Greening roofs is as old as history itself and has got a long tradition in many cultures. Some people even say this dates back to the ‘Hanging Gardens of Babylon’. But the real breakthrough has been taken place since the last years. The area of newly built green roofs and walls is increasing permanently because they are a good alternative to

counteract recent environmental problems in urban areas.

So, green roofs and walls are a simple combination of positive impacts?

They are cool! They are thrilling, modern and fascinating!

Under the motto ‘The passion for comfort’ the Recticel Group as Europe’s biggest producer of polyurethane foam strikes to make a real difference in daily comfort for all, on-going with innovative solutions in all its businesses.

As market leader in most of its activities, Recticel provides work to more than 8,000 employees in some 120 establishments in 27 countries. In 2009 Recticel realised a turnover of 1.3 billion Euro.

One of the latest innovations of Recticel is its unique hydrophilic product line Polygrow®.

Basically developed as substrate for horticulture, Polygrow® has been adapted to

green roofs and walls.

extend the life time of roofs

decrease energy costs

enhance acoustic insulation

improve air quality

clean polluted rain water

unburden the canalisation

provide the cooling of cities

better biodiversity

Green roofs…

The sustainability of green roofs

Motor-driven traffic and the industry cause polluted air and rain water. Due to their vegetation green roofs can filter up to 20% of particulates in the air and thus positively influence the quality of the ground and surface water.

They also have a great impact on flood prevention. They retain precipitation and lead it back to the natural hydrologic cycle by evaporation. Especially ones with Polygrow® that can buffer water up to 70% of its volume minimize the peak load of rain water and unburden the canalisation.

Green roofs also counteract ‘heat islands’ and save energy costs. They act as a cooling system. Studies have shown: while the outside temperature is between 25 and 30°C rooms underneath a green roof will be 3 to 4°C colder. Additionally green roofs can reduce sound reflection by approximately 3 dB and enhance acoustic insulation by up to 8 dB.

Every day, UV and IR radiation or temperature changes damage the roof membranes. Protected by a green roof membranes can easily double the life time due to less material fatigue, crack formation or leakage.

The variety of Polygrow® - YOUR INDIVIDUAL SOLUTION Traditional light weight green roof

Next generation green roof

Polygrow® PG D1 slabs are available in different heights and are used as substrate layer in combination with traditional green roof systems (drainage, filter, substrate, vegetation layer). Advantages: Light weight by replacing soil

based substrates Savings in transport

Vegetation: Weight: Costs:

Sedum, grass, herbs, wildflowers, shrubs, others - -

Polygrow® PG D2 slabs are a unique 3in1 system acting as substrate, drainage and water buffer in one. Thus PG D2 is saving installation time, costs and weight.

Advantages: Light weight by replacing the layers of traditional green roof systems + high water buffer

Cost saving in transport Cost and time saving in

installation

Vegetation: Weight: Costs:

Sedum, grass, herbs, wildflowers, others - -

Architectural green roof – PG D3

Corrugated green roof – PG GD1 & PG GD80

Polygrow® PG D3 shows that flat roofs don’t need to be flat at all. On top of the basic PG D2 slab that is used to guarantee the functionality of the green roof system or in combination with a drainage layer, a waved sheet is placed to give flat roofs a unique look. Individual shapes on request. Advantages: Light weight

Creation of individual landscapes on the roof

No loose granules/ no shifting

Vegetation: Weight: Costs:

Sedum, grass, herbs, wildflowers, other - -

Polygrow® PG GD 1 is a special slab usable for corrugated sheets. PG GD 80 is the appendant bonded foam version for pitched roofs. Both will be adapted to the shape of the roof cover. Advantages: Light weight

Perfect adaptation to corrugated roofs

Individual adaptable

Vegetation: Weight: Costs:

Sedum, grass, herbs - -

Pitched green roof – PG SD 80

Thermal insulated green roof – PG TD1 & PG TD80

Polygrow® PG SD 80 is a bonded polyurethane foam whose basis is the standard Polygrow® formulation. Due to its better stiffness and capillarity PG SD 80 can be used for pitched roofs with a max. angle of 40 degrees. Advantages: Light weight

Less supporting structures No risk of shifting (granules) Cost and time saving in installation

Vegetation: Weight: Costs:

Sedum, grass, herbs - -

Polygrow® PG TD1 and PG TD80 are suitable for green roof solutions in combination with Recticel Insulation material. Advantages: Increased insulation value

Light weight Easy installation and transport

Vegetation: Weight: Costs:

Sedum, grass, herbs, wildflower, other - -

Vertical Green – PG W80

Polygrow® PG W80 is as PG SD80 a bonded polyurethane foam based on the standard Polygrow® formulation. Due to its better stiffness and capillarity PG W80 is usable as substrate for vertical green. Advantages: Light weight

No loose granules and thus no shifting

Always re-wetting

Vegetation: Weight: Costs (system):

various

The single Polygrow® products and their properties

Whether flat or pitched roofs, sedum, grass or shrubs, a great water buffer or a higher thermal insulation value, Polygrow® has got a customized solution. The following pages show all Polygrow® solutions including their technical specifications and adaptability on roof structures in detail: PG D1 as substrate layer for flat roofs PG D2 as 3in1 solution for flat roofs, saving time, costs and weight PG GD1 and PG GD80 for roofs with corrugated sheets PG SD80 as 3in1 solution for pitched roofs. PG TD1 and PG TD80 for a higher insulation value Not especially listed is the PG D3 version with its shape adaptability. These build-ups will be customized on specific projects and ideas which makes it hard to list general specifications. The same is with PG W80 as vertical green solution. The thicknesses and sizes will be individually realised based on the customer needs.

PG D1

Drainage

Roof membrane

Polygrow® PG D1

Vegetation blanket

Concrete ceiling

Height of the slabs [cm] 4 6 8 10 Weight dry [kg/m2] 1.4 2.0 2.7 3.3 Weight saturated [kg/m2] 29.4 47.0 62.7 73.3

Water buffer [l/m2] 28.0 45.0 60.0 70.0

CDH 40% dry [kPa] 9.7 8.7 9.7 8.5 CDH 40% saturated [kPa] 6.6 6.0 5.8 6.4

Material : Polyurethane foam Available sizes (length x width): 100 x 100 cm Bulk density (dry) : 33 kg/m3 200 x 100 cm Max. water capacity: 70 Vol.% Available sizes (height): 4, 6, 8 and 10 cm Air volume at max. water capacity: 28 Vol.% Pore volume: 98 % pH value: 6 Usable roof pitch: 1 - 5º / 1 - 9 % All listed specifications are related to the PG D1 slabs, not to the total mock-up

The Polygrow® PG D2 system

Water will become more and more important for all of us.

With a water uptake up to 70% of its own volume, the unique PG D2 system is able to save a huge amount of rain water, also over a

long period of time. On one side this decreases the need of irrigating. On the other side it counteracts the peak loads of the precipitation and unburdens the canalisation in urban areas. But future green roofs won’t only become more diversified and sustainable. Future green roofs also need to be more simplified systems that are not affecting deterrence by their complexity. They need to be self-explanatory , cost effective and thrilling in one.

Polygrow® meets these challenges by its unique 3in1solution: PG D2! These slabs are acting as substrate, water buffer and drainage in one single layer. There is no need to install 3 different layers separately.

Polygrow® PG D2 slab specialised on vegetation and water buffer capacity

Polygrow® profiling to guarantee a perfect drainage of waste water

Polygrow® coating for a better system stiffness and additional water buffer due to its semi-permeability: The coating is not spread all over the profiles. There are about 20% left that the water can run off.

PG D2

Roof membrane

Polygrow® PG D2 as 3in1 system

Vegetation blanket

Concrete ceiling

Material : Polyurethane foam Available sizes (length x width): 40 x 60 cm Bulk density (dry) : 33 kg/m3 100 x 100 cm Max. water capacity: 70 Vol.% 200 x 100 cm Air volume at max. water capacity: 28 Vol.% Available sizes (height): 6, 8, 10 and 12 cm Pore volume: 98 % pH value: 6 Usable roof pitch: 1 - 5º / 1 - 9 % All listed specifications are related to the PG D2 slabs, not to the total mock-up

Height of the slabs [cm] 6 8 10 12 Weight dry [kg/m2] 1.8 2.4 3.2 3.8 Weight saturated [kg/m2] 35.0 50.0 65.0 80.0

Water buffer [l/m2] 31.5 45.5 59.5 73.5

CDH 40% dry [kPa] 7.6 6.2 8.2 8.2 CDH 40% saturated [kPa] 4.1 3.4 4.7 5.3

PG GD1

Roof membrane (corrugated)

Polygrow® PG GD 1/PG GD 80

Vegetation blanket

Concrete ceiling

4cm

Height of the slabs [cm] 6 8 Weight dry [kg/m2] 1.4 2.0 Weight saturated [kg/m2] 29.4 44.0

Water buffer [l/m2] 28.0 42.0

Material : Polyurethane foam Available sizes (length x width): 100 x 100 cm Bulk density (dry) : 33 kg/m3 200 x 100 cm Max. water capacity: 70 Vol.% Available sizes (height): 6 and 8 cm Air volume at max. water capacity: 28 Vol.% Pore volume: 98 % pH value: 6 Usable roof pitch: 1 - 5º / 9 - 84% All listed specifications are related to the PG GD1, not to the total mock-up

PG GD80

Roof membrane (corrugated)

Polygrow® PG GD 1/PG GD 80

Vegetation blanket

Concrete ceiling

4cm

Height of the slabs [cm] 6 8 Weight dry [kg/m2] 3.2 4.8 Weight saturated [kg/m2] 30.2 44.8

Water buffer [l/m2] 27.0 40.0

Material : Bonded polyurethane foam Available sizes (length x width): 100 x 100 cm Bulk density (dry) : 80 kg/m3 200 x 100 cm Max. water capacity: 66 Vol.% Available sizes (height): 6 and 8 cm Air volume at max. water capacity: 43 Vol.% Pore volume: 97 % pH value: 6 Usable roof pitch: 5 - 40º / 9 - 84% All listed specifications are related to the PG GD80 slabs, not to the total mock-up

PG SD 80

Front view

Roof membrane

Polygrow® PG SD80 as 3in1 system

Vegetation blanket

Concrete ceiling

Material : Bonded polyurethane foam Available sizes (length x width): 100 x 100 cm Bulk density (dry) : 80 kg/m3 200 x 100 cm Max. water capacity: 66 Vol.% Available sizes (height): 6 and 8 cm Air volume at max. water capacity: 43 Vol.% Pore volume: 97 % pH value: 6 Usable roof pitch: 5 - 40º / 9 - 84% All listed specifications are related to the PG SD80 slabs, not to the total mock-up

Height of the slabs [cm] 6 8 Weight dry [kg/m2] 4.0 5.6 Weight saturated [kg/m2] 37.0 51.6

Water buffer [l/m2] 33.0 46.0

CDH 40% dry [kPa] 38.7 27.1 CDH 40% saturated [kPa] 17.8 16.0

Perfectly insulated from top to bottom with Recticel Insulation If you’re going to build, you’re going to do this once in your life. That’s why you’re going to chose sustainable materials with a high quality - the key when thinking about insulation. A good insulation gives a lot of advantages – for your whole life: it saves a lot of money you normally have to spent for energy costs. It increases the value of the building en positively influences the environment by less CO2 emission. In combination with a green roof, these will be boosted.

Recticel covers a wide range of sustainable and intelligent insulation products and solutions with an excellent insulation value. Especially for flat roofs in combination with a green roof Recticel adapts Powerdeck® F, Eurothane® Bi-3 en Eurothane® Silver.

The advantages of the sustainable Recticel insulation: More information about the keymark and sustainable insulation at www.recticelinsulation.nl

High insulation value Extreme thin insulation resulting in less laying out Keymark, quality label Ideal and perfectly accessible insulation Suitable for new construction and renovation

Great stability and light weight

Easy and fast to install

Roof structures and green roofs Basically, the roof structure needs to be strong enough to carry a green roof build-up. The waterproofing membrane needs to be root resistant. If that’s not the case, a root resistant foil (based on the FLL guidelines) needs to be placed on top of the waterproofing membrane. Warm roof (non-ventilated roof) A warm roof is a roof construction without a ventilated air space beneath the structural deck. The insulation layer is placed between the ceiling and the waterproofing roof membrane. It is recommended to use a vapour control layer on top of the ceiling, underneath the insulation boards. Generally, all types of green roofs, whether extensive or intensive can be installed on a warm roof – depending on the load bearing capacity.

Roof membrane

Insulation

Polygrow® PG D2

Vegetation blanket

Vapour barrier

Note: The green roof will be installed directly on top of the waterproofing membrane. During installation take care that this membrane won’t be damaged, e.g. by the maintenance materials like inspection chambers or while cutting the Polygrow® slabs or vegetation blankets.

Cold roof (ventilated roof) A cold roof is a roof construction with an independent substructure and usually an insulation layer between this substructure and the ceiling/ structural deck. But also if insulation boards are used a ventilated airspace has to be in between. Cold roofs are also used without insulation boards, e.g. when these are not necessarily required as above underground car parks. In general, the limited load bearing capacity of the substructure allows only light weight extensive green roof solutions. But depending on the load capacity it could also be possible to install intensive ones.

R. membrane & Interlayer

Substructure

Polygrow® PG D2

Vegetation blanket

Concrete ceiling/ structural deck

Insulation

Note: A green roof may affect the aeration between the different layers of the roof structure due to its cooling effect. On the other side, cold temperatures may cause frost underneath the substructure and result in the damage of the vegetation of the green roof.

Inverted roof An inverted roof is a roof construction with the insulation boards on top of waterproofing membrane. Before installing a green roof the moisture diffusion has to be measured and considered. On the other hand, the insulation can be designed in the way resisting heavier green roof build-ups. Generally, all types of green roofs, whether extensive or intensive can be installed on a warm roof – depending on the load bearing capacity.

Interlayer Insulation

Polygrow® PG D2

Vegetation blanket

Concrete ceiling/ structural deck

R. membraneInterlayer

Note: green roof may affect the vapour diffusion processes of the insulation

PG D2 material test based on the FLL guideline for one-layer green roof systems Particle/ grit size not applicable Bulk density Wet conditions 0.36 g/m3 Dry conditions 0.04 g/m3 Water-Air-Ratio Pore volume 84.3 Vol.% (2 hours after saturation) Max. water capacity 45.0 Vol.% (2 hours after saturation) Air volume at max. water capacity 39.3 Vol.% (2 hours after saturation) Water permeability 85 mm/min PH-value (CaCl2) 6.6 Salt content and nutrients Salt content (water extract) 0.0 g/l Nitrogen (N) 2 mg/l Phosphorus (P2O2) 0 mg/l Potassium (K2O) 4 mg/l Magnesium (Mg) 3 mg/l Organic substances not applicable Plant tolerance positve

Installation Manual Green roofs

Green roof installation instructions Before starting with the installation of your green roof, please be aware of the following things:

Checklist BFORE the installation

Substructure of the roof (steel, concrete, wood etc.) & load bearing capacity (constructural analysis) – check with Polygrow® product specifications

Pitch of the roof – check with Polygrow® product specifications Connection to walls/ facades, roof outlets and height of roof edges (minimum 8

cm) Waterproofing (no damage, root resistance etc.), Note: the root resistant foils are

not for waterproofing, they are only for root protection Water run-off (sufficient slope and unblocked rain pipes/ roof outlets, no ponding

on the roof) Water & irrigation supply (for installation & maintenance) Wind-drag load (wind power) Accident prevention and accessibility of the roof (for installation & maintenance,

consider current health and safety legislations when working on heights above 1metre)

Cleaning of the waterproof membrane before starting with the installation

Checklist AFTER the installation – maintenance

Up to 3 weeks after the installation the Polygrow® slabs have to be kept saturated and watered (including nutrients) until the roots penetrated the slabs. After this period of time, also extensive green roofs are not totally maintenance free. The following things have to be kept in mind:

Extensive green roofs have to be maintained once to twice a

year, intensive ones even more prevent that dominant species take over pull out any weed and unwanted plants brought by birds or wind mow or trim grass, herb and wildflower roofs to prevent moss

growth and remove the trimmed material replace plants that failed give nutrients once to twice a year on extensive roofs, on

intensive even more irrigate regularly on intensive roofs, depending on the plant

species keep the roof outlets, rain pipes and borders free of plants check the inspection chambers

Step 1: Water proofing and root resistance If the water proofing membrane is not root resistant, a root protection foil (e.g. an LDPE foil according to the FLL guideline) has to be installed. Therefore: Clean the existing roof membrane and remove any sharp materials Roll out the root protection foil and keep a surplus at the roof borders/ edges If more than one foil sheet is required make sure that the single sheets are overlapping by 1.0 to 1.5 metre Pay attention to the water flow directions/ slope of the roof when overlapping the foil sheets Cut out an opening where the rain pipes/ roof outlets are located Note: The root protection foil doesn’t has to be fixed on the roof membrane Step 2: OPTIONAL: Edge profiles Edge profiles are used to restrain the vegetated green roof part from the roof borders or walk ways. These might be aluminium or plastic panels. Because the Polygrow® systems don’t include lose materials like granules the use of these edge profiles is not essential.

Installation Steps (example PG D2) The following installation instructions show how an extensive green roof with vegetation blanket can be installed with Polygrow® PG D2 sheets and which requirements have to be determined.

Step 3: Polygrow® PG D2 slabs Lay down the Polygrow® PG D2 slabs one by one directly on top of the roof membrane/ root protection foil without gluing or any other fixing. Due to the wind uplift you have to keep the roof borders free and fill these with heavy materials like grit, gravel or concrete tiles. These free spaces have to be between 30 and 50 cm. For the details please look at step 5. It is important that the Polygrow® slabs are laid down in half stone bond to prevent displacements as shown in the following picture:

For adapting the sizes of the Polygrow® sheets, a sharp knife or a ripsaw can be used for cutting. Note: The cutting has to be done carefully that the water proofing/ root resistant membrane will not be damaged. If there are rain pipes/ roof outlets in the middle of the roof where the Polygrow® slabs are placed, cut out the PG D2 slabs at these locations to keep the outlets free. Place the control shafts/ inspection chambers on top of the roof outlets.

Polygrow® PG D2 sheets in half stone bond

Edge profiles (optional)

Grit around the borders

Roof border/ edges with waterproofing membrane

Step 4: Vegetation blankets Directly on top of the Polygrow® sheets, the vegetation blanket have to be rolled out. This has to be done in half stone bond and by overlapping the Polygrow® sheets by minimum 20 cm as shown at the drawing below and at the next page.

Additionally, the vegetation blankets have to overlap each other by approx. 10 cm (see drawing on next page). This guarantees that the growth of a connected vegetation ‘carpet’. NOTE: TAKE CARE THAT THE POLYGROW® SLABS ARE COMPLETELY COVERED ON ITS TOP BUT ALSO ON ITS SIDES TO PREVENT THEM FROM UV RADIATION. In the case that seeds or single plants are used instead of pre-grown vegetation blankets, the Polygrow® slabs have to be covered by a substrate layer of minimum 3 cm.

Polygrow® PG D2 sheets in half stone bond

Edge profiles (optional)

Grit around the borders

Roof border/ edges with waterproofing membrane

Vegetation blankets in half stone bond

PG slab no.1

PG slab no.2

Vegetation blanket no.1

Vegetation blanket no.2

Vegetation blanket overlapping the borders of the Polygrow® sheets on both

sides

min. 20 cm min. 20 cm

Vegetation blanket no.1 overlapping blanket no.2

approx. 10 cm

Step 5: Grit/ gravel borders As mentioned in step 3 the edges and borders along the roof have to be filled with heavy material like grit, gravel or concrete tiles. To prevent wind suction this material should withstand specific forces depending on the roof pitch & height. Based on DIN 1055-4 (FLL guideline) the following table shows the possible maximum wind suction forces:

If the gravel sizes of 16/32 or 16.25 are used single gravels being ≤ 8mm might have to have a maximum mass fraction of 5%. For fire safety a 30cm high upstand or a 1m wide gravel/ concrete tile strip has to be installed every 40m.

Wind suction force W [N/m2]

Roof pitch

Building height [m]

Edges

Borders

0°-25° 0-8 8-20 20-100

2400 3840 5280

1350 2160 2970

25°-35° 0-8 8-20 20-100

1350 2160 2970

825 1320 1815

a

a/8

b > 1.5a a/2

Step 6: Irrigation After the installation it is necessary to irrigate the green roof to establish the plant growth. Therefore the first two to three weeks are critical. To help the plants enrooting they need regularly water. The Polygrow® sheets have to be kept wet. Additionally, it would be even better and helpful to saturate the Polygrow® sheets before the vegetation layer will be laid down. Depending on the climate and planted vegetation the further irrigation has to be set up. Normal sedum roofs don’t need an additional irrigation at temperate regions with regular rainfall. In drier and tropical climate zones also these need an irrigation. Intensive roofs will need irrigation regularly. The frequency is depending on the plant type and climate, too.

Köppen Climate Classification: A: Tropical climate B: Dry (arid & semiarid) climate C: Temperate climate D: Continental climate E: Polar climate

Construction requirements & considerations Roof borders, edges and upstands

Roof perimeter For inspection and maintenance as well as for fire safety and wind uplift a min. 30cm wide strip of grit, gravel or concrete tiles has to be installed along the roof borders. The waterproofing membrane between the top of the strip material and the roof border has to cover min. 10 cm

Rooflight dome For inspection and maintenance as well as for fire safety reasons a min. 50cm wide strip of grit, gravel or concrete tiles has to be installed around rooflight domes. The waterproofing membrane between the top of the strip material and the rooflight dome has to cover min. 15 cm.

≥ 10 cm

≥ 30 cm

≥ 15 cm

≥ 50 cm

Vent pipe Mainly for fire safety, but also for inspection and maintenance a min. 50cm wide strip of grit, gravel or concrete tiles has to be installed around vent pipes. The waterproofing membrane has to be 15cm higher then the top of the strip material.

Roof outlet For a correct water run-off as well as for inspection and maintenance, inspection chambers has to be placed on top of the roof outlets. Around them a min. 50cm wide strip of grit, gravel or concrete tiles has to be installed.

≥ 50 cm ≥ 50 cm

≥ 15 cm ≥ 15 cm

≥ 30 cm ≥ 30 cm

Facade connections and door thresholds

Facade connections Mainly for fire safety, but also for inspection and maintenance a min. 30cm wide strip of grit, gravel or concrete tiles has to be installed between a façade and the vegetated green roof area. The waterproofing membrane has to be 15cm higher then the top of the strip material.

Door thresholds Mainly for fire safety, but also for inspection and maintenance a min. 50cm wide strip of grit, gravel or concrete tiles has to be installed between a façade and the vegetated green roof area. The waterproofing membrane has to be 5cm higher then the top of the strip material , the rain pipes or a grille.

≥ 15 cm

≥ 30 cm

≥ 5 cm

≥ 50 cm

Fire safety

Fire wall Fire strip For fire safety fire walls or fire strips have to be installed on green roofs, not exceeding 40m between them. The firewalls have to have a minimum height of 30cm with a water proofing membrane minimum 15 cm above the strip of grit, gravel or concrete tiles. The gravel has to have a minimum size of 16-32mm. Instead of fire walls fire strips can be installed every 40meters. They have to have a minimum width of 100 cm.

≥ 30 cm

≥ 15 cm

≥ 30 cm ≥ 30 cm

≥ 15 cm

≥ 30 cm

≥ 100 cm

≤ 40 m

Bitumen Bitumen membranes are often used for the waterproofing of a roof. There exist special ones including a root protection for green roofs. BREEAM BREEAM is the most used certification mark for buildings worldwide including nine different categories: Management; Health & Wellbeing; Energy; Transport; Water; Materials; Waste; Landuse & Ecology; Pollution. Brown roof Brown roofs are similar to green roofs with the difference that they don’t have a closed vegetation in the beginning. Thus, the term ‘brown roof’ goes back to its initial colour due to the soil that is used. Their aim is to encourage and increase biodiversity: more species of plants and animals. CO2 reduction Green roofs can absorb and thus reduce CO2 in cities, depending on their vegetation. A study done in Utrecht (The Netherlands) has shown that its 71 million m2 roof surface could reduce 20% of the CO2 when it’s turning into green.

Extensive green roofs Extensive green roofs are mainly vegetated by moss, sedum or herbs. Their goal is to create a nature-like roof surface with low weight and maintenance. They are not suitable for daily walking. EPDM and synthetic roof membranes Next to the typical bituminous membrane EPDM as a rubber based membrane or PVC membranes are used as alternative. They are seen as a more sustainable solution in particular concerning the lead. FLL The abbreviation FLL means Forschungsgesellschaft für Landschaftsentwicklung und Landschaftsbau e.V. (Landscape Research, Development and Construction Society). Located in Bonn, Germany, the FLL is the editor of the most important green roof guidelines. Green roof A green roof, often known as vegetated roof, mean roofs being covered by a drainage, substrate and vegetation layer. They clean polluted air, buffer rainwater, counteract the heat island effect,

decrease energy costs, enhance acoustic insulation, double the lifetime of roofs and better the biodiversity in cities. Intensive green roofs Intensive green roofs are like gardens and terraces on roofs. Their vegetation covers grass, herbs, shrubs and in some cases also trees. This leads to a very high weight and needs a strengthened roof structure. They also need an adapted water regime and more maintenance then extensive roofs. NOx Nitrogen oxides are the main cause of air pollution. Green roofs can help to counteract them. Additionally there are roof membranes with a special coating with minerals that can reduce the amount of NOx. Maintenance No green roof, being extensive or intensive, is maintenance free. Also not simple sedum roofs. Extensive green roofs need to be maintained once to twice a year (as described at the Polygrow® installation guide), intensive ones even more. During maintenance the safety requirements (e.g. fall protection) have to be kept.

Particulate matter Particulate matter means all air particulates of different origin and chemical composition being < 10 micrometer. Studies have shown that particulate matter might be dangerous for health when it’s being breathed in. Roof drainage In case of heavy rainfalls a correct water run off has to be ensured when a green roof is planned and installed. Also during maintenance a special check of the roof outlets needs to be done. Roof pitch Generally, green roofs can be divided into flat and pitched ones, whereby a minimum roof pitch of 1° is advisable for extensive green roofs to guarantee a good water run-off. Intensive ones don’t cause any problems on pitchless roofs. Nevertheless ponding areas should be replaced. Special green roof construction should be used for roofs pitches > 5°. Roof structures A roof structure includes all layers being necessary to build up a roof system. Generally, three different roof types can be mentioned:

cold roofs (ventilated roofs), warm roofs (non-ventilated roofs) and inverted roofs. Roof thermography With the help of thermography the temperature of a building can be measured from far away. Based on estimations 30% of the heat disappears through the roof. Roof usage Today it is common that roof surfaces are used multifunctional. These are combinations of photovoltaic panels, green roofs and terraces or building technologies. Because this increases the requirements of the roof structure and construction they have to be considered at an early stage of the total planning. Root barrier Roof membranes can be damaged by root growth causing leakage and thus wetting of the roof construction and in the worst case at the rooms beneath. To prevent this whether root resistant roof membranes have to be chosen or a root resistant foil according to the FLL guidelines has to be placed on top of the roof membrane.

Run-off coefficient The run-off coefficient describes the part of the rainwater that is not buffered on a green roof. Concerning the FLL guideline the average run-off coefficient of a green roof with a substrate thickness of 10-15cm is 0.3. Sedum Sedum is a typical succulent and mostly used on extensive green roofs. These plants are don’t need a lot of maintenance and can easily adapt to dry or wet conditions. For green roofs there are special pre-grown sedum blankets to create a minimum 80% green surface already after the installation. Structural analysis (statics) Basic need and key element before the installation of a green roof is the load capacity of the roof. Extensive green roofs are used for light weight roofs. Normally, minimum 80 kg/m2 are calculated for a sedum roof with a traditional green roof system, including drainage, substrate and vegetation layer. With the Polygrow® PG D2 system extensive sedum roofs can already be realised with 50 kg/m2. For typical intensive green roofs minimum 250 to 300 kg/m2 should be calculated. Additionally the live load have to be considered.

Substrate The substrate or vegetation base layer is the rooting material of a green roof allowing good growth circumstances for the plants. Important is a good air-water-balance and easy enrooting possibilities. Water buffer One of the properties and advantage of a green roof is it’s water buffer capacity to unburden the canalisation in cities. Depending on the thickness of the substrate and drainage layer green roofs can absorb up to 50% of the rainwater. Water retention Water retention means the water that is hold on the roof due to water buffering capacity of a green roof. This reduces and time-shifts the water run-off and peak loads. There are special retention roofs being installed only for water buffering with more than 50l/m2. They can hold up a 15m rain shower to 3 hours. Wind suction The FLL guideline refer to DIN 1055-4 including the maximum possible wind suction forces on green roofs. There is a differentiation of the inner corner and the outside corners/ roof

edges and borders that has to be considered when planning and installing a green roof. For loose laying waterproofing green roofs are able to take over the load function due to their weight.