Green roofs have become very popular over recent years, partly because they take up so little space and are considered such environmentally-friendly projects. But how much does a green roof cost? Do they vary on the different types of green roofs? Are there other factors to consider when installing a green roof? We’ve created this guide to help clarify matters. 

What are Green Roofs?

A green roof is a roofing system made up of plants, installed to improve the visual appearance of a structure and, most importantly, improve its energy efficiency. These initial steps are always taken care of by a professional company that will come to your home and take care of all the necessary installations needed before your total green roof project can begin. Green roofs are available in a multitude of colors and designs, so take the time to find out what’s best for your home before diving into any further details!

Green roofs are increasingly being installed in city centres and are designated as environmental areas that reduce the effects of the heat generated as a result of human activities largely concentrated in urban areas. 

Also known as living roofs, they are characterised by their use of primarily native plants and other vegetation such as wildflowers, mosses, and grasses.

The latest trend in environmentally-conscious building design is to install large patches of vegetated material on top of conventional roofs. These roofs have become known as “green roofs” because they reduce heat absorption and increase property value by keeping heat in, rather than risking leakage and exposure that occur during rain or dew.

Everyone is talking about the green roofs that are being built all over the world. It is becoming the new trend to use green roofs to graciously reduce our carbon footprint.

Businesses considering investing in green roofs for their buildings are often led by senior executives who have been involved in environmental issues for their entire careers.

Different types of green roofs 

Green roofs can be designed in many ways depending on your requirements. The main difference between the types of green roofs is due to the depth of the material placed on the roof. Broadly, these can be categorized as extensive and intensive green roofs. Another alternative is to look at “semi-intensive” green roofs which lies between the above two spectrums.

Based on your requirements, professional green roofing contractors will be able to recommend the best solution for you. Let’s look at each in turn.

Extensive Green Roofs

Extensive green roofs are comparatively much easier to install and require significantly less maintenance compared to intensive green roofs. It is therefore a highly versatile roofing material, suitable for new-builds and retro-fits alike.

An extensive green roof is low-maintenance and provides a home for plants and mosses, whereas an intensive green roof boasts a great depth of active layers that protect the building from extreme temperatures. These roofs can be installed to provide a long-term, sustainable garden as part of an industrial building or other facility.

The most common variety of green roofs are extensive, which create habitats for birds and plants, but this is not the only option for green roofs. Another possibility is to install what is known as a biodiverse roof, whereby the habitat of a given animal, bird or insect is reproduced. Biodiverse roofs can serve to recreate the habitats of rare and endangered species. This variety of green roof can include a larger range of different objects (sand, logs, rocks, etc.) being placed on the roof.

Intensive Green Roofs

On the other hand, intensive green roofs are more suited to tall buildings with strong roofs. This is due to the significant weight of the roofs itself given that it generally includes soil, drainage systems and vegetation. As such, it is common to see them mostly installed in urban areas that have high rise buildings. 

Generally, when intensive green roofs are installed, most roofing contractors make structural improvements to the roof in order to make it stronger. This will require the expertise of a specialist structural engineer.

Given that intensive green roofs require more labour and resources to install, they are generally more expensive than extensive green roofs. They also require much more gardening work on site. This is therefore a cost effective option for medium to large scale projects.

What are sedum green roof plants?

Sedum green roof plants are one of the popular choices of plants for green roofs given that it’s lightweight and is easy to nurture with little maintenance. It is also an inexpensive option compared to other combinations of plants which has contributed towards being a popular option. 

Additionally, it covers a range of flowering plants and has up to 600 different variations. Not only does this improve its biodiversity to your green roof (by providing a habitat for insects and butterflies) but also makes it look pleasant with a breadth of color, sizes and texture.

The right time to prepare your sedum green roof is during Autumn. This is because it gives the sedums the right foundation and enough time to blossom in the following Spring. They are also great in absorbing and reducing pollution which is especially beneficial in city centres and urban areas. Furthermore, these work great in absorbing any excess water and supporting the drainage system during wet climatic conditions. 

Additionally, you must note that depending on the type of sedum that you choose, the green roof cost can vary.

How does a green roof work?

It must be noted that a green roof is a simple construction that is fitted on top of a building that uses plants and sometimes earth to create a habitat for living things. These types of structures work best when installed on buildings with flatter tops. Green roofs are built in shallow layers (about 12″) to accommodate drainage, control erosion, insulate the building, and provide aesthetics.

In some cases, it may be less expensive and more efficient to build an extensive rather than intensive roof garden. An extensive roof garden has a thin layer of soil with poorly rooted plants, while an intensive roof garden has deeper soil and larger, stronger plants that take up more soil volume.

When installing a garden on a green roof space, you must consider the weight. This should not only take into account the dry weight of your garden, but also how much it will weigh once there’s rainfall. A qualified roofing contractor will be able to assess the integrity of your existing green roof.

A complete survey will let you analyse the entire structure and its integrity for installing a green roof. It may be that your roof will need some additional support before it is safe to proceed. In most cases, the green roof cost can be assessed at this stage too.

Benefits of a green roof

The benefits of a green roof extend well beyond just saving the earth from the ravages of time. With proper care and maintenance, a green roof will bring many environmental benefits to your home. 

One can realise the benefits of a green roof depending on the type of green roof installed, i.e. intensive vs extensive. The latter on the whole is more modest than those offered by intensive ones given the smaller range of vegetation and depth.

However, in general, the benefits of a green roof are as follows:

• Lower carbon footprint as much of the heat is absorbed by the vegetation and plants. This in turn will also reduce the demand for heating and air conditioning.
• They contribute towards reducing the urban heat island effect as green roofs are capable of reflecting less solar radiation.
• Helps create natural habitats for various animals and insects such as butterflies. They provide the perfect conditions for them to breed and provide vegetation which works great especially in urban areas.
• The vegetation on the green roofs provides an opportunity to absorb harmful and toxic particles released by commercial activity. This in turn can help local air quality.
• Green roofs work great in noisy areas as trees and plants are capable of absorbing noise pollution.
• The lifespan of a roof can be extended when there’s a green roof installed. The protection from temperature fluctuations helps contribute towards this.
• They provide protection from severe weather conditions which in turn increases the lifespan of the roof.
• The presence of green roofs can further align towards a positive company image as it is considered to be an eco-friendly solution. 
• Green roof cost is justified in the long term as it boosts the economic value of the overall building.
• It can also significantly reduce the risk of fire.

Can I put a green roof on my roof?

Green roofs can be both installed and retro-fitted on new buildings. As mentioned above, the extensive green type is shallower and therefore likely to be more suitable for smaller and domestic buildings than the intensive type.

There are certain things you as a property owner need to consider when putting one up. Apart from green roof cost, you must also take into account the angle or the pitch of the roof. Though it’s easier to install on a flat roof surface, if your roof has a steep angle, it would require additional structural improvement work using steel or concrete structures.

You would also need to evaluate the load-bearing factor. This is especially the case with intensive green roofs and it has more depth, higher proportion of vegetation thereby contributing to the overall weight of the green roof. As such, you would need an experienced roofing contractor to assess the same.

How much does a green roof cost?

One of the easiest ways to determine a budget for green roofs is to understand the average price per square meter. You can either measure the roofing area yourself or request a professional roofer to determine the area more accurately.

This will then help you determine the green roof cost based on the rates below:

For example, based on the above rates, if you have a green roof area of 300m², the total estimated cost for an extensive green roof would be between £15,000 to £30,000.

Other green roof cost to consider

Apart from the costs mentioned above, there are costs you would need to consider based on your requirements. Some of these include

• The type of green roof, i.e. intensive vs extensive. Given that intensive roofs have more depth, they are more costly.
• The use of professional contractors to install the green roofs versus doing it by yourself.
• How easily accessible is the roof; 
• The degree of structural engineering required to make the roof stronger.
• The types of plants and vegetations to be used. For example, sedum roofs are comparatively less expensive than wildflower roofs.
• Need for additional structures such as drainage systems, water storage facilities etc.

Green roof maintenance costs

Maintenance is a highly important factor when considering the viability of the installation of green roofs. Depending on the type of green roof, the need for maintenance can vary. However, all green roofs and walls will require some level of maintenance, no matter what type is chosen for a specific project.

Some of the maintenance tasks include:

• Ensuring that the plants and vegetations are healthy and are replaced if required;
• Keeping edges tidy and gutters clear to stop damage to your roof and the underlying building.
• Ensuring the drainage system and water collection is running smoothly.
• In cases of extensive and biodiverse green roofs, you would need to ensure that they satisfy the BREEAM stipulations.

Accordingly, green roof maintenance costs will be determined based on the level of support required and the complexity of the same. 

For instance, extensive varieties of green roofs are usually designed to have relatively simple maintenance requirements whereas in the case of large intensive green roofs, it may be necessary to hire people to undertake the gardening work (mowing lawns, replacing plants, pruning, weeding etc.) for you.

As noted above, the level of maintenance depends on a number of factors, including the height and area of the green roof, local weather conditions, and the type of plants used. You could consult with your green roof’s installation contractor to determine its maintenance requirements.

Do I need planning permission for a green roof? 

In general, planning permission for a green roof is not necessary for new developments. If you wish to maintain your current roof, there is a certain amount of paperwork that needs to be submitted. This is because green roofs are prone to moisture damage which can cause structural damage in high winds.

During the planning stage, you would need to get in touch with the Devon County Council or a professional green roofing contractor to check the following:

• If planning permission for a green roof is required
• If building regulations approval is required.
• Any specific planning policies/guides relating to green roofs.

In certain instances, installing green roofs are encouraged and therefore makes it easier to obtain planning permissions.

Hiring a green roofer contractor checklist

Installing a green roof can be quite a complicated process and it is important that you choose a roofing contractor that has the right expertise to match your requirements. Most importantly, you should ideally be working with a contractor you feel most comfortable with and are able to accommodate to your custom requirements. 

Additionally, it’s important that you consider the below points when hiring a green roofing contractor:

• Working Location: It’s always a good idea to look into the working locations of a roofing contractor that you have shortlisted. It’s important to find one that’s easily reachable and accessible. At SPS Roofing, our working locations range across South West England.
• Accreditations: If the roofing contractors have relevant certifications and accreditations, this can provide you with a peace of mind and be confident that they are credible. At SPS Roofing, we are certified by SMAS, Constructionline Gold Membership, CSCS, CITB, City & Guilds, NFRC and Bauder Approved.
• Follow Local Regulations: Given that green roofs require planning permissions, it’s important that you choose a roofing contractor that understands the local regulations. Given that SPS Roofing has been operating in Exeter for more than 15 years, we have extensive knowledge on the local regulations put forward by the Exeter City Council.
• Strong Network of Suppliers: It’s important that you work with a roofing contractor that uses industry standard materials to ensure that your green roofs are long lasting. At SPS Roofing, our main supplier is Bauder who has been a pioneer in the roofing industry.

Final thoughts

There are many factors to take into account before deciding upon installing a green roof. These factors include the material used for the roof, how it will be maintained, whether it will block natural light or daylight, and much more.

If you would like to find out more about how you can get started installing a new green roof, then please consult our professional roofers at SPS Roofing to ensure you get the highest quality green roofing services at an affordable price. Most importantly, remember to ask questions before signing any legal contracts or giving money up-front!