This is perhaps the most ubiquitous question asked by thatched roof owners and the most difficult to answer. Thatched roofs degrade over time, due to the exposed plant stems gradually rotting away. There are many factors involved which all need to be taken into account and given weight, depending on the attitude of the person making the decision!
In essence, the two main factors which would provide motivation for considering re- thatching are either deteriorating aesthetics or a loss of function, ie: allowing the elements to enter the property. It’s possible for both situations to occur simultaneously, or one but not the other.
For example, a thatch could be seen to deteriorate aesthetically over the course of many years, but be perfectly functional as a roof covering to keep out the rain, wind and insulate the property against extremes of temperature.
Conversely, it’s entirely possible for a thatch to appear visually pleasing, but have faults which render it unsuitable as a functional roof.
Clearly, most reasonable people would consider function to be important. Usually a loss of function leads to a re-thatch. However, thatched roofs can also be repaired and patched almost indefinitely, to extend their working lifespan, although there inevitably comes a point where this becomes economically unviable.
With the rise of thatched property values in Dorset and a gradual shift towards relatively affluent ownership, thatch owners are increasingly likely to consider the maintenance of their roof a priority.
For many owners, aesthetics are just as important as function. However the decision is an individual one and may not be as simple as it first appears!
The only way to arrive at a truly informed conclusion is to commission a master thatcher to perform a specialist thatched roof survey.