What is thatching?
Thatching is the craft in which bundles of dried reed are fixed to a roof slope layer by layer from the bottom up and dressed with a leggett into one dense, evenly falling surface. Only the top few centimetres of each stem are visible; water runs down over the stems without ever reaching the structure.
How it is done
- Prepare the deck — for a screwed roof the boards and any fire-resisting layer, for a traditional roof the battens
- Fix the wires — heavy galvanised wire is screwed horizontally across the roof, on a screwed roof with special screws with an eye
- Distribute the bundles — reed is passed up in courses and spread across the slope
- Fix it down — thinner binding wire clamps the reed under the heavy wire; the wires are twisted together and pulled tight
- Dress it — the butts of each course are driven up with the leggett until the reed lies dense and even
- Finish — the ridge, valleys, hips and eaves are detailed separately, the ridge usually with ridge tiles
Guidance on thickness
The Dutch trade federation works to an average thickness of at least 30 cm of good-quality reed. For a slope of no more than 7 metres from ridge to eaves, a pitch of 40 degrees or more and reed shorter than 1.50 m, the rule is at least 32 cm at the eaves and at least 30 cm at the ridge.
Practical points
- Pace. Thatching is labour-intensive. A gang of three will take a good week over one roof slope of a house
- Work in dry spells and sheet over open slopes overnight
- Use a specialist. Clamping force, layer thickness and the detailing at ridge and valley decide whether the roof lasts thirty years or ten
- Maintenance. Have the roof inspected periodically, keep gutters and eaves clear of leaf litter, and treat algae growth early
- Cost. The thatching work alone (excluding the deck) usually falls in the order of 80 to 150 euros per square metre
Related terms
- Thatching reed
- Roof pitch
- Mortar
- Renovation
- Facade
Want to learn more about construction terms? Visit our knowledge base at fredsdiyplans.com.