Chapter 1: Why do ridge tiles keep coming loose on our hilltop house in Hindhead?
What we find
At 250 metres or so above sea level, there is little between your roof and the wind. A ridge is the row of capping pieces that closes the very top of the roof, and the older ones were bedded on a strip of sand and cement mortar. Gusts lever at those tiles all winter, and rainwater gets into hairline cracks, freezes and widens them. Eventually the bond lets go and a tile rocks or slides.
You might first hear a clunk in the night, or find a piece of tile on the lawn. From the ground, a ridge that looks wavy, or a dark line where mortar has fallen out, is a warning. The same applies at the verge, the sloping edge of the roof above a gable wall, where wind can get under the tiles and lift whole rows.
What we fix
We take a few ridge tiles up and check what is beneath them. Where the tiles themselves are healthy and just the mortar has given up, they go back on. BS 5534:2014 asks for mechanical fixing at the ridge, hips and verges, so mortar alone does not carry the job, so on exposed roofs we favour dry-fix: the capping fixed by screws and clips to a long batten, with a ventilated roll underneath to keep out wind-blown rain. BS 8612:2018 covers those systems.
Dry verge units clip over the tile ends at a gable and resist uplift far better than a mortar fillet. Published UK figures for dry-fixing the ridge of a semi sit between £900 and £1,600, with £300 to £900 more for scaffold, and our own written figure arrives after the survey. The ridge tile repairs page has further detail on the fixings.