Thatch Styles and Life Expectancy

Water Reed - 25 - 40 years.
Combed Wheat Reed - 25 - 35 years.
Longstraw - 15 - 25 years.

The life expectancy of your thatch will vary according to:

The Material used.
The quality of the material used.
The pitch of the roof.
The skill of the thatcher.
The geographical location of your property - i.e. humidity, winds, rain. High humidity will shorten the life of your thatched roof.
The proximity of trees.
Pollutants and other environmental considerations.
Damage from vermin/birds .
Damage to the roof from other trades people not familiar with thatch.