Taking on a project of this size the preparation is key. Taking photos and measurements of the geometric pattern in situ is vital. Then creating a digital diagram of the space and laying the original historic geometric pattern into it. We use a variety of traditional and contemporary tiling methods to achieve the highest ascetics in our work. Using the original floor tiles combined with reclaimed historic tiles and where reclaimed colour matches cant be found we will use reproduction geometric tiles from Winklemens or Craven Dunnills.
As with all historic floors the problems come from the substrate supporting the tiles in one form or another. It can be the structural movement of the building, movement from supporting joists or floorboards, or damp and water ingress into the substrate or wood. In the main it comes from the fact that the mortar beds were put directly onto floorboards and across joists and not overboard as is common practice today. Over the last 100 years the substrate has moved because of the settlement of the building, the wooden joists and floorboards expand and contracts over time and that movement leads the Mortar bed to move and crack and then tiles become damaged, chipped or cracked.
With any conservation project, we start by removing the tiles from the damaged area so we can analyse the substrate. All substrates from this era were poured in a few stages, much in the same was they were in Greek and Roman Times. With a Statumen, Rudus, Nucleus and setting bed, these are Roman Terms that have been found in architectural books of the classical era. The Statumen is a bedding of fist sized stones or slabs, followed by a rudus, which is a mix of rubble and lime or sand cement beaten solid to a thickness of around 9 inches. Then the upper layers, a finer mortar mixed with three parts of crushed tiles, slate, ceramic and brick, again mixed with lime or sand cement. Then lastly, the setting bed, this is often various depths and this is usually where the two layers become detached from the each other.
When analysing historic floors, sometimes only the setting bet is damaged, which requires much less work. The layer is removed to the point that the substrate is solid and stable. From this point, the original mortar bed needs to be moisturised, with a mix of water and SBR, so a new setting bed can be poured and bind to the original Mortar.
With this project, the buildings movement cracked right down through to the original boards/substrate and the substrate becomes Boss, meaning the screed is detached (lost its adhesion) from the fixed substrate (floorboards/ground earth). In this instance the Mortar bed needs to be removed entirely, along with all the tiles. Then the original floorboards over boarded with cement board and a new mortar bed/levelling compound or screed poured. This will allow slightly more flexibility if more movement occurs. Putting another layer of protection between the structure and the tile.
Once all the preparation is complete we have to clean all the original tiles taken from the floor. This is done with a combination of soaking the tiles overnight in solution. Then cleaning all the tiles but hand with electric and manual tools. Once they are cleaned they need to be washed down and dried then the tiling can begin. We start with the field (central geometric pattern) by squaring off the central section with batons to keep us square. Once the field area is tiled. We continue by working out from the field with the differing borders until we are left with only the filler tiles to complete. These tiles are cut from 150mm squares, cut into walls, which often run off slightly. But the cuts of the tiles take your eye away from the fact the room is unusually not square. The tile sizes may differ in size anything 5mm to 10mm depending on the size and shape of the room but this is difficult for your eye to pick up when entering a room as your eyes are drawn to the central pattern.
Once the tiling is complete and grouted the final clean can begin. We do all our cleaning with a combination of Machine and hand cleaning. Using specialist floor machines, combined with diamond cleaning pads that only require water, although we do occasionally use cleaning products depending on the state of the floor. Once the floor has been stripped and cleaning. Once the floor is dry we return to colour intensify and seal the floor. This can be burnished with either a Matt finish, which leaves the floor in a more natural state. Or we can seal the floor in a wax coating. This is a more traditional way the floors were probably originally finished, although this finish does require more maintenance.