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Boathouse 4 by Walters & Cohen Architects

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Walters & Cohen has created an unpretentious working boat-making and visitor centre in Portsmouth Historic Dockyard, says Laura Mark


Built in 1939 as part of the rearmament programme leading up to the Second World War, the steel shed of Boathouse 4 is a rare relatively modern addition to Portsmouth’s Historic Dockyard.

One of the most visible of the dockyard’s buildings as you approach it from the rail station, the large building with its sawtooth roof stands as a fine example of ’30s military architecture. Intended to be much larger than it stands, a corrugated iron wall was put up mid-way through its construction as the onset of war created a sudden urgency and the building needed to be put into immediate commission. It was never completed as originally intended and still has in place this ‘temporary’ wall, a reminder of the impact of war on the built landscape of the dockyards.

Despite its place in history, the building, which incorporates its own dock and a pair of locks controlling a tidal canal which channels through the building and into the Mast Pond behind, had fallen into disrepair and was even threatened with demolition. But, following a successful Heritage Lottery Funding bid and an invited competition won by Walters & Cohen Architects, the industrial shed has been saved.

Using its expertise in school and college design, Walters & Cohen has transformed the vast space into both a college for traditional boat building skills and a museum and exhibition space. Now home to the International Boatbuilding College Portsmouth and Highbury College, the building and its unique showcase of historic boats will help to keep traditional boatbuilding skills alive.

At the side of the building overlooking the harbour, an enclosed mezzanine café has been added, giving views out across the harbour mouth towards Gosport. Beneath this is the college’s teaching space. Here, on the day I visit students are learning to build wooden canoes using traditional techniques. The pieces are laid out in the long space, which is filled with light from the high-level windows.

On the other side of the building a smaller mezzanine has been replaced by a longer one that spans the length of the huge shed and houses an exhibition charting the history of the UK’s naval boats. This space also offers a fantastic view of the many boats below. It gives visitors a chance to view the innards of Boathouse 4’s historic exhibits, many of which are in the process of being restored. By wrapping these new additions high around the sides of the building, Walters & Cohen has managed to keep this central space clear and its size can be fully appreciated.

On the outside the building is largely unchanged. The main intervention – the addition of a large glazed window facing the entrance to the dockyards and naval base – opens up the scheme and signals its new use as a public and cultural space. At this window, with its strategically-placed boat restoration demonstration area, the internal goings-on are revealed to passers-by, enticing them in.

The fabric of the building has stood the test both of time and of harsh port-side conditions. Despite some concrete erosion from the salt water, internally its condition was pretty good, so much of it has been preserved.

All of its steel Belfast trusses and columns have been retained and painted a bright and striking yellow, while the north-facing rooflights in the boathouse’s sawtooth roof also remain largely untouched. Its gantry cranes – camouflaged from German bombers while the building’s roof was constructed – are still in place. They await further funding to restore them to a working condition.

It would be easy to say that in the vast space of this great shed, Walters & Cohen hasn’t really done very much. But what they have done is unpretentious, robust, and performed with a light touch. Through clever use of colour and small, unobtrusive additions, the practice has brought this building back to life. With its unfussy materials the refurbishment encourages its use as a place of making which is not precious about its heritage and leaves space for further transformation. As you walk through the doors there is a sense of awe at the openness and scale of the space. It is a cathedral to boats and traditional crafts that are under threat in today’s digital world.

Ground floor plan

Boathouse 4 by Walters and Cohen

Boathouse 4 by Walters and Cohen

First floor plan

Boathouse 4 by Walters and Cohen

Boathouse 4 by Walters and Cohen


Boathouse 4 by Walters and Cohen

Boathouse 4 by Walters and Cohen


Boathouse 4 by Walters and Cohen

Boathouse 4 by Walters and Cohen

The south-western zone of Boathouse 4 projects over the dockside to enable boats to enter the building directly from the harbour through the tidal canal. This section is supported on a substructure of reinforced concrete V-beams over precast piles and caps. These had suffered considerable deterioration over the years, due to the severe exposure to seawater, and extensive repairs to this undercroft structure were carried out before any additional load was applied by the new building.

The new space is insulated and heated, sitting within the unheated existing shell. The first floor slab of the new building is designed to be as light as possible, constructed from lightweight concrete on profiled metal decking; by restricting the lifting capacity of the gantry cranes, loading on the existing foundations is further reduced.

The building within a building is deliberately set down from the level of the cranes and the existing shed structure, and hugs the external walls so as to amplify the steelwork and the sheer volume of the space. This also has the advantage of providing first floor spaces that sit between the boatbuilding activity and the sea.

Inside the restaurant/café, a long slot window enables views back over the central space and the raised oak floor is acoustically separated from the noisy workshops below. Both the existing lattice pillars and new steel columns are revealed, and the education spaces at ground floor level have large sliding metal doors that open to the central space in the warmer months. Their sliding gear is left exposed, taking advantage of the industrial feel of the building.

Kirsten Holland, associate, Walters & Cohen Architects

Boathouse 4 by Walters and Cohen

Boathouse 4 by Walters and Cohen

Source: Dennis Gilbert/VIEW


The aim of the client, Portsmouth Naval Base Property Trust, was to revitalise Boathouse 4 at Portsmouth Historic Dockyard by restoring the existing building fabric, giving visitors free access to a permanent boat exhibition and café, and providing boatbuilding facilities. Walters & Cohen established the brief with reference to Heritage Lottery Fund guidelines and in consultation with four stakeholder groups: PNBPT, a new international boatbuilding college, Highbury FE College, and a group of volunteers. The brief defined: how these groups would use the building; opportunities for sharing facilities; the visitor experience and exhibition space; the café; and conservation and revitalisation.

Boathouse 4 by Walters and Cohen

Boathouse 4 by Walters and Cohen

Source: Dennis Gilbert/VIEW

Architect’s view

Following a successful Heritage Lottery Fund Stage 1 bid and a competition, Walters & Cohen was appointed by the Portsmouth Naval Base Property Trust (PNBPT) to transform an industrial shed in Portsmouth Historic Dockyard into a destination that promotes the building’s historic value as a timber boatbuilding enterprise, upholding teaching skills that would otherwise be lost and exhibiting the PNBPT’s historic small boat collection. 

Original features within the space have been restored in a way that enriches the significant historical relevance of Boathouse 4. For example, the existing boatlifting cranes were refurbished with the conservation of their function very much in mind, and the new first floor provides dramatic views over the original tidal dock. 

The vision was for this impressive space to become a ‘cathedral’ to boatbuilding. A large window to the south provides a welcoming frontage, transparency and views to the activity inside. The generous new entrance area is full height and essentially part of the boatbuilding shop beyond. Visitors immediately experience the full impact of this unusual space, made yet more dramatic by the suspension of a boat over the entrance. They circulate around the building, watching the boatbuilding activities below, and arrive at the dual-aspect restaurant/café with its unique position overlooking the boatbuilding and the sea. 

Walters & Cohen worked with exhibition designer Real Studios to develop a permanent exhibition celebrating the heritage skills of boatbuilding in an engaging and immersive way. At first floor level a selection of small boats are placed in a series of dry docks, allowing visitors to view and touch the vessels. 

Michál Cohen, director, Walters & Cohen Architects

Boathouse 4 by Walters and Cohen

Boathouse 4 by Walters and Cohen

Source: Dennis Gilbert/VIEW

Client’s view

In an area dominated by Georgian and Victorian architecture, Boathouse 4 offers a striking contrast in architectural style. It is the only significant 20th century building in the dockyard, offering a unique link to this important period in naval history as the nation prepared for the Second World War.

Several years ago many were advocating its demolition to make way for a hotel and exhibition hall; the impressive result vindicates beyond all doubt those who fought so hard to retain this 1930s industrial jewel, providing it with a new lease of life and, gratifyingly, for a purpose for which it was originally built. The late Colin Stansfield-Smith, a trustee and a great supporter of the project, would have been delighted by the result.

Walters & Cohen has done well to retain the amazing sense of space highlighting the elegant steel structure that supports the four gantry cranes and, for the first time ever, visitors to the Historic Dockyard will be able to view the archaeology at ground level in the form of the 17th century tunnel which connects the Mast Pond with Portsmouth Harbour.

As the largest industrial complex in the world for two centuries there can be no better place than Boathouse 4 to learn and acquire the skills required to practice boatbuilding, marine engineering as well as those needed to preserve our maritime and built heritage. The design team has demonstrated the art of skillful intervention, providing the perfect compact of ancient and modern.

Peter Goodship, consultant chief executive, Portsmouth Naval Base Property Trust

Boathouse 4 by Walters and Cohen

Boathouse 4 by Walters and Cohen

Source: Dennis Gilbert/VIEW

Engineer’s view

Max Fordham proposed a simple and robust response to the M&E engineering. This was in part due to the fact that Boathouse 4 remained open to the elements for essential day-to-day operations while environmental improvements and architectural additions were carried out. 

Early in the design process the client agreed that the large, existing building would remain unheated and uninsulated as before. New, purpose-built, heated rooms within the boatshed accommodate the shipwrights, students and visitors in a comfortable and more protected environment. Heat losses are kept to a minimum in these rooms with upgraded fabric and insulation, and double-glazed modules stand in the place of single-paned glass. 

The building makes best use of the natural ventilation and daylight. Ultra-efficient lighting systems augment available daylight in the central spaces on darker days, while absence detection and daylight activated dimming controls help reduce energy use. 

In the tall workshop spaces, fast-response, high-efficiency overhead radiant panels raise the ‘real feel’ room temperature. This maintains comfort while keeping the actual air temperature relatively low. 

Acoustic absorption and acoustically treated walls ensure the banging and clanging from the workshop and noise from mechanical-fume and dust-extraction systems does not impinge on apprentices’ training or the visitors’ experience. 

Zoned energy metering systems for water, electricity and heating help the various organisations operating under the same roof measure their use and carbon demand autonomously. 

Alex Martin and Michael Pangalis, project engineer and senior engineer, Max Fordham

Boathouse 4 by Walters and Cohen

Boathouse 4 by Walters and Cohen

Source: Dennis Gilbert/VIEW

Project data

Start on site August 2014
Completion September 2015
Gross internal floor area 3,400m2
Form of contract Traditional JCT
Construction cost Undisclosed
Architect Walters & Cohen Architects
Client Portsmouth Naval Base Property Trust
Structural engineer Jane Wernick Associates
M&E consultant Max Fordham
Acoustic consultant Max Fordham
QS Focus Consultants 2010
Exhibition design Real Studios
Fire safety consultant Fusion Fire
Heritage and conservation consultant Conservation Plus
Project manager Focus Consultants 2010
CDM co-ordinator PFB Construction Management Services
Main contractor Interserve
CAD software used Vectorworks

Boathouse 4 by Walters and Cohen

Boathouse 4 by Walters and Cohen

Source: Dennis Gilbert/VIEW


Double glazed units in refurbished existing window frames by SashGlass Slimlite Double Glazed Units 

Floor in restaurant by Havwoods Henley Oak Grove, oiled 

Timber floor in exhibition by Brooks Bros Kebony SYP PEFC certified 

External windows in restaurant by Steel Window Service and Supplies W20 section steel window 

Louvres mounted into existing window frames by Renson Fabrication 483 Glazed in Louvre Panel 

Large metal sliding doors to joinery shops by Jewers Doors Kingfisher manually operated door 

Paint to existing steelwork in a marine environment by Sherwin-Williams Two pack epoxy primer & buildcoat and a urethane finish, site applied

Boathouse 4 by Walters and Cohen

Boathouse 4 by Walters and Cohen

Source: Olwen Holland

Cost data

Frame £111 10.89%
Roof £3 0.29%
Staircases £4 0.39%
External walls £21 2.06%
Windows £76 7.46%
Internal walls and partitions £72 7.07%
Internal doors £18 1.77%
Wall finishes £18 1.77%
Floor finishes £26 2.55%
Ceiling finishes £22 2.16%
Furniture £65 5.97%
Sanitary appliance £7 0.69%
Space heating and air treatment £152 14.92%
Electrical services £153 15.01%
Lift installations £12 1.10%
TOTAL  £1,019 
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