Reed thatch: a tradition making a comeback

Reed is one of the oldest roofing materials in Europe. For centuries it covered homes along the coasts and lakes, until industrial materials pushed it aside in the twentieth century. Today it is coming back, because people are once again looking for materials that are natural, long-lived and age well.

A tradition around the Baltic and the North Sea

In Lithuania, a reed roof brings to mind the Curonian Spit and the lagoon shore. In Nida and other villages on the Spit, fishermen's houses built from the mid-nineteenth to the early twentieth century were mostly thatched with reed, and some still stand. The material was close at hand, growing along the lagoon and in the Nemunas delta.

The same tradition runs across the Baltic and North Sea region. In the Netherlands, reed covers not only old farmhouses but new homes as well. In Denmark thatch belongs to the villages of Jutland and the islands, and in England, Norfolk has long been known for its reed and its thatchers.

What these places share is wet shores where reed grows in abundance and a windy, changeable climate: exactly the conditions in which a thick, breathable roof proves its worth.

When and where reed is harvested

Roofing reed is common reed, which grows along lakes, lagoons and river deltas. It is cut in winter, when the stems have ripened, shed their leaves and dried, and the water is covered with ice. The reed beds are easier to reach then, and they grow back in spring.

In Lithuania, reed is harvested on the Curonian Lagoon, among other places. The best stems for roofing are straight and strong, roughly 5–10 mm across at the cut, and are sorted and tied into bundles.

How a reed roof is laid

The bundles are laid in courses from the bottom of the roof upwards, butt ends down. Each course is pressed onto the battens, fixed with stainless steel wire and dressed with a special paddle until the surface is even and dense. The next course hides the fixings of the one below.

Water does not soak into a reed roof but runs off the tips of the stems, dripping from one to the next on its way down. That is why density and pitch matter as much as thickness. On REEDOME domes the reed layer is 30–35 cm thick.

It is skilled handwork: a well-laid roof looks calm and continuous, while hurried work shows within a few years.

How long a reed roof lasts

A well-laid, well-maintained reed roof is commonly expected to last around 50 years. Conditions matter more than the number, though, and the main rule is simple: the drier a roof stays, the longer it lasts. The Dutch thatchers' federation estimates that roughly half of a roof's potential life comes down to the quality of the reed, and about a quarter to its pitch and the length of the slope.

• Pitch. A steep slope sheds water faster and dries sooner. Thatchers generally recommend a pitch of at least 35–45 degrees.
• Ventilation. Reed needs to dry from both sides, so a ventilated gap is left beneath it.
• Trees and shade. A shaded roof dries more slowly and gathers moss sooner. A tree dripping onto the roof can cut its life by as much as half.
• Maintenance. Regular inspections, clearing leaves and timely small repairs repay their cost many times over. North- and west-facing sides dry more slowly and deserve a closer look.

Fire safety

Countries with many thatched roofs manage fire risk through a few clear measures, which apply equally to a dome.

• A non-combustible layer under the reed. It separates the reed from the structure and the rooms below.
• Fire-retardant treatment. Reed can be impregnated with a fire retardant. Dutch insurers point out that this protection needs renewing from time to time.
• Chimneys and lightning. A chimney through a thatched roof needs a spark arrester, and for a house standing in open country, lightning protection is worth considering.

Warmth and quiet

Reed insulates to some degree in its own right, but in a REEDOME dome the main insulation sits beneath it: up to 30 cm of wood fibre or cellulose. The reed acts as an outer coat against wind, rain and summer sun.

The other benefit is easiest to hear in the rain: drops do not drum on reed as they do on metal, and wind and traffic noise arrive much softened.

Why reed suits a dome

On a conventional house, a thatched roof has its weak points: the ridge, the valleys, and the joints with walls and chimneys. That is where water usually finds its way in first, and the ridge needs attention soonest.

On a dome, roof and walls are one surface. The reed forms a continuous shell from the base to the crown, with no gutters, ridges or joints, so there are far fewer weak points. Near the base the slope is steep and water runs off quickly, while towards the top, where the curve flattens, the finish is designed separately and with particular care.

How reed ages

A new reed roof is a warm, golden colour. Over time, sun, rain and wind give it a silver-grey patina, much like weathered timber or fieldstone.

This is not a sign of wear but the natural course of the material. As it greys, the roof blends into the trees, the grass and the sky, and the house looks as though it has always been there.

Reed thatch on a REEDOME dome

Every REEDOME dome is covered with 30–35 cm of hand-laid water reed. Beneath it lie a non-combustible layer, a ventilated gap and the full build-up of insulation and structure, so the roof works as one system. If you would like to talk about how it would look on your plot, fill in our short questionnaire and we will be in touch.