Installing and Maintaining a Green Roof: How Much Does It Cost?

Green roof systems are growing in popularity year-on-year as awareness of green spaces grows in urban areas. As houses and flats replace more grassland and fields, green roofs are a simple and effective way to ensure that nature still has somewhere to excel.

Thanks to extensive innovations and development of products like modular green roofs from Wallbarn in green roof technology, installing and maintaining your green roof is now cheaper than ever. But, first, you need to decide whether to choose from a rollout or modular, the type of plants you'd like on the roof, or whether you want a biodiverse or intensive green roof.

What are Green Roofs?

Green roofs, also known as living roofs, are a growing trend amidst busy cities, creating an oasis for plants to flourish and helping combat our carbon footprints. These rooftop gardens create beautiful environments that we can enjoy and significantly reduce urban heat created by high-rise flats and office buildings.

What are the Benefits of a Green Roof?

A green roof system undoubtedly points towards your goal of creating a sustainable home. Despite offering an aesthetically pleasing look, a living roof provides various advantages such as:

1. Improved Air Quality: Green roofing help filter and purify the air by absorbing carbon dioxide, particulate matter, and harmful gases. They act as natural air filters, contributing to cleaner and healthier urban environments.

2. Urban Heat Island Mitigation: Living roofs help combat the urban heat island effect, the phenomenon of urban areas being significantly warmer than surrounding rural areas. By absorbing and evaporating heat, green roofs reduce ambient temperatures and minimize the need for air conditioning, thereby decreasing energy consumption and carbon emissions.

3. Stormwater Management: Green roofing effectively manages stormwater runoff by absorbing and releasing rainwater slowly. They act as natural water retention systems, reducing the burden on drainage systems and helping to prevent flooding and sewer overflows.

4. Biodiversity Promotion and Habitat Creation: Green roof systems provide additional green spaces in urban environments, creating habitats for birds, insects, and other wildlife. They contribute to preserving biodiversity and can serve as stepping stones for the movement of species in urban areas.

5. Energy Efficiency: The insulating properties of living roof help regulate indoor temperatures, reducing the need for heating in winter and cooling in summer. This leads to energy savings, lower utility bills, and a decreased carbon footprint.

6. Noise Reduction: Green roof system can help mitigate noise pollution by absorbing and blocking sound waves, providing a quieter and more peaceful living or working environment, particularly in densely populated areas.

Different types of Green Roofing

Several living roof types vary in design, maintenance requirements, and the kinds of plants they support. However, here are the most common types:

• Extensive Green Roofs:

Characteristics: Extensive green roofing are lightweight and have a shallow soil depth of around 2-6 inches (5-15 cm). They are designed to be low-maintenance and require minimal intervention.

Plant Selection: They typically feature hardy, drought-tolerant plants such as sedums, mosses, and grasses. These plants can withstand harsh weather conditions, including heat, cold, and limited water availability.

Benefits: Extensive green roofs are cost-effective, provide insulation, reduce stormwater runoff, and can be installed on various buildings, including residential, commercial, and industrial structures.

• Intensive Green Roofs:

Characteristics: Intensive green roofing is more complex and has a greater soil depth, typically ranging from 6 inches (15 cm) to several feet. They allow for a wider variety of plants and support trees, shrubs, perennials, and even small gardens.

Plant Selection: Intensive green roofs offer more design possibilities, allowing for diverse plantings, lawns, flower beds, and even small trees. They require regular maintenance and irrigation.

Benefits: Intensive green roofs provide more excellent aesthetic value, create additional usable spaces for recreation or gardening, support a broader range of biodiversity, and have a positive impact on the building's thermal performance.

How Much Does a Green Roof Cost?

In the UK, extensive green roofs offer an affordable approach to sustainability — costing approximately £100 per square metre. However, intensive green roofs can be expected at around £150 per square metre for a more substantial installation with additional features and benefits.

Rollout and modular trays are the two most accessible and cheapest ways of installing a green roof system. Involving the cost of turning substrate to green, the wall barn modular tray costs £28.51. In addition, Wallbarn offers all the mandatory materials required to install a live roof.

Recent contributions in live roofing technology promote easy living roof installation, meaning lower installation and labour costs. In addition, materials continue to decrease in price as the demand for live roofs increases. So installing a healthy and natural green roof is well within your budget!

How are green roofs installed?

Wallbarn's rollout and modular green roof range are cost-effective and to be installed on flat roofs. Each element is delivered and then installed separately. The materials are lightweight and easy to maintain - a standard grass roof for almost any situation.

Modular Green Roof 

M-Tray modules are neatly packaged and swiftly delivered to their destination on strapped pallets. For greater convenience, these can be expertly craned onto the roof if needed. Unpacking the pallets is a swift and effortless task. A person can manage each module, ensuring all contents are secure throughout transportation without risking spills or messes.

• To ensure your waterproofing system remains undamaged, install a geotextile filtration layer from Wallbarn. Recycled fleece provides superior protection and resists abrasive elements for long-term durability.

• Begin on the centre of your new living roof and build outwards. Place down a module, then click the next one into place. Each module has two connection points, one on its two sides. The module will be secured on all four sides after it is attached on all four sides.

• Any exposed edges or areas where the stones must be removed from drainage outlets can be finished with an aluminium edge trim.

• Because of the modular parts, creating neat lines and details around things is made more accessible. Complex landscaping elements like asphalt and decking on Wallbarn pedestals can be added to the area to provide regular access. Drainage is unimpeded because everything is hung on top of the deck.

Wallbarn's Modular M-Tray is super quick to install. Over a few days, they form a seamless live roof with excellent drainage. This form of grass roof works best in hard-to-reach places. Instead of paying for a specially-shaped green roof, you can use modular pieces to create the same roof.

Rollout Green Roof

This is the classic rollout roof, and although it sounds like an astroturf which you might install in your back garden, a rollout roof has several different layers that need to be laid before the seedbeds. It's a lightweight form of living roof with low maintenance costs. Once installed, it should naturally look after itself with minimal watering needed.

Do green roofs need to be maintained?

Green roofs are still living parts of nature and require a maintenance schedule to be effective. Certain seedbeds, like sedum, require less maintenance than grass roofs, but both will need looking after over the year.

Much of this maintenance can be carried out yourself, especially if the roof is easy to reach. Pulling weeds out by hand, fertilising the soil during the spring, and ensuring that areas that look sparse are reseeded, are a few examples of necessary maintenance. These are low-cost and won't take much time - it's like looking after your garden!

Green Roof Maintenance Costs

One of the best things about living roofs is that they need minimal maintenance. This is because seedbeds and plant types are specifically chosen to respond well to British weather conditions and not grow too wildly out of control. 

Both rollout and modular green roofs are designed for optimum drainage, which means living roof maintenance costs are lower. 

Rollout vs Modular

Wallbarn's modular green roofs are a cost-effective and straightforward solution for roof maintenance. Accessing decking under a rollout of green live roofs requires costly soil and plant life removal - not to mention it is much more complicated! With Wallbarn's modular roofing system, removing segment by segment makes access a breeze – so you can do your job timeously without overspending.

Do I need planning permission for a green roof?

Planning permission is usually optional to install a living roof on existing structures. However, it is always advisable to contact your local planning authority before making any alterations to a plan.

Although no special building rules apply for green roofs, there could be issues with load capacity, fire safety, or water removal from the installation's surface. Several situations necessitate obtaining building regulation permission, including:

• When you develop a new structure.

• When you add on to or modify an existing structure

• If you replace windows or convert a loft.

If you're installing a green roof, you should submit a Building Regulation Approval Notice application, which calls for a council-approved inspector to check your property to see if it's appropriate for a living roof. Your installer can walk you through the process if they support the Green Roof Code.

Frequently Asked Questions

What are the disadvantages of green roofs?

One drawback of green roofs is that, over time, the drains become blocked by vegetation growth, causing water to damage the deck and run down the walls of your home. Wallbarn has significantly improved its drainage to futureproof its living roof effectively.

Can you walk on a green roof?

The modules are not designed for foot traffic but can tolerate being stepped on for maintenance purposes.

Can M-Tray grow in partial shade?

Yes, however, like any living plant, light is required.

Are there any requirements?

Yes. According to fire standards, there must be a clear separation between plants and building walls and around elements like roof lights and fall arrest. 

Is there a full cover of vegetation?

Wallbarn M-Trays have been grown at the farm for several months before delivery. Therefore, they will arrive with a minimum of 90% cover. 

What other materials will I need to buy along with my M-Trays?

This depends on your requirements.

Standard:

• Geotextile fleece to protect existing roof/membrane
• Riverstone pebbles to be used as a firebreak and to go around drains

Optional:

• M-Tray Irrigation Kit
• Access chamber
• Aluminium edging