Maintaining traditions for
Due to the distinctive aesthetics of traditional slate and the conservation
regulations for listed properties, re-roofing a heritage site can often be a
difficult task for contractors. Here, Julian Gomez, marketing director at
CUPA PIZARRAS, takes a look at some of the key issues that need to be
considered when selecting and replacing a slate roof on a heritage property
– with a particular focus on Scottish projects
Natural slate has been a popular roofing
material for many centuries, and
is still quarried around the world
today. However, events like the Great
Depression and the Second World War caused
many slate mines in the UK to close.
The unfortunate decline of natural slate was
further exacerbated by competition from other
roofing materials, such as tile, during the 1960s
Although mining did continue in some parts
of the UK, such as in Wales and Cornwall, the
well-known Ballachulish slate from Scotland
has not been mined in over 50 years, making it
difficult to source an accurate replacement for
re-roofing work on heritage sites.
Adding to the complication is the fact
that roofing contractors are under strict legal
obligation to keep a listed property as is, due to
the Town & City Country Planning Act 1990 and
the Planning (Listed Buildings and Conservation
Areas) Act 1990.
As such, a suitable replica slate that matches the
original roof must be sourced to ensure a heritage
property remains aesthetically the same. However,
finding a like-for-like material of the original slate
is no easy task, and roofers must also consider the
quality and longevity of the chosen slate.
Slates are available in a variety of thicknesses,
colour variations and textures, and often this is
associated with the geographical location of the
mine or quarry. For instance, Welsh slate has a
purple hue, a fine grain and a smaller thickness,
while Scottish slate is blue-black in colour, thick
and has a coarse-grain.
This means that when looking for a like-forlike
alternative, it is often not possible to use slate
from a different geographical region, as the slates
would not be aesthetically compatible, and the
CUPA PIZARRAS specified its CUPA Heavy 3 natural slate for the
Ardgartan Hotel, near Arrochar
What is roof daylighting?
Daylighting is a term used to describe all
the available methods for bringing sunlight
into an inside space for the purposes of
enhancing your living experience and even
slashing your energy bills.
At Roofgiant, the company is a huge
advocate of daylighting and believes in
taking full advantage of all the natural
light solutions available on the market.
• Sun tunnels – Solar tubes, light tubes
or sun tunnels channel sunlight from
the surface of the roof, down through
a reflective cylinder that finishes at the
ceiling, bringing natural light straight
into the home or office space.
• Pitched roof skylights – A more
conventional and classic method of
daylighting, pitched roof windows light
up a home without compromising on
living space, and solve lighting issues
in any roof space where the gradient is
between 15° and 90°. We stock a range
of pitched roof skylights, which include
a dirt and moisture protective finish and
laminated safety glazing as standard.
• Flat roof windows – For dimly lit flat
roof buildings, our flat roof windows or
top covers come in a range of design
options, allowing access for ventilation
or simply operating as a sealed window
light source. Many of our products
feature a low energy two-layer pane
and a highly insulated PVC construction.
• Awning blinds – Once your method of
daylighting is in place and sunlight is
flooding in, you might want to consider
some intelligent heat control options to
prevent a home or office from becoming
Made exclusively for VELUX windows,
these high-tech black net awning blinds
are designed to block UV rays before they
hit the glass, preventing unwanted heat
from entering the home by up to 72%.
They are also completely transparent as to
not compromise the outdoor views.
end finish would not be the same.
While roofing contractors could look to salvage
previously used slate on heritage sites, on average
50% of the material is lost during the re-roofing
process. It is also important to consider the costs
associated with sorting through and trimming
salvaged slate, as well as the additional cost of
sourcing reclaimed slate, should the original
product be insufficient to cover the roof.
Therefore, the ideal scenario is to look for new
slates that have the same aesthetic characteristics
of the original slates, with a longer lifespan for the
most economic solution.
Replicate regional slate
There are a range of modern options on the
market that replicate the aesthetics of traditional
slate from different regions. However, when it
comes to Scottish heritage roofs, in particular, it is
important to look for manufacturers that provide
slate in a variety of sizes and thicknesses.
While some Scottish quarries produced slates
in standard sizes, most produced the material in
varying sizes and thicknesses to ensure the most
efficient use of the quarry output. This led to the
practice of laying the material in diminishing
courses also known as random roofing. Here, the
slates are laid with the largest tile at the base of
the roof and the smaller ones laid near the ridge.
CUPA PIZARRAS’ Heavy 3 natural slate, is a
great example, as it has the same colour, texture and
markings as Scottish Ballachulish, including the
recognisable pyrite fragments. It is also available
in a Random version, providing the option for
diminishing courses so that the style of laying the
slates can be easily replicated. What’s more, its true
heaviness, thanks to a thickness of 7mm – 8mm,
provides it with the strength to withstand harsh
weather conditions, and also coastal environments.
Backed by a 100-year warranty, Heavy 3
also provides a long-lasting, trusted solution in
comparison with repurposed materials.
When selecting slate for a heritage project, it is
important to consider the geographical location
of the property and to pay close attention to
the original product used to establish a correct
specification. Modern slate provides a great finish
for heritage projects, and when purchased from
a trusted manufacturer, that effectively replicates
the size, thickness and weight of traditional slate,
roofing contractors can reduce the lifetime costs
of a property and ensure accordance to the strict
planning permissions associated with heritage
58 www.rcimag.co.uk June 2020