How do I tell when I need to replace my roof?
Q: How do I know when I should replace my roof? It’s a clay tile roof and the house dates back to 1905. A few tiles have come down, which I have replaced, but the roof is quite old. I asked a roofer, and he said I need to replace it, but he was obviously keen on new business. It is such a huge amount of money (tens of thousands of pounds) that I don't want I replace the roof until I absolutely have to - but how do I tell when that is? Can I keep it going another 5 years?
This is a pitched roof with clay tiles , which dates from when the house was originally constructed in 1905, and ‘a few tiles have come down’. It is now over 100 years old and on a ‘rule of thumb’ basis might now be expected to have reached the end of it’s useful life. That said, there are many old tiled roofs which are still in service, usually to preserve the character of a building but they will have been subject to an extensive overhaul and will need regular maintenance.
The majority of clay tiles from this era will be reliant on nibs to their rear faces, which rest upon timber battens. Only occasionally will nails be used additionally. Whilst by now, nails will no doubt be virtually rusted away, tiles don’t tend to ‘come down’ unless either the nibs have broken off, they are cracked through or the battens have given way. Signs to look out for, to determine when wholesale renewal is necessary, are tiles ‘coming down’ increasingly more often, many slipped due to perished knibs, white salts to the underside, extensive spalling and or cracked/ snapped/broken battens.
It should be possible to coax a few years extra life from a clay tiled roof, provided the battens are still sound, by simply replacing individual defective old tiles with new, where needed (as they’re usually not nailed in place it’s not an overly difficult task).
Andrew McWhirter, McWhirter Associates, Chartered Surveyors
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