Care and Conservation of Historic Architectural Tiles
Decorative tiles are found in the walls, floors and roofs of historic buildings. Glazed and unglazed, functional as well as decorative, they've been used as a building material for thousands of years.
Ceramic can be very stable, but like other building materials it's vulnerable to structural defects and surface damage.
For more information on the conservation of tiles and the specialist area of mosaics, see the Earth, Brick and Terracotta volume of Historic England’s Practical Building Conservation series, and the list of references for further reading. For information on roofing tiles, see the Roofing volume in the same Practical Building Conservation series.
What kinds of tiles are found in England?
- Roman tiles
Roman tiles found in Britain are mainly of roof tiles, flat building tiles, and tiles for heated baths. After the Romans left in 410 AD, tile production ceased but Roman tiles were often re-used in early medieval buildings. There are some surviving Roman mosaic pavements; however, these are made from small pieces of cut stone and ceramic (tesserae).
- Medieval tiles
There was a revival in tilemaking from the mid-12th century. From this date they are found in a range of high-status buildings in England. There were different ways of making them: the medieval inlaid (or encaustic) tile is the most familiar. They also used stamping, and a version of stone mosaic called opus sectile. Tile pavements were popular until the mid-16th century, when many were either removed to be re-used in small churches and dwellings, covered or replaced. On ruined sites, many became overgrown.
- ‘Delft’ tiles
Tin-glazed tiles were popular in Europe from the 16th -18th centuries, often called ‘majolica’ or ‘faience’ or ‘Delft’, depending on where they were made. These tiles were imported into England, but there is evidence that they were also made here. Colourful and attractive, these tiles were not very durable, and were more fit for walls, or around fireplaces, instead of floors.
- Industrial tiles
The term ‘industrial tiles’ refers to the mass-produced tiles of the 19th century: Victorian and Edwardian encaustic and geometric floor tiles; the glazed wall tiles of pubs, hospitals, pumping stations, schools, and railway stations; and the glazed or unglazed ‘quarry’ floor tiles found in many modern buildings. After the Second World War, tile production became more mechanised and they became a cheap form of decoration. However, there are many fine examples of tile murals from this period.
What kind of damage do we see in tiles?
Tiles are in a vulnerable position at the interface between the building fabric and the exposed environment. From the building side, they're affected by structural defects and water ingress. From the exposed side, they're subject to variations in environmental conditions and deliberate or accidental damage. Common types of damage include:
- Detachment and tenting
‘Tenting’ is when the edges of tiles rise up and buckle. Ground movement, moisture infiltration, rapid drying-out or incompatible bedding materials can all cause this type of detachment of tiles from the substrate.
- Loss of glaze
Almost all medieval tiles have lost their protective lead glaze, so are particularly at risk from abrasion and fracturing, especially if they are found outdoors.
- Abrasion, cracking, flaking and crumbling
This is a particular problem with tiles in heavy-tread utility areas such as dairies and kitchens. Floor tiles are most vulnerable to abrasion from footfall, which brings in dust and grit.
- Biological growth
External tiles are prone to biological growth (algae, lichen, moss) that can penetrate into the clay body, feed on the surface, or grow underneath and lift tiles away. This can also affect damp and poorly ventilated interior surfaces.
Soluble salts are present in the ground, the building materials, or the tile itself. Changes in the environment can cause them to crystallise below the surface of the tile or between the bedding mortar and the tile, causing significant damage.
How are tiles treated and repaired?
Preventive measures should always be considered before treating tiles. See the Earth, Brick & Terracotta volume in Historic England’s Practical Building Conservation Series for more detail on treatment and repair of tiles.
In listed buildings, you'll need listed building consent to carry out remedial treatments and for any conservation work on pre-industrial tiles you should use only accredited specialists in tile and mosaic schemes.
Common types of treatment for historic tiles include:
- Removing microbiological growth
On robust surfaces, you can control microbiological growth with regular cleaning. We don't recommend the use of biocides as a long-term control measure. (See the UK Health and Safety Executive website for approved chemicals and their manufacturers). Improving ventilation and reducing moisture is often the soundest approach. Keep in mind that fluctuating temperature and humidity may cause damage if salts are also present.
It's important not to over-wet any tile during cleaning. The moisture could soften the bedding and loosen the tiles. It could also activate salts. Cleaning medieval tiles is the responsibility of a conservator specialising in their treatment. Most industrial tiles are robust enough to withstand the low level of chemicals in pH neutral detergents. Take care when using acid or alkali-based products as they may affect certain glazes. Wire wool brushes or hard abrasives should not be used.
- Rebedding and regrouting
For rebedding and regrouting historic tiles it's important to use compatible mortars of appropriate strength.
Areas with heavy footfall should have mats to remove grit from shoes. A protective cover, or ‘drugget’, can be placed over important historic tiles (with an underlayer). Installation should be specified and supervised by a conservator. Carpets or druggets are inadvisable on damp floors, as they could promote mould growth. Coatings are not appropriate for pre-industrial tiles, except in special circumstances. Modern coatings have not been fully tested on historic floors, and should be used with caution.
In certain cases, such as large industrial tile schemes, and especially areas of heavy tread such as geometric patterned floors, it may be necessary to restore areas of loss with replica tiles.
Specialist sources of advice
For further information on historic tiles and their care, see the Tiles and Architectural Ceramics Society (TACS) website which also includes details of the TACS conservation grants for work on historic tiles or architectural ceramics. The Building Conservation Directory provides advice and information on craft skills, conservation products and specialist services.
Commissioning a conservator
Historic England recommend using a specialist conservator. Accredited conservators, who have obtained professional recognition through ICON, the Institute of Conservation’s Professional Accreditation of Conservator-Restorers (PACR) system, can be found on the Conservation Register database.
Historic Environment Scotland’s Ceramic Tiled Flooring guide, part of their INFORM series, provides guidance the cleaning and maintenance of tiles.
The USA’s National Park Service Preservation Brief 40 looks at the history of architectural tiles and their conservation.
Durbin, Lesley, (2015) Architectural Tiles: Conservation and Restoration, 2nd edn, Abingdon: Routledge
Zaki Aslan, Sarah Court, Jeanne Marie Teutonico, and Jane Thompson (editors) 2018 ‘Shelters for Archaeological Sites with Mosaics’