Portland Stone flooring can be used in a wide variety of locations from domestic houses to busy offices and public buildings. We would suggest that an experienced stone fixing company, rather than a tiling company is selected to install Portland Stone Flooring.
The designer needs to assess the strength of the whole floor assembly, which is provided by the substrate, not the stone. The likely loadings and pedestrian traffic will influence the base structure, but once the stone is laid and providing the adhesion to the bed is maintained, the stone will not structurally fail unless the bed fails. Movement joints may be necessary in large areas of flooring, See Stone Federation Code of Practice (SF CoP) – Natural Stone Flooring, Section 30.0.
Portland stone is suitable for laying on timber structure, pedestals, and acoustic systems but the guideline should be carefully followed in sections 19.0 to 26.0 in SF CoP – Natural Stone Flooring
There are a number of options for the levelling screed including sand and white cement and proprietary screeds and the thickness will typically vary between a minimum of 25mm to 75mm depending on the type of screed selected. It is important that the screed selected is suitable for the intended application, any underfloor heating specified, and Portland Stone. Ensure enough time has been allowed in the building programme for the screed to fully cure and dry and for any underfloor heating system to be properly tested prior to the stone installation. An uncoupling membrane that prevents stresses from the substrate being transferred to the stone is normally incorporated into the floor build up, see SF CoP – Natural Stone Flooring sections 6.0 to 9.0.
There are a number of different options for the bedding, but most stones are bedded on adhesives. However, mortar or cement sand beddings can still be suitable in certain applications. Ensure the adhesive complies with the requirements of BSEN 12002 or 12004 and is compatible with the light-coloured Portland Stone. Water is used as a coolant during the stone cutting process, so ensure that bedding selected is suitable for a damp stone or ensure that the stone are thoroughly dry when laid. The stones should be fully bedded when laid, ensuring all edges are fully supported, see SF CoP – Natural Stone Flooring section 18.3.
The optimum size for Portland Stone flooring is either 400mmx400mm, 600mmx400mm, 600mmx600mm or gauged widths (max. 500mm), random lengths. All these sizes are suitable at 20mm thickness, and the gauge widths random length due their lower wastage will have a lower carbon footprint and lower price. Larger format stones are available but the thickness may need to be increased and may require lifting equipment for installation. These larger stones will have a larger carbon footprint due to increased wastage which could impact on the price.
The stones are cut to the tolerances set out in BSEN 12058, so suitable for joints of 5mm +/- 1mm. The pointing can be either sand or stone dust and white cement or a suitable proprietary grout. The grouting process should follow the guidelines set out in section 17.0 in the SF CoP – Natural Stone Flooring.
All Albion Stone’s Portland Stones are regularly tested for their slip resistance, and with the recommended honed finish have excellent slip resistance in dry and wet situations. Other surface finishes are available but not required to increase slip resistance, please contact us for further information and prices.
Albion Stone’s Portland Stones are regularly tested to BSEN 14157 for abrasion resistance and the results typically range between 22 and 26. Although this suggests that some are suitable for the most intensive applications in shopping malls and railway stations, we would suggest that moderate applications such as shops, hotels, and offices with footfalls of 5 million pedestrians are more appropriate for our stones.
There are a number of differing types of pedestals that can be used for internal flooring. They allow the easy access to the void under the stones and it is the stone’s weight rather than grout and bedding that holds them in place. It is important to ascertain that the pedestals provide enough support for the intended loadings based on the stone’s flexural strength.
The tread should be laid as with the flooring on a suitable bed. The riser seated on the top of the tread, set against the mortar, and secured with a stainless-steel pin, as set out in Section 27 in the SF CoP – Natural Stone Flooring.
Portland Stone has been successfully used in bath and shower surrounds and steam rooms; however, we would suggest that the designer seeks specialist advice on the sealing and on-going maintenance.
The stone has also been used for swimming pool surrounds, but advice should be sought depending on how often the stone will be wetted with the pool water and the chemicals used in the pool.
We do not recommend Portland Stone for the following applications:
The pallets of finished stone are wrapped in recyclable plastic to protect the stone during the transportation, unloading and limited site storage, not for prolonged external storage.
All stone need to be carefully handled on site by experienced fixing operatives. The designer should also ensure that the relevant lifting and manual handling regulations are considered at the design stages.
The best method of achieving satisfactory finished work, free from unsightly staining, mortar accretions and smearing, is prevention and good workmanship from an experienced Portland Stone Fixing Contractor. Care should be taken to avoid damage and suitable protection may be required, but if a replacement stone is required, Albion Stone will attempt to complete the work as expediently as possible.
Over time, the action of foot traffic on a Portland Stone floor will hone the surface and form a natural patina on the surface of the stones. This action will allow the untreated tiles to develop their own rich tones and character.
However, in areas of higher footfall this process will be concentrated on the trafficked areas, so a surface treatment may be suitable for a more consistent finish. In certain application such as a kitchen, it may be sensible to apply an impregnator to provide water repellence. It is important that the impregnator is suitable for the Portland Stone Flooring and that the manufacturers application and maintenance procedures are carefully followed.
For further information please see SF CoP – Natural Stone Flooring sections 34 to 39.
The floor should be swept frequently with a soft brush or vacuumed (brushes down) to remove any dust and loose dirt.
Highly trafficked larger floors can be maintained with the occasional use of a rotary cleaning machine with pads or brush set. For lower trafficked floors, use a specific mop with clean water and a suitable product such as Lithofin Wash and Clean, approximately once per week.
All spillages should be treated promptly with a damp cloth and with continuously replaced clean water and not left to soak into the tile. In most cases, this initial treatment will minimise any potential staining- please note the stone will still be affected by acidic contamination.
It may be impossible to remove some old dried-in stains, particularly if they were caused by acidic liquids. These areas may need attention from a specialist stone restoration company.
Bleach, household soaps and detergents should all be avoided. Lithofin products can be used to remove most common household stains in Portland Stone floor tiles and should be applied strictly in accordance with the manufacturer's instructions. Acidic products such as cola and red wine may attack as well as stain the limestone and should always be cleaned immediately. For any further contamination to these areas, contact the Lithofin Technical Line for guidance on cleaning these areas.
Albion Stone, a fourth generation family business pride ourselves on having a helpful and skilled workforce as well as modern and traditional manufacturing process to enable us to produce the highest quality Portland Stone with minimal environmental impact.