A hollow pantile is a curved, half-round roof tile laid with the hollow (concave) side up, so that rainwater runs down through it. The joint between two hollow tiles is covered by a convex tile laid the other way up. Together they form the hollow-and-cover system.
How it works
- The hollow tile (nun) lies like a channel on the roof and carries the water away
- The cover tile (monk) lies concave side down over the joint and keeps it watertight
- This is one of the oldest roofing principles, derived from the Roman tegula and imbrex
The system is widely known as monk and nun: the lower hollow tile is the “nun”, the covering upper tile the “monk”.
Application
- Historic and traditional roofs — monasteries, churches and old houses
- Restoration — on listed buildings the monk-and-nun covering is kept as far as possible
- Usually of fired clay, at a roof pitch that gives enough fall for water run-off
Points of attention
- The system uses relatively many tiles and is labour-intensive to lay
- Good roof boarding or a sub-roof limits rain penetration in driving rain
Related terms
- Roof tile
- Monk and nun
- Hollow and cover tiles
- Dutch pantile
- Roof pitch
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