By Isla Quinn
Twisted hazel. That is what holds a thatched roof down: hair-pin sticks called spars, or gads, pushed in over horizontal wooden rails called sways. Wikipedia’s article on thatching says so, and it says something else worth knowing before you look up at any thatched cottage in winter. A roof is only as good as the amount of correctly laid thatch covering the fixings.
Three materials
Three materials are typically used on thatched roofs in the UK: long straw, combed wheat reed and water reed. Good-quality straw can last more than 50 years when applied by a skilled thatcher, the article says. Water reed is rarely used outside East Anglia. It has traditionally been a “one coat” material: weathered reed is usually stripped and replaced with a new layer.
Water reed may last 50 years or more on a steep roof in a dry climate, the article says, but modern imported reed on an average English roof, laid by a proficient craftsman, is likely to last roughly 40 years. It adds that over 80 per cent of the water reed used in the UK is imported, and that an average house needs 4 to 5 acres of well-managed reed bed. Large reed beds have been uncommon in most of England since the Anglo-Saxon period.
The reed itself
Wikipedia’s article on common reed describes a plant of damp ground. It grows in standing water up to a metre deep or as a floating mat, with erect stems reaching 2 to 4 metres. Where conditions suit, it can spread 5 metres or more a year by runners. In late summer it carries a dense dark purple flower head 15 to 40 centimetres long. Stands, called reed beds, can reach a square kilometre or more. The article says common reed is the main source of thatch for traditional roofs in Europe and beyond.
The Broads
Wikipedia’s article on the Broads says “Norfolk reed from the broads has been a traditional material for thatching houses”. The area covers 303 square kilometres, most of it in Norfolk, and the current landscape of reedbeds, grazing marshes and wet woodland comes from flooded medieval peat workings. Some broads are surrounded by fens, which it describes as reed and sedge beds. The Broads Authority became operational in 1989 under the Norfolk and Suffolk Broads Act 1988, which took effect on 1 April 1989. The article gives no dates for cutting and no harvest figures, and neither do we.
How it is fixed
Straw, the thatching article says, is bundled into “yelms” before it goes up to the roof. Each course is attached with spars over the sways. Longevity depends on the depth of thatch covering each course’s fixings and not on the depth of the new layer. When the sways and spars become visible near the surface, the roof needs replacing.
Traditionally, new straw was laid over the weathered surface. The article says this built up accumulations over 7 feet (2.1 metres) thick on very old buildings, and that over 250 roofs in southern England have base coats applied more than 500 years ago. It says medieval wheat could grow almost 6 feet tall in poor soil, and that specialist growers have returned to older, tall-stemmed varieties, among them Squareheads Master (1880), N59 (1959), Rampton Rivet (1937), Victor (1910) and April Bearded (early 1800s).
Pitch and weather
A thatched roof is usually pitched between 45 and 55 degrees, according to the article. At least 50 degrees lets rain run off before it can get in, and steeper pitches are needed in areas of heavy snow.
Fire
We give no fire advice here. For current guidance on thatched homes, see the thatch page of your local fire and rescue service, for example Warwickshire Fire and Rescue Service, and speak to a thatcher and your insurer.
Dates and figures in order
- Anglo-Saxon period: large reed beds already uncommon in most of England, according to Wikipedia.
- 1 April 1989: the Norfolk and Suffolk Broads Act takes effect, according to Wikipedia.
What kind of sources these are
Three Wikipedia articles: thatching, common reed and the Broads. Anyone can edit them. We found no trade body, heritage body or museum page that loaded, and we have left out the three English thatching styles, local ridge patterns and any account of who thatches where, since none of the sources covers them. Our reading, which no source states, is that a lifespan quoted as a range reflects pitch, climate and craftsmanship together.
Questions a buyer would ask
What is it made of: long straw, combed wheat reed or water reed? Where did the material come from? How old is the base coat? When was the ridge last replaced? We name no thatcher and make no claim about any particular roof.
What we left out
We left out the edible uses of the plant, its effect on other wildlife where it spreads, and its use in water treatment, none of which concerns a roof. We also left out lifespan claims beyond the ranges given.
Quick answers
How long does a thatched roof last? Wikipedia says good straw can last more than 50 years, and imported water reed on an average English roof roughly 40 years.
What pitch does a thatched roof need? Wikipedia says usually 45 to 55 degrees, with at least 50 degrees letting rain run off before it can get in.
What is Norfolk reed? Wikipedia says reed from the Broads has been a traditional material for thatching houses.
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