Conservation & Heritage Issue 52 Summer/Autumn 2026 - Flipbook - Page 32
Quarry manager Mark Haysom describes the geology with
an enthusiasm that is catching. The two Purbeck stones are
Cretaceous limestones, formed around 135 million years ago
in shallow estuary lagoons rather than in open sea: “If you
look closely at the surface, you’ll see little black ring shapes —
those are fossilised freshwater mussels, bivalve shells washed
into the lagoon. With the Grub in particular, you’ll see white
calcite lines, which are ancient cracks re-cemented by water
flowing down through the joints of the stone over millions
of years. There are even places where burrowing crustaceans
disturbed the sediment and turned the shells up on edge.
You’re looking at something deposited in what was essentially
a tropical mangrove environment.”
“
was a single-skip, single-wagon compound, and a programme
in which every subcontract trade depended on every other.
Project manager Neil Moss describes the planning challenge:
“The bespoke joinery was on six to eight months’ lead time;
the encaustic tile deliveries were on 24 weeks. So we did a
lot of planning, initially, with ABM, phasing the programme
around their deliveries. That allowed us to follow on with
the bespoke joinery, and then in areas where the tiles had
gone down, to do the wrought ironwork. Everything was
done in zones — things came at exactly the right time to work
progressively through the cathedral.”
ABM Tiling’s role, in other words, set the rhythm of the
entire project. Their delivery schedule governed when every
other specialist trade could move. Construction director
Mark Cregan is direct about what made it work: “The big
thing at the beginning, from the client, was that it had to be
a collaborative, teamwork building. If this wasn’t done as a
team, it would have been impossible to deliver it. That was a
driving factor right from interview level.”
We ran out of stone exactly at the end of the contract.
We couldn’t have done a more demanding spec on the
squares — and we’ve run out of the material making
what you see behind us now.”
— Mark Haysom,
Manager, Haysom Purbeck Stone
That geological character — thin, varied, irreplaceable —
made supply the defining constraint of the project. The
Grub deposit is only four to five inches thick, and quarrying
several hundred square metres of flooring stone from it is,
Haysom says, highly unusual. The specification was so finely
judged that the material ran out at precisely the moment the
contract completed. The triangular detail running along the
central aisle was not merely decorative: it was designed in
close collaboration between Haysom and the Purcell team
specifically to stretch the yield from the quarried block,
allowing pieces that would not make the required square size
to be cut to triangle instead. Design and quarry working as
one.
“
Below this beautiful floor you’ve got the build-up, the
underfloor heating — the whole cathedral floor was
lifted and re-laid.”
— Neil Moss,
Project Manager, Simpson (York)
The adhesive specification added another layer of technical
precision. ARDEX products were selected for the limestone
elements of the floor, with rapid-dry technology chosen
specifically to minimise the risk of water staining and
curling on the sensitive stone substrate. John Stewart from
ARDEX notes that the technical demands of the project
were exceptional: “We can’t understate the requirements
of what this project involved. We have a building from the
1800s that has to conform to today’s building regulations —
meeting those requirements through innovation and making
the process simple was key.”
Precision In An Imperfect Building
Encaustic floors are unforgiving by nature. The pattern is not
printed onto the surface but inlaid one to two millimetres
into the body of each tile, and on the larger panels the design
flows continuously from tile to tile. Any error in setting out
is immediately visible across the full expanse of the floor. At
Salford, ABM Tiling faced that challenge at an exceptional
scale: bespoke 25-panel bay patterns, continuous border
runs, and coat-of-arms centrepieces — all of which had to
align with one another across the full length of a cathedral
nave, in a building where, as Tom Brigden of Purcell puts it,
“the walls are not square and not plumb.”
The Grub and Thornback Purbeck limestones carry 135-million-year-old fossils
within their surfaces — freshwater mussels and calcite veins formed in ancient
estuary lagoons.
A Programme Built Around The Materials
Chris Cox of Craven Dunnill Jackfield, who understands
the installation challenge from the tile-maker’s perspective,
describes precisely why it is so demanding: “All the tiles have
to line up — because the pattern transfers from one tile to
the next. Getting the borders to run through, and the larger
panels where the pattern flows from tile to tile: it’s actually
The complexity of the floor was not only material but
logistical. Simpson of York, the main contractor, took full
possession of the cathedral at the outset — made possible
by the foresight of the cathedral commissioners, who had
built a temporary church so the congregation could continue
services throughout the works. What Simpson then faced
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