Chapter 1: Why does the hip on our slate roof drip after heavy rain?
What we find
On a hipped roof, every corner has a hip, where two slopes meet at an outward angle. On Georgian slate roofs like the one on Wargrave Manor, hips are finished either with lead rolls laid over the slates or with slates cut and mitred to meet exactly. Both rely on small details: the lead is held by clips and its laps shed water, the mitres by sound slates and sealed edges.
With age, the lead roll cracks at the folds, a clip lets go, or one of the mitred slates slips. Rain then runs down the inside of the hip, along the rafter and out onto a ceiling. The stain usually appears in an upstairs corner, some distance from the opening, which makes it hard to trace without getting up there. A stucco house adds a further complication, because water that gets behind the render can run down inside the wall and show up far below the roof.
What we fix
We trace the water from the loft along the hip rafter, then examine the lead and slates from above. Small splits may be repairable, but if the lead has cracked or the fixings have failed, we replace the hip covering with new lead sized and lapped to suit, and refix any loose slates beside it. Mitred hips are carefully re-cut rather than covered over, since the roof should keep its original look.
A single slate repair is typically quoted at £100 to £250 for labour, with the slate itself £5 to £25, as typical UK ranges. Your fixed quote follows the survey. The slate roofing page covers the wider picture, including when to repair and when to re-slate.