Cardiff Castle and Gateshead\'s Old Town Hall, two of the UK\'s most important stone restoration projects, have received Building Maintenance Awards from the Institute of Maintenance & Building Management (IMBM).
The Institute\'s main award went to Cardiff Castle, where the current £8million restoration programme that started with investigations in 2000 should be completed this summer.
Most of the stonework was carried out by Chesterfield conservation and restoration specialists Philip Turton Building & Consulting Services.
John Edwards, Surveyor to the Fabric of the Castle and project manager, says the project was unusual in that by the time Philip Turton were appointed all the criteria for the work had been determined through a series of specialist investigations.
Initial research had seen monitors and probes positioned all over the castle as Environmental Building Solutions recorded the environment and moisture levels within the relatively thin Blue Lias and Forest of Dean stone walls - the walls of a tower that is more than 40m high, for example, are just 150mm thick.
Because the walls are so thin, moisture had penetrated them and was damaging the Victorian interiors designed by architect William Burges that had been identified in the conservation plan as of major significance.
It was discovered that moisture was getting in through the mortar and Ingram Consultancy were commissioned to carry out analysis of the mortars in the walls.
The accepted conservation approach would be to reproduce the mortars as closely as possible, but because the interiors were considered so important they were modified, notably by the choice of aggregates and the addition of magnesium stearates, for the building\'s repointing.
The intention was to prevent the ingress of moisture while still having a mortar that is softer than the surrounding stone and permeable so as to avoid trapping moisture in the stone.
The castle as it appears today includes Norman architecture on Roman ruins, including what is still the largest stone keep in Wales. There were further additions in the 15th, 16th, 18th and 19th centuries and there is now also a 21st century addition in a new Forest of Dean stone visitor centre that was part of Philip Turton\'s work.
As a result of the project there is now access to parts of the Castle that have never before been open to the public.
It was a Cardiff City Council project. The architects were Donald Insall Associates and financial assistance was provided by Cadw, the Wales Tourist Board and £5.7million from the Heritage Lottery Fund.
In Gateshead it was the restoration of one of their finest Victorian buildings, the Grade 2 listed Old Town Hall, that gained the council and their contractors, Historic Property Restoration of North Shields, Tyne & Wear, the IMBM award. John Niven Architects headed the work.
Blaxter High Nick sandstone, from a quarry then operated by Ennstone and since taken over by Stancliffe, was used for the work. Chris Green, Historic Property Restoration\'s contracts manager on the project, says 700 individual new stones were produced to repair the building, all having to be worked to match the original mouldings and carvings. The work included six new stone urns for the parapet, the largest being 800mm x 600mm.
The nine-month restoration of Gateshead\'s Old Town Hall included substantial restoration and conservation of the external fabric of the building, refurbishment of a small hall to create a new cafÈ, restoration of the original Victorian plasterwork, sash windows and doors, and the internal refurbishment and development of the main hall as a cinema.
The building has had a wide variety of uses since the town\'s new Civic Centre opened in 1987, but has now been reoccupied by Gateshead Council in a £1.2million plan to create a cultural hub for arts and other projects in Gateshead.
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