Terracotta
Architectural terracotta and glazed faience were used extensively from the middle of the nineteenth century for facades, dressings, mouldings and ornament, particularly in industrial cities where they resisted soot better than stone. They are hollow, fired units bedded and jointed like masonry, and they fail in characteristic ways: crazing and loss of the fireskin, corrosion of the internal iron cramps and armatures, and failed joints allowing water into the hollow cores. The specialists here survey, match, replace and repair terracotta, and produce new units from moulds taken off the original.
What this category covers
- Survey and condition assessment of terracotta and faience
- Mould-making and replacement units matched to the original
- Repair mortars and piece-in repairs to damaged units
- Removal and replacement of corroded internal ironwork
- Cleaning, repointing and joint repair to faience elevations
Andrew Churchman Ltd
BULDING CONTRACTOR: Andrew Churchman Ltd is a long-established company based in Belper, ...
Bath Stonemasons Ltd
RESTORATION, BUILDING AND ALTERATION: Bath Stonemasons Ltd is an experienced stone restorer ...
Bullen Conservation Ltd
Bullen Conservation is a building conservation contractor founded in 2003 and based ...
THE BATH STONE GROUP
STOKE GROUND BATH STONE: The Bath Stone Group produces awardwinning Stoke Ground ...
Repairing architectural terracotta
Look for the iron. Most serious terracotta failure comes from corroding cramps, dowels and internal armatures, which expand and split the units from within. A survey should establish where iron is present and what condition it is in before repairs are specified.
Protect the fireskin. The dense outer surface formed in firing is what makes terracotta durable, and once it is lost through abrasive cleaning, frost damage or careless repair, decay accelerates. Cleaning methods and repair mortars both have to respect it.
Expect shrinkage when replacing units. Terracotta shrinks in firing, typically by a significant percentage, so moulds have to be made oversize and taken from an undamaged original. This is skilled work with a long lead time, and it should be programmed early.
Get the jointing right. Terracotta units are jointed with fine joints, and repointing in hard cement mortar concentrates stress on the arrises and causes spalling. Lime-based mortars matched to the original joint width are the normal specification.
Questions to ask
What causes terracotta to crack and spall?
Most commonly the corrosion of iron cramps and armatures inside the hollow units, which expands and forces them apart. Water entering through failed joints, frost action and loss of the fired outer skin through harsh cleaning are the other main causes.
Can damaged terracotta be repaired rather than replaced?
Often yes. Localised damage can be repaired with matched repair mortars or by piecing in, which retains original material. Replacement units are usually reserved for severe loss, since they require mould-making, firing and a long lead time.
How are replacement terracotta units matched?
By taking a mould from an undamaged original unit, allowing for firing shrinkage, and matching the body and glaze by trial firings. Colour matching of glazed faience in particular takes several attempts, so samples should be approved well before the main order.
All 5 businesses listed under Terracotta
- Aldis & May Ltd Suffolk
- Andrew Churchman Ltd Derbyshire
- Bath Stonemasons Ltd Bath and North East Somerset
- Bullen Conservation Ltd Lancashire
- THE BATH STONE GROUP Bath and North East Somerset
Directory information is provided to help visitors identify potentially relevant specialists and suppliers. Inclusion does not constitute a recommendation, approval or guarantee by Tuscan Foundry Products. Please check current services, credentials, availability and suitability directly with each business.