APPENDIX - K GREEN ROOF SYSTEM

Transcription

1 APPENDIX - K GREEN ROOF SYSTEM

2 Uniclass G581 CI/SfB (52.3) July 2004 Green Roofs Alumasc Alumasc Technical Helpline

3 Contents Contents page 3 4 Why have a Green Roof? 5 Replicating Nature on roofs 6 The Build-up of a Green Roof 7 Extensive Green Roofs 8 Intensive Green Roofs 9 The Control of Water in a Green Roof 10 Alumasc Integrated Systems 12 Green Roof Track Record 14 Design Overview 15 Design Considerations 16 What Kind of Green Roof? 19 Green Roof Soils 20 Plant Selection 22 Safety 24 Installation 25 How Work 26 Step-by-step Installation 28 Planting Extensive Landscapes 30 Maintenance Extensive Green Roofs 31 Green Roof Solutions Floradrain FD Green Roof Solutions Floradrain FD Green Roof Solutions Floradrain FD Green Roof Solutions Floratec FS Green Roof Solutions Elastodrain EL 200 and EL Green Roof Solutions Irrigation System 42 Application Details & Product Data 43 Floradrain FD Floradrain FD Floradrain FD Elastodrain EL 200 and EL Sloping Roofs 52 Product Data 53 2 Alumasc Technical Helpline

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5 The rapid growth of our cities over the last 60 years has seen vast areas of countryside swallowed up in concrete and asphalt. Even the open spaces within cities have been decreasing due to the demand for building land. Many cities are constantly covered in a pall of polluted air. Extensive construction of high rise buildings reduces the aeration effect of the wind, adding to the unhealthy environment of higher temperatures, lower humidity and high air pollution. To a great extent our cities and industrialised areas are impervious to water, resulting in the overloading of the drainage and sewerage systems, increasing the risk of flooding following heavy rainfall. Replacing the land lost to construction by landscaping the roofs of our buildings can help to redress the balance of nature and reduce water run-off. Using s 30 years experience in Green Roof technology Alumasc can provide a wide range of green roof systems to suit every type of roof structure to replace lost landscape. The Green Roof Concept There are a wide range of green roof landscapes available to suit every taste. In general they tend to fall into three categories: Extensive Designed to be lightweight and support only hardy plants, which require a low maintenance regime and no irrigation. Access is for maintenance only. Semi-intensive Still lightweight with a shallow soil structure, but designed to support a wider variety of plants such as lavenders, wild flowers etc with minimal maintenance. Generally accessed by adjacent patio areas. Intensive Very much lighter than the traditional green roof. The system will support a wide variety of plants, shrubs and trees. Often designed to be accessible for recreational use. Requires irrigation and a regular maintenance regime. Intensive roof Jubilee Gardens, Canary Wharf 4 Alumasc Technical Helpline

6 Why have a Green Roof? In the competitive world of construction every new idea or concept has to justify itself, not only environmentally, but commercially. Green Roofs are no exception and indeed offer the client a number of benefits both physically, environmentally and most importantly, profitably. retains 50 90% High water retention Depending on the green roof design, the immediate water run-off can be reduced by up to 90%, greatly reducing the drainage flow rates. This enables the outlets, downpipes, ground drains, sewer pipes etc, to be reduced in capacity, thereby reducing construction costs. heat and light CO2 oxygen water nutrients H2O O2 root deposits Improves the climatic environment Green roofs cool and humidify the surrounding air creating a microclimate which has beneficial effects within the immediate area % less dust Reduction of dust and smog levels Green roof vegetation helps to filter out dust and smog particles. Nitrates and other harmful materials are absorbed out of the air and rainfall and bound within the soil. 80ºC 25ºC Increases the life expectancy of the roof A green roof protects the waterproofing from climatic extremes, UV exposure and mechanical damage. This greatly increases the life expectancy of the waterproofing. up to -3 db Reduced noise levels Green roofs reduce reflective sound by up to 3 db and improve sound insulation by up to 8 db. This is most effective with buildings near airports, or noisy nightclubs and factories. cold up to 50% saving Additional thermal insulation Green roofs improve the thermal insulation in both summer and winter. Some specialised systems are certified as thermal insulation. warm up to -8 db Use of space Converting or designing normally unused roof areas into green roofs, particularly for recreational or sporting use not only makes use of expensive space, but saves the costs of purchasing additional land. Green roofs often assist in gaining planning consent. Natural habitat for animals and plants Green roofs encourage wildlife to remain within built-up areas. Alumasc Technical Helpline

7 Replicating Nature on Roofs When designing and installing a green roof it is important to provide a growing environment as close as possible to the plant s natural environment. The most important factor is to compensate for the lack of sub-soil. systems have the structure to retain the necessary quantities of water to support the plants, whilst draining off the excess. The required amount of water is determined by the plant type, geographical region and the roof itself. Apart from creating the correct green roof system to support the plants, it is very important to protect the waterproofing from both mechanical damage and attack from plant roots. systems provide a number of solutions to these problems. green roof systems have been designed to function naturally, even though there is no direct contact with the ground and the roof build-up is normally not very deep. Nevertheless, the plants receive a stable environment without adversely affecting the waterproofing. The Answer is in the Build-up Each layer of a green roof system performs a particular function, just like natural soil. These functions include: provision of nutrients water retention aeration drainage In the case of sloping roofs there is also a need to prevent shear stresses and protect against erosion. Top soil with humus Growing medium Sub-soil Filter membrane Parent rock Drainage element Moisture mat Warm roof construction with thermal insulation and waterproofing 6 Alumasc Technical Helpline

8 The Build-up of a Green Roof The range of systems ensures that the right build-up can be provided to meet the requirements of any landscape option, including: Extensive and intensive landscapes Sloping and flat roofs Ponds, paving and play areas Vehicle access onto the roof Landscaping with additional thermal insulation At the heart of the green roof system is one of the patented drainage elements (Floradrain, Floratherm or Floratec) with its systems of channels on the underside, ensuring drainage of water, even with dense root growth. The profiled troughs in the drainage elements retain water, even on a sloping roof, and have strategically placed holes to ensure the roots receive the necessary aeration and allow the water to diffuse. Carefully selected plants for extensive, low maintenance landscaping, suitable plants include mainly the drought resistant, self-regenerating varieties. Plants for intensive landscaping such as roof gardens can be supplied by garden centres and nurseries. Growing medium must have a well balanced structure and low weight. The ph values, nutrients, degree of porosity and vapour permeability must be suitable. The type and thickness of the substrate soil ultimately determine the plant growth as well as the structural load imposed on the roof structure. Filter membrane to prevent fine particles being washed out of the substrate soil and therefore maintaining the efficiency of the drainage layer. Drainage element retains water in the profiled troughs, even on sloping roofs. Excess water drains away through the channels between the troughs. Strategically located holes provide the necessary aeration and ensure that moisture from the moisture mat diffuses up through the planting soil. Moisture mat made of non-rotting fibre to retain moisture and nutrients as well as providing mechanical protection to the root barrier and waterproof membrane. Not required in inverted roof assemblies. Root barrier prevents roots from affecting the waterproofing. The type, thickness and method of installation depend on the nature of the landscape planned and the shape and slope of the roof. Not required over root repellent membranes. Waterproof membrane Alumasc recommend the use of Derbigum or Hydrotech as the waterproofing membrane under green roofs due to their extreme durability and longevity. Thermal insulation situated below the waterproof membrane to form a warm roof construction. Inverted roof assemblies may also be accommodated, especially where Hydrotech is the waterproof membrane. Vapour control layer situated between the structural deck and insulation to prevent the formation of condensation. Structural roof deck must be designed to support the weight of the green roof and any live loads. Alumasc Technical Helpline

9 Extensive Green Roofs Extensive green roofs use a selected range of hardy plants, making them attractive to look at and requiring little maintenance. They are not intended for recreation, but are usually chosen for their appearance and for ecological reasons. They also provide excellent protection to the waterproof membrane. With green roof systems, extensive roofs are easy and economic to install. When established, they need relatively little maintenance. Extensive roofs only require a shallow soil depth typically from as little as 50mm to 150mm and therefore add little structural load to the roof below. With some Floradrain systems weighing as little as 65 kg/m 2, it is possible for many inverted ballasted roofs to be brought back to life by replacing all or part of the ballast with extensive landscaping. The increasing use of extensive roofs in cities significantly reduces the risk of flooding, as 50-90% of rainfall is retained in the green roof system, to evaporate slowly. The natural evaporation from the soil cools the air and reduces dirt and smog levels. Plant types for extensive roofs need to be drought, wind and frost resistant such as self-generating stone crop and sedums. See page 22 for a list of suitable plants for extensive green roofs. The water stored in the growing medium, drainage layer and moisture mat is sufficient to sustain the drought resistant plants between periods of rainfall, and irrigation systems are not normally required. Extensive green roofs can be applied to flat roofs, minimum fall 1:60, and sloping roofs with a pitch of up to 25º, provided the appropriate measures are taken to cope with the shear forces see page 52. Extensive roofs are: Lightweight Extensive green roof Soil Easy to install Simple to design Easily maintained Extensive roofs are ideal for: Lightweight roof decks Inaccessible roofs Filter membrane and Drainage layer Moisture mat, Root barrier and Waterproofing layer Insulation Vapour control layer Roof structure Roofs that require greening for planning purposes Flat or sloping roofs Reducing water run-off and ground draining capacity requirements 8 Alumasc Technical Helpline

10 Intensive Green Roofs The landscape variations with an intensive green roof are virtually limitless. Intensive roofs are intended for recreational, sporting and leisure purposes and are often indistinguishable from natural gardens in appearance. intensive green roofs follow the same design concept as the extensive green roof build-up. However, the drainage layer is usually deeper to provide greater water storage and to support a greater depth of soil. The depth of growing medium (intensive soil), which contains a great deal more organic matter than its extensive counterpart, will generally dictate the type and size of plants that can be grown. Intensive green roof designs usually consist of a mixture of hard and soft landscaping. It is therefore important that the selected drainage layer can support any type of landscape from roadways and paths to soil and trees, so as to permit excess water to drain unobstructed beneath. Intensive green roof Soil Filter membrane and Drainage layer Moisture mat, Root barrier and Waterproofing layer Insulation Vapour control layer Roof structure The water retention capacity of the drainage layers is used to assist with the irrigation of the plants it is not a substitute for an irrigation system, which should always be installed within the intensive green roof. Alumasc provide a unique irrigation system based on the diffusion of water stored on the roof beneath the drainage layer up into the soil. It is self regulating and saves up to 30% on water usage. By the very nature of their more complex design and greater variety of plants grown, intensive green roofs require regular maintenance. Alumasc Technical Helpline

11 The Control of Water in a Green Roof Water Storage Providing moisture to the roots is essential to maintain good healthy plants on a green roof. Much of the moisture is supplied by natural rainfall, which is collected and stored by the layers in a green roof. The drainage layer plays an essential part in storing rainwater that filters through the growing medium. Once the troughs in the drainage layer are full, excess water overflows, to be soaked up by the moisture mat. Only water that cannot be absorbed by the moisture mat drains from the roof down the roof outlets. Irrigation There should always be easy access to a water point for irrigation purposes, especially for intensive roof gardens. An automatic system is the ideal solution as it provides a constant water supply. The Sub Landscape Irrigation system is simple and reduces the water lost through evaporation which occurs during surface applied irrigation by up to 30%. See page 42 for further details. In dry periods, stored water gradually diffuses up through into the growing medium for uptake by the plant s roots. Storing rainwater 1. The intensive/extensive soil is highly porous, storing up to 3 litres/m 2 per 10mm depth of soil. 2. Once the soil is saturated, the excess water filters into the drainage layer and over into the moisture mat below. 3. The profiles of the drainage layer permits excess water to drain in any direction to the outlets. Typically, green roofs will store between 50 and 90% of rainfall. Releasing moisture 1. As the soil dries out through plant usage and evaporation the water stored in the drainage layer diffuses up into the soil. 2. Once the drainage layer has run dry the moisture mat releases its moisture through diffusion up through holes in the top of the drainage layer. 10 Alumasc Technical Helpline

12 Floradrain drainage element A close up of a Floradrain unit clearly shows how rainwater percolating through the growing medium is stored. When the water level in the drainage tray is replenished, excess water flows over the edge of the trays. The overflow water is absorbed by the moisture mat. Any unabsorbed water can flow easily to the roof outlets through the channels formed under the drainage layer. The holes in the drainage layer allow water from the moisture mat below the layer to diffuse up into the growing medium, helping to keep it moist. Jacobs Island, London White Horse Inn, Norfolk Alumasc Technical Helpline

13 Alumasc Integrated Systems An Integrated Systems Approach Alumasc recognises that every building is a synthesis of complementary products and services. Through a core Integrated Systems concept, Alumasc provides a total solution to all aspects of building exteriors and drainage - bringing together technical solutions and support, price control, procurement, installation, warranties and after sales support. Alumasc offers a comprehensive menu of building exterior and drainage solutions reflected by the following application categories: Architectural Rainwater Systems Engineered Drainage Systems Flat Roofing & Waterproofing Systems Metal Roofing Systems Façade Systems The Alumasc Integrated Systems concept is project-centred and holistic. Alumasc technical support teams work closely with specifiers on a project basis. An integrated exteriors and drainage solution is developed, based around complementary Alumasc products and systems most suited to the project in question. The ensuing specification embraces all aspects of the building envelope in a way that protects the architect s design and results in the best overall product mix for the job in respect of design and performance. Rethinking Construction Alumasc fully embraces the philosophies and recommendations contained in Sir John Egan s report Rethinking Construction, with collaboration and support from an early stage within a project. Alumasc Integrated Systems provide a value-engineered approach with quality and efficiency being the driving forces in delivering a risk-free and zero-defect building envelope and drainage solution for both new build and refurbishment. Alumasc Promoting Partnership We are proposing that the industry develops long-term alliances that include all those involved in the whole process of delivering the products, from identification of client need to fulfilment of that need. Sir John Egan Rethinking Construction Alumasc is committed to the partnering ideals of Rethinking Construction and is a member of the Construction Manufacturers Partnering Association (COMPASS). COMPASS is a body operating as an independent, nonprofit making Best Practice group, specifically promoting long-term strategic value-chain partnership amongst all members of the construction team. The construction value-chain embraces all parties involved in the construction process, including manufacturers, distributors, specialist and main contractors, designers, surveyors, cost consultants and clients. Alumasc actively supports the philosophy that project teams must embrace the entire value chain from start to finish, that all partners share in the rewards of improved efficiency, and provide better value for customers through the teamwork approach. By signing the COMPASS Charter, Alumasc signifies that it fully endorses the principles of Rethinking Construction, and is a progressive, forward-thinking company, with a strong customer focus and total commitment to delivering quality and value for money. Alumasc actively promotes partnering and welcomes enquiries from similarly committed organisations with an interest in developing partnering alliances. 12 Alumasc Technical Helpline

14 The Alumasc Offer Alumasc offers a fully integrated and managed service-based package through three key areas of project support, ensuring that the selected Alumasc products and systems integrate seamlessly into a total green roof solution. Why Alumasc? The Company combines three key strengths that enable it to deliver these in-depth support services: 1. An unrivalled product and system that offers a complete solution to structural waterproofing. Alumasc A-TECH Design: ensures that the products and choice of systems will reflect the designer s intentions. Alumasc technical staff work closely with the design team throughout the entire pre-contract stage of any project. Their expertise embraces design advice, brief preparation, specification development including NBS, CAD details, and specialised calculations. Alumasc A-TEAM Approved Contractors: ensure co-ordinated installation of the waterproofing elements of a green roof. Alumasc A-Team Approved Contractors are fully trained and accredited installers with specialist knowledge of all the different facets of roofing and waterproofing. These contractors are monitored on site by Alumasc to ensure that all aspects of work are completed without technical or programming conflicts at the interface with other building elements. Contractors agree to abide by the following terms: Perform their work to meet the mutually agreed works programme Carry out all installation proficiently in a workmanlike manner Keep the building as watertight as possible during the installation of the works Keep the site clean and organised during their work and leave the site clean and tidy when they finish Keep the customer informed about all project activities during the works Guarantee a prompt response to any problem at any time once the work has been completed and any leak reported 2. Extensive and co-ordinated technical expertise that helps designers and specifiers to select and apply the most appropriate components and establish an operationally efficient and cost-effective configuration for green roofing. 3. A long-standing service ethic that safeguards the implementation of the Alumasc offer through all stages of the building cycle from inception to lifecycle assurance. Quality Assurance Alumasc is registered as a Firm of Assessed Capability, in accordance with BSI Quality Assurance Standard BS EN ISO 9001: 1994 Registration Numbers Q and FM Alumasc A-SURE Warranties: after the completion of a project, a range of warranty options covering the waterproofing installation can be offered to provide long term assurance and peace of mind. The length of warranty can vary depending on specification by agreement with Alumasc on each project. Warranties are available for periods of 12, 15 or 20 years and cover the building owner against entry of water as a result of latent product defect, errors of installation, and consequential loss, all as set out in the terms and conditions of warranty. Alumasc Technical Helpline

15 Green Roof Track Record International architects have consistently chosen the Alumasc green roof system above all others. The selection of prestigious projects below is an indication of the consistent long term performance of Alumasc green roofs. Project Date Size (m 2 ) Architect Main Contractor Royal College of Gynaecology & Obstetricians Nicholas Hare Associates Willmott Dixon Merrill Lynch European HQ, London ,000 Swanke Hayden Connel Mace Jubilee Gardens/RT3, Canary Wharf, London ,000 BDP London Canary Wharf Contracts New Providence Wharf, London ,000 Skidmore, Owings & Merrill Ballymore Royal Artillery & Gunnery Quays, London ,000 RMA Architects Barratt Homes BMW/Rolls Royce, Chichester ,000 Nicholas Grimshaw BMW Odyssey Car Park, London ,500 BUJ Architects Carillion Royal Pavilion, Aldershot ,000 RTKL Architects John Mowlem Kensington Village, London ,500 EPR Architects Ltd. Carillion Eden Project, St Austell Nicholas Grimshaw Robert McAlpine Millennium Seed Bank, Wakehurst Stanton Williams Lovell Construction Polygon Hotel Development, Southampton ,000 Morgan Carn Partnership Barratt Homes Prince Regent Gate, London ,000 CHBC Architects Barratt Homes Golf Hotel, St. Andrew s ,000 Parr Partnership HBG Maths Faculty, Cambridge University ,100 Edward Cullinan John Laing Construction 88 Wood Street, London ,000 Richard Rogers Partnership John Laing Construction Jacobs Island, London ,500 Broadway Malyan Berkeley Homes No.1 Poultry, London Michael Wilford, London Laing Construction Museum of Scotland, Edinburgh ,000 Benson & Forsyth, London Laing Scotland & Bovis Holmebridge Water Treatment Works ,000 Jones Stock Partners, Leeds Birse Chaucer Street Car Park, Nottingham ,500 James McArtney, Nottingham Wimpey Castle Mall, Norwich ,000 Lambert Scott & Innis, Norwich Bovis Construction Management Rank Xerox Data Centre, Micheldene ,500 HLM Architects, Twickenham Wates Integra Jubilee Gardens, Canary Wharf, London BMW/Rolls Royce, Chichester 14 Alumasc Technical Helpline

16 Design Overview Design Overview Alumasc Technical Helpline

17 Design Overview Design Considerations Warm, Cold or Inverted Build-up It is possible to design a green roof system to suit a warm, cold or inverted build-up. The green roof principles remain the same, only the position of the insulation alters within the overall build-up. Membrane Selection Alumasc recommend the use of either Derbigum or Hydrotech as the waterproofing membrane for a green roof. Both systems have a proven record of high performance and longevity. Insulation The soil element of a green roof does have thermal insulation value, but as this varies with the moisture content it should not be taken into account when calculating the U-value requirement on the roof structure. Warm roof waterproof membrane above insulation However, the soil will significantly help to insulate against sound, such as over flying aircraft. Roof Falls/Pitch As a rule, flat roofs should be laid to falls of at least 1:60. With its shallow drainage layer and soil this is particularly important when designing extensive green roofs (which must have a minimum 1:60 fall) as any deflection in the deck allowing water to pond above the drainage layer will be harmful to the plants. Inverted roof insulation above waterproof membrane Cold roof cross ventilation above insulation However, green roofs can be installed on roof decks with zero degree falls, for instance when using Alumasc s unique irrigation system, provided that the correct build-up is designed to avoid the danger of drowning the plants. Designing a green roof for a sloping roof up to 25º is fairly simple, using the Floratec drainage system. Slopes over 20º require special design to ensure the system remains stable on the roof. Inverted Green Roof The characteristic of an inverted roof is that the insulation is above the waterproofing. Extruded polystyrene insulation is used for inverted roofs because it is impervious to water. However, the insulation is not impervious to water vapour. It is therefore essential to avoid forming a vapour barrier directly above it when installing a green roof. The following must be taken into account when designing an inverted green roof: Plant level eg, rockery type plants Roof planting soil Filter sheet SF Floradrain FD 25 or 40 If a root barrier is required, it must be placed below the insulation The weight of the soil must be adequate to prevent wind uplift and flotation It is not possible to use the roof dam irrigation system Water can be stored in the Floradrain layer without affecting aeration or vapour pressure Extruded polystyrene thermal insulation Alumasc Roofmate TF Root barrier WSF 40 Roof construction with waterproofing 16 Alumasc Technical Helpline

18 Design Overview Roof Drainage Landscaped roofs retain a high proportion of the rainwater that falls on the roof which therefore reduces the strain imposed on the surface water drainage systems. However, there is always excess water that needs to be drained by means of: roof outlets box or eaves gutters water spouts Roof Falls Extensive roofs Provide falls of 1:60 to 1:40 Intensive roofs Provide falls of 1:80 to 1:40 As a safety precaution there should be at least two outlets, or one outlet and an overflow. The outlets must be kept clear of vegetation by installing inspection chambers over them. In the case of terraced areas, a terrace grill can be installed over the outlet. Roof Penetrations Roof penetrations for pipes, equipment, rooflights, etc. are best concentrated in one area whenever possible. This helps by simplifying waterproofing details and ensures unbroken areas for the plants. Slopes from 20º to 30º need extra shear protection Safety Safety considerations are paramount and maintenance operations must be considered at the design stage. Appropriate access, anchorage points, safety rails and barriers must be provided, bearing in mind both the general use of the roof and anticipated maintenance operations. Roofs should be completely flat where a roof dam is being used Upstand and Perimeter Details The same waterproofing principles apply to green roofs as to conventional flat roofs. Waterproofing should be taken up a minimum 150mm above the finished surface. In the case of green roofs, this means the soil, paving surface etc. The Alumasc Rainwater Design Service Alumasc Technical Services can calculate the number and size of outlets needed to drain a green roof. Using dedicated software in conjunction with the requirements of BS EN 12056:2000, the software checks the capacity of downpipes used and suggests a minimum size. The software takes into account: area of green roof and any other roofs discharging onto the green roof local rainfall intensity building life and safety factor frequency and size of outlets and downpipes For information, the table below lists the run-off coefficient ψ which is the proportion of rainwater that drains from a green roof into the surface water drainage system for roofs with a pitch below 5%. System Substrate Plant type Water Water run-off depth retention (%) coefficient (ψ) Extensive Moss, sedum >40 60 Sedum, moss > Sedum, moss, herbs > Sedum, herbs, grasses > Grasses, herbs Intensive Lawn, perennials, woody plants > Lawn, shrubs, bushes >500 Lawn, shrubs, bushes, trees > In front of doors the upstand height can be reduced to 50mm if a linear drainage grill is installed. It is strongly recommended to provide vegetation barriers at all vulnerable points to prevent possible damage by plants. This includes the roof perimeter, all upstands, abutments and roof protrusions such as rooflights and inspection chambers. Strips of 16-32mm grade pebbles, mm wide are normally used for this purpose. Protection Against Wind Uplift Green roofs have to be designed to remain stable in high wind uplift conditions. Wind pressure varies over a roof area from fairly low pressure in the centre, where even a thin layer of soil is adequate ballast, to the perimeter and corners of the roof where wind uplift is such that coarse gravel or even concrete paving slabs may be needed to prevent wind uplift. Alumasc Technical Helpline

19 Design Overview Design Considerations The higher the building, the greater the risk of wind uplift. There is usually no problem if the waterproofing system is bonded or mechanically fixed. However, where the waterproof membrane is loose laid, or the insulation is placed above the waterproof membrane, as in an inverted roof, the green roof will be acting as the ballast. In wind exposed locations and in the case of sloping roofs, it is essential to protect the substrate soil layer from erosion until there is close plant cover. Fire Prevention Intensive green roofs that are irrigated regularly and have relatively deep soil are accepted as fire resistant to flying sparks and radiant heat. Extensive green roofs, which are generally not irrigated are accepted as fire resistant provided that: The substrate soil is at least 30mm deep and contains no more than 20%, by weight, of organic material There are gravel or concrete fire breaks in the vegetation every 40m, with a minimum width of 1m or a height of 300mm There are gravel strips around all roof penetrations (eg rooflights) and in front of walls with openings In the course of annual maintenance the safety strips must be kept free of flammable vegetation Structural Requirements The following issues should be considered at the design stage: The height, size and maximum loadbearing capacity of the roof structure Type of roof structure, number and position of drainage outlets and any roof penetrations The superimposed loads resulting from a landscaped roof must be taken into account when calculating the structural load. For roofs with an existing gravel or concrete paved surfaces, it is possible to install an extensive green roof system with the same or a smaller area load. Experience has shown that on roofs with a limited loadbearing capacity there are areas where it is possible to have a deeper layer or a mound of substrate soil, such as above a structural column. In such areas, it is possible to plant taller shrubs or small trees, thereby increasing the design possibilities. Any additional weight must, of course, be allowed for. Design loads on a green roof Layers Build-up Weight per unit area height dry saturated mm kg/m 2 kg/m 2 Protection layer Root barrier with protection mat Drainage layer Floradrain FD FD FD 60 filled with Zincolit Floratec FS Elastodrain EL 200/EL Vegetation layer (for every 10 l/m 2 ) Zincolit Extensive soil Intensive soil Zincohum Plant level Sedum, small shrubs and lawn approx. 5.0 Shrubs and low bushes approx Shrubs and bushes up to approx. 1.5m high approx Bushes up to approx. 3.0m high approx Large bushes and trees cause a greater Individual values concentrated load due to the additional must be given tipping movement under wind pressure. Examples Gravel surface approx Paving slabs approx Vehicle surface from approx. 500 Extensive landscaping approx Intensive landscaping approx Location of building and access availability Transport and storage availability, water and electricity supplies 18 Alumasc Technical Helpline

20 Design Overview What kind of Green Roof? Ecological protection layer or Garden roof? Basically there are three categories of green roof system: Extensive Minimal maintenance required No irrigation requirement Landscape of: Moss + sedum Sedum + moss + herbs Sedum + grasses + herbs Grasses + herbs Extensive soil Build-up height mm Semi-intensive Periodic maintenance Periodic irrigation Landscape of: Grass + herbs Shrubs + woody plants Woody plants Semi-intensive soil Build-up height mm Intensive Regular maintenance Regular irrigation Landscape of: Lawn Hedges Bushes Large bushes Trees Intensive soil Build-up height mm Where access is not required an extensive green roof is ideal. It imposes minimum weight so can be installed on almost any roof deck. Extensive green roofs are ideal on large industrial structures where apart from being attractive protection to the waterproofing they also significantly reduce water run-off and thus lessen the risk of flooding. Where the roof is visible and all year round colour is needed with minimum maintenance, then a semi-intensive green roof is the ideal solution. Compared with the extensive roof, the semi-intensive roof has greater water retention capacity and an increased depth of soil which allows a wider range of plants to be chosen. For access purposes, patios, paving and dwarf walls are often included in this type of design. Virtually any type of garden landscape can be created using the intensive green roof design. Lawns, water features, large shrubs and semi-mature trees are all possible. The type of planting and its ultimate size will determine the depth of soil that is needed and type of irrigation system necessary. The maintenance regime will also depend on the species of plant installed. Alumasc Technical Helpline

21 Design Overview Green Roof Soils The soil is an integral part of a green roof system. The correct structure and mix of the soil is vital to the long term health of the plants specified. The soil should provide: Good aeration to the plant roots even when saturated Compaction resistance to provide and retain good drainage within the soil Substrate Depth The depth of soil will generally control the plant type and growth. Alumasc are able to supply a system to support any proposed landscape. From a sedum carpet on a 50mm depth of soil to one with more than a metre to support trees. The diagram below illustrates the Elastodrain system (as an example) beneath different landscapes. Good water retention Slow release of nutrients Good anchorage for the plants to resist wind and water erosion In addition the soil should be delivered free of weeds, diseases, pests and in the case of extensive soil be fire retardant to DIN The mix and structure of the soil will depend on the plants specified and their ratio requirement for water retention, aeration and nutrients. Extensive Landscape Low maintenance No irrigation Sedum Semi-intensive Landscape Periodic maintenance Periodic irrigation Woody plants, lavenders, heathers Intensive Landscape Regular maintenance Regular irrigation Trees, grass lawns, large bushes Grain size Coarse Fine Water retention capacity Air volume Low High High Low Low Nutrient reserves High 20 Alumasc Technical Helpline

22 Design Overview Alumasc Roof Planting Soils Alumasc offer four different soil types: Alumasc Zincolit Drainage Substrate The substrate is used to infill the Floradrain FD 60 drainage layer and to act as an additional drainage medium over a shallow drainage layer. General notes: The soil is supplied in 1m 3 bags or in bulk The soil mix is composed of recycled products and regularly tested to comply to the German FLL standards A list of plant varieties suitable for both extensive and intensive roofs is given on pages 22 and 23. Alumasc Extensive soil Extensive soil is designed to support Sedum type plants which are wind, frost and drought resistant. Allow up to 3% settlement after installation. Alumasc Semi-intensive soil The addition of organic matter increases the range of plants that can be specified, which are basically hardy plants such as lavenders, heathers, wild flowers etc. Allow up to 15% settlement after installation. Alumasc Intensive soil Intensive soil will support most varieties of plants. The depth required will generally depend on the plants specified and their maturity. Allow up to 25% settlement after installation. Alumasc Technical Helpline

23 Design Overview Plant Selection Extensive Green Roof: Sedum Carpet (min. depth of 50 mm growing medium) Botanical name Height (cm) Leaf colour Flower colour Months in bloom Location Sedum album (different varieties) 5-10 winter green white 6-8 Sedum ewersii summer green blue grey 8-9 Sedum floriferum Weihenstephaner Gold 5-10 winter green dark green 6-8 Sedum hispanicum var. minus 5-7 summer green grey green 6-7 Sedum hybridum Immergrünchen winter green fresh green 7-8 Sedum reflexum evergreen blue green 7-8 Sedum sexangulare 5-9 winter green green 7-8 Sedum spurium pink summer green green 7-8 Sedum spurium red summer green dark red 7-8 Sedum spurium white summer green white 7-8 Extensive Green Roof: Rockery type plants (min. depth of 80 mm growing medium) Botanical name Height (cm) Leaf colour Flower colour Months in bloom Location Sedum album (different varieties) 5-10 winter green white 6-8 Sedum floriferum Weihenstephaner Gold 5-10 winter green dark green 6-8 Sedum hybridum Immergrünchen winter green fresh green 7-8 Sedum kamtschaticum summer green yellow 7-8 Sedum reflexum evergreen blue green 7-8 Sedum sexangulare 5-7 winter green green 7-8 Sedum spurium pink summer green green 7-8 Sedum spurium red summer green dark red 7-8 Sedum spurium white summer green white 7-8 Achillea tomentosa 5-20 winter green yellow 6-7 Allium senescens ssp. montanum summer green pink 6-8 Dianthus carthusianorum winter green dark pink 6-9 Dianthus deltoids 5-15 winter green dark pink 6-8 Dianthus plumarius winter green pink/white 6-7 Hieracium aurantiacum winter green orange 6-9 Hieracium pilosella winter green light yellow 6-8 Koeleria glauca winter green blue green 6-7 Petrorhagia saxifraga summer green white (pink) 6-9 Potentilla neumanniana 5-10 summer green yellow 3-4 Saponaria ocymoides summer green deep pink 5-7 Saxifraga paniculata 5-25 evergreen white 6-7 Sempervivum-Hybrids 5-15 evergreen red/pink 7-8 Thymus serpyllum 3-7 evergreen light pink 5-8 Semi-intensive Green Roof: Heather with Lavender ( mm growing medium) Botanical name Height (cm) Leaf colour Flower colour Months in bloom Location Sedum floriferum Weihenstephaner Gold 5-10 winter green dark green 6-8 Sedum hybridum Immergrünchen winter green fresh green 7-8 Sedum reflexum evergreen blue green 7-8 Sedum sexangulare 5-7 winter green green 7-8 Sedum spurium pink summer green green 7-8 Sedum spurium red summer green dark red 7-8 Sedum spurium white summer green white 7-8 Allium tuberosum white white 8-9 Aster amellus summer green violet 7-9 Carex humilis summer green insignificant - Carex ornithopoda summer green insignificant - Dianthus carthusianorum winter green dark pink 6-9 Dianthus deltoids 5-15 winter green dark pink 6-8 Dianthus gratianopolitanus 7-20 winter green pink 5-6 Festuca amethystina winter green blue green 6-7 Helianthemum nummularium 5-10 winter green yellow 5-6 Helicotrichon sempervirens winter green insignificant - Lavandula angustifolia evergreen violet 7-8 Melica ciliata summer green insignificant - Oenothera missouriensis summer green yellow 6-9 Origanum vulgare winter green violet 7-9 Pennisetum alopecuroides Compressum summer green insignificant - Prunella grandiflora summer green deep violet 7-8 Saxifraga paniculata 5-25 evergreen white 6-7 Sedum telephium Herbstfreude summer green brown red 8-10 Teucrium chamaedrys summer green pink 7-8 Thymus vulgaris evergreen violet Alumasc Technical Helpline Key full sun half shade

24 Design Overview Intensive Green Roof Plants Botanical name Height (m) Leaf colour Flower colour Months in bloom Climbing plants Akebia quinata 5-8 summer green crimson 4-5 Clematis montana rubens 2-4 summer green pink 5-6 Clematis tangutica 3-4 summer green yellow 6 Hedera helix evergreen - - Lonicera henryi 3-4 evergreen yellow/red 6-7 Parthenocissus quinquefolia 10 summer green with tendrils greeny 6-8 Parthenocissus tricuspidata 20 summer green minimal Perennials Alyssum montanum 0.2 green yellow 4-5 Arabis procurrens 0.1 winter green white 4-5 Aster ammellus 0.6 dark green purple/pink 7-9 Aster dumosus 0.4 dark green pink 8-9 Aster linosyris 0.6 grey yellow 8-9 Centranthus ruber 0.6 blue/green red 6-8 Coreopsis verticillata 0.6 feathery foliage yellow 6-8 Doronicum caucasicum 0.4 green yellow 4-5 Erigeron hybridus adria 0.7 spiky leaved blue 6-7 Geranium macrorrhizum 0.3 scented leaves pink 6-8 Inula magnifica scented leaves yellow 7-8 Lavandula angustifolia evergreen violet 6-7 Linum perenne 0.5 blue/green blue 6-8 Molinia caerulea blue/green green 8-9 Oenothera missouriensis 0.25 light green yellow 6-9 Origanum vulgare scented leaves pink/red 7-9 Phlox subulata 0.1 evergreen pink 4-5 Rudbeckia sullivantii 0.6 dark green yellow 8-10 Sedum telephium 0.6 fleshy leaved rust/red 9-10 Thymus serpyllum 0.05 evergreen red 6-7 Thymian vulgaris 0.3 dark green bright pink 7-9 Grasses Avena sempervirens winter green green 6-8 Calamagrostis acutifolia fresh green grey/green 7-8 Melica ciliata 0.4 grey green silvery 5-6 Pennisetum compressum 0.6 blue/green brown/green 8-9 Leafy wood shrubs Amelanchier canadensis 1-2 summer green white 4-5 Berberis verruculosa 1 evergreen yellow 5-6 Buddleja davidii 1-2 summer green violet 7-8 Buxus sempervirens 1-2 evergreen insignificant Calluna vulgaris j h hamilton 0.25 evergreen pink 8-9 Calluna vulgaris county wicklow 0.25 evergreen red 8-9 Caryopteris clandonensis 1 summer green blue 8-9 Cornus kousa 1-2 summer green white 8-9 Corylopsis pauciflora summer green yellow 6-7 Cotoneaster adpressus 0.25 summer green pink 3-4 Cotoneaster dammeri creeper white white 6 Cytisus decumbens creeper summer green yellow 6 Cytisus kewensis 0.2 summer green yellow 5 Daphne cneorum 0.3 summer green pink 5 Deutzia gracilis 0.7 summer green white 5-6 Euonymus fortunei creeper evergreen insignificant Genista lydia 0.5 summer green yellow 5-6 Hypericum pat hidcote 1.5 evergreen yellow 7-10 Jasminum nudiflorum 2-3 winter green yellow 2-3 Kolkwitzia amabilis 1-2 summer green pink 5-6 Ligustrum vulgare londense 0.5 winter green does not bloom Pontentilla fructicosa goldfinger summer green yellow 7-9 Prunus tenella 1-2 summer green pink 4-5 Rosa nitida 0.5 summer green pink 5-6 Spiraea arguta 1-2 summer green white 4-5 Spiraea bumalda 1 summer green red 7-8 Spiraea japonica 0.4 summer green pink 7-9 Viburnum fragrans 1-2 summer green pink 1-2 Evergreens Juniperus chinensis 1-2 evergreen insignificant/minimal colour Juniperus communis hibernica evergreen insignificant/minimal colour Juniperus communis hornibrookii evergreen insignificant/minimal colour Juniperus horizontalis evergreen insignificant/minimal colour Microbiota decussata 0.5 evergreen insignificant/minimal colour Pinus mugo mughus evergreen insignificant/minimal colour Pinus mugo mops 0.2 evergreen greenish Taxus baccata evergreen red fruit Taxus media evergreen poisonous Alumasc recommend expert advice is sought from a horticultural specialist when designing an intensive green roof Alumasc Technical Helpline

25 Design Overview Safety Any work on a roof is high risk and good safety standards are essential. Risk assessment and method statements A risk assessment should be carried out for all roof work. It is essential that all risks are identified before the work starts and that the necessary equipment, appropriate precautions and systems of work are provided and implemented. Working on Flat Roofs Regulations require that safety precautions are taken if work is being carried out on roofs with a low parapet. This could be in the form of scaffolding, railings or safety harnesses. Unless the roof parapet provides adequate safety, temporary edge protection will be required during work on flat roofs. Both the roof edge and any openings in it need to be protected. Any protection should be: In place from start to finish of the work Strong enough to withstand people and materials falling against it Accidents occur not only to those constructing roofs, but also to people maintaining, cleaning and inspecting them. Maintenance and Inspection Work Green roofs will inevitably involve regular maintenance and appropriate safety measures are essential. The Health and Safety Executive advise: It may not be reasonably practicable to provide edge protection during short-duration work. In such cases anyone working nearer than 2m to any unguarded edge should be using a safety harness. Where safety harnesses are used they need to be: Appropriate for the user and in good condition full harnesses are essential, safety belts are not sufficient Securely attached to an anchorage point of sufficient strength Fitted with as short a lanyard as possible that enables wearers to do their work Actually used tight management discipline is needed to ensure this The Fallnet system Fallnet Fallnet is a system for providing anchorage points that has been specifically designed for use on green roofs with a slope of up to 5%. It complies with DIN EN 7905: Class E. It consists of a 4m x 4m net of high grade steel wire, which is encased in a 5m x 5m fleece material. At each side of the net are attached eyes, formed in steel wire. These are threaded through anchorage plates to hold the eyes above the level of the vegetation. Fallnet is simply laid over the filter membrane and held in place by the weight of the planting soil of the green roof (minimum 120 kg/m 2 ). Up to two people can attach their lanyards to the eyes of the Fallnet at the same time. The Fallnet system is supplemented by wall-mounted brackets for use where appropriate. growing medium Fallnet Anchorage point Protection layer 24 Alumasc Technical Helpline