All he surveys: What are mathematical tiles? Grant Crossley sums up the vernacular building material

Mathematical tiles or ‘M-tiles’ are notorious for their characteristic use in Brighton and Lewes, circa 1700 and 1800. Today they are often mistaken for conventional brickwork, especially to the untrained eye: a material my early mentor repeatedly confused aspiring building surveyors with.

The tiles are laid in a convincing interlocking brick-effect bond/pattern; typically hung and fixed to horizontal timber battens and secured to the external façade of a timber-framed building (in a similar way to traditional tile hanging). To bamboozle you even more they’re neatly pointed flush with a lime mortar to imitate brickwork.

Many believe the influence of mathematical tiles was due to architectural fashion – simply, at the time timber became old hat! Although, not considered the primary motive, the tiles were easier to lay than bricks and less skilled workmen were required (sorry roofers!). Their use also avoided the Brick Tax levied in 1784 – a government initiative to raise additional revenue. 

This fashion was certainly not a modern method of construction; mathematical tiles were used to provide protection against the elements way before the enforcement of brick tax. Unsurprisingly, whilst they initially had the added price advantage over brickwork, being used in newer buildings, the tiles later become liable to tax.

Their shape bears a resemblance to brickwork and can be found in a mixture of colours: red, greys, cream and the distinguished black-glazed surface which features throughout early parts of Brighton. In particular, the much-loved crescent-shaped terrace of houses situated on Royal Crescent is a worthy example.

Adding up
Indeed, the appearance of mathematical tiles can be very misleading at a quick glance and somewhat difficult to tell apart from a traditional brick building. However, you don’t need to be a mathematician to work out the answer. Corners and exposed window reveals are often a big give-away. Friable mortar joints can also give some clue to a tile’s profile. Similarly, decayed timber battens and corroded fixings behind can subsequently result in slippage and missing tiles which expose the conspiracy. If in doubt a sound rap of the knuckles followed by the echo of a tile could mean a modest timber-frame structure clad in the fashion of its time.