Original flagstones are a beautiful feature in a period property – but renovation can be challenging. In many cases, stones are laid directly onto the ground, with no damp-proof membrane underneath. This installation method allowed the stone to breathe, and to absorb and evaporate moisture freely through the stone’s porosity. For a successful renovation, it’s essential that this isn’t compromised, and that the correct treatments and methods are adapted to ensure that the stone isn’t damaged in any way. In LTP’s latest case study, we visit a Blue Lias project and discuss the renovation carried out by stone maintenance specialist, Silex UK.
About Blue Lias Limestone
Blue Lias Limestone dates back to the late Triassic and early Jurassic period, some 195-200 million years ago. It is named after quarrymen’s dialect for layers – ‘Lias’. The stone is made up of layers of limestone and shale, and it has a distinct blue/grey tinge due to its fossils, ores and iron content. It’s mainly found in Somerset and Dorset.
The Renovation – cleaning
Located within a Grade II Listed property in Sparkford, the Blue Lias limestone was laid throughout an area totalling around 100m2. It included the side entrance, kitchen and a narrow corridor leading into the main open hall area, including the dining area and lounge.
LTP advised the Silex UK team on the best cleaning and protection method, in view of the stone’s age and environment. Being a historic installation, the floor was laid directly onto the earth, without a damp-proof membrane.
Before the floor was cleaned, Alastair Niddrie from Silex carefully removed salt, flaky residue and paint deposits by hand. LTP Grimex was then used to clean the limestone and remove greasy residue. Grimex is an intensive cleaner that removes oil, grease, ingrained dirt, water-based paint and old layers of wax. It’s safe to use on all types of natural stone and it can be used at different dilutions to suit application. Alastair used a 1:3 dilution, applying the cleaner to the flagstones with a broad brush. The treatment was left to react for 5-10 minutes, during which time the floor was kept wet with additional solution. It was then agitated with a brush, residue was removed and the surface was rinsed thoroughly with clean water.
LTP Solvex – an intensive cleaner/stripper – can also be used alongside Grimex to remove oil-based paint, wax, oil, silicone, acrylic, polyurethane sealer and residual epoxy grout. Like Grimex, it has a non-caustic formulation and is safe to use on natural stone.
The Renovation – Phase II – protection
Flagstone floors are often enhanced and protected using wax-based treatments. This method cannot be used on a floor without a damp-proof membrane, as it blocks the stone’s porosity and the passage of moisture and salts through the limestone. If the stone isn’t able to breathe, it will eventually break up. Walls can also be compromised, as moisture looks for other ways to escape.
At the property, Silex used LTP’s ECOPROTEC Colour Enhancing Stone Sealer. A water-based impregnating treatment, the sealer enhances and protects, strongly repelling water, oil and grease. It was applied after the intensive cleaning and before re-pointing. A further coat was applied 24 hrs after the stone had been cleaned up to remove any residual grout. The final coat covered the re-pointed joints as well.
ECOPROTEC Colour Enhancing Stone Sealer is non-film forming so it allows the surface to breathe and helps to reduce efflorescence. The sealer is applied following a thorough clean and after the floor has been left to dry for 24 hours. To ensure a good application into the uneven surface, Al applied the treatment with broad paint brush. Once cured, the floors were buffed using a rotary machine fitted with white pads; this gave the surface a beautiful lustre. The flagstones were then polished by hand with woollen pads.
To find out more about the specification and ECOPROTEC treatments, please visit www.ecoprotec.co.uk or contact the ECOPROTEC technical team on 01823 666213 and email firstname.lastname@example.org
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