GOVERNMENT HOUSE WELLINGTON, NEW ZEALAND www.dreadnought-tiles.co.uk BACKGROUND Government House Wellington, the official residence of the Governor General, is an historic, 100 year old building in an awardwinning landscape and forms an important part of New Zealand’s heritage. Athfield Architects were engaged along with a number of other consultants to provide an analysis of the existing building fabric and review its functionality. The result of this analysis was a concept plan to meet the future needs of Government House while retaining and conserving the heritage features of the building.
CHALLENGE The original roof tiles on the roof of Government House were supplied in 1910, they were manufactured in the UK by Tunstall Tileries of Thomas Peake Limited, a North Staffordshire manufacturer that ceased trading over 50 years ago. A sample of these existing tiles from the roof was sent to Dreadnought by Athfield Architects, where it was established that the tile was single cambered, made from Etruria marl clay with a predominantly deep red colour. However, the tiles also exhibited a limited amount of subtle colour variation from tile to tile and a bluer colouring around the tail and the bottom of the sides of the tiles, a phenomenon known as “picture framing”. This occurs when the iron rich Etruria marl clay is exposed to a mild reduction atmosphere in the kiln, particularly in the areas where the tiles were in contact with one another. It also confirmed that the tiles were naturally coloured without the use of any surface pigments or stains. SOLUTION To reproduce the original colouring of the roof as closely as possible it was suggested that a mix of Plum Red tiles together with a small proportion of Brown Antique tiles would best match the original appearance of the roof. To test this on site a selection of samples were sent to Wellington to establish the right proportions of the mix. Following the creation of this mock up a ratio of 80% Plum Red and 20% Brown Antique was settled on to introduce the original subtle colour variation on the roof and recreate a limited element of blue around the tails of some of the tiles. Dreadnought advised against the repeat of the inappropriate use of fittings on the original roof. Arris hips for a 35º roof pitch were recommended and adopted for the re-roofing; they provided the same visual roof profile, were greatly more robust, and were easier and more economical to fit.
RESULT The painstaking specifcation by Athfield Architects and the high level of workmanship by the main contractor and roofing contractor have yielded a refurbishment of exceptional quality which is not only faithful to the buildings historical context but which has also introduced the degree of structural upgrade required in many areas. The refurbishment carefully balanced the responsibilities of reinforcing and celebrating the heritage attributes of the house and grounds while incorporating a level of contemporary amenity, and acknowledgement of contemporary cultural place and time in New Zealand. With a 100 year design life this conservation project has successfully drawn on the strengths and beauty of the existing spaces and structures of high profile building and introduced the subtle interventions that will improve the experience and functionality of the environment for both visitors to the house and grounds for generations to come.
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