Gravel around a green roof
Do you need gravel around a green roof?
Yes, gravel should surround your green roof if you have a zinc gutter or lead flashing. This prevents sedum from growing under these eaves, which can cause leaks.
Not sure what type of roof you have? Then read on or watch our video.
Why a gravel strip around your green roof?
A gravel strip prevents leaks by keeping sedum from growing under gutters or lead flashings, creates a neat finish to the roof and helps with drainage, preventing flooding during heavy rains.
What gravel can you use on a green roof?
Sedum roof gravel
This gravel has rounded edges and is sold in 20 kg bags. The color is a mixture of different shades and contrasts nicely with the green of the sedum.
Olivine gravel
Olivine gravel is a sustainable alternative because it begins to remove CO2 from the air as soon as it comes into contact with water. This gravel has a natural appearance.
All the benefits of gravel around your green roof
- Protecting the sedum: The edges of a green roof are easily too wet or dry, in addition, the top edge of the roof can heat up because it is dark in color. This can cause the vegetation at the edges to become barren.
- Control growth: A gravel strip prevents sedum from growing under a lead flashing or zinc gutter, thus preventing leaks.
- Roof flooding. In the winter, a green roof can freeze, which causes water to reach the drain less quickly during rainstorms. This can lead to flooding. Gravel helps the water drain faster.
- Protection against moisture damage: A gravel strip at least 10 cm wide along lead seams prevents moisture damage to walls.
Disadvantages of gravel around your green roof
- Weight: Gravel is heavier than sedum, which makes the roof as a whole heavier. This is usually not a problem, but it is something to consider.
- Less greenery: More gravel means less sedum, which reduces the water buffering capacity of the roof.
How much gravel do I need around my green roof?
We recommend a 10-inch gravel border. This allows you to enjoy the benefits of gravel without sacrificing too much weight or greenery. You can assume about 4 meters per 20 kg bag.
Maintaining gravel around a green roof
2 times a year you should go up your roof to maintain the green roof. In doing so, remove the weeds from the gravel edge and clean the drains well.
Can I put a green roof on top of gravel? (gravel as a substrate)
It is not recommended to put sedum directly on top of gravel. Gravel is already quite heavy and does not make an ideal substrate for a green roof. It is better to remove the gravel first and then install a suitable sedum roof package.
Tip: Use leftover gravel for the edges of your green roof to prevent leaks and create a neat finish. Then also inspect immediately for leaks and any damage.
Learn more about installing a sedum roof
View our comprehensive guide or contact us for professional advice on installing a green roof ?
Frequently Asked Questions
Of course, it’s best to order the gravel directly with your green roof package order. But you can always buy this at your local hardware store as well.
You bet! On our socials, we post weekly content about installing green roofs!
Learn all and more about sedum and why it is so suitable for roofs!
Read: What is a green roof.
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