Blending In, Standing Out: Precast solutions bring contextual accuracy to heritage design

Advances in colour, texture and shaping mean that precast concrete can sit sensitively in historic or natural settings.

Once seen mainly as a quick, robust way to build, precast concrete has evolved into a highly flexible material capable of complementing even the most sensitive heritage sites. By using three key techniques - colouring the concrete, adding surface finishes, and shaping it with detailed moulds - designers can create facades that echo local materials, respect conservation areas and blend into landscapes, while still benefiting from the efficiency and safety of offsite production.

Historic renovations straight out of the offsite ‘Scottish play’ book

Perched above the River Ness, Inverness Castle is one of Scotland’s most iconic landmarks. Originally built from red sandstone, the castle has witnessed centuries of history, from the Macbeth legends to its partial destruction by Bonnie Prince Charlie’s forces in 1746.

The Inverness Castle Delivery Group were tasked with adding new extensions to the building without compromising its original appearance or character. They turned to Creagh Concrete Ltd to supply a bespoke £34.5m precast cladding system, including specially made columns, wall panels, copings and sills, along with flooring units. The challenge was to match both the tone and texture of the local sandstone while providing the durability and accuracy expected in modern construction.

The durability of concrete provides long-term weather resistance, high fire performance and better thermal efficiency (with insulation added in the factory) - all essential qualities for structures that have already stood for more than 200 years.

Hitting the right hue

To recreate the distinctive warmth and grain of the original stone, Creagh carried out extensive in-house trials, testing a variety of natural materials and colour mixes. The final blend used red granite from Creagh’s quarry, combined with white cement and red pigment. Using materials from their own quarry helped keep the look consistent.

Each panel was then treated to reveal a refined surface that interacts with light and shadow in the same way as hand dressed stone, creating harmony with the existing masonry rather than a noticeable contrast.

Perfectly placed

Installation at a heritage site required careful planning and coordination. Creagh’s site team used large mobile cranes to manoeuvre and install the precast elements safely within the restricted working area.

This method allowed precise placement of large units, ensuring maximum control, minimal disruption and compliance with heritage and safety standards. Offsite production further reduced on-site labour while ensuring high accuracy across complex elevations.

The toolbox for achieving contextual harmony

Achieving a close visual match in sensitive projects requires early collaboration between architects and manufacturers, ideally during the early design stages, to confirm colour, material and mould details before planning. Three useful techniques for architects and designers to be aware of when working with precast concrete are:

1. Pigment

Adding colour directly into the concrete mix creates a consistent, long-lasting finish. Because the colour runs through the whole panel, it naturally weathers over time and won’t peel like paint. Using white cement and selected aggregates also helps achieve the desired shade and overall look.

2. Facing materials and surface texture treatment

Surface treatments give precast concrete character and individuality. Panels can be designed to replicate stone, reveal decorative aggregates, or incorporate brick and textured finishes.

Common approaches include:

• Acid etching: Removes a thin layer from the surface to reveal fine natural materials beneath, giving a more natural appearance.
• Sandblasting: Creates a textured, tactile finish.
• Polished finish: Produces a smooth, refined surface with a soft sheen.
• Flexible formwork liners: Create textured or patterned surfaces that can mimic materials such as stone or wood.
• Brick or natural stone facing: Thin pieces of brick or stone can be cast into the surface to create an authentic traditional look with the benefits of factory-made precision.

3. Form and moulding

Concrete is a sculptural material. The shape of panels - including depth, profiles around windows, and decorative details - plays a key role in how new buildings fit with older neighbours. Modern precast techniques can create curves, projections and detailed mouldings that help new concrete align with the intricacy of older stonework.

Image Credits: Creagh Concrete Ltd