breath’. It is important to make sure the sealant used protects against both water and oil based stains, particularly in a kitchen environment.
The amount of sealer to be used depends on the porosity of the stone. It is always better to apply two to three thin coats, the first of which must be applied before grouting. After grouting a second and if necessary a third coat should be applied. There is a saturation level beyond which the stone will not take any sealant. Excessive sealing will leave streaks on the surface which are difficult to remove.
The sealers always work best when applied to dry stone. This can present a problem because stones normally arrive slightly wet and then absorb further moisture from the adhesive. Ideally one should wait until the stone is thoroughly dry, clean it and then apply the sealant.
A cement-based grout should be used, with an admixture to increase flexibility. It is important to use the right colour of grout, usually a light beige or light grey is the best option. If the right shade is not available off the shelf, a darker colour should be mixed with white. When grouting limestone it is important to work very cleanly, avoiding any reside at all drying on the surface of the stone. This is important because the normal way of removing grout is with an acid, which would attack the limestone.
Width of joint is a question of taste. As a general rule a wide joint (6 to 10mm) will give a more rustic look than a narrow one (2 to 3 mm).
Once the floor has been laid and sealed care is relatively low. As a general rule the lighter and less marked shades of limestone require more attention. Ideally floors should be dry dust mopped daily to remove dirt and grit. |Periodic mopping with a proprietary stone cleaner should be sufficient. From time to time it may be necessary to scrub the floor with a still bristle to remove dirt, which will have accumulated in the pores. Every three to four years a further coat of sealant can be applied after thoroughly cleaning the floor and allowing it to dry. For localised dirt use the stone detergent with nylon brush or a soft scouring pad. It is important that the mop and pads used are cleaned after each use. Any dirt retained will only get transferred onto the floor with the next usage.
A sealant will protect the floor from most stains but care must still be taken, particularly with oil and acid based products. Spillages should be cleaned as soon as detected . Most stains which occur can be removed with special chemicals. We can recommend specialist help for repair and stain removal.
The above text should be taken as general information only. Should you require more technical information please contact our sales office.
We have found it is not practical to publish a pricelist as there are so many variables with bespoke stonework. We are however more than happy to provide you with a price by email. Please contact us for a competitive quote.
We will advise you on whether the stone is a practical choice and in most cases can provide you with a sample to test for peace of mind.
Generally granite is the most practical option as it is extremely hard. Limestone and marble will etch after contact with acidic juices and leave a dull patch, despite sealing. On a honed surface this can be re-honed and re-sealed but the same may happen again. It is important to be able to live with this aspect before committing to a purchase and to clean any spillage at the earliest opportunity. Despite this advice we sell many limestone and marble worktops as our clients love the look and feel of natural stone and its many practical advantages.
We have years of experience in this field and our bathtubs have been installed in luxury yachts as well as penthouse apartments. Please contact our sales team for further advice if you have such a project in mind.
Yes we sell a stone maintenance kit and stone detergents.
All over the world.