Chapter 1: What has loosened the ridge tiles on our post-war semi in Ash Vale?
What we find
Houses built after the war were typically roofed in concrete interlocking tiles. The ridge (the capping along the top) and the verge (the edge at a gable end) were bedded in sand and cement. After generations of winter frost, summer sun and rain that mortar shrinks back from the tile, the bond weakens, and a ridge tile starts to rock in its bed. A strong gust can then lift it clear.
Look for crumbs of mortar on a path or in the gutter, or for one ridge tile sitting proud of the line of the others. In the loft, a chink of daylight beside the ridge timber, or a damp mark on the wood beneath it, tells you rain is getting in. Neighbouring houses built around the same time tend to be failing in much the same way, and an earlier patch repair can leave a mix of old and new mortar.
What we fix
Our first step is to take up a handful of ridge tiles and judge whether the tiles are in good order and the mortar alone has perished, as it usually has. Under BS 5534, mortar by itself is no longer enough to hold the ridge, hips and verges; each tile needs a mechanical fixing. On these houses we therefore recommend a dry-fix system, with screws or clips holding the tiles to a continuous batten on top of a breathable roll. BS 8612 covers dry-fix products.
Verges can be done during the same visit with clip-on dry verge units that keep wind from getting beneath the tile ends. Our ridge tile repairs page sets out the choices, and you see photographs of the old ridge before you decide. A typical UK range for dry-fixing a semi-detached ridge is £900 to £1,600, and scaffold can add £300 to £900. Your fixed quote follows the survey.