A green roof can extend the life of your waterproofing and save you money

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If you are thinking about a green roof installation, but are concerned about the longevity, then you needn’t worry. A green roof can extend the lifespan of your roof by up to 300% and typically your roof will last at least twice as long.

When a green roof is correctly installed, then the vegetation and substrate will form a protective layer that will ensure your waterproof membrane lasts much longer than normal.

How does a green roof protect your waterproofing?

Every roof has a membrane of some sort to keep the elements at bay and an exposed membrane is hit hard by solar radiation during the daylight hours.  At night the roof's surface temperature drops considerably.  This transition from hot to cold and back to hot again, combined with the detrimental effects of UV light puts a great deal of stress on the membrane. Eventually cracks and faults appear and the roof inevetibly leaks.  

A study in Toronto, Canada, revealed that a membrane on a standard roof hit 70ºC, while a green roof on a neighbouring building did not rise above 25ºC.

graph showing temperature differences of green roofs and standard roofs

Graph is from Miami science museum and shows how the roof membrane is protected from temperature fluctuations

 

Layers of drainage matting, growing medium and vegetation will protect your roof from sun damage, extreme temperaturesand inclement weather to extend its lifespan. 

Flat roofs face the additional problem of pooling water and this water has time to find cracks, seep into them and cause further damage.

leaves floating on a puddle

Puddles are great but if water sits on a flat roof for a long time it can be detrimental

In fact, almost every roof suffers with this kind of damage as rainwater seeps into literally every crevice, settles and responds to the changing temperatures. Water vapour getting in to the eaves will also degrade the roof over time and, without a completely waterproof membrane, that is an inevitability.

Extra benefits of a green roof

Because the protective layers of a green roof will double the lifespan of your waterproofing, they will also halve the amount of waterproofing that ends up in landfill - which is a good thing for everybody.

In the winter,  the green roof protects the building from extreme cold, and this comes with a wealth of other benefits. These include reduced heating bills and even a reduction in noise. Combined with the aesthetic and environmental benefits of a green roof, these practical, cost-saving measures are a welcome bonus at worst and at best they are a driving force for fitting sedum matting and setting about creating a green roof.

How to create a simple sedum green roof