Roof greening guide from singpore

‘A Concise Guide to Rooftop Greening’ was jointly prepared by National Parks Boardand The Centre for Urban Ecology and Greenery (CUGE).Contributors: Ng Cheow Kheng Nur Faezah Mohd Sanif Peter Hunt Poh Choon Hock Shirley Ling Simon LongmanWe would like to thank the following organisations for their contribution: Bedok Reservoir – Punggol Harmony Resident’s Committee City Developments Limited Elmich Pte Ltd Far East Organization Frasers Centrepoint Limited Garden and Landscape Centre Pte Ltd Hitchins (FE) Marketing Pte Ltd Housing Development Board Khoo Teck Puat Hospital National Archives of Singapore Shaw Organisation Singapore Botanic Gardens Surbana International Consultants Pte Ltd Uniseal Waterproofing Pte Ltd Zinco Singapore Pte LtdAll rights reserved. No part of this work may be reproduced or copied in any form or by any means, electronicor mechanical, including photocopying, without the prior permission of the copyright owner.©National Parks Board, 2010

CONTENTS introduction 2 benefits of rooftop greenery 4 i . . . good for the environment 5 ii . . . brings economic rewards 7 ii . . . ideal for social interaction 9 ii . . . enhances a building’s aesthetic appeal 10 types of rooftop greenery 12 green roofs 13 roof gardens 15 a selection of rooftop greenery in singapore 16 ready for rooftop greenery? 17 i . . . provision of rooftop greenery to new building 17 ii . . . provision of rooftop greenery to existing building 18 faqs 19

INTRODUCTIONHave you ever thought about greening your building’srooftop? Well, the art of rooftop greenery is fastbecoming very popular in Singapore. Over the pastfew years, more and more buildings, both privateand public, have decided to go green over theirroofs. You will find some interesting rooftop greeneryalong the shopping belt in Orchard Road and manyothers in the heartlands of Punggol, Queensway andWoodlands.If you are keen to find out more about rooftopgreenery, this concise guide will provide you withuseful information and guidelines for this greenjourney. 2

BENEFITS OFROOFTOP GREENERYOne of the many benefits of greening your rooftop isthat a green roof will last longer than a conventionalone. It looks more attractive and it also helps reducethe urban heat island effect that is currently affectingmany urbanised cities like Singapore.But that’s not all. Rooftop greenery is also... 4

...GOOD FOR THE ENVIRONMENT Bare rooftops and concrete surfaces act as heat sinks, making Singapore’s urban areas o 3 C hotter than the rural ones. Rooftop greenery shields bare surfaces from the harsh Study of Urban Heat Island in Singapore - Dr Wong Nyuk Hien, 2004 tropical sun, cooling the urban environment. Are you staying in one of these hotspots? Improve air quality Rooftop vegetation improves the air quality directly by filtering airborne particles in their leaves and branches. Through photosynthesis, plants on green roofs contribute to maintaining the stability of the atmosphere’s composition. Better acoustic insulation Rooftop greenery can reduce noise levels by up to 50 dB.5

Conventional Roof vs Green Roof Conventional Roof Green Roof Higher surface temperature Reduces surface temperature Higher indoor air temperature Reduces room temperature Higher waterproofing damage Reduces carbon emission Reduces rain water discharge …compared to green roofs. …for cooler and cleaner environment.Improve rainwater retentionRooftop greenery improves rainwaterretention to help storm drains copewith severe downpour, reducing flashfloods.Rooftop greenery can filter heavymetals and nutrients present inrainwater, keeping our reservoirsclean and vibrant. 6

...BRINGS ECONOMIC REWARDS Create more usable space In urban areas, rooftop greenery can be used to reclaim lost space and create lush green views. Reduce cooling resources through better insulation Rooftop greenery serves as insulation, cooling buildings and leading to savings of up to 15% from improved energy efficiency of air conditioning.7

Provide savings in drainage infrastructureThe ability of green roofs to retain rainwater and tolower peak runoff can aid in reducing the extent ofstormwater drainage infrastructure.Provide space to cultivate vegetablesand foodIn urban areas where high-rise dwellers lack spacefor a garden, rooftop greenery helps to facilitateagricultural production. 8

...IDEAL FOR SOCIAL INTERACTION Foster community interaction Facilitate recreational and leisure activities Roof gardens atop high-rise residences or office buildings can provide an alternative relaxing setting As there is a high premium for land at street level for neighbours and colleagues to mingle. in the cities, rooftop gardens provide less crowded, less polluted and less noisy spaces for informal Therapeutic effects and improve recreation. health of its users Plants can have a restorative effect, which leads to decreased stress, improved patient recovery rates, and a higher resistance to illnesses.9

...ENHANCES A BUILDING’S AESTHETIC APPEALImprove aesthetic appealLandscaping has often been used to improve theappearance of the urban environment. Greeneryprovides visual contrast to the highly built-up cityenvironment and relief for tired eyes.Hide unsightly rooftop servicesResidents and workers in high-rise developmentsoften look down on large expanses of ugly asphalt,tiles, slates and flat roofs. Rooftop greenery provides acover and creates better visual interest for rooftops.Integrate well with buildingsA layer of plants can enhance good design or disguisebad design in building developments. Plants addvisual interest to plain walls and roofs and soften the‘straight edged’ features of industrial and commercialproperties. 10

TYPES OF ROOFTOP GREENERYThere are three types of rooftop greenery - Green Roofs, Hybrid Gardens &Roof Gardens. The basic layers remain the same although designs may differ. Green Roofs Hybrid Gardens Roof GardensPlant Group Grasses and/or Grasses and/or Grasses, groundcovers groundcovers groundcovers, and low shrubs shrubs and treesSystem build-up up to 150 mm up to 250 mm up to 1500 mmheightSystem build-up ≤ 150 kg/m2 ≤ 300 kg/m2 ≤ 500 kg/m2weightMaintenance Low Periodic HighThe above values are estimates. It is advisable to consult a Professional Engineer and landscapeexperts for the calculation of loads. 12

GREEN ROOFS Do not be unduly worried if your green roof looks a little unkempt with overgrown weeds and shrubs - it is part of the natural green roof look. Green roofs are not designed for public access. They are mainly developed for their aesthetic and ecological benefits. With their thinner vegetation support layer, green roofs are lighter compared to the heavier roof gardens. They also support a limited range of vegetation species – with preference for drought- tolerant vegetation with shallow roots. Requiring minimal maintenance, green roofs are potential value-adding features to both existing rooftops and new buildings. Access to green roofs is limited to periodic maintenance.13

Vegetation Growing Medium Drainage Layer / Water Reservoir Insulation (optional) Membrane protection & Root barrier Roofing Membrane Structural Support Typical Cross Section of a green roof systemThere are many ways in which green roofs can be landscaped and set up. Here are the two popular models: Blanket Model / In situ Green Roof Model Modular Model Involves the in situ assembly of green roof Involves the modularisation of green roof components in sheet layers, directly across the roof components into standard small trays that are Allows lateral migration of water and roots assembled and planted ex situ, and later installed on the roof Has a seamless look Each tray is equipped with a filter layer, drainage Is customised to fit roof site area and storage cells to hold the substrate media for the plants Has the appearance of a grid 14

ROOF GARDENS Roof gardens are developed to be accessible for use. They usually incorporate areas of paving and seating. With potentially deeper soil depths to support a wide range of plant species, roof gardens are more suitable for new buildings where the building structure can be appropriately designed to cater for the higher overall loading. Regular garden maintenance such as mowing, fertilising, watering and weeding is required for such intensive landscaping.15

A SELECTION OF ROOFTOP GREENERY IN SINGAPORESingapore Botanic Gardens HDB Carpark Roof @ 180 Edgefield PlainsSingapore Flyer School of Art, Design and Media, Nanyang Technological UniversityPeople’s Association Headquarters Khoo Teck Puat Hospital 16

READY FOR ROOFTOP GREENERY? PROVISION OF ROOFTOP GREENERY TO NEW CONSTRUCTION Incorporating rooftop greenery into the original design of a new construction will save you time and money. But before deciding on one, do consult the architects to develop a detailed plan for your rooftop greenery.17

PROVISION OF ROOFTOP GREENERY TO EXISTING BUILDINGThe approach for greening an existing rooftop should be a holistic one. Here are some of the considerationsyou have to take into account prior to installation:Load-bearing capacityThe weight of most green roof systems is between50 to 150 kg/m2. Check the current load for the existing roof The roof’s load bearing capacity is usually found in building’s floor plansExisting rooftop surfaceEnsure that the roof surface is made good prior toinstallation of any rooftop greenery. Existing waterproofing of the roof Roof must be smooth and even Installing a green roof over a waterproof membrane Roof must have minimal or zero cracks significantly extends the life of the waterproof membrane and the life cycle of the roof. Roof must be adequately sloped to fall Ensure water-tightness on the rooftop before installing any rooftop greenery Drainage Blockage of drainage leads to the continuous contact of roof surfaces with water or wet soil. It also leads to unwanted stagnant water which can be a fertile ground for breeding mosquitoes. Inspect drainage on rooftops and ensure drainage routes are not blocked 18

FREQUENTLY ASKED QUESTIONS (FAQs) If plants are exposed to a prolonged period of Will a green roof affect my waterproofing? drought, will they grow back subsequently? Correct installation of a green roof will not have any It depends on your choice of plants, which should be adverse affect on the waterproofing. The additional hardy and drought-tolerant. layers of a green roof can protect the roofing membrane from UV rays, extreme temperature What is the average weight of a green roof system? fluctuations and puncture. The reduced stress can The average weight of green roof system ranges from double the waterproofing’s serviceable life. 50-150 kg/m2. Is rooftop greenery expensive to maintain? It is advisable to consult a certified Professional Engineer on the load bearing capacity of the roof structure, Maintenance costs vary. You can work with your regardless of whether you are working with a new or contractor to design a solution to fit within your existing building. budget. Is an irrigation system required? For the lowest cost, consider a sustainable green roof where plants are allowed to flourish together as nature Green roofs are intended to be non-irrigated. Usually, intends. Maintenance is infrequent and this is the best the drainage layer comes incorporated with an choice to achieve biodiverse, environmentally friendly integrated water reservoir. However, green roofs with rooftop greenery. integrated irrigation are not uncommon. If you are considering installing irrigation for your green roof, drip-irrigation is the preferred choice. Sub-surface drip irrigation optimises the use of water by directly dampening the substrate. What is the lifespan of green roof? The lifespan of a green roof is about 20 years. It can last longer when well maintained. The conventional exposed roofs need maintenance every five to ten years.19

SUGGESTED READINGCUGE STANDARDS PUBLICATIONSThe CUGE Standards is a set of written guidelines for voluntaryadoption in the landscape and horticulture industry. They are written Selection of Plants for Green Roofs in Singaporethrough a formal process that involves consultation with relevant (2nd Edition)bodies and reaching consensus across all interested parties so Editors: Tan Puay Yok & Angelia Siathat the final document meets the needs of business and industry.All standards take the form of either specifications, methods, This handbook presents a selection of over seventy plants that arevocabularies, codes of practices or guides. suitable for green roofs in Singapore. ISBN 978-981-07-0052-2CS E 01: 2010- Guidelines on Design Loads for Rooftop Greenery Introduction to Vertical Greenery Editors: Derek Chan & Kelly ChiangThe Guidelines On Design Loads for Rooftop Greenery includessuggested landscape materials and their appropriate placement. A An introduction to vertical greenery systems, some basic principlesuseful reference for designers and installers of rooftop gardens. for set-up, a quick look at classification of systems, and largely with details on the vertical green systems at Hortpark.ISBN 978-981-08-5231-3 ISBN 978-981-08-1623-0CS E 02:2010- Guidelines on Design for Safety on Rooftop Greenery Vertical Greenery for the Tropics Editors: Kelly Chiang & Alex TanThe Guidelines on Design for Safety on Rooftop Greeneryhighlights safety considerations during the design, installation and This publication outlines the benefits, technical know-how, andmaintenance phases. A useful reference for designers and installers considerations for design and maintenance in the implementationof rooftop gardens. of vertical greenery in Singapore and it will serve as a usefulISBN 978-981-08-5232-0 resource for policy makers, city planners, developers, students and professionals in the architecture, landscape and horticulture industries, who will be able to glean a greater understanding ofCS E03:2010 current trends, technical and design considerations as well as the- Guidelines on Substrate Layer for Rooftop Greenery advantages of vertical greenery.The Guidelines on Substrate Layer for Rooftop Greenery is ISBN 978-981-08-3973-4intended to provide an understanding of the constituting substrate-components, their respective Technical Properties & recommendedPerformance Criteria, for effective monitoring of the substrate’soverall performance and quality control.ISBN 978-981-08-7203-8CS E04:2010- Guidelines on Filter, Drainage and Root PenetrationBarrier Layers for Rooftop GreeneryThe Guidelines on Filter, Drainage and Root Penetration BarrierLayers for Rooftop Greenery is intended to provide an understandingof the filter layer, the drainage layer, the root penetration barrierlayer and their respective constituting materials. The guidelineswill also provide the recommended Technical Properties andPerformance Criteria for the effective monitoring of the layers’overall performance, design and installation considerations.ISBN 978-981-08-7206-9

National Parks BoardHeadquartersSingapore Botanic Gardens1 Cluny Road, Singapore 259569Tel: (65) 64717808, Fax: (65) 67621383Email: skyrisegreenery@nparks.gov.sgwww.nparks.gov.sg/skyrisegreenery

Roof greening guide from singpore

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