How Does Reed Age?

Hardly any other organic building material is exposed that much to changing weather conditions as the reed that makes up the roof of a thatched house. It owes its high durability to the fact that reed contains a high percentage of silicates. That is why today the reed-thatched roof, in contrast to the straw-thatched roof, can still be found in Germany.
Straw-thatched roofs, which in England are still common, have to be renewed after 15-20 years. Reed-thatched roofs last 25-40 years, if they always get the chance to dry after a rain. Reed, on the one hand ages through natural wear and tear (being exposed to sunlight, wind, rain and frost), on the other through permanent humidity penetration, which can lead to the decomposition by microorganisms.
On a thatched roof only the butt ends of the reed are exposed to natural wear and tear. Permanent humidity spreads through the roofing, so that the entire length of the reed cane is affected by fungal decay and the decomposition by bacteria. Fungi and bacteria can colonise all organic building materials. Under the right living conditions (humidity of >20% and temperatures of >12°C) they can proliferate and attack the reed. The decomposition of the roof caused by fungi and bacteria exceeds natural wear out many times over.