The transformation was made through a restoration project that carefully balanced conservation with contemporary design. A key element of this approach was the specification of approximately 300 metres of Renderplas PVC shadow gap beads, installed around door openings, circulation areas and skirting interfaces.
Working with Hay Castle Trust, specialist contractor John Weaver (Contractors) delivered extensive structural and architectural works across the site. Alongside the conservation of historic masonry and architectural features, the design team introduced contemporary interior detailing to support the building’s new public function.
Here, the profiles created clean, recessed shadow lines between walls, frames and floors, replacing traditional skirting boards and architraves with a more minimal finish.
Gary Matthews, Quantity Surveyor at John Weaver, said: “Achieving the right level of modern intervention was critical to the scheme’s success. The use of PVC shadow gap beads from Renderplas helped us deliver sharp, consistent lines across the interiors while maintaining the durability required for a public building.”
Historical finishing challenges
Winner of the 2024 Royal Society of Architects in Wales (RSAW) Building of the Year and the RSAW Conservation Award, the project was praised by judges as “an excellent example of how to approach conservation and heritage with spirit and expertise”.
The detailing strategy was particularly significant given the building’s historic character. Skirting boards were not introduced until the late 15th century and door architraves appeared even later, during the Georgian period. The project adopted a contemporary shadow gap solution that complemented the building’s layered history while providing practical advantages.
Since traditional wet plaster methods were used across much of the castle, contractors installed short plasterboard sections to interface with the shadow gap profiles. PVC was chosen over metal alternatives for its durability, flexibility and resistance to rust or staining, helping maintain crisp lines despite uneven historic substrates and the demands of heavy public use.
This project demonstrates how carefully specified, contemporary detailing can enhance both historic and modern buildings. In heritage settings, shadow gap profiles provide a discreet way to introduce modern finishes without compromising architectural character. In new-build projects, they help achieve the clean, minimalist aesthetic increasingly favoured by designers. PVC shadow gap beads offer a practical and long-lasting solution for creating sharp, consistent finishes across a wide range of applications.
About Renderplas
Renderplas was formed in 1990 to offer the plastering industry a new concept in beading. The first manufacturer of PVCu beads in the UK, Renderplas is the leading exponent in the field.
The business sets out to address the shortcomings of traditional profiles by designing a range of beads in PVCu to suit the British and Continental market. The key benefit of PVCu beads is that they use the most cost-effective, non-corrosive material to produce robust plasterer friendly beads. Renderplas PVCu beads conform to BS EN 13914-1:2016 - External Rendering.
Renderplas products are designed to be unobtrusive with an extremely narrow arris, making it ideal for scratched or scraped finishes. Very popular with major house builders, its beads are available in white or ivory as standard to blend with most coloured renders. However, in order to give architects and contractors even more freedom to use through-coloured renders in more vibrant colours, a range of beads in 7 further colours are also available for popular render depths.
Used internally, whether, in conjunction with wet plastering or dry lining, they will not stain during lengthy drying out periods and offer superior protection against impact in heavy traffic areas.
By specifying a Renderplas PVCu bead, the problems associated with traditional beads and the aggravation of costly callbacks are avoided.
