www.stpltd.com WATERPROOFING OF GREEN ROOF
www.stpltd.com FIRST GREEN ROOFHanging Gardens of Babylon
www.stpltd.com Hanging Gardens of Babylon • Gardens were attributed to the Neo – Babylonian king Nebuchadnezzar II, who ruled between 605 to 562 BC. • He built it for his homesick wife • Garden got destroyed by several earthquake after 2nd century BC. • Many Greek and Romans writers referred in their creation. • No archaeological evidence has been found
www.stpltd.com What is Green Roof • A building roof which is partially or fully covered with vegetation and a growing medium, planted over a waterproofing membrane along with root barrier, drainage and irrigational system. • Green roof does not refer green coloured roof with tile or shingle finished. • Green roof is also called living roofs/eco- roof/vegetative roof. • Cool roof with solar thermal collector or photovoltaic panel are also covered under green roof
www.stpltd.com Types of Green Roof • Depending on types of vegetation ,the green roof is divided into: • Intensive type • This is like an elevated park having a foot of growing medium with trees, plants, walkways, benches with their complex structural supports. It creates a load of 36 – 68 kg/sft • Extensive type • Supports lighter vegetation like grasses, hubs, sedum, etc. The weight in this case is 7 – 23 kg/sft
www.stpltd.com Typical Green Roof Structure
www.stpltd.com Benefits of Green Roof Social Benefits – Improved Livability Aesthetic Benefit- Better look and usefulness Environmental Benefits- Helps to mitigate heat island effect and pollution reduction Noise Reduction- Thick roof acts as an Acoustic Insulator Fire Protection- Reduces Fire risk Energy Conservation- Reduces indoor temperature and traps blowing snow Helps Municipal septic system by reducing storm water runoff and absorbing water
www.stpltd.com Anatomy of a Green Roof Vapour Barrier:a breathing thin synthetic membrane allows to release entrapped water vapour. Thermal Insulation: Preferably Extruded Polystyrene of 50 /75 mm thickness in single layer Protection Layer: An isolation layer of geotextile or could be a synthetic board
www.stpltd.com Anatomy of a Green Roof Waterproofing Membrane Leak in green roof leads to an extreme discomfort and other complex. The heart of the system is waterproofing Membrane. Membrane must be reliable in performance having excellent past track record and with Properties Highlighted in next slide.
www.stpltd.com Properties of Membrane Desired Properties of Membrane Sufficiently Elastic to withstand building movement and unforeseen shock Totally Impermeable Good Mechanical Properties Must withstand ponding water Non Biodegradable Preferred to be root resistant
www.stpltd.com Recommended Membrane PVC Membrane PVC Membrane produced manufactured by Calendaring and extrusion process and laminated under strict on line quality control and a thorough post manufacturing checks . Membrane may be reinforced/ non reinforced ; also with fleece or without fleece. Fleece is a back up with non woven geotextile. Minimum Thickness of PVC membrane shall be 1.5mm without fleece. Membrane is applied loosely or adhered with adhesive And all overlap joints are fully sealed by machine with hot air welding .
www.stpltd.com Recommended Membrane Liquid Membrane Water based polyurethane blended with specially formulated cold bituminous compound Having high elongation and other desired Properties. Cold applied with brush or roller with a primer coating in two or more layers with a reinforcement or no reinforcement
www.stpltd.com Anatomy of a Green Roof Root Barrier As a safety it is recommended to have a root barrier membrane which is primarily a plastic material like HDPE sheet, Plant root would repel and change direction. Filter & Drainage Layer This helps to drain the excess water .It is a dimpled HDPE sheet forming a channel to assist flow of water
www.stpltd.com Anatomy of Green Roof Non Clogging Separation A synthetic fabric of polypropylene of 120 can do the purpose which allows only water to pass through avoiding any hindrance to water flow. Water Retention layer This is to provide the plants an extra in time of drought or prolonged high temperature. Usually any fibrous felt absorbing water in its pores suit the purpose
www.stpltd.com Anatomy of a Green Roof Growing Medium A specially designed soil light in weight , good water storage property , low organic content and with well distribution of particle Size are recommended. Appropriate Plant Selection of the right plant keeping in view of the height of growing medium is important to have an efficient green roof system.
www.stpltd.com Quality Assurance Steps for Ensuring Quality Selection of a good certified applicator Approval of a shop drawing with all termination details before starting of work Sole access of waterproofing contractor till system is laid, tested and protected Check by flood testing or Leak Detection system Followed by a joint inspection
www.stpltd.com Other Steps to Ensure Quality Submittals All product data sheet with back up of manufacturers’ test certificates Authorised Applicator certification Sample Warranty certificate Warranty A single point warranty is provided by the certified applicator with back up warranty for products from Manufacturers Facilities Waterproofing contractor must be treated with a respect with all desired facilities and conditions to have an efficient system in place. All checks must be done at the membrane level for waterproofing work to correct the shortcoming
www.stpltd.com CASE STUDY for A Green Roof • Building: Grand Hotel, Kalidria, Italy • Objective: Improvement of Ecology, creation of open space, Energy savings and self sustained irrigation system with a reduction in water supply from external sources. • Roof Area: 25000 sft, 80 % covered with green roof • Green roof : Extensive Type
www.stpltd.com Case Study • Slope of Roof: Flat • Soil Mix : Mix of mineral ,coarse sand and permissible organic element • Fertilizer: Mix of gypsum, sulphate,pottasium and minimum urea, • Plant Type: Drought Tolerant • Irrigation : 45 minutes Drip irrigation on every alternate day • Maintenance: Height of plant to maintain 9 to 12 inches with the help of occasional trimming and regular cleaning of weeds.
www.stpltd.com Case Study • Structural Load : 50 lbs/sft • Cost: US$ 2.00 per sft • Architect: Xavier and Partner • Landscape Designer: Milano Eco Forum • Waterproofing Contractor/ Authorized Applicator: Lima & Company , a certified applicator of RENOLIT SA, Germany.
www.stpltd.com Case Study- Roof Construction • RCC Roof • Vapour Barrier: HDPE Thin Film • Thermal Insulation: 50 mm Extruded Polystyrene with Ship lap edges • Waterproofing Membrane: RENOLIT ALKORPLAN LA 1.5 mm thick loosely laid PVC membrane with a fleece back • Root barrier: 50 gsm Polypropylene non woven mat
www.stpltd.com Case Study • Drainage & Filter layer: ShaliDrain of 8mm Dimpled sheet of HDPE with a top layer of nonwoven polypropylene of 100 gsm • Water Retention layer: 40 mm thick rock wool fibre mat
www.stpltd.com Challenges & Benefits Tight completion target of 45 days for all work up to soil laying. Substantial reduction to the extent of 8 deg C of Indoor temperature resulting a significant energy savings Storm water collection helped to have self sustained irrigation system and with an additional support of reduction in water procurement.
www.stpltd.com Conclusion • Green Roofs must be popularised for social, environmental and economic reasons. Thanks to IGBC for its leadership and dedication. • A good attention needs to be paid in selecting materials particularly waterproofing membrane to ensure the first step towards efficient system. • Manufacturers must share information and closely interact with the specifiers. • Upgradation Applicators through adequate training also equally important.