Monday, August 29, 2011

Church roof over 500 years old, study reveals

A SCIENTIFIC study has confirmed a "truly spectacular find" that proves oak timbers from a church in a heritage town are over 500 years old.

The timbers from the roof of the Holy Trinity Church of Ireland in Fethard, Co Tipperary, were sampled in June and examined at Queen’s University in Belfast.

It is now the only medieval roof in Ireland to be accurately dated.

David Brown, of the university’s school of geography, archaeology and palaeoecology, said analysis of the tree rings from the roof revealed a felling date of 1489, plus or minus nine years.

The church itself is an important feature of the walled town in Fethard and was originally built in the early 13th century, but now consists mainly of a mid-19th century remodelling.

However, concealed beneath the Baltic pine roof from about 1800 and above the plastered Victorian barrel-vaulted nave is an ancient arch-braced, clasped purlin oak roof some 24 metres (80 feet) long.

Architect Margaret Quinlan made the discovery of the roof, which can only be accessed through a small hatch leading from the belfry into the roof cavity.

Under licence from the National Museum and the Minister for Arts, Heritage and the Gaeltacht, 10 samples were taken from the roof last June and analysis was commissioned by the Fethard Historical Society and part-funded by South Tipperary County Council.

All the samples returned a close match in growth pattern, which enabled the team in Belfast to assemble a chronology of 77 years for the batch. This chronology was then compared with the master chronology held at Queen’s, which showed the samples were growing between 1384 and 1460.

In the absence of bark and although much of the sapwood was missing, the team was able to come to a conclusion as to the felling dates of the roof wood.

Back then, timber frames of this kind were erected "green" for ease of assembly (before the wood hardened and became difficult to work) and so the assembly and raising would have taken place almost immediately after the felling date.

David Brown estimates that the trees used in Fethard were immature at the time of felling — perhaps less than 100 years old — and derive from the first regeneration of oak trees planted after the Black Death of 1348.

Mr Brown described the find as "a truly spectacular result for an Irish roof and for dendrochronology", the science of tree-ring dating.

Oak-framing practitioner Paul Price identified "see-sawing" marks on one of the collars, indicating the wood was converted (from tree to beam) using a long-lost medieval technique. 

This would appear to be the first time that see-sawing has been identified in Ireland.