"Magnificent" Great Barn joins Open House weekend

The Great Barn in Harmondsworth is described as “a magnificent building” in the catalogue of over 800 buildings in the London area that the public can visit for free during Open House weekend, which is on 16th and 17th September.               

The Great Barn looks stunning with its renovated roof - drop by and sit it for yourself

The Great Barn looks stunning with its renovated roof - drop by and sit it for yourself

This annual festival features buildings of architectural interest, from private homes squeezed into unlikely gaps between buildings to St Paul’s Cathedral library and even a windmill.  

Open House weekend is celebrating its 25th anniversary this year and its sad to think that the Great Barn has been under threat for more than half of that time.  Heathrow has drawn a boundary line on its third runway proposals that appears to spare the ancient barn and St Mary’s church next door (which is also open to the public this weekend), however, both buildings rely on the support of the community for their continued existence.  If a runway went ahead, most of the parish and its residents would have been forced to leave.

It's almost certain that the barn only survives in its current condition because of the dedication of local residents who set up a group called The Friends of the Great Barn to ensure it was maintained for future generations to enjoy.

These residents were concerned when the barn’s owner, who wasn’t living in England, neglected maintenance and repair of the building.

Eventually English Heritage took ownership in late 2011 and arranged a detailed survey, followed by a complete restoration in 2014, which included a new roof tiles.

The Open House catalogue gives the Great Barn’s history.:

The Royal manor pre-dates the Norman Conquest and was acquired in l391 by William of Wykeham as part of the endowment for his foundation of Winchester College. By 1547 the land was owned by Sir William Paget, whose family farmed it until the 18th century, and it remained in agricultural use until the late 1970s.

Work on the barn itself was begun in 1424-5 when William Kyppyng and John atte Oke inspected timber near Kingston-on-Thames on behalf of Winchester College. It was at least partly completed by 1426 and the tilers were paid for finishing their work in 1427. It replaced earlier storage barns that appear to have come to the end of their economic life and led to an increase in the income from the manor. Documents relating to its planning and construction survive at the College.

At 193ft in length, 39ft wide and 37ft high the barn is the largest medieval timber-framed barn to survive in this country. Over 95% of the structural timbers and the majority of the cladding are original.The construction of a building on this scale, with the use only of axes, saws and adzes, was an awesome undertaking, using a complex but effective system of bracing not unlike the nave and aisles of contemporary Gothic church buildings, with in this case only oak dowels to secure it.

There are 12 bays and three entrances from the east, each of which had threshing floors (in the 3rd, 7th and 10th bays from the south). The base of the walls is a low plinth of natural ferricrete (which slopes 1ft north to south so that all the trusses lean a little) and the huge inverted tree trunks of the main posts stand on blocks of Reigate stone. The roof is covered with new hand-made clay peg tiles hung on riven oak battens.

Further details can be found at http://www.english-heritage.org.uk/visit/places/harmondsworth-barn/history and in a newly-published book: The Great Barn of 1425-27 at Harmondsworth, Middlesex by Edward Impey with Dan Miles and Richard Lea (Swindon: Historic England, 2017).

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