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The Restoration And Conservation Of The Historic Leinster House

Leinster House Restoration

Duggan Brothers faced many challenges on its Leinster House restoration and conservation project, but its expertise and ability to work collaboratively with its client and supply chain meant that the historic project’s success was never in question. ROBBIE COUSINS reports.

A Prestigious Contract

The restoration and conservation of Leinster House was a most prestigious contract for Duggan Brothers (Contractors) Limited to win. The restoration and conservation of this iconic building represented a unique opportunity to bring together a broad range of traditional skills, most of which are extremely scarce in the modern built environment. This 250-year-old exquisite townhouse was crying out for comprehensive restoration; a restoration that would also include incorporating state-of-the-art services, fit for a building at the centre of Ireland’s modern democracy. 

Critical Challenges

However, several critical issues discovered when the building was opened meant the project management team and skilled craftspeople needed to call on their experience and expertise to deliver for the client.

As is regularly the case with conservation projects, particularly of this scale, the potential for change due to unforeseen conditions is considerable. Duggan Brothers’ approach to the works was such that the successful management of change, counteracted much of the inevitable delay and additional costs. Three directors from Duggan Brothers met with a senior management team from the Office of Public Works regularly, and weekly at critical points. This intensive and hands-on/ cooperative approach, together with a commitment to responsible contractual behaviour is one of the key reasons why the project has been such a success.

Quality conservation work

The quality of the conservation work is acknowledged to be appropriate for the most important 18th-century townhouse in the State. With this extensive restoration work, Georgian Leinster House has been preserved for future generations of the country’s political leaders as the home of parliamentary democracy in Ireland, and for its many thousands of visitors each year. The client’s requirement concerning safety, security, fire protection, communications, and the coordination of the client fit-out works, were met in full.

The client acknowledged that the working environment for the members and their staff and the staff of the Houses of the Oireachtas was maintained to an exceptionally high standard, throughout the works. Given the forensic nature of the conservation and restoration works completed and the scale of the building, which is located in the very heart of the day-to-day business of both houses of the Oireachtas, it is acknowledged by the stakeholders that this critical project objective was met in full.

Leinster House History

Leinster House was first occupied by James Fitzgerald, 20th Earl of Kildare, later the first Duke of Leinster, in 1745. In 1815, it became home to the Royal Dublin Society. It has been the seat of the Oireachtas since 1924. While the house has been carefully maintained over the years, intensive use and continuous upgrading of services have impacted the fabric of the building.

A 2008 Office of Public Works (OPW) report confirmed significant structural issues and fire safety concerns in Leinster House. Upper floors had no alternative egress route and needed urgent remediation. Floors sagged due to overloading, and important plasterwork ceilings in the 255-year-old building were at significant risk.

The house had almost 30 different wiring systems, dating from various decades. Windows, shutters, joinery, fireplaces, plasterwork, roof and stonework were all in need of restoration and conservation.

Photography: Peter Moloney, PM Photography – www.pmphotography.ie

Duggan Brothers Brief

The OPW’s comprehensive Leinster House Restoration brief to Duggan Brothers covered the renewal of mechanical, electrical and communication services, together with new lift installation; structural strengthening works; ‘fire-protection’ systems upgrades; and air-handling systems replacement. It also included the refurbishment of existing historic windows, shutters and other internal joinery; stone repairs internally and externally; stabilisation and restoration of existing historic plaster ceilings; re-roofing works, including asbestos slate removal, lead and copper work repair and renewal; fitting of new WC’s at various levels; redecoration; and all necessary finishing works.

Site Preparation

To facilitate the Leinster House restoration, an elaborate scaffold was erected that encapsulated Leinster House. A temporary corridor that linked the Dáil and modern office accommodation in Leinster House was also used to house a temporary exhibit on the first 100 years of the Dáil.

Work on restoring and conserving Leinster House was carried out between December 2017 and August 2019. The footprint of the original house was the focus of the restoration works, which incorporated the Seanad Chamber, the Reading Room, the main hall and corridor towards the Dáil Atrium, the Ceann Comhairle’s Office, the Cathaoirleach’s Office, the Seanad Office, and the Enquiries Office.

Leinster House Restoration on-site challenges

While it was known that extensive work was required on wooden doors and windows, and delicate plasterwork, several hidden structural issues were revealed as the building was opened up.

Seamus Duggan, Joint Managing Director, Duggan Brothers, explains some of the issues that arose.

“Significant cracking was found in internal brick walls in several locations. OPW structural engineers developed bespoke solutions on a case by case basis,” Seamus Duggan explains. “The cleaning of the outer stone revealed that significant additional stone repairs were needed. This applied unwelcome pressure to the programme, given that the specialist skilled resources were in short supply. Substantial chimney repair works were also required. Two large stone chimney stacks were so structurally unsound that they had to be rebuilt entirely.

“A significant structural problem with the floor adjacent to the Seanad Office necessitated redesigning the primary services route in this area. The oak timber supports of the concealed gutters in the outer roof – which had once been infested by death-watch beetles – had rotted entirely and needed to be replaced.

“While there were some known areas of movement within the structure of the building, which were understood to be stable, upon opening up, many were discovered to be potentially unstable and in urgent need of repair. Shattered and snapped bricks were removed and stainless steel bars grouted into the walls to tie them together. New brickwork was inserted before the walls were lime plastered again,” Seamus adds.

Structural Integrity

The structural integrity of the building was at the heart of the design intent, to the extent that the opening-up, floor strengthening and fireproofing works could only take place on a progressive basis, as the vulnerable building’s structural integrity was enhanced. The sequence of these structural enhancement works for the Leinster House restoration was set out in the works requirements, which prevented full-scale opening-up works for structural evaluation and detailed design at an early stage in the project.

It was initially intended to retain all materials for re-use close to their original location. The intent behind this restriction was to prevent overloading of the weak structure. Ultimately, these were removed off site to alleviate some of the loading issues and provide for more significant areas of works to be opened up concurrently. They were later brought back to site for reinstatement. The process was managed through weekly structural workshops, and frequent high-level programme review meetings at critical stages throughout the project significantly assisted.

“Many of these significant defects were only discovered as fireproofing works were progressing, particularly upon the removal of the ornate door surrounds,” Seamus Duggan explains. “This necessitated significant additional out-of-sequence works and additional lime plastering.

“There were some welcome discoveries too,” he adds. “For example, intricate hand-carved details around windows and doors were uncovered after decades of paint was removed. It is estimated that well over 60 coats of paint had been applied to the very extensive and delicate hand-carved wooden mouldings throughout the building. However, this brought the requirement for additional highly-skilled craftspeople who were in scarce supply. We responded to these challenges by appointing additional crews of skilled tradespeople, working weekends and night shifts, for months on end.”

Photography: Peter Moloney, PM Photography – www.pmphotography.ie

Stone flooring

Duggan Brothers appointed P Mac, which has extensive experience in laying stone floors, stone indent repairs, mortar repairs, stone cutting, and working with lime mortar.

Existing floors were cleaned and inspected. A full schedule of works was generated, which included the breaking out of existing concrete and laying of new Portland stone, lifting and relaying existing stone, indent repairs, and the glueing and filling minor cracks. Then, there was a final clean of all joints and repointing in sand and lime mortar. A sealant layer was applied to the stone floor on completion.

Timber flooring

All existing timber floorboards were removed, numbered and taken off site for the duration of the floor strengthening, mechanical and electrical first and second fix works. Upon completing these trades, each floorboard was reinstated in its original location.

Once the floors were opened up, a thorough assessment of the nature and condition of the existing floor structure was undertaken. Each room required a bespoke structural design, which included steel strengthening to timber trimmer joists, connected to the masonry structure. The prescribed sequence of floor strengthening works as set out in the works requirements, together with the requirement to detail, fabricate and install the new floor structures on a room-by-room basis, all dictated a painfully slow critical path. All new steel elements were fire protected together with the complete floor void, which was also fully fire protected. The installation of containment for mechanical and electrical services could only commence once the fireproofing works were fully completed. Repairs to the existing floorboards included de-nailing, cleaning and making-good notches from old service penetrations. Splice repairs were carried out by cutting out damaged or decayed timber. New pine floorboards were used where required. Repairs were also carried out on existing oak floorboards under radiators in window recesses.

The Works

Ceilings and plasterwork

The emphasis was to retain and repair the existing historic fabric, particularly external and internal plaster coatings and decorative cornices. New coatings and crack filling were carried out using various lime and sand mixes. Ceilings were protected and retained during the structural upgrade to the floors above. Once the floors were strengthened, the historic ceilings beneath were restored and redecorated.

Duggan Brothers contracted George O’Malley, who has extensive experience in this field, as a specialist contractor. Marked up drawings were submitted by the specialist subcontractor and approved by the OPW before any works commenced. The same process was carried out for the plasterwork repairs to the walls. All boast plaster was removed, and marked up drawings were issued to the OPW for approval following the specialist subcontractor’s assessment. Sampling was carried out on the different elements of the plaster repair works to match existing finishes, including lath and plaster, cornice repairs, raking out and filling of cracks.

Stone conservation and restoration

Stonework included conservation and repair of all stone to the south, north, east and west facades, the east entrance porch and east balustrade. Works included removing all vegetable matter and encrusted salts from the stone, cleaning of all the stonework, raking out the joints where pointing material was not original, defective or discoloured. These areas were then repointed. Oldstone Conservation carried out these works on behalf of Duggan Brothers.

There was a significant level of stone replacement at the parapet cornice where the flashings and the blocking course was lifted out and reinstated. The Ardbracken cill course required removal and replacement with a new profiled cill course. Limestone was sourced in Cavan Ross Limestone Quarries and then cut and shaped by McConnell Stone. There were localised stone replacements, indent repairs, and mortar repairs to the granite limestone. Chimneys were rebuilt with granite from McEvoy Stone.

The retaining walls to the basement area were also restored, with existing render removed and limewash applied. The granite walls and balustrade above, including Portland stone balusters and steps to the porch, were repaired and reconstructed.

Windows

Detailed surveys were undertaken on each sash, frame, and shutter. Ironmongery was removed, cleaned and reinstated to its original position. Sashes and shutters were removed to a workshop, where repairs were carried out following OPW schedules. Original glass was kept and, where required, new cylinder glass installed.

Throughout this work, specialist contractor Lambstongue retained as much of the undamaged timber as possible. Carved staff beads had the paint removed and, where new ones were required, new carved staff beads were installed to match the existing.

In-situ works were carried out on frames, cill blocks were replaced where required, and new replica, profiled components to match existing ones were installed. Decayed bottom ends of the frames and outer beads were spliced with new timber to match the existing. In some cases, frames were repositioned in the openings. Pulleys were brought back to full working order and the original weights re-used.

Slate, lead and copper roofing works

All-natural slating from the roof slopes was surveyed, numbered and carefully removed and stored for re-use. The slates were cleaned, sorted and graded to be reinstated once new felt and battens were installed. Sarking boards were cleaned down and re-used. The existing box gutter required extensive timber repairs. The extensive flat areas of the inner roof were stripped and re-covered in lead to the highest standard. This element comprised a very comprehensive scope of intricate and highly detailed work and was executed by specialist contractor, M&I Lead.

Chimneypieces

All fireplaces were protected during the strip out works. Hearths were removed for the structural upgrade works and reinstated upon completion. Flues were surveyed and cleaned, and masonry repairs carried out, with structural steel installed for supports where required. Duggan Brothers employed chimneypiece specialist, Stone Art Conservation for works required in cleaning, removal and repairing in accordance with a detailed schedule of works for each fireplace. Almost all fireplaces were repaired in-situ. Elements such as hoods and grates were removed to the workshop for ease of repair.

Internal joinery

Works to doors included the repair, replacement and upgrade of existing doors and installation of existing and new ironmongery. Samples of timber elements, joints, panels, etc, were presented to the architect for approval before works commencement. Selections of timber from the site were identified and used for repairs. Each component of work was inspected, marked up and approved before works were carried out. Upgrading of existing doors was carried out, and certification was provided on completion. Existing dado panels and carved architraves were repaired as necessary.

Leinster House Restoration Handover

Eddie Cleary, Contracts Director, Duggan Brothers, explains that delays occurred due to the discoveries made when the building was opened up.

“Towards the latter half of 2018, and following extensive discoveries about the poorer than anticipated condition of the building, it became apparent that substantial completion was not going to be achieved on the Leinster House restorationto allow sufficient time for the client’s fit-out during the Oireachtas recess period of summer 2019,” he explains. “However, a strategy to overlap the fit-out and the completion of the construction works resulted in the successful parallel completion of the construction and fit-out works by the end of the summer recess 2019. This was particularly relevant in the context of the Seanad Chamber, where specialist furniture and specialist services systems, and commissioning and testing of same, required an extensive period in a dust-free environment.”

The completed Safety File and Operation and Maintenance documentation to the standard set out in the works requirements was delivered to the client on the date of Substantial Completion.

The restoration and upgrading of the historic Leinster House is an iconic project for any contractor to have in its portfolio. Rectifying damage as a result of the many building interventions required over the building’s busy history might have presented insurmountable challenges for some. But, by keeping a cool head, maintaining an open dialogue with a client well-versed in historic buildings, and having a team of the top specialist craftspeople in the country on site, Duggan Brothers prevailed and delivered for the client and the people of Ireland.

To learn more about Duggan Brothers (Contractors) Ltd visit www.dugganbrothers.ie

Design Team

Client: Office of Public Works

Main Contractor: Duggan Brothers (Contractors) Ltd

Architect: Office of Public Works

M&E Engineer: Office of Public Works

Civil & Structural Engineer: Office of Public Works

Fire and Access Consultants: Office of Public Works

Quantity Surveyor: Mott MacDonald

Conservation Architects: Richard Ireland, Plaster and Paint,

Fire Consultants: Office of Public Works (OPW)

Stone Conservation Consultant: Slattery Conservation Architects

Fire Protection Specialists: Brian Mottram.

Contracting Team

Conservation Consultants: Carrig Conservation

Stone Conservation: Oldstone Conservation Windows Restoration: Lambstongue

Stone Floor Conservation: P Mac

Fireplace Conservation: Stone Art Conservation

Lime Render Plaster & Historic Ceiling Restoration: George O’Malley

Roofing (Slate Lead and Copper): M&I Lead

Flooring (New): Aston Crean

Joinery Supply: Ballingly Joinery

Mechanical: KD Group

Electrical: Designer Group

Fireproofing: Niall Healy Construction

Specialist Joinery Contractor: P&L

Glazed Screens: SI Comm

Fitted Furniture: Truwood

Ironmongery: Perrem Design Hardware

Scaffolding: McRory.