Water Reed vs Wheat, Oat and Barley Straw

Water reed lasts 40-60 years where straw lasts 15-25 — and the difference comes down to fibre length and resin content.

Water reed (Phragmites communis) is cut between November and March, while the plant is dormant. Commercial long reed supplied for thatching runs roughly 1.5-2.5 m, and that fibre length is a large part of its durability.

Wheat, oat and barley straw are supplied in bales of about 300-400 mm and laid in courses spaced 200-250 mm apart up the slope. The shorter fibre and lower resin content give straw its shorter service life of about 15-25 years.

Both materials need the same roof geometry: a pitch of at least 45-50 degrees, usually laid at 50-55 degrees, so water runs off instead of sitting in the material. Below that pitch, neither reed nor straw will reach its expected lifespan.

Ventilation is the other shared requirement. The covering is ventilated at the eaves and ridge rather than closed with bitumen felt, and a well-ventilated roof is the condition attached to reed's 40-60 year figure.

The maintenance calendar differs by material. On reed the ridge is renewed about every 8-12 years; on straw, every 5-8. Over a 40-60 year reed roof, that means several ridge renewals before the covering itself is due.

• Water reed: 1.5-2.5 m long, cut November-March, lasts 40-60 years.
• Wheat, oat and barley straw: 300-400 mm bales, lasts 15-25 years.
• Both: courses at 200-250 mm, pitch of at least 45-50 degrees, ventilated at eaves and ridge.

Further reading

• When to Strip Back and When to Revet
• Laying Courses, Fixings and Ridge Cops