In the latest of our series Goofs on the Roof, Mat Woodyatt, Technical Training Manager of Redland looks at some examples of poor practice; and how a project should have been properly tackled. In this one, he considers the abuse of an aged school roof in Scotland.
Roofs are like all of us: there comes a point in our lives where we start to creak and crumble; and the cracks begin to show. In this first example from our Goofs series, we have a school roof of a ‘certain age’ that has not received the tender loving care we might normally expect to be shown to the elderly.
Obviously, the longevity of a roof depends on factors such as the construction detail, weather exposure, location and so on; yet typically for plain tiles – as the case here – the manufacturer’s guarantee for them would be in the region of 50-60 years.
Therefore, in a roof of the age and condition shown, we might expect to see a few problems. These will range from tile delamination, degradation of nibs from freeze thaw action, failure of the underlay and, at the most extreme, rotten timber elements beneath. These mean the roof is well on the way to needing replacement.
However, replacement may not be immediately possible and repairs can be undertaken; and this is where our goofs on this roof have caused as many problems as they have solved.
First, given the fissile nature of the tiles because of their age, extra care must be taken on the roof itself – here you can practically follow the footprints of the ‘repairers’ in broken tiles as they’ve trampled up the roof.
Second, the tile loss that they have sought to repair (with the white tiles centre right) should lead them to anticipate further failures: a decent rule of thumb is 10:1 – for every four missing, there’s bound to be 40 about to go. For clay tiles the old trick of checking the ‘ring’ of the tiles when tapped with a hammer is as good a method of any as ascertaining the strength and integrity of the tiles; a dull sound being a sure sign of internal degradation even if outwardly the tiles look OK.
Third, the way they’ve approached the repair suggests no regard for the soundness of the structure. As above, there will be widespread degradation, nail loss (depending on fixing frequency) and likely batten, and possibly rafter, failure – and the potential for a serious accident.
As alluded to, the best solution for this roof would be a re-roof. Either salvaging perhaps 50 per cent of the tiles for re-use to match in with aged effect or reclaimed tiles; or purchasing new tiles. There are some excellent heritage-look tiles these days, such as Redland’s Rosemary Clay Craftsman, which will provide a good match with the added benefit of the strength of a brand-new tile. Either way this will allow the much-needed installation of new underlay, and a change of battens as well as reinforcing any suspect timbers beneath.
Whatever course is taken the answer is not to continue to tinker at the edges with minor repairs, risking expensive damage to the property beneath. Do the job that needs doing and give this character-filled installation another half century protecting the property from the elements.