A thatched roof is a rare and prized design element and a much-romanticized rural idyll.
Straw has been used as a roofing material for thousands of years and was the dominant material in much of the UK and Europe until the late 19th century. A large number of charming thatched cottages survive today, and for fans of chocolate-box cottages, they rank among the best homes in the world.
The material was also used by early settlers in the United States, although the practice fell sharply in the centuries that followed.
Today, thatched roofs are not a common sight in the US, but they exist across the country. In fact, it is believed that crafting for new homes, eco-homes and garden room ideas is becoming more and more popular as the current eco-home improvement trend is towards the use of more natural materials.
Types of thatched roofs
There are different types of thatched roofs, but they vary depending on the local vernacular.
Straw has been used in thatching for centuries, although alternatives found on every continent include water reeds, heather, bracken, rush, beach grass, flax and even wood shavings and potato stalks!
Here are some of the main types:
- long straw The roofs look shaggy – not like the reeds – and their eaves have hazel mesh.
- water reed Roofs are traditional in wetlands. The eaves usually protrude less than with thatched roofs and the surfaces appear uniform. Ridges can be of sedge.
- combed wheat Reed is actually interspersed like water reed. Eaves are not cut, but cut (so the stems have angled ends).
How do you repair a thatched roof?
A thatched roof ridge needs to be renewed several times between re-roofing of the main mantle and is usually required every 10-15 years.
It also provides an opportunity to strip thatch around chimneys to reveal masonry flaws that pose a fire hazard. All connections, including fillets and grout fillets, must remain watertight.
Localized areas of rot, such as B. worn channels where rainwater is concentrated can be repaired with new straw, along with damage caused by wind, birds or small animals. This can extend the life of thatched roofs and avoid more costly replacements.
Netting can be used where straw is vulnerable to damage from birds and animals. However, mosses, lichens and fungi do not have to be removed.
How long does a thatched roof last?
A thatched or thatched roof can last at least 30 years, but will eventually need to be re-roofed if the fixings are close to the surface and water can penetrate.
How to re-roof a roof
Re-thatching water reeds usually requires stripping the existing roof down to the joists. However, with straw, a new top coat is usually applied over existing base coats – or ‘saved’, care being taken not to build up an excessively thick layer of straw.
It is important not to remove roofs where a rare medieval smoke-blackened thatched roof survives. Modern screw fasteners are less damaging to old timbers than metal hooks.
Consult an architect, surveyor, or engineer before beginning work if there are any structural issues.
Choose a reputable roofer who works according to local tradition and does not automatically substitute reeds for long straw.
Over the centuries, regional differences in materials and styles for the thatched roof have developed, so maintaining these is important not only to preserve local diversity but also to avoid durability issues.
Problems with thatched roofs
One of the main problems with owning a thatched roof is that there are occasional shortages of supplies, usually due to a poor harvest. At times like this, consider a timely, localized repair rather than a full recap to add several years to a roof’s lifespan.
Roofs with heavier wear may be protected with a thin layer of combed wheat reed or long straw with surface attachments (known as a “rick coat”). While a thin Rick coat can last around three years, a heavier coat can last up to ten years.
A flush ridge might be considered rather than a raised block ridge. Flush ridges require less material, last as long as block ridges, and have generally been the traditional ridge type.
Are thatched roofs a fire hazard?
The most common cause of straw fires is improper installation or irresponsible use of wood stoves.
The risk is so high that there is now a trend to remove wood-burning stoves from thatched cottages and reintroduce open fireplaces such as inglenooks. The presence of a stove must be declared to the building insurance company so that no claims are forfeited.
Other fires in straw are caused by improper fuel or kindling, bird nests blocking flues, and igniting tar deposits due to improper flue, chimney, spark arrestor, or bird screen cleaning.
Deep, layered thatch increases the risk of fire by concealing defective chimneys and reducing the chimney’s height above the roof surface.
This provides a shorter route for embers exiting the top of the chimney to fall down before reaching the straw.
Options are an increase in the chimney height or the reduction of excessive thatch thicknesses (possibly with a listed building permit).