Here’s what you need to know about having a thatched roof

Thatching is the oldest form of roofing still in existence; it has been in use for around the last 10,000 years. In the last century, with building developments expanding, thatching lost favour with many people as it was often regarded as an expensive way of roofing your house. However, the last few decades has seen an increase in thatching's popularity.

Indeed, it is widely used today on country houses and cottages, and on converted barns to provide a traditional look. Thatching is also popular throughout the country for garden structures and fixtures, such a gazebos. Thatching can be shaped into a wide range of designs, which can either adhere to local traditions of the area or provide a unique design.

Why should I thatch my roof?

Thatching provides many qualities which make it more desirable than other forms of roofing:

  • It is an ecologically renewable source.
  • Provides an individual look.
  • Makes for a superb insulator in winter, yet is also cool in summer.
  • When compared with tile roofing, thatching is comparatively cheap.
  • Planning departments look upon thatching favourably when it comes to planning applications.
  • It raises the selling price of a house, so proves to be a good investment.

Types of thatching

A range of materials are available for thatching, and you should discuss with each thatcher what material would be best for you. Types of materials available are:

  • Norfolk Reed (Water Reed, Marsh Reed, Continental Reed) – This is the most popular type used due to its long lifespan. The preparation of the reed is also less labour intensive and the thatcher can learn this method faster than the others.
  • Combed Wheat Straw (Devon Reed) – This is probably the oldest type of thatching material that is used. Its preparation takes longer than that of Norfolk Reed and it also has a shorter lifespan, making it slightly less popular.
  • Long Straw – The preparation of this material is very labour intensive and has a relatively short lifespan. However, it gives the “tea cosy” look which many people may want from their thatch and the laying rarely affects historic ceilings and timbers, thus making it more suitable for older or historic houses.

What is the ridge?

The ridge is the thatch which covers the upper part of the roof where the covers join. This part of the thatch has a great deal of character and the thatcher will hand craft it. Many thatchers stick to one pattern, acting as a sort of signature. However, there are a range which you can choose from, provided by a variety of different thatchers.

Ridges are either flush, meaning that they are flat to the rest of the thatch and at the same level as it, or block, meaning that they stand away from the rest of the thatch. Instead of using a reed or straw ridge, a sedge ridge can be used instead. This is a very sharp type of moss.

Types of ridges you can choose from include:

  • A simple straight pattern and thatch cut. This is often specific to the thatcher.
  • A complex egg and dart pattern, which consists of an egg shaped design followed by a dart, anchor or arrow shaped one.
  • A hearing bone pattern, which is a zigzag pattern.

How long will the thatch last?

The lifespan of the thatch depends of a variety of factors including the ability of the roof to shed water, which depends on the pitch of the roof, and the climatic conditions of the region, high humidity and wind are the main influencing factors. The type of thatch used also affects how long the thatch will last and generally the following life spans can be applied to each type of thatch:

  • Norfolk Reed – 55-65 years
  • Combed Wheat Straw – 20-40 years
  • Long Straw – 15-20 years
There are some exceptions to these life spans though depending on how well they are looked after.

The thatching process

  • Before thatching begins, the thatcher will inspect, treat and repair any of the beams in the roof if necessary.
  • The thatching process begins by setting up the eaves, attaching yealms (prepared drawn layers of straw or reed) horizontally to the ridge and apex with spars, which are lengths of twisted hazel with pointed ends, to make them more secure. Traditionally daub was used to bind the yealms. Making a solid eave is the foundation of the thatching process. This first layer of the thatching process is called the brow course.
  • Further yealms are then added in the same way to finish the brow course, until the apex or the ridge is reached. Each yealm is laid in the same direction and overlaps the layer below so that there is a continuous depth of straw over the entire roof.
  • The next segment, the weathering thatch, represents the main body of the thatch. The type of thatch laid at this point is referred to as the “skirts”. Vertical strips approximately 100 cm wide called “strakes” or “stulchs” which run from eave to apex are applied next. These will be laid in layers until the weathering thatch measures around 35 cm thick. When the reed or straw is applied to the roof, it is attached to the rafters using steel thatching crooks and horizontal hazel or steel sways.
  • The thatch is then combed with a rake to get rid of any short or loose straw or reed, and to make sure that all the straw is lying vertically. Liggers, which are long lengths of split hazel or willow tapered at each end, are then attached to the eaves and apex to help fix the thatch in place. The eaves and apex are then cut with an eaves knife and hand shears to make the thatch neat and straight.
  • The ridge is then added to keep the work in place. On average, a ridge will have to be replaced every 8-12 years as they are exposed to the elements, and by this time will have lost their ability to keep the ridging material in place. A netting material is placed over the ridge to keep birds off it, but also acts as a fixing.
  • Reed thatching needs more work than straw thatching, as the thatcher has to knock the reed into shape with a tool (a leggett) once he lays it.
  • For re-thatching, the original thatch will usually be removed only down to the brow course and then another weathering thatch layer will be laid over the top of this. However, sometimes damage to the original thatch is so bad that another brow course may have to be lain as well.

How much will a thatched roof cost?

The cost of thatching your roof will vary greatly according to a number of factors. These include:

  • The size of the roof.
  • The shape and design of the roof.
  • The types of thatching material used.
  • The type and pattern of ridge used.
  • The height to the ridge.
  • The height to the apex.
  • The type of additional features which may be used in the thatching process.
  • If there is existing thatching and this needs to be removed.
  • The condition of the timber as it may need to be repaired or treated before thatching takes place.
  • The required thickness of the thatching coat.

In general though thatchers work in squares which measure 10 feet by 10 feet. Each of these squares will cost on average between £600 and £800 depending on all the factors listed above.

There may be additional costs which at first would not be apparent to the thatcher. For example, from surface inspection the complete condition of the roof timber or existing thatch may not be totally determinable. This is why it is important to get at least 3 separate quotes from different thatchers to see if any of them identify something which the other may have overlooked.

Thatch fires

Thatch fires are not as common as you might think. There was only one death from thatch fires in the 20th century and the fire brigade have estimated that only around 2% of house fires come from thatch roofs. It is thought that most of these fires come from the chimneystack. If there are cracks in this then hot gases are leaked and escape from the flue into the thatch. If you have a working chimneystack and a thatch roof it is worth getting it regularly checked to stop this from happening.

What should I ask the thatcher?

  • Are all your materials ecologically renewable resources?
  • What type of thatch do you think would be most suitable for my roof and why?
  • What maintenance will I need for the thatch? Do you provide this, if so will it be an additional cost or included?
  • How long will the thatching take?
  • Can you advice me about suitable insurance?
  • What type of drainage will you use?
  • What type of ridge can (or do) you lay?

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