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.