Specialist Works

JBO Holywood Road – Roof Refurbishment

Belfast, Northern Ireland

Specialist Works

Date Completed

2025

Sector

Commercial

Main Contractor

Bell Contracts

Project Overview

Project Brief

Thornton were appointed to undertake the refurbishment of multiple flat roof areas at a commercial facility on Holywood Road.

The existing roofing system had been significantly degraded over time, largely due to ongoing maintenance traffic associated with rooftop plant. Localised failures, worn finishes, and poor detailing at penetrations and parapets had led to increased risk of water ingress and long-term performance failure.

The project involved the replacement of approximately 830m² of roofing, alongside extensive perimeter and detail works including parapet upstands, outlets, penetrations, and plant interfaces.

The works were complicated by the presence of live mechanical and electrical plant across the roof areas. Full removal of plant was not within Thornton’s scope, requiring the works to be carefully sequenced around existing services while maintaining safe access and avoiding damage to both the new and existing roof areas.

Thornton undertook intrusive surveys at tender stage to establish the extent of the in-situ roofing system, giving the clinet confidence in our price.

Method & Outcomes

The existing insulation boards were removed down to the retained waterproofing layer, allowing full inspection and preparation of the substrate prior to installation of the new system.

A Bauderflex warm roofwas installed, comprising a vapour control layer, 220mm PIR insulation, self-adhesive underlayer and torch-applied capping sheet, achieving a U-value of 0.11 W/m²K . The system was fully bonded to provide long-term durability and resistance to wind uplift.

Given the refurbishment nature of the project, detailing was critical. New insulated upstands were formed, with the waterproofing system lapped and sealed into all vertical interfaces to maintain continuity. Parapet areas were rebuilt to accommodate the increased insulation depth, incorporating new plywood upstands, vapour control continuity, and insulated aluminium copings designed to match the existing façade.

Drainage performance was improved through integration of refurbished outlets and allowance for overflow provisions, addressing the limitations of the existing system and ensuring a free-draining roof.

Designated access routes and maintenance zones were incorporated using contrasting cap sheet finishes, providing safe, durable walkways around plant and high-traffic areas.

The project was delivered within programme despite the inherent uncertainties of refurbishment, with the completed roof providing a robust, compliant and thermally upgraded system, extending the service life of the building while maintaining full operational continuity throughout the works.