How Waterproof is Thatch Material?

How Waterproof Is Thatch Material?

This week we look at the water repellent properties of thatch materials and how you can make your building 100% waterproof.

How does a roof, consisting of material that is not waterproof in itself, keep the rain at bay. The answer lies in the physical properties of water, in the form of rain. Fortunately, when rain strikes a roof it does not strictly follow the laws of gravity and will happily run across a surface, as long as it’s in a downwards direction. The surface itself does not have to be waterproof, as long as it is steep enough to speedily shed the water before it can penetrate that surface.


With a thatched roof the water is also constantly forming drops, by dripping from one piece of thatch to the next; this effectively keeps the water in small amounts, as it flows over the roof. As long as both thatch and roof structures are at the correct angle water will not penetrate more than an inch (25mm) or so. So the working surface of a thatched roof is actually quite thin.


Thatch can be made more waterproof by using a water repellent coating – this adds a long lasting, anti mould, protective barrier from moisture absorption, reed mould, growth of moss and algae, rotting and discolouration.

Let’s examine our own thatch materials to note their level of waterproofing:

Cape Reed – Natural Thatch – 99% Waterproof

Cape reed is naturally waterproof and once piled on top of one another as done when roofing, creates an impermeable material that won’t become waterlogged or seap into the interior.

Tropical Thatch – 99% Waterproof

Our tropical thatch is again a natural product from the same material as Cape Reed but uses the flower and seed part of the reed for a rustic look.

Fibre Thatch – 100% Waterproof

Fibre thatch is a simulated UPVC thatch which when lined with a sub roof lining is 100% waterproof.

Fibre Palm – 100% Waterproof

Fibre palm is a synthetic thatch with a tropical appearance and is 100% waterproof.

Combination Thatch – 99% Waterproof

Natural thatch with an artificial overlay makes this thatch type 100% waterproof.