Preston's terracotta roofs: what 80 to 100 years does to them
The terracotta tiles on Preston's Californian bungalows were handmade and fired to a quality that modern concrete tiles rarely match, and many are structurally excellent after a century of Melbourne weather. What fails first is always the surface seal (the tile glaze has worn back to bare terracotta in older tiles, allowing moss colonisation) and the ridge mortar (rigid cement that cracks under freeze and thaw cycling has been failing progressively for decades). A Preston restoration typically involves a thorough clean and de-mossing treatment, replacement of any cracked or slipped individual tiles, a full rebed and repoint of every ridge cap in flexible polymer mortar, and a quality two-coat weatherproof coating. Done properly, it extends the roof's weatherproofing for another 10 to 15 years. Repointing alone, catching it before caps start shifting, can add years to a roof that doesn't need a full restoration yet.
