Guide To The Essentials of Thatch Roof Design and Style
Ever since the first bundle of reed was hoisted to the top of a building to begin the roof thatching process, thatch roof design has been an integral part of ensuring that this centuries-old craft has withstood the test of time. Indeed, roof thatching in Great Britain dates to the eighth century when property owners used an abundance of natural materials to construct their dwellings. The exquisite design and engineering of experienced craftsman have helped to keep thatching alive even today.
For the record, thatching is not a simple matter of laying bundles of reeds on top of a roof and tying them down. If it were that easy, anyone could do it. The fact is, thatching is an honourable craft requiring training and a lot of hands-on, practical experience. The most skilled craftsmen have spent countless hours perfecting their craft.
Today, thatch roofs are making a comeback in the UK. Property owners and builders are recognising the fact that thatching is relatively inexpensive, efficient, and exceptionally friendly to the environment. So where local codes allow for new thatched roofs, greater numbers of property owners are opting to do so – which leads us to the topic of thatch roof design.
Technical Aspects of Design
Roof thatching is not highly regulated to the same degree as other forms of roof construction. As such, a lot of the aesthetic aspects of roof design are left to individual thatchers. Underneath the aesthetics are certain standards that have been the basis of thatching for as long as the practice has been around.
Thatch roof design must account for numerous environmental factors:
Precipitation – in the form of rain, sleet and snow – should be kept off the underlying roof structure to keep it out of the space below. In this regard, the choice of materials will determine how the roof is designed. Water reed is a good example. Water reed has excellent waterproofing properties due to how tightly the cells of the plant are held together. By placing bundles of water reed close together and in patterned layers, a thatcher can create an outer surface that is virtually impermeable. Any moisture that does get into the thatch does not penetrate more than an inch or so.
Temperature Changes - The natural materials used for roof thatching tend to be excellent insulators. Again, let us use water reed as an example. Water reed is actually a hollow plant that makes for a very good insulator. Craftsman design their roofs to take advantage of the insulating properties of the materials in order to protect against the cold of winter and heat of summer. There is a reason thatched roofs are said to create 'cosy' homes.
High Winds - The geographic properties of the British Isles mean we are always subject to windy conditions. Sometimes, winds can be devastating to structures, so thatch roof design has to take windy conditions into account. Rest assured that thatchers do not merely place bundles of reeds on top of the structure and walk away.
Bundles are held securely to the structure's underlying shell using a series of lath strips, screws, and steel wire. A well-designed and properly constructed roof can withstand pretty high wind gusts without any damage.
Thatchers must also design their roofs in such a way as to promote ventilation. Without ventilation, moisture can easily be trapped between the thatch and underlying roof structure, eventually leading to rot. Thankfully, thatching materials are exceptionally breathable in their natural state. Attic venting is not necessary as long as a thatched roof is designed and installed correctly.
Thatch Roof Design and Regional Styles
Thatched roofing is making a comeback in Great Britain thanks to the many benefits it offers. From re-roofs to new builds, thatchers are increasingly busy these days. What's fascinating about it is the realisation that there are different design styles from one region to the next. Thatchers should be aware of those styles and, where local regulations require, be able to replicate them in their work.
The regional styles of thatch roof design are usually the result of the materials that were historically used for roofing in times past. For example, regions where wheat straw was the preferred building material tend to have roofs that are more rounded than angled. In areas where water reed became popular at the turn of the 20th century, straight lines and clean edges are preferred.
The distinctions in regional styles have diminished somewhat in recent history due to the tendency of thatchers to use imported materials. That has led to some local authorities producing their own guidance intended to keep regional styles intact. Consider Devon as an example.
Devon published a document1 in 2003 outlining the county guidance for roof thatching based on locally sourced materials that have been used for hundreds of years. The guidance suggests that both re-roofs and new builds adhere to a specific regional style known as 'Devon Thatch'. Owners of listed properties do not have a choice.
It is interesting to note that Devon is home to the largest volume of traditional thatch in the world, with about 4,000 structures boasting thatched roofs. Most of these are structures that have been built with a similar design that can be easily seen in roof ridges, peaks, and ornamentation.
There are six different aspects to thatch roof design that make it possible to separate one regional design from another. These are:
ridge design
ridge peaks
flashing techniques
ligger design
verge construction
eave design.
How a thatcher implements the six aspects of thatch roof design determine what the finished product looks like. You can see this throughout Devon, where thatched roofs have a very distinct and recognisable look that you will not find in other parts of Britain.
Modern Thatch Roof Design
Designing a thatch roof is a multi-stage process not all that different from designing a more conventional roof. Designers begin with the mechanics of structural integrity, insulating properties and moisture resistance, then add to it the aesthetic features that will make the finished product pleasing to the eye. None of this has changed over hundreds of years. But that is not an indication that modern thatch roof design isn't somewhat different from past design. It is.
New construction is creating a decidedly new look for thatching across the UK. At the heart of this new design is the imported water reed so many builders and thatchers are now using. Water reed, by its nature, requires designs that are more modern looking via sharp lines and steep slopes.
It turns out that imported water reed is the ideal material for achieving the modern look. With water reed, builders get all the benefits of a traditional thatched roof but with a sleeker look that better matches modern architectural trends. The new designs of the 21st century are not necessarily appealing to historical purists, but they are helping breathe new life into the thatching industry.
A New Age of Roof Thatching
Over the centuries thatched roof design has been largely influenced by building materials and craftsmen who have plied the thatching trade. Today, design is also being driven by modern architectural trends that give a nod to the past on the one hand while bringing roof thatching into the 21st century on the other.
There is no way to know where thatch roof design will go over the next 50 to 100 years. But we can say this: as long as there are skilled craftsmen and property owners who truly understand the beauty and benefits of thatching, this historical method of roofing a home will live on. And with it, the designs of the past will be remembered and celebrated.
Sources
http://www.traditional-thatch.org.uk/content/wp-content/uploads/2013/06/Thatch-in-Devon.pdf
