How to choose the right type of thatch to prolong the life of a thatch roof

All thatch has a lifespan – it’s a fact. No matter how well it is maintained, no matter how well it is thatched and to what thickness it is thatched at, all thatch roofs will eventually get to the point of no return and will need to be re-thatched.

There are however, ways to prolong the life of the roof; one (as mentioned above) is to have an effective maintenance plan in place. The second and most important is the choice of thatch when the roof is originally built.

A few months ago the Cintsa Thatching team were working in Port St. Johns on two large thatched roofs. One was thatched in hyparrhenia hirta and was positioned approximately 50m from the sea. The second was thatched in Cape Reed and was positioned around 200m from the sea. With both roofs within 150m of each other, the difference in the individual state of them was astounding! The larger roof, originally thatched well (spare a minimal thickness) in hyparrhenia had been thatched roughly 15 years ago and although it was ready for a good brushing, it was in almost perfect condition and had received minimal maintenance over its lifetime. The latter roof, thatched in Cape Reed was newly thatched around 4 years ago and has received several courses of maintenance over the past 3 years, was truly rotten. Although all materials suffer increased damages on the coast from the sea and salt air, humidity, wind and other potentially harsh weather conditions, this difference in the behaviour of the thatch types is something to be noted.

When to choose Cape Reed (a Thatch Reed) 

Cape Reed is a heavy thatch with a strong core. Now here’s the logic…Cape Reed grows in a varying climate with wet, cold winters with rainfall and hot dry summers. It is therefore not highly suited to areas which have hot humid summers and dry winters. The combination of the humidity in the air and the rain in the summer promotes rotting in this inland reed. Cape Reed is highly effective in inland areas and can last for 20-30 years in cared for properly, in this dry climate.

When to choose Hyparrhenia Hirta (a Thatch Grass) 

Hyparrhenia is a light weight thatch with a hollow core which grows in areas like Mphumalanga, Natal and the Transvaal. The climates of these areas are quite tropical with summer rainfall and high humidity. This thatch is therefore logically more suited to its natural climate which includes coastal areas.

The quality of thatch chosen also has a great effect of the lifespan of a thatch roof and it is possible that the roof thatched in Port St. Johns, in Cape Reed was built in a low quality thatch. There are many different qualities of thatch; the quality is determined by several factors such as the climate it has grown in, when it is harvested and how it is stored. It is important to know that a contractor is using a high quality thatch to ensure a prolonged lifespan with few problems over time. In the end a contractor or customer using low grade thatch will get a cheaper job but will not get a quality, long lasting roof and will potentially give thatch types a bad name unnecessarily.

Choosing quality Hyparrhenia Hirta

Hyparrhenia Hirta is a “one season growth” thatch which means that it is harvested yearly. It grows in big inland belts in South Africa and should only be harvested after the second frosts of the winter season. These frosts cure the thatch and toughen it. Poorer quality hyparrhenia is however cheaper and a lot of contractors use this thatch because the low price brings down the cost of the job and allows them to undercut other contractors. For more advice on buying quality hyparrhenia click here.

Choosing quality Cape Reed 

Cape Reed takes 3-4 years of growth before it can be reaped making the growth process much longer and the thatch more expensive. Some contractors purchase thatch from suppliers before the thatch is fully matured. Again, this lower grade thatch will be cheaper but will be prone to rotting much more quickly. 

When considering a new thatch roof ask the thatching contractors who quote which types and qualities of thatch are available and which is better suited to the climate where your roof is; if you are DIY thatching think logically about the local climate and what thatch types are available in the area. If you are at all unsure of which type of thatch to use, it pays to ask an expert for advice before embarking on the job.

For more in depth specifications of Cape Reed and Hyparrhenia Hirta visit the Cintsa Thatching website.