Guinness Storehouse Gravity Bar Expansion
RKD Architects

The Guinness Storehouse is a protected structure. The original building was constructed in 1904 and was the first mild steel building in Ireland and one of the first in Europe. The Storehouse visitor experience was designed by RKD in 1997 and opened to its first visitors in 2000.  Since opening, over 20 million visitors have passed through this world-class tourism venue, learning about one of Ireland’s most iconic brands, Guinness. The experience unfolds across seven floors, concluding with the highlight, the iconic Gravity Bar, Dublin’s highest bar, where one can enjoy panoramic views of the city.

In 2017, the client commissioned RKD to design, detail and contract manage the expansion of the existing gravity bar over the existing Storehouse building and infill approximately 15% of the floor plate at 5th floor level. The client required the existing Storehouse to remain fully operational during all construction works. RKD were required to develop a detailed methodology and approach to the works method statement for issue as part of the tender process.

Located on the seventh floor of the Guinness Storehouse, Gravity Bar is a fully glazed circular structure that sits on top of the original industrial building. Taking advantage of the height of the massive former fermentation house, visitors to Gravity Bar can enjoy the stunning near 360-degree vista that embraces all of Dublin, from mountains to the sea, while enjoying a pint of the famous stout. Such uninterrupted and breath-taking views are prioritised through steel frame construction with floor to ceiling glass walls. Access is by two glazed lifts, which rises through the centre of the Storehouse building.

The client’s brief was based on the Storehouse building operating at capacity in terms of visitor numbers, within the existing fire safety certification. When the figures were analysed, it indicated that there was a maximum capacity of 270 persons in the existing Gravity Bar. From survey information taken from customers it noted that comfort levels in the gravity bar are regarded as poor when numbers are approaching capacity. It was considered that when the numbers go above 200 persons in the Gravity Bar comfort levels began to decrease. The proposal to extend the Gravity Bar as per the plan drawings submitted was to relieve the pressure on the existing Gravity Bar. With the proposed expansion consideration was also given to increasing the availability of enhancing the corporate hospitality offers, thus an increase in the service areas attached to the Gravity Bar. This was achieved by the introduction of the kitchen and toilets at Level 5.

The development comprises of an extension west of the existing Gravity 1 Bar at Level 7, consisting of a new circular in plan gravity bar located and supported directly above the existing vertical stair B and passenger lifts. The existing stair and passenger lifts were extended up to serve the new gravity bar expansion. Gravity 2 is linked at level 7 to the existing Gravity 1 via a smaller circular transition space, which houses the existing stair A and glazed passenger lifts. The two new circular spaces are constructed in a similar manner to the existing gravity bar, i.e., steel frame construction with floor to ceiling glass walls as noted in the Buildability & Assembly text. The new expanded Gravity Bar 1 and 2 are now served by 4 no. passenger lifts greatly improving the accessibility of the area for public use.

The interiors were designed to be contemporary and to reflect the brand identity, with dark oak flooring, exposed ceiling structure, acoustically treated with a spray on Sonaspray acoustic product, a bespoke designed welded blackened steel bar counter to reflect the shape of the structure itself. The walls were treated to look like exposed concrete, where in fact a specialist Armourcoat plaster wall finish was used.

The architecture of the extension integrates successfully with a strongly established architectural form of the existing Gravity 1 Bar. As part of the project the interior of Gravity 1 was upgraded to reflect the interior of the new Gravity 2. The extension creates a holistic solution that perfectly integrates with the existing, taking into consideration both form and finishes materials to ensure a seamless connection and intervention.

On Level 6 (the roof of the Storehouse) mechanical service plant was located on the flat roof area adjacent staircore B and screened in a similar manner to service plant located on this level currently serving the Level 5 restaurant areas below. This was a planning consideration for this protected structure to ensure that no mechanical plant was visible from any current adjacent buildings.

On Level 5 there was a section of the storehouse which housed one of the existing 1900 century large steel water tanks. This tank needed to be recorded for historical purposes before it could be carefully dismantled and stored in the archive storage building in the St. James’s Gate Campus. The vacant floor space following the removal of the water tank, allowed for the introduction of circa 500sqm of new floor space for a large commercial kitchen with associated cold rooms and stores to service the extended gravity bar above. Adjacent the kitchen is a new fully Part M compliant toilet core to service the visitors to the building whose numbers have increased since the Storehouse design was envisaged in 1997. The brand offices were located directly below the new level 5 interventions and were decanted for the duration of the works. These offices were reinstated into the level 4 area (as a separate contract) following completion of the project above.

The detailed design of Gravity 2 externally was determined by Gravity 1; however, taking into consideration current building regulations and greater understanding of structural glazing to ensure Gravity 2 was brought up to date. As part of the overall project, we refurbished the zinc soffit of Gravity 1 to ensure new and existing were seamlessly connected.

There were numerous structural challenges in developing what is now appears as a relatively simple curved façade detail. The principal challenge of the façade was to ensure that the top and bottom curved PFCs were connected at the exact level of the existing PFCs. Gravity 2’s radius is 11,000mm some 2000mm larger than Gravity 1. Gravity 2 is supported off a circulation core and 4 strategically placed columns, which penetrate the existing Storehouse building. Primary diagonal beams span 13,700mm and support cantilever beams of 3500mm in length, which taper to 255mm ensuring a continuous slim edge detail to the perimeter. 800mm deep fabricated box girders are utilized as the primary support beams ensuring the façade deflection criteria was achieved for the large faceted glazed panels.

The roof, a single ply membrane on semi-rigid insulation with a continuous circular recess for drainage, leading to rainwater downpipes concealed within the perimeter columns, allowing for a cleaner aesthetic. A 50mm diameter steel section curves around the top perimeter PFC which has the double function of support abseiling for maintenance and visually reducing the mass of the parapet upstand.

The glazing consists of laminated extra-clear annealed glass of 19+15mm in thickness, supported by continuous stainless-steel angles top and bottom. The floor comprises of wide engineered timber planks fixed to plywood on concrete base supported by the extensive steel structure below, all fully concealed by a radial designed zinc soffit. The soffit of the concrete deck and steel is clad in insulation exceeding U-value requirements. The chosen semi-rigid insulation system also gives the primary steel it’s 90-minute fire protection. Ventilation ducts route through both primary and secondary beam below the floor level and this present as slimline ventilation grilles at floor level.

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Judges' comments

22 years after the main Guinness Storehouse renovation project won Highly Commended, this new roof top expansion to the existing gravity bar is this year's outstanding Winner for the medium to large category. The sympathetic modification of the current structure is sustainable in terms of energy, history and culture and should be applauded. It is an exemplary illustration of integrating a new structure with an existing functioning building. With fantastic technical detailing, the project showcased excellent buildability and asssembly techniques which allowed the expansion of the Gravity Bar whilst keeping the Guinness Storehouse fully operational.

Complex structural challenges were overcome, including connecting new curved PFCs to the existing curved PFCs at roof top level and then threading the new structural loads down through the existing listed main building. The building functionality has been greatly improved for all end users and completely accessible. Material choices were well considered for the environment and complement the existing historical setting. Sustainable measures included enhanced building envelope insulation, LED lighting and automatic lighting controls with thermal values exceeding Building Regulations. A fantastic project truly celebrating Architectural Technology through the use of multiple design and construction technologies.