Are Green Roofs Expensive?

Green roofs are not only aesthetically pleasing, but they're also useful. They can provide many environmental benefits and give people a space to visit and unwind. 

But, are green roofs expensive?

Generally speaking, green roofs count as costly projects. 

How much you can expect to pay for a green roof depends on the type of green roof you want to install. 

For example, intensive green roofs are more expensive than extensive green roofs. 

There are other factors to think about. These include installation costs, structural requirements, location, and more. 

If you want to find out more about the cost of green roofs, this article will provide you with all the necessary information. 

How Much Does a Green Roof Cost?

There is no set price for installing and maintaining a green roof. The cost of this project depends on many factors. 

These factors may include:

1. The type of green roof
2. Structural requirements
3. Size of the green roof
4. Location
5. Required materials
6. Labour costs 
7. The complexity of the project 

When it comes to the cost of a green roof vs. a conventional roof, green roofs are far more expensive. 

With so many additional expenses that come with a green roof installation, the cost can increase by 50% to 100% compared to a traditional roof. 

The Type of Roof 

The first factor to think about is the type of green roof you are looking to install. 

The two main types of green roof designs are extensive and intensive green roofs. 

Extensive roofs have shallower substrates (shallower than 250mm). They are primarily used for their environmental benefits rather than accessibility. 

Intensive roofs have deeper substrates (deeper than 250mm). They serve as usable outdoor spaces that you can visit and spend time in. 

Since intensive roofs have deeper substrates, they need more maintenance. Because of the extra weight, they also often need more structural support.

Extensive roofs are more lightweight and they need less maintenance over time. 

These factors make intensive roofs more expensive than extensive roofs.

Installation Costs

The installation of a green roof involves waterproofing, root barriers, drainage systems, substrate, and plants.

The installation costs can vary depending on the:

1. Labour rates
2. Geographical location
3. Access

Skilled labour is required for the proper installation of a green roof. Labour costs can vary based on local labour rates and the complexity of the project.

The cost of materials and labour can vary significantly depending on the region. 

Major cities like Sydney, Melbourne, or Brisbane might have higher costs because of logistics and higher labour rates.

Difficult roof access or the need for specialised equipment can also increase installation costs.

Extensive green roofs are easier to install. The price usually ranges from $155 to $465 per m².

Installing an intensive green roof is a much bigger project. It costs approximately $420 to $835+ per m² to install an intensive green roof on a building.

An entire extensive green roof that covers 100 m² can therefore cost $15,500 to $46,500.

A larger intensive green roof, of, let's say, 500 m² will be significantly more expensive. The price can range from $210,000 to $417,500 or more.

Maintenance Costs

Green roofs need ongoing maintenance, especially in the first few years. 

That way, the planted greenery will be able to thrive for years to come. 

Regular maintenance isn't only necessary to keep the vegetation healthy. It also helps the drainage system function properly. 

Just like with installation costs, maintenance costs vary widely. They can include:

• Regular inspection to check for drainage issues, plant health, and the integrity of the waterproofing membrane.
• Weeding to prevent invasive species.
• Fertilisation and nutrient addition to maintain substrate and plant health.
• Maintenance of the drainage system.
• Regular pruning and watering to keep the green roof vibrant and healthy.
• Replacement of plants as necessary, especially if they are not thriving.
• Maintaining walkways, paths, and any hardscaping features.

So, for example, maintaining a medium-sized extensive green roof of about 500 m² can cost from $2,500 to $10,000 per year.

Maintaining an intensive green roof of the same size will cost approximately $7,500 to $25,000 per year.

Additional Costs 

When talking about the cost of a green roof, we also have to think about other costs that may be added to the total price. 

These additional costs can include:

1. Structural reinforcement
2. Waterproofing and root barrier
3. Drainage and irrigation system
4. Safety restraints/barriers 

Older buildings may need extensive structural support to bear the weight of a green roof. This can significantly increase the cost.

If the building requires additional structural support, it can add $80 to $310 per m² to the total price, depending on the requirements.

High-quality waterproofing membranes and root barriers are very important. They can cost between $45 and $155 per m².

Drainage and irrigation systems are also something to think about. Proper drainage and, in some cases, irrigation systems are necessary. These can add around $30 to $155 per m².

Financial Benefits of Green Roofs

Even though installing a green roof is an expensive project, it comes with some long-term financial benefits. These include:

• Energy savings
• Extended roof lifespan
• Stormwater management
• Higher ROI

Green roofs can provide better insulation, potentially reducing heating and cooling costs.

They can protect the roof membrane from UV rays. This can significantly increase the roof's lifespan. 

Green roofs can also buffer temperature changes, reducing thermal stress on the roof structure and potentially doubling the lifespan of the roof.

They can reduce the need for stormwater management systems. They do so by absorbing rainwater, which can be a cost-saving in areas with high stormwater or potable water fees.

While the initial costs of green roofs are higher, the long-term savings and environmental benefits can make them a cost-effective option over time.

Installing a green roof also comes with a high ROI (return on investment). 

Green roofs can improve the appearance of a building, making it more attractive to buyers or tenants. This can increase property value and lead to higher rental or resale prices.

How Much Is a Green Roof?

It's nearly impossible to determine the exact price of a green roof because it depends on so many circumstances.

The type of roof, labour costs, maintenance, and location are just some of them.

While the initial investment in a green roof can be higher than that for a traditional roof, these financial benefits can provide a strong return on investment over time.

If you're looking for a green roof specialist, Evergreen Infrastructure is an expert in green roof design, installation and management.

If you want to what to expect for this type of project, we'd be happy to help. Feel free to reach out to us if you have any questions.

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