How did green roofs begin?

Green roofs are said to have originated as far back as the Babylon Gardens, where specialist irrigation systems were used to keep the vegetation lush. Other notable historical uses of green roofs are in Scandinavia, where traditional sod or turf roofs were used for insulation and camouflage. 

The modern day green roof originated in Germany in the 1970s. Serious storm water runoff needed a solution and the modern green roof was born. Now with advances in technology green roofs offer more benefits than ever before and prove to be a great alternative to standard roofing.

Why should I install a green roof and what are the benefits?

There are many benefits to installing a green roof. They reduce storm-water runoff to reduce the risk of flooding in drainage basins; they reduce energy use of heating and air-conditioning by insulating the roofs and keeping the building warmer in winter and cooler in summer; a roof’s lifespan is increased by reducing heat fluctuations and UV exposure which degrades roof membranes; they help to mitigate the effects of global warming; the urban heat island effect is lessened in large cities; air and water quality is improved; they act as noise insulation and can reduce noise transfer by 8 decibels; they increase biodiversity and reclaim land lost by development and urban sprawl; and of course, they look beautiful! 

Why use Sky Garden?

Sky Garden is the UK’s leading independent green roof installer and contractor. We source and grow all our products sustainably in the UK and have sales teams around the country that are happy to help with your green roof specifications and needs. Our experts in the field have developed drainage systems that can be used on any angle of slope and can even install living walls. Our award winning team can supply and install bespoke designs and have the experience of many large commercial and domestic projects. See our gallery for more information on past projects.

What are the different types of green roof?

A green roof is any structure that is topped by live vegetation supported by a layer of substrate. Brown roofs are types of green roof that are not initially seeded or covered in pre-grown live material. They are left with the substrate exposed to allow self seeding of the local plants and attract the natural wildlife of the area. Biodiverse roofs can feature areas of seeded, pre-grown blanket or bare ground and are designed to increase biodiversity and create an environment that appeals to the native flora and fauna of the region. Their construction often features piles of logs, boulders or artificial habitats that are designed to replicate the environment preferred by birds, mammals, reptiles and amphibians.

Can I choose what plants to have?

Sky Garden’s seed and blanket mixes have been specifically designed to work well on green roofs. The thin, low nutrient substrate and exposure can make it hard for some plants to grow well. However we do offer bespoke plants and systems, especially on intensive green roofs. For a full quote and design brief for a bespoke system please contact our sales team

Will a green roof affect waterproofing?

Although we can only install green roofs on top of previously waterproofed surfaces, the addition of vegetation should in fact help increase the lifespan of the roof. The green roof reduces fluctuations in temperature and exposure to UV light which can damage the waterproof layer. Our drainage systems ensure there is no excess standing water so waterproofing is not impaired by pooling. Protection fleece is laid down before our rigid HDPE drainage board to preserve the integrity of the underlying membrane.

Will a green roof add weight to my roof?

Yes. Green roof systems tend to add around 100kg/m2 to a roof system depending on which system is chosen and the depth of the substrate. Most roof structures can tolerate this added weight but some may need to be reinforced. We cannot carry out structural surveys so it is worth having your roof checked by a structural engineer before installing your green roof.

Do I need planning permission?

Most green roofs can be installed with no planning permission, however some do require it. This depends on the location, type of building, height etc and should be consulted before installation. Green roofs are increasingly mandatory for new developments. Planning consent can stipulate that the area must blend into the surrounding landscape or mimic the water runoff of nearby Greenfield sites. Green roofs can allow constructors to overcome these terms.

What is drainage board?

Drainage board is a specifically designed layer that absorbs enough water for the plants to grow naturally but allows excess water to run off. This means the substrate does not get waterlogged but the board holds water to be accessed when precipitation levels are lower. It also contributes to reducing runoff as it holds and stores water when rainfall is high for the plants to use when needed.

Do I need to water my green roof?

Sedum is used because it is drought resistant and very hardy. Under normal circumstances the roof should not need regular watering. However, live material must be irrigated immediately following installation. This irrigation must continue in the first few months following installation and again in especially hot and dry periods. Sky Garden recommends full saturation of the system once a week in these periods.

What maintenance is needed on a living roof?

The amount of maintenance needed depends of the type of green roof installed. Sedum roofs require little maintenance; clearing gutters periodically and occasional weeding to clear unwanted self-seeding species are recommended. Biodiverse roofs are designed to be left and to be as natural as possible so maintenance is again minimal with just periodic gutter clearing of organic matter. Wildflower roofs require more maintenance and may need strimming once a year in autumn. We recommend irrigation systems on all steeply sloped systems to ensure they remain at their optimum throughout hot spells of weather. Sky Garden offers a full maintenance package which includes two site visits a year where gutters will be cleared, fertiliser applied, any weeds removed, strimming of vegetation is undertaken and vegetation barriers and fire breaks are cleared of any unwanted vegetation.

Will Sky Garden provide habitats for wildlife?

Sky Garden strives to create the most diverse roofs with the best provisions for wildlife. Our seed mixes are designed to replicate optimum conditions for a whole host of wildlife. With certain systems habitat creation comes as standard; with log piles, rock mounds and areas of bare sand to replicate natural environments. Bat, bird and bee habitats are also available to increase the attractiveness of your green roof to the local wildlife population.

What is BREEAM and how can I improve my rating?

BREEAM stands for Building Research Establishment Environmental Assessment Method and essentially sets the standard for the best practice in design for large scale developments. It is used to assess the environmental performance of buildings and communities. The addition of a green roof can increase the building’s BREEAM rating by making the building more environmentally friendly. You can learn more about BREEAM and green roofs on our Downloads page.

What access requirements are needed to install my green roof?

The components of a green roof system can be delivered in m3 sacks, which is the best option for larger builds with crane access. However, on smaller installations with less access 25kg bags can be used and distributed by hand if the transporter cannot get close to the roof. 

Can I still have solar panels?

Yes. Green roofs can be designed to fit around solar panels or the panels can fit on top of the roof. This can not only increase the efficiency of the solar panels, but the shade created by the solar panels can increase biodiversity of the underlying green roof. Special care must be taken when selecting plants to be installed in the shaded areas to ensure they grow well in low light conditions.