This month the Inspector looks at a prime example of when it’s time to stop repairing and start re-roofing.
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 the example right (see pic), we have a school roof of a ‘certain age’ that has not received the necessary attention and maintenance to keep it in optimum condition.
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 is 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.
In our example, however, some repairs have been undertaken but unfortunately, the nature of the repairs seems to have caused as many problems as it has solved.
‘Trampled up the roof’
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.
The ‘ring’ of the tiles
Second, the tile loss that they have sought to replace (with the white tiles, see left) 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.
When it comes to clay tiles, the old railwayman’s trick of checking the ‘ring’ of the tiles when tapped with a hammer is as good a method as any for 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 mentioned earlier, 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% 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 available, such as BMI 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.