What is a thatch ridge tile?
A thatch ridge tile is a purpose-made arched clay tile used to cap the ridge of a thatched roof. The Dutch terms are rietvorst and strovorst. The ridge is the most vulnerable point of a thatched roof: two slopes meet there and the stems no longer lie steeply enough to shed water.
Characteristics
- Material — fired clay, usually red or blue-grey (smoked)
- Shape — a generous arch, so the tile passes over the thick layer of reed
- Size — around 660 x 235 x 210 mm is common; clearly larger than an ordinary ridge tile for a tiled roof
- Fixing — the tiles are bedded in a lime-rich mortar and pointed flat or with a raised seam, which absorbs the variation in size
More than ninety per cent of thatched roofs in the Netherlands, Belgium and France are finished with ceramic ridge tiles. In Britain a ridge of sedge or straw is the more familiar tradition.
Alternatives for the ridge
- Copper. A copper ridge capping is light, extremely long-lived, and weathers to green over the years. Copper ions washed down by rain also suppress algae and moss on the slope below. It does call for precise sheet-metal work
- Timber. A boarded ridge construction, mainly in traditional and regional forms
- Turf or heather. A planted ridge of heather, grass or turf; German roofs often use a heather ridge, while in Normandy ridges are planted as flower beds
Points to watch
- Mortar choice. Use a lime-rich, relatively soft mortar. Hard cement mortar cracks as the reed and tiles move, and then draws water inwards
- Inspect the ridge annually. Loose tiles and cracked pointing are the most common cause of leaks in a thatched roof
- Replacement. Re-bedding loose tiles is far cheaper than waiting until the reed under the ridge has rotted
Related terms
- Thatching reed
- Thatching
- Mortar
- Roof pitch
- Facade
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