Green flat roofs: Benefits, prerequisites and servicing at a glance

The wonderful sight of a lush green area on your own roof is a real alternative to classic roofing. But that is not all: a green flat roof offers you several immediate advantages  and will create a direct connection between your building and nature.

With a green roof, you are bring a piece of greenery back to nature and fully protecting your roof covering entirely coincidentally. With foresight during design and planning, green roof coverings are easy to implement and quick to install. In this overview, we show you the benefits and prerequisites for green flat roofs, and all other important aspects for green roofs.

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Benefits of a green flat roof

The demand for green flat roofs has grown and grown in recent years. This is not least due to the numerous advantages that a green roof brings with it. If you opt for an extensive green flat roof, annual servicing and maintenance work is also minimal. This means you will enjoy the many benefits in a state of calm and can simply relax.

Benefit 1: improved thermal insulation in winter and heat protection in summertime

Thanks to flat green roofs, you can improve the thermal insulation of your house, permitting you to cut your energy costs and bills. What acts as improved insulation in wintertime, additionally also acts as heat protection during summertime. During the summer months, the green flat roof covering functions as a natural climate control system, keeping the inside of the house pleasantly cool.

Benefit 2: Relief for drains and sewers, natural air humidification and filtering pollutant

The plants of green flat roof coverings can absorb fine dust from the air and filter pollutants out. Thus, green roofs can help reduce fine dust pollution in cities and municipalities. In addition, the plants in green flat roof coverings gradually release their stored water. This transpiration humidifies the air, creating a natural cooling effect. This effect contributes to improving ambient atmospheric conditions and providing a pleasant climate for humans and animals. Storing rainwater relieves the burden on drains and sewers. Excessive water produced during heavy rainfall, which can no longer be absorbed by plants, is retained and released into the drains and sewers with a time delay.

Benefit 3: Additional protection for waterproofing roofs

Green roof coverings on flat roofs extend the life of your roof compared to ‘bare’ roof surfaces, with no green covering. The additional layer of green roofing protects the existing waterproofing on the roof against influences from wind and weather, heat and UV radiation.

Benefit 4: Contribution to preserving biodiversity

The number of waterproof surfaces in individual cities and municipalities continues to grow and grow. Therefore,  it is important to create environmental compensation areas and surfaces, in order to return habitats to plants and living creatures. With green flat roof coverings, you are returning a piece of greenery to nature and making an important contribution to preserving biodiversity. Bees, wild bees, butterflies and other insects can be found settling on a green roof - so it is not only people who enjoy green roof coverings.

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Prerequisites for green roof coverings

In order for you to benefit from the numerous advantages, you should consider a few important points even during the design stage and prior to construction of the flat roof. For extensive green flat roof coverings, you must consider an additional weight per unit area of approx. 90kg/m² - 120kg/m². This additional weight is essentially determined by fitting the substrate of the green roofing build-up.

The additional weight per unit area will be even higher if you opt for an intensive green flat roof covering. Make sure the static engineering requirements and load-bearing capacity of your roof are  checked by a suitable specialist. If you decide to have a green roof covering retrofitted to a flat roof at a later date, you must also take the condition of current waterproofing of the roof into consideration. Only proceed with a green roof covering on a flat roof where flawless, root-resistant and watertight roof seals are present, which comply with FLL guidelines. The scope of green flat roofing options solutions is determined by the condition of your roof.

Subsidies for green flat roofing solutions

The wise variety of grants and subsidy programmes available in Germany, make it almost inconceivable you will not lose the overview in the funding jungle. Some subsidy measures for environmentally friendly and energy-efficient buildings also deal with green roof coverings on new-builds and renovation projects. Increasingly, cities and municipalities in Germany promote green roofs by means of direct financial subsidies or indirect measures, such as reduced charges for rainwater.

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Build-up for a green flat roof covering

The build-up of a green flat roof covering consists of a total of 6 individual layers which are concealed beneath the wonderful appearance of lush greenery. When installing a flat green roof, first and foremost static engineering parameters of the roof structure must be taken into account. In addition to static engineering, there should also be a minimum inclination  of approximately 2%. Please note that if you are unsure about the static conditions of your roof, it is essential you seek expert advice from a roofing contractor.

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Layer 1: Flat roof

The first layer of the green roof build-up is always the roof itself. If your flat roof fulfils the prerequisites for green roofing, you can continue with construction. If you are not sure, consult a roofing contractor.

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Layer 2: Root protection

Once you have checked your flat roof for the weight per unit area, you must ensure root protection is in place. If your roof seal does not comply with FLL guidelines, an additional certified root protection foil must be installed on the roof membrane.

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Layer 3: Protective fleece layer

A protective fleece must be installed in order to provide additional protection from mechanical loads, alongside existing root protection. This is simple to install, slightly overlapping across the entire surface of the roof and drawn upwards at the roof edges. (not shown)

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Layer 4: The flat roof shell

Thanks to the innovative installation principle of TOPGREEN's green roofing system, you can now simply lay the flat roof shells onto the protective fleece. Using a "tongue and groove principle", the shells are laid alongside one another, and form the drainage layer of build-up.

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Layer 5: TOPGREEN’s roof substrate

The vegetation carrier layer is formed by the TOPGREEN substrate which is simply filled into the flat roof shells present. The substrate is evenly distributed across the entire surface of the roof, with an installed depth of 8cm.

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Layer 6: Vegetation layer

Now we finally achieve a green roof. You can plant greenery for your flat roof using sedum shoots or with the help of pre-cultivated sedum matting. We mainly use species of sedum for extensive green roofs.

Servicing and maintenance tips for green flat roofs

Once you have created the green roof build-up for your flat green roof covering, you should thoroughly water the entire surface of the roof once more. You should check the moisture of the green roof covering regularly during the first 4-6 weeks following installation, so plants will have enough water to grow. As a rule, flat roofs are green in the period between approximately May and October. Regular maintenance after the growing period for extensive green roofs is limited to 1 to 2 service or maintenance visits per year. You should weed the green roof during these visits and remove unwanted tree seeds. This low care and low-maintenance species of sedum for extensive green roofs have the advantage of being largely self-sustaining. which is why the effort required for the servicing and maintaining extensive green roofs is very low.

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TOPGREEN green roofing system - The simple way to provide flat green roof coverings

Are you looking for a suitable system for your flat green roof? With our TOPGREEN green roofing system, you will benefit from a simple and safe way to transform your flat roof into a green oasis. Thanks to the innovative installation principle, greening your roof is a swift and simple process. If you want to install the green roof covering yourself - no problem, we also have the right package for you. We will be happy to advise you on the optimum design for your flat roof. You can find more information about the TOPGREEN green roofing system and products here.

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Pitched green roofs, inclined up to 45°

Green roofs on pitched roofs with pitches of up to 45° - is that even possible? Thanks to our pitched roofing system, you can easily realise your dream of a green roof even on a roof inclined up to 45°. The TOPGREEN green roofing system for pitched roofs is especially convincing due to its especially secure anti-slip and shear protection. The structure of the substructure is similar to that for an ordinary tiled roof. We have compiled all the information you need for pitched green roof coverings in our comprehensive overview. You can find out more here.

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Installing a green roof covering on a garage yourself

Installing a green roof covering on your garage roof yourself - no problem with our flat roofing package. Costs, benefits and solutions - find out more here.

Benefits of green roofs

The green roof - not only beautiful to look at, but also characterised by numerous environmental advantages. Find out more of the benefits in our overview.

Plant list

Not every plant can cope with the extreme conditions on a green roof - we show you here which ones are nevertheless suitable for green roof coverings.