Tegulae: manufacture,typology and use in Roman Britain

Peter Warry kindly notified the ACBMG list of his new publication:

... my book on tegulae (Tegulae: manufacture,
typology and use in Roman Britain. BAR417) has now been published.
It broadly follows my PhD thesis. The structure and a few of the
conclusions are set out below. I would be delighted if anybody
wishes to offer any data or arguments that either support or
contradict my conclusions.
Peter Warry

Chapter 1 – Introduction

Chapter 2 - Manufacture: showing that tegulae were made with wet
clay in a four-sided mould and shaped with a wire (the clay was too
wet/adhesive to be rolled). In the later third century some
manufacturers converted to an inverted box mould and some imbrex
manufacturers also changed from upright to inverted formers around
the same time.

Chapter 3 – Typology: the form of the lower cutaway changed over
time and a sequence of four distinct cutaway groups (found
throughout the province) are proved. Using this cutaway sequence,
tegula size reduces steadily through time with the flange dimensions
and cutaway lengths also reducing in proportion. At the end of the
sequence some regions develop their own unique forms.

Chapter 4 – Dating: the cutaway groups fall into date ranges (A= up
to 120, B=100-180, C=160-260, D=240 onwards, regional forms 300
onwards). Substantially more data are required to verify these date
ranges, in particular the Group C forms could have a much more
extensive overlap with the Group B cutaway forms. The Legio XX
tiles stamped "VERO III COS" are more likely to be 126 rather 167.
The tiles with the Britannica cognomen from Carpow are more likely
to be 180 than 210.

Chapter 5 – Stamps: Legionary stamps had an average life of twenty
years. Many of them were in use contemporaneously which suggests
that each cohort had its own stamp. Military practice, when they
stamped tiles at all, was to stamp all of their production not just
a proportion; unstamped tiles are likely to be produced by
contractors. All of Legio XX output (including that with stamps)
may have been produced by contractors from c125 onwards whereas
Legio II did not use contractors for roof tiles until the third
century.

Chapter 6 – Roof Construction: Early roof design used large tegulae
of graduated sizes that were laid upon a bed of mortar and daub
without fixing nails; this design was superseded by tegulae all of
similar size that were laid directly onto common rafters with the
lowest row being secured with nails. In the mid-third century the
pitch of roofs may have increased and every other tegula was secured
by a nail or in some cases with a wooden dowel. A third century
roof would have used roughly 40% more tegulae than a first century
one (due to the reduction in size of the tegulae) but the
improvement in tegula design meant that the roof would have weighed
some 14% less.

Chapter 7 – Vaulted roofs: over 20% of tegulae are longitudinally
convex such that they would form an arch shape when placed on a flat
surface. These were not wasters but deliberate manufacture for use
on vaulted roofs where they were secured with mortar rather than
nails. Examples of this approach occur in Rome and there is more
circumstantial evidence from Britain.

Chapter 8 – Economics: a typical civilian tile works would have
employed just five people gathering wood and preparing clay in the
winter and making tiles in the summer. Military tile works were
considerably larger: the Classis Britannica tile works employed
between 30 and 80 men depending upon whether they worked all year
round or just during the summer months. Based on the labour cost,
tegulae would have cost just over 5 denarii each.

Chapter 9 – Conclusions

Peter Warry's book is available from: Archaeopress: BAR 417 2006: TEGULAE Manufacture, typology and use in Roman Britain by Peter Warry. ISBN 1841719560. £34.00. 167 pages; 126 figures, maps, plans and drawings; 114 plates. 5 data Appendices.