So as to complement the study of architectural form, the following article outlines the development of building techniques in Anjou and Touraine, concentrating principally on the medieval period. Until the 11th century, the most common type of masonry is of rough stone. However, the 10th and 11th centuries seem to be a key period; a time when experiments were taking place using various techniques (genuine ‘petit appareil’, ‘appareil decoratif, ‘appareil composé’, ‘appareil mixte’, ‘moyen appareil’).

‘Moyen appareil’ using ‘tuffeau, a soft limestone, gradually took the place of rough stone, and became standard in the first half of the 12th century. Its increased use seems largely to be due to the way in which the production of dressed stone was rationalised, a process which was accomplished around the end of the 11th century at the latest. In the workshop, the prefabrication of dressed stone blocks in homogeneous series whose height corresponded to various precisely defined modules became the norm. The lengths of these blocks, though not strictly speaking standardised, were none the less also grouped around a central value.

One can distinguish several stages in the development of both the extraction and the working of stone. From the 12th to the middle of the 15th century, the dimensions of dressed stone do not show any significant change; variation in length is limited and the weight of an individual stone is such that it would often allow a single workman to both carry and lay it. By the second half of the 13th century, marks cut into the wall surface appear, indicating the height of particular courses.

Between the second half of the 15th century and c. 1550 a new phase of experimentation can be detected, marked by the introduction of exceptionally large stone blocks. This was then followed by a further period of rationalisation, culminating in the mid-19th century with the employment of ashlar blocks standardised in both height and length.

Mortar courses, which are very thick in both rough stone and in ‘petit appareil’, continue to be substantial throughout the middle ages. An analysis of over 5,000 mortar samples of all ages has shown that considerable variations exist in both the composition of the aggregate and in the lime content, whatever the period under consideration.