Jaffa Clock Tower.
Erected in 1906, as gift for the Ottoman Sultan Abd al-Hamid II, the ruler of the Ottoman Empire, which included at that time also the Holy Land.
In 1965 the Tower got a make-up, which included new stained glass windows, iron ornaments and plaque commemorating the capture of Jaffa in 1948.
The original zinc cladding of the Tower’s spire, from 1903, was probably redone at that time too, in copper, though some sources put this event later, in the early 80ies.
In 2001 the Clock Tower was renovated again, together with the elongated square it stands on and with the surrounding streets, in an attempt to have it enlisted on UNESCO list of Cultural Heritage sites.
The tower was cleaned thoroughly, the 1965 artwork dismantled, serviced and reattached, new clocks were installed and the copper roof which was in its final stages of deterioration redone.
It was my privilege to participate in this work. It was done with proper KME copper, using methods and sensibilities used by the masters from the “old school”.
However, in my opinion, the aged wooden infrastructure should receive much closer attention than it did. As the project had to conform to schedule and budgetary constrains, it got only new layer of 7/16″ OSB on top of the original decking, and the exposed timber a coat of tar.
Only time will tell when Jaffa Clock Tower roof will get a shiny new metal cladding again, for the fourth time.
The history of the various metal claddings of Jaffa Clock Tower spire makes an interesting study case.
The original zinc work, done by the “old school” trademen seemed to fare pretty well, judging by postcards from early 60-ies. Life span of 65 years (or 80 according to the other sources) is good, comparing to 75 years generally accepted for zinc, considering that the hostilities of 1948 left their mark on the roof and the damages were never addressed properly.
The second reiteration of the Jaffa Clock Tower roof, in copper didn’t survive 36 years (or 20, basing on the other sources). The reason for such poor performance lies in:
Damaged timber, which being left untreated in 1965, caused considerable sagging in the dormers and leaks. In 2001 some timbers were completely rotten away;
Inferior grade of copper, with elevated contents of impurities (such as zinc and iron), which virtually rusted away in splash zones like iron would rust;
Lack of determination and knowledge to do things properly; inferior workmanship.
Copper roofs have life expectancy of 100 to 150 years. The limiting factor is aging of their wooden infrastructure.
There are numerous well documented cases of copper roofs surviving 500-600 years. In these cases the robust timber, made of timber, made of woods much more resistant than the common pine or spruce may last even longer. But for the roofing grade copper 0.7mm to 1.0mm thick, with its wash out rate of over 1/1000mm per year, that is the limit.
Having this in mind, we can see that the first re-roofing, done somewhere between 1965 and early 80-ies did survive 20% of its expected service life, while the “economical” grade copper only 5%!
Making generous assumption that the copper used was half the price of one of prime quality, it still leaves it 10 times more expensive for its intended usage!