Project Description

Project Overview

The Limerick Courthouse development formed part of the Government’s €2.25 billion Infrastructure Stimulus Package which was announced in 2012. The project is one of seven state courthouse upgrades which make up the €135 million Courts Bundle Public Private Partnership awarded to BAM PPP PGGM and managed by the National Development Finance Agency. BAM Building acted as the main contractor for the Limerick Courthouse project and appointed Malachy Walsh and Partners as Civil and Structural Engineers. The design team also included Wilson Architecture and Homan O’Brien Mechanical and Electrical Engineers. Construction started in December 2015 and the new courthouse achieved service commencement on 5th February 2018 with a project capital cost of approximately €26 million.

Building Description

The new development is located on the site of a former 19th century  artillery barracks, known locally as Costello’s Yard, one of four in existence in Limerick in the 19th century. It is bounded by Mulgrave Street and Roxboro Road and is located close to Limerick Prison. With two of the barracks’ historically significant buildings remaining on the site, this project delivered a landmark civic building while contributing public access to this old institutional district of Limerick. The contemporary building design is mindful of its history and integrates the two protected structures and the surrounding environment is softened and enhanced through the use of planting.

The new Limerick Courthouse at Mulgrave Street will house District, Circuit and Criminal Court sittings under one roof in a state-of-the-art central complex which varies from two to four storeys in height and has a total floor area of 7,350m2. The building contains six courtrooms and a public office and user facilities include a vulnerable witness suite, victim support room, legal practitioners and visiting professional room, enhanced custody facilities, jury selection and reception rooms, judge’s chambers, media room, consultation rooms, plant rooms and general administration offices. The existing Gate House Lodges, fronting on to Mulgrave Street, were refurbished to accommodate additional offices. All circulation routes within the building (public, staff, judiciary, custody and jury) are fully accessible. The building also contains a 200m2 courtroom which is the largest courtroom in Ireland and will primarily host District Court sittings.

Malachy Walsh and Partners were also responsible for the design of the underground services, external works and associated site structures which included a 7m high precast reinforced concrete secure yard wall.

Structural Design

The building form is an insitu concrete ground floor over partial basement of reinforced concrete construction supported by a raft foundation bearing on engineered fill which is in turn founded on a stratum of generally firm gravelly clay. The superstructure is formed using a combination of various precast concrete elements forming the walls and upper floors of the Courts building which includes solid and twin wall load bearing walls, solid and hollow core prestressed floor units of various thicknesses with precast beams. The roof is a metal deck insulated zinc roof carried on an arrangement of  structural steel beams fixed to the pre cast concrete frame. The precast structure was designed, manufactured and installed by Oran Precast Ltd.

The new development features a perimeter cantilevered wing beam profile in Courtrooms 1 & 6. Courtrooms 3 & 4 feature 11.5m high single twin-wall panels. Multiple floor level changes occur across the building, particularly at 1st floor, in addition to non-stacking walls and deep beams which combine to make this a very challenging project for the Structural Engineers, requiring significant coordination and detailing. The use of steel member supports was incorporated within the precast package due to the congested Mechanical and Electrical service runs and minimal suspended ceiling zones.

The main roof comprises a metal deck and structural steel beams or trusses supported on the precast concrete elements. Temporary works design was made complicated by the fact that many of the full height courtroom walls were only braced in the permanent condition once the roof steelwork was installed. Behind the protected Gate House Lodge buildings is a new structurally independent glazed link with a standing seam composite panel roof which provides the entrance into the new courthouse building via a structural grid of steel column sections with square hollow section horizontal members providing lateral restraint and supporting the glazing system. This open glazed circulation space overlooks the historical public buildings and the vertical colonnade treatment to the north elevation provides a framing view across limerick city and enhances the frontage along Mulgrave Street.

Building Information Modelling

Building Information Modelled (BIM) was used for the project to develop  a coordinated design solution which aligned with the architectural design intent of the building fabric, external finishes and facade elements. Malachy Walsh and Partners created a full 3D Revit model of the building structures which aided development of design intent drawings and enhanced and conserved the existing site features and protected structures. The underslab building drainage was also modelled using Revit 3D and the underground services were modelled with Civil 3D. BIM was also an important tool for coordinating services and equipment to facilitate the proposed operation requirements of the new building.