KBS Maritime Commences Renovation of 25 Store at Portsmouth Naval Base

KBS Maritime has commenced a significant project aimed at upgrading and repurposing a Grade II listed building, known as 25 Store, at Portsmouth Naval Base. The project is part of the regeneration of Portsmouth Naval Base under the Future Maritime Support Programme (FMSP) contract.

Dating back to the 1700s, 25 Store, originally home to wheelwrights, block and capstan makers, is a two-story structure finished in Flemish bond red brick is one of the oldest surviving structures on site, having escaped bomb damage in both World Wars. The KBS Maritime led project aims to transform the building into a state-of-the-art facility, forming part of a suite of facilities across the base in support of Navy Command operations.

The 25 Store project, which will span over multiple years, involves a series of stages leading to the full completion of the building. The upgrade will include roofing enhancements and repairs, energy-saving measures both internally and externally to support the Royal Navy’s net-zero goals across the base, the project will culminate in transformation of this historic building into a facility fit for 21st-century operations.

In May 2024, KBS Maritime, in collaboration with the contractor Ideal Scaffolding Southern, successfully completed the first stage of the project. This initial phase entailed the waterproofing of 2200 sqm of roof space. The construction process included erecting full access scaffolding and a temporary roof, which provided coverage for 2436 sqm, along with façade sheeting across 2700 sqm to achieve complete encapsulation of the building.

During the initial stage of the project, S&J Building Services and Concept Building Services provided essential support. On the technical front, Optima Scaffold Designs LLP and George Roberts Scaffolding Supplies—both prominent UK-based companies in the scaffolding sector—played a pivotal role. The temporary scaffolding structure incorporated 120 tons of materials and 13,000 fittings, boasting a remarkable unsupported span of 38 metres.

Laying out all components, including sheeting, end-to-end would cover a distance surpassing 19 miles. The considerable span was realised with a 1.3m deep X Beam produced in the UK. The concept of rolling out a temporary roof was devised in response to the site’s constrained space. This approach negated the need for a crane, thereby reducing disruption in the vicinity and ensuring the main access and car park stayed operational throughout the installation. This method also enhanced safety and eliminated the typical downtime associated with crane operations hindered by wind conditions. The innovative solution, and a first for Ideal Scaffolding and the most extensive unsupported span that Optima has designed to date, entailed constructing a temporary launch gable. Subsequently, materials were hoisted using powered access, and trusses were assembled on-site and rolled out sequentially until all 18 bays were positioned and secured. Despite weather challenges, the scaffold installation was completed in just under fifteen weeks and will remain in place for the duration of the refurbishment and upgrade project, a feat that would have been impossible if the traditional method of lifting in the trusses by crane had being adopted.

Stage two of the project, which will take place later this year, will be to repair, weatherproof and strengthen the existing hipped slate roof.