Pre-grown, low maintenance biodiverse green roofs

We often speak about adjusting the planting design for a living wall so it provides more value for biodiversity.  Whilst this is important to get the most out of your installation (if improving biodiversity is your purpose), the plants are only half the story.

Soil is hugely important for biodiversity, and enables you to reach the right biodiversity net gain score.  For the environmental success of any green infrastructure habitats, soil is key.  It allows for:

• Burrowing insects
• Solitary bees
• Provides water storage/buffer
• Fungal biodiversity
• Resilience against adverse conditions

Here is a list of our accreditations:

• ANS is a Constructionline Gold member
• In-line with CSCS
• SMAS Worksafe contractor
• Compliant with SSIP
• Trained under Site Supervisors Safety Training Scheme (SSSTS)

Once regular growth has been established, your green roof will not need watering unless it has been through an extended dry period or is an intensive green roof.

Extensive green roof systems tend to come pre-grown and established so watering is not necessary unless as mentioned, you are going through an unusually dry period.

Essentially, green roofs require some form of establishment watering until the plants have developed a root system.

Yes, most green roofs you can walk on.  We don’t advise regular footfall on brown, biodiverse or extensive green roof systems apart from during maintenance. For instance, when fertilizing the roof once a year or weeding the roof.  This is where stone borders or paths come in handy, as they can be used to access areas of the roof without affecting the planting.

They type of plants you choose will depend on the application (is it domestic or commercial?) the type of green roof system you have and how much maintenance you want to be carrying out on it. For low maintenance, we advise using Sedum varieties (often used in extensive systems) as the specie is hardy and self-sufficient. However, if you are looking for more design freedom and don’t mind carrying out or scheduling regular maintenance, you can start to look at wildflower, semi-intensive and intensive green roof systems, where you are able to design with a large variety of plants. Read more on which plants are best for your green roof in our blog.

In most cases where green roofs are installed on existing buildings, planning permission is not required. However, it is always advisable when making any kind of alteration to a building to contact your local planning department.

For new construction as well as existing buildings, a green roof certainly contributes to the LEED or BREEAM score, when paired with a combination of other measures. As the certification depends on many factors, no uniform score can be given – but it will definitely help towards the score.

Maintenance depends on the green roof system you have; some systems need little to no maintenance like the biodiverse and extensive systems. However, the semi- intensive and intensive systems will need regular maintenance. Read our blog on green roof maintenance to find out more.

A green roof will be more expensive to install than a traditional flat roof, as the underlying structure may have to be strengthened to cope with the extra load.  The cost is entirely dependent on the scope of your plans.  An intensive green roof will be a lot more costly than a sedum or wildflower roof.  Most green roofs can be adapted to suit budgets. However, green roofs offer too many benefits to not consider an installation in an appropriate area and as they increase the roofs lifespan, are often in the long-term more economically logical.  This especially applies to extensive green roof systems which are the lower cost option but have the same benefits of longevity.

First off, before creating your own roof garden, you need to confirm with a structural engineer the weight loadings your roof can take.  Next you need to confirm how the roof garden will be used:  will it be for relaxing on in a deckchair for example or socialising with friends, or will it be a pretty sight that is overlooked but not actively used?

It’s important to confirm early on as it determines which system and build-up you should go for.  If you’re roof is to act as close as possible to a traditional garden, you need to start looking at semi-intensive or intensive green roof systems.  With these systems you are able to create a better garden feel, including shrubs, trees, a wide variety of other plants, pathways, seating and with the bigger build-up structure, the ability to walk and use the space recreationally. 

However, if you are looking to cover up an unsightly flat roof that is overlooked and are not planning on using the space recreationally, we’d recommend an extensive green roof system.  This is more budget-friendly and is often sold as a DIY solution (like our GrufeKit – green roof kit).  Plant choice is usually focused on the sedum varieties (which can turn lovely shades of yellow, pink, red, orange and different greens), wildflowers and other shallow-rooting plants. 

Essentially, your roof garden is dependant on the structure, how you will use the roof and your budget.  If you’d like to discuss which is the best fit for your roof, please get in touch with us!

A biodiverse green roof, often known as a brown roof, is generally intended to provide a habitat with diverse flora and fauna, unlike a traditional sedum roof (or an extensive green roof). 

Biodiverse roofs are often designed to either recreate or even improve a habitat lost through construction.

Whatever green roof system you go for, you have options to improve its impact on local biodiversity.  It’s good to bear in mind that soil plays an important role in supporting biodiversity, so the deeper the substrate (as long as it’s natural, and ideally an intensive substrate), the more benefits your roof is having for local ecology.

Let’s take a look at how you can design your green roof to support biodiversity:

Firstly, ensure you’re using a substrate (soil) that is natural and will support your chosen plant palette.  In the planting design, there is huge scope for improving biodiversity: focusing on native species (plants that are naturally found in your region); a variety of plants; using plants that provide sources of nectar, seed and fodder; using recycled aggregates, logs, rope and other materials to create piles which can become micro-habitats on your roof; and incorporating habitat homes such as beehives, bird and bat boxes.

Whether your green roof needs irrigation or not depends on the type of roof.  Irrigation is optional for brown and extensive green roofs, periodical for semi-intensive green roofs and regular for intensive green roofs.  It also depends on the location’s climate and immediate conditions (shady, full sun, windy etc) and the planting design.  Different plants require different levels of water, and for example, if your roof was in a windy location, the plants and soil would tend to dry out quicker, therefore requiring more water.

Most living roofs require maintenance, however the frequency and intensity can vary quite a bit.  Let’s take a look at the requirements for the four main green roof types:

Brown or Biodiverse roofs

Biodiverse roofs tend to require minimal maintenance.  As they are left to naturally seed (natural colonisation) and have the purpose of improving biodiversity, they reap the most benefits being left alone most of the time.  With any green roof type however, clearing gutters and debris is always recommended to maintain roof (and plant!) health.

Extensive green roof

Usually planted with hardy plants such as sedum varieties, extensive green roofs require low maintenance, simply clearing gutters of debris and clearing any leaves off the roof.  There are other optional maintenance tasks to carry out, such as hand weeding and removing any unwanted seedlings, feeding the roof with an organic phosphate and potassium feed, and keeping any stone perimeters clear of dead and live plants.  The GrufeKit is a good example of a simple extensive green roof system which requires limited maintenance.

Semi-intensive green roof

Semi-intensive green roofs require periodical maintenance, and we’d advice that you have a programme in place to ensure it is carried out.  As semi-intensive roofs tend to be designed with a greater variety of plant species, these will need tending to.  The frequency of the maintenance depends on the design of the roof, but at a minimum you’d need to schedule 3-4 visits per year.

Intensive green roof

Intensive green roofs require high maintenance, and as they are often designed for recreational use, or as a park-like garden, tend to involve a large variety of plants, including grasses, perennials, shrubs and trees.  Like a garden, they tend to require similar type and frequency of maintenance.

A green roof can weigh anywhere between 65kg to 500kg per m2, it’s all dependant on the system you choose and the design.  For example, an extensive green roof can weigh between 60-150kg/m2 whereas an intensive roof tends to range from 180-500kg/m2.  A lot of the weight is dependent on the type and depth of the substrate and the planting design (for example are you including trees?  Or is it low-level, light weight planting?), rather than the system itself.

Maintenance costs for green roofs is dependant on who is carrying out the maintenance.  If you’re planning on tending to the roof yourself (only advised if you’re experienced or your roof is a simpler brown or extensive system), you’ll need to factor in costs for any feeds, watering, and your time.

If you will be sub-contracting the maintenance of your roof, you’ll need to get costs from your chosen partner.  Feel free to email us at enquiries@ans.global and we can share some budget costs for the maintenance of your roof.

Your location and aspect of the roof isn’t such a big factor affecting your green roof choice as you might think.  Sedum is a very hardy plant that is resilient to most climates, and wildflowers come and go as they please and need no maintenance.  As long as the area where you will be installing the GrufeTiles receives some light during the day, it will be fine.  For example, we wouldn't recommend a green roof if the roof is under dense tree canopy.

The main factors that should affect your decision are the purpose of the roof, and the aesthetic you’re aiming for.

If you're wondering whether your location is suitable or not, send us a photo!  You can reach us at enquiries@ans.global.

Maintenance is usually minimal for our green roofs.  We detail how to care for your green roof in our maintenance guide here.  This involves clearing the gutters or drainage outlets, feeding the roof when necessary and weeding or strimming the wildflowers as you move into Autumn.

If you've experienced an unusually dry or cold few weeks and your green roof is suffering, we recommend lightly irrigating the roof regularly for a few weeks and feeding it with fish, blood and bone (which can be found in most garden supply stores).  Otherwise, your green roof is mostly self-sufficient and requires only one full maintenance session a year.

Watch our How to Install video.

Component green roofs consist of a drainage layer, filter layer, substrate and sedum blankets or plugs, all installed separately.  Once installed the green roofs need irrigation and regular maintenance to aid establishment for 6-9 months after installation, requiring access and a permanent water supply to the roof.  In contrast, extensive sedum or brown modular roofs are pre-grown for 12-16 months prior to installation, and therefore do not require intensive aftercare or irrigation once installed.  This mitigates the risk of failure.  Modular systems are typically easier to install in most applications.

We recommend these few tools to help you install your GrufeKit (some are only necessary if you need to cut the modules to fit):

• Hacksaw
• Pliers
• Handsaw
• Tape measure
• Scissors
• Gloves
• Utility knife

Extensive green roofs and intensive green roofs sit (almost) at two opposite ends of the scale.  This page highlights the key features of both and how they can be designed for different purposes.  Let’s take a look at the key differences between extensive and intensive green roofs in different areas:

Maintenance: Extensive green roofs require low maintenance whereas intensive green roofs require higher levels of care (more intensive maintenance!). 

Irrigation: Extensive roofs do not require irrigation, whereas intensive roofs, due to the often more detailed planting designs, do require regular irrigation to stay healthy and looking good.

Planting design:  The planting design between extensive green roofs and intensive green roofs differs massively.  Extensive green roofs tend to have low-growing plants (due to the shallow substrate), such as moss, sedums herbs and sometimes grasses and wildflower.  On the other hand, as intensive green roofs have a much deeper substrate, there is greater plant choice.  This means that you have huge scope for design with an intensive roof, where you can incorporate grass lawn, perennials, shrubs and even trees.  The route you go down with your roof garden planting designs is dependant on the depth of the soil.  For example, a tree would require a deeper substrate to take root in, whereas if you were focusing on shrubs and perennial planting, you wouldn’t need the substrate layer to be so deep.

System build-up height:  Whilst extensive green roofs tend to stick around the 60-100mm height, intensive green roofs can range from 150 – 1000mm, which also drastically changes the weight.

Weight: As mentioned above, the depth of the soil has a big impact on the weight of your green roof.  Extensive green roofs tend to range from 60 - 150kg/m2, whereas intensive green roofs range from 160 – 500kg/m2.

Costs:  Extensive green roofs tend to be lower in cost, ranging from £30 - £90 per square metre, whereas with intensive green roofs, as you have so much flexibility with build-up and design, the cost whilst it is much higher, can not be prescribed easily.  To get a better idea of costs for an intensive green roof we’d recommend getting in touch.  Email us at enquiries@ans.global or call +44 1243 545818.

Use: Whilst extensive green roofs tend to be used as ecological protection layers or to cover a grey flat roof, intensive green roofs tend to be integrated to create a roof garden, where you have plenty of room for designs and creating a space for recreational use.  Extensive green roofs are rarely designed to be walked on (unless for access/maintenance), whereas intensive green roofs are often designed just for that purpose.

There are a number of reasons to consider including stone areas on a green roof, including factors like the roof's exposure to wind, the regulations you are following in the area where you are installing, and whether the aesthetics were a reason behind the installation of you or your client's green roof. 

 Let's go into more detail:

 Access: as plants such as Sedum are not intended to support frequent foot traffic it would be a good idea to consider stone paths if frequent access is required for maintenance or leisure

Aesthetic: some roof designs use stone areas to create artistic patterns or even a simple border might add character in some situations

Fire break: the FLL Guidelines and the GRO Green Roof Code include requirements for the provision of fire breaks within green roof design

Wind resistance: in particularly blustery areas a stone border can be used to prevent the chance of wind uplift pressures on the green roof

Prevent debris: a stone border can effectively stop wind-borne plant parts and debris reaching the edge of the roof and gutters

Meet regulations: some councils stipulate the inclusion of stone areas for a number of reasons (usually to act as a fire-break)

So while not all green roofs require stone areas it is often a wise consideration based on the reasoning above. If you are looking to include stone in your green roof we have some quality Scottish pebbles for this purpose, and for roofs needing a stone border where there is no parapet or upstand, you might consider using a GrufeGuard too.

Your GrufeKit will be delivered on a pallet with your chosen GrufeTiles and accessories, along with the correct amount of protection fleece (comes with the kit FOC).

Yes, you can lay the GrufeTiles on any waterproof membrane, including single ply, GRP fibreglass, EPDM rubber and felt.

Yes. As the GrufeKit is pre-grown and the plants are already acclimatised before they are delivered to site, there is no need for feeding and irrigation for the first 6-9 months to help the plants establish.  The sedum is also a hardy plant and requires very little maintenance.  You may need to clear out gutters of dead leaves and check the roof over in the Autumn, and if you feel necessary, strim the wildflowers at the end of the Summer.

You need a structural engineer to work out whether your roof is strong enough.  The saturated weight of the GrufeTiles are as follows: 65kg per sqm for sedum and 75kg per sqm for brown wildflower and sedum and wildflower.  However for other systems such as intensive or semi-intensive, the weight can vary with design.

Yes, the modules can be cut down with hand saw or a grinder.  The cut edge then needs to be placed so it faces into the rest of the green roof so it’s supported by the next module. 

We recommend the GrufeGuard if there is no upstand or parapet.

If you don’t have an upstand, we recommend you use the GrufeGuard.  This will make the finished roof look neater and protect the edge.  The 100m height of our GrufeGuard means it covers the GrufeTile but the plants can be seen above to create a stylish finish.

Each GrufeTile is 540mm x 540mm x 90mm.  With vegetation the height can increase to 140mm (with the sedum GrufeTile.  This can increase further when wildflowers are included).

The GrufeTile of your choice, protection fleece and accessories of your choice delivered on a pallet.