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t h e b u i l d i n g c o n s e r vat i o n d i r e c t o r y 2 0 1 3
T w e n t i e t h a N N i v e r s a r y e d i t i o n
3.1
Structure & Fabric : Roofing
Figure 16 The Pennine chevron valley differs from the
Welsh in having single stone slates laid as a lining
and cut to sit against the main slates on either side.
Figure 20 Laced valleys where the stone slates are
turned up to fit against a lozenge shaped slate in the
valley are always used for Collyweston slating.
in a radical difference of appearance in the
finished roof or laying problems during
construction.
The future of roof conservation
The 20th century saw many regrettable
developments in roofing. New materials were
adopted which often proved to be detrimental.
Specifications for re-slating often included
default details such as lead valleys because it
was assumed that the vernacular detail was
inadequate or slaters have been left to make
their own poorly informed decisions on what
was appropriate.
Happily this is changing. Guidance
on vernacular roofing is being published
increasingly regularly, training is being
provided for slaters, and an accreditation
scheme for roofers which includes the
principles of conservation is being run by the
National Federation of Roofing Contractors.
Those responsible for maintaining historic
buildings (especially main contractors with
an eye to keeping to programme above all
else) now need to take advantage of these
initiatives and recognise that good work costs
more and shouldn’t be rushed. They should
also recognise that high quality work pays off
in the long run. Of all the things that have
resulted in problems for re-slated roofs, the
culture of accepting the cheapest tender has
been the greatest culprit.
Recommended Reading
F Bennett and A Pinion, Roof Slating and
Tiling, Donhead, Shaftesbury, 2000
G Emerton, The Pattern of Scottish Roofing,
Historic Scotland, Edinburgh, 2000
English Heritage, Practical Building
Conservation: Roofing, Ashgate,
Farnham, 2013
English Heritage, Stone Slate Roofing,
Technical Advice Note, 2005 (available
online via
)
TG Hughes, ‘Vernacular Slate and Stone Roofs
in England’ in England’s Heritage in Stone,
English Stone Forum, Folkestone, 2008
(available online via
hughes-vernacular)
TG Hughes, ‘Sourcing Roofing Slates’,
The Building Conservation Directory,
Cathedral Communications, Tisbury, 2009
(available online via
sourcing-slates)
The Society for the Protection of Ancient
Buildings, SPAB Regional Advice Note 2:
Slating in South West England
Stone Roofing Association, Horsham Stone
Roofs, 2009 (available online at
stoneroof.org.uk/horshamguide.html)
Stone Roofing Association, Glossary of Stone
Slate Roofing, 2010 (available online via
TERRY HUGHES
BSc FIoR DpMan is the
secretary of the Stone Roofing Association
and a specialist consultant. His company,
Slate & Stone Consultants, based in
Caernarfon, advises on slate and stone
roofing construction, materials and
conservation, and on sourcing new material
to match the existing.
Figure 17 The West Country collar and tie uses very
narrow slates in the valley but it works because the
slating is triple lapped. A similar valley is known
from Pembrokeshire.
Figure 19 Half-swept valleys are common in Wales
especially on dormers where the slating is swept across
from the main slope and underneath a raking cut.
Figure 18 The distinctive Cotswold swept valley
carries tapered slates across the courses.
