A roof does not fail on a date in the calendar. It fails when one of its parts gives up, and different parts have very different lifespans. The covering usually outlasts the fixings, the flashings and the underfelt beneath it, which is why a roof can look sound from the ground while water is already getting in.
Typical service life by covering
- Natural slate: 80 to 100 years or more, though the nails often fail first at around 60 to 80 years
- Clay tile: 60 to 100 years depending on whether it is handmade or machine made
- Concrete tile: 40 to 60 years, with surface erosion and moss growth arriving earlier
- Bitumen felt flat roof: 10 to 20 years for older built up systems
- EPDM rubber flat roof: 30 to 50 years when correctly detailed and laid on a sound deck
- Lead flashing and valleys: 60 years or more, but frequently the first thing to fail if the original gauge was too thin
Nail sickness, the most common reason for a full replacement
Victorian and Edwardian slate roofs across Hertfordshire, Oxfordshire and Buckinghamshire were fixed with iron nails. The slate itself is often still perfectly serviceable after a century, but the nails corrode and snap, so slates begin to slip in ones and twos. Once that starts, patch repairs become a rolling cost and a full strip and re slate is usually the cheaper answer over any reasonable time frame.
Signs your roof is at the end of its life
- Slates or tiles slipping repeatedly, not just after a storm
- Daylight visible through the roof space during the day
- Sagging between the rafters, which suggests a structural rather than a covering problem
- Damp patches on upstairs ceilings that return after each spell of driving rain
- Mortar bedding on ridges and verges cracking away in sections
- Widespread surface erosion on concrete tiles, where the aggregate is exposed and the tile feels rough
Repair or replace?
The honest test is proportion. If less than around a fifth of the covering is affected and the fixings elsewhere are sound, repair is the right answer. If failures are appearing across the whole roof, or the underfelt has perished, money spent on repairs is money spent twice. A survey should tell you which of those two situations you are in, in writing, with photographs.
Not sure which applies to your roof? We will survey it and tell you plainly. Call 01296 325155 or request a survey.
