Background:
The Leonardo Royal Hotel in Edinburgh is a landmark £58m mixed-use redevelopment. The project delivers an extension, adding 100 new bedrooms, expanded restaurant facilities, residential apartments and retail units, across a complex multi-structure site just off the Royal Mile.
BD Roofing and Building Ltd, based near Edinburgh, were appointed as the specialist roofing contractor for the full pitched and flat roofing package. Their scope covered approximately 2,000 m2 of natural slate across 15 roof pitches on up to five storeys high, extensive interlinked flat roof areas incorporating seven levels of balconies, and pitched elevations finished with a standing-seam single-ply membrane system.
Assistance with the product specification was provided by AccuRoof, and materials were supplied by SIG Roofing local branches. All warranties were then issued by SIG with products supplied for the pitched roofing areas covered by the SIG Roofing One Warranty scheme. Products for the felt/single ply areas were issued separately by AccuRoof.
Product Choice:
- SIGA 112s 400 x 250 smooth, dark blue/grey slate
- Armourplan PSG single ply
- SIGnature Torch-on felt
- Metatech PMMA liquid waterproofing
- Vapour control layer – SIGnature Torch on with a polyester reinforced aluminium-cored SBS modified bituminous membrane
- 140mm Tapered PIR insulation
- Permavent underlay to all slated roofs
- Continuous ridge system
- Cast iron gutters
The Leonardo Hotel project has seen the refurbishment and extension of the original hotel building, alongside three separate buildings that host a new NYX hotel, residential apartments and retail blocks. The original building hosting the Leonardo Hotel was built in the 1950s. Although not a listed building, it sits within Edinburgh’s UNESCO World Heritage site and is adjacent to grade A, B and C listed buildings. As such, any materials chosen had to meet strict planning requirements.
Natural slate was required for pitched roof areas, with SIGA 112 (400x250mm, smooth, dark blue/grey) selected for its close match to traditional Scottish slate used in classic Edinburgh architecture.
For the pitched flat elevations, zinc was originally specified but would have been too expensive for the budget. AccuRoof, together with the main contractor and B & D Roofing, then undertook a value engineering exercise and identified Armourplan PSG with hot-air-welded standing-seam profiles as a cost-effective alternative that achieved the same visual appearance.
The original Leonardo building had a bumpy cobblestone finish, which meant the team couldn’t detail the upstands correctly with either felt or single ply. Instead, Metatech liquid was chosen to solve the problem. SIGnature torch-on felt was chosen as a robust waterproofing layer for the balconies, which was then overlaid.
The roofing contractors worked with AccuRoof, part of SIG Roofing, to provide technical drawings, wind uplift calculations and BROOF (t4) fire tests for the roof systems.
Installation:
Due to the extensive groundworks required for this project, the roofing work had to be delivered in phases over two years, with each roof area handed over by the main contractor as the deck was completed.
The pitched roof areas cover approximately 2,000 m² across 15 elevations. Working on individual sections, the installers would first lay the Permavent breathable underlay and then install the new cast-iron gutters along the roof perimeter, including concealed verge details and expansion joints to accommodate thermal movement.
Each batten course was marked out and checked against the measurements to ensure consistency across the entire elevation. Vertical datum lines were struck to guide the slating teams and ensure all joints remained straight throughout the build. The SIGA 112s slates were then installed, fixed in an 18” x 10” pattern with copper nails, and continuous eave layers were fixed throughout. Flashings were formed at all valley and chimney abutments, and Kytun dry verge systems incorporating slate-and-half units were installed at the verges. This was to provide uplift resistance, essential in an exposed city centre location. The ridge was finished with the Permavent Continuous Ridge/Eave System.
Armourplan PSG was used around the flat roof areas, including on dormer windows and smaller pitched roof elements. Applied to a plywood base, the single ply membrane was adhered and the joints hot air welded. A decorative standing seam profile was then hot air welded to help replicate the look of a traditional standing seam roof. Additional IKOfix mechanical fixings were incorporated following wind uplift calculations confirming elevated loads at the upper levels.
The SIGnature felt system was installed on a concrete deck on flat roof areas of the NYX hotel and between the slate roofs. The build-up consisted of 140 mm of tapered PIR insulation to accommodate different pitches and create the correct falls for drainage.
To achieve the detailing at the junctions between the old and new buildings, Metatech PMMA was cold applied using a wet-on-wet technique.
Challenges:
The whole site is landlocked by surrounding buildings in a tight city centre location with virtually no on-site storage. All materials had to be delivered by small vehicle through a narrow alley to a single crane point, then lifted to each individual roof level within pre-booked crane slots. Deliveries were therefore co-ordinated through SIG Roofing’s local branches on a timed basis.
The sheer size of the project and phased installation windows made this an incredibly challenging project for BD Roofing.
Summary
Despite the two-year programme and complex phasing, the roofing works were delivered within budget and the agreed programme for each phase. Final roofing completion was achieved in January 2026, in line with the hotel’s overall reopening programme.
Costs were managed through specification of the projects with SIG Roofing, the material supplier, including the decision to change from zinc to a cost-effective solution with an Armourplan PSG with standing seam profile.
The most distinctive commercial feature of this project is that BD Roofing, supported by SIG Roofing, provided a single point of warranty. This covered four separate roofing technologies on the same building: natural slate, modified bitumen felt, PVC single ply membrane, and PMMA liquid waterproofing. This single-source approach was instrumental in BD Roofing securing the work on this sizeable roofing project.
