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Is a green roof suitable for a rooflight?

November 27, 2021

We all want to do our bit for the environment. And it’s well-documented that attracting more bees and insects gives nature a boost and is good for our ecosystem.

One way to do this is by installing a green roof on your flat roof. But what if you also want a roof light? Can you have both? And how much maintenance will they need?

In this post we’ll answer those questions and more. But first, what is a green roof and why should you consider having one?

 

What is a green roof?

A green roof — also known as a living roof — is a roof that is planted with greenery.

Practically any building can have a green roof, including homes, shops, offices and even garden sheds. And they can be installed on any kind of roof, whether it’s flat or has a steep pitch.

 

The four types of green roof

If you’re thinking of installing a living roof, there are four main types to choose from. The more elaborate roof you choose, the higher the cost will be.

Extensive green roof (sedum roof)

These roofs are shallow and lightweight. They’re usually planted with sedum, which requires very little maintenance and makes them popular with homeowners.

Intensive green roof

Intensive roofs are more like small gardens. They can be planted with a wider variety of plants, including bushes and small trees. These roofs need a thicker layer of planting material, which makes them deeper and heavier than an extensive roof. They also need a lot more maintenance.

Semi-intensive green roof

A semi-intensive green roof sits somewhere between the extensive and intensive roofs. It’s a little deeper than an extensive roof and can support a wider variety of plants.

Biodiverse green roof

The main purpose of these roofs is to promote biodiversity. These roofs often include recycled materials and are built specifically to encourage more wildlife.

 

Green roofs pros and cons

Benefits of a green roof

The benefits of a green roof are many. Here are some of the main ones.

Visually appealing

A living roof is a beautiful addition to any building. They allow us to create more green spaces in our urban areas and in our residential and industrial developments.

Long-lasting

The natural materials used to create the roof are weather-resistant and durable.

In Germany, where green roofs are more common, they’ve been found to last three times longer than a traditional roof when properly installed and maintained.

With traditional asphalt roofs lasting 20 years on average, this means a green roof could last for 60 years or even longer.

Fire-resistant

Because of the moisture it contains, a green roof is highly resistant to fire.

A defence against flooding

Green roofs help to absorb rainwater, filter it and delay its release into the sewage system. This means that drains are not overwhelmed and the risk of flooding is reduced.

An air purifier

The plants in a green roof filter pollutants and toxins from the air and convert carbon dioxide (CO2) into oxygen.

A temperature regulator

Plants both absorb and reflect heat from the sun. In a green roof they can help to keep your home warmer during winter and cooler during the summer.

A noise insulator

A green roof can provide sound insulation up to 8dB. To put that into context, a 10dB reduction in outside noise would make your home around 50% quieter.

A natural living habitat for wildlife

Green roofs promote biodiversity by providing green spaces where wildlife, like bees and other insects, can thrive.

 

Disadvantages of a green roof

There are also some disadvantages of a green roof.

Increased weight

A green roof weighs heavier than a traditional roof, which means some roofs will need additional structural support. This will depend on the type of roof you have and the supports already in place.

More expensive

They’re more expensive than a traditional roof. Part of the cost involves reinforcing the roof supports so they can hold the extra weight.

Needs ongoing maintenance

The greater the variety of plants it has, the more maintenance a green roof is likely to need. Some roofs will need the same amount of maintenance as a regular landscaped garden.

 

Green roof construction

A green roof comprises several layers, which all have different functions.

At the bottom are the structural supports, which are topped with a roofing membrane. On top of that are the membrane protection, insulation and root barriers.

The central layers deal with storing/draining water and aerating the planting material.

On the top is a layer of planting material, such as soil, into which the greenery is planted.

 

Green roofs and roof lights

Can you install a green roof where there’s a roof light?

Yes. A standard flat roof can easily be converted to a living roof, providing the guidance is followed. And if the roof contains a roof light, there’s guidance for installing the green roof around it.

To do this successfully, you need to keep a sufficient gap between the edges of the roof light and the vegetation planted on the roof.

Can you install a roof light in a green roof?

Yes. If you have a green roof, you can install a roof light in it by following the guidance provided.

There’s some additional work in this scenario, because you’ll have to remove a section of the living roof and the base roof underneath it.

What’s the best roof light to have on a green roof?

Green roofs are typically installed on flat roofs or roofs with a small incline. With this in mind, Roof Maker would recommend the Fixed Flat Rooflight — or the Opening Flat Rooflight if you want your roof light to open.

Does a roof light on a green roof need more maintenance?

The roof light itself won’t need more maintenance. All Roof Maker rooflights have easy clean glass as standard, which reduces the need for manual cleaning. The coating means bird droppings and dirt are broken down by the sun and washed away naturally by the rain.

However, you will need to make sure the green roof is properly maintained, including keeping the recommended gap between the plants and the roof light.

What are the benefits of having a roof light on a green roof?

The main benefit of any roof light is to let more light into the property. On a green roof, you may also be able to see more birds and insects outside.

Could birds and wildlife damage the roof light?

You might be wondering if encouraging more wildlife onto your roof could put your roof light at risk of damage.

All Roof Maker rooflights are finished with a marine-grade powder coating that’s tough and long-lasting. The coating is highly resistant to damage from adverse weather conditions, birds and other wildlife.

Thinking about a roof light for a green roof?

Roof Maker rooflights are the ideal addition to a green roof.

They offer:

  • Marine-grade powder coating for exceptional durability
  • Easy-clean glass to keep dirt and bird droppings at bay
  • Minimal frames to maximise your viewing window and fill your room with natural light

Maybe you’re considering a roof light for an existing green roof. Or maybe you’re thinking of getting a green roof and a roof light installed together.

Either way, talking to our experts will help you make the right decisions to get the beautiful result you’re looking for.

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