Syphonic Roof Drainage A D V A N C E D P L U M B I N G T E C H N O L O G Y Design Guide SYPHONICS Advanced Roof Drainage Technology
Design, Manufacture and Installation TSB Call Centre, Cardiff. Millenium Plaza, Cardiff. The Light Office Block, Leeds. Honda Car Factory, Swindon. The Lowery Galleria, Manchester. Tesco, Old Swan. Stoke City FC.
Design, Manufacture and Installation Geberit Pluvia is the leading syphonic roof drainage system used throughout the world. Architects, Consultants and Contractors have chosen the system for some of the most prestigious and ground breaking building designs due to the freedom and flexibility it provides. Pluvia uses the ingenious gravity induced vacuum principle to create a syphonic action, which allows the complete drainage of a roof area with smaller diameter pipes than used in a conventional gravity system. Geberit Syphonic roof systems are widely used in the industrial and commercial sector for all roofs. Geberit Pluvia Advantages new architectural flexibility in building and use no slope in pipework required less underground pipes less sitework fewer pipes and fittings reduced pipe dimensions less space required self cleaning action a simple and speedy fastening system Conventional System Fall 1-3 % Many down pipes Long underground pipes Syphonic System No fall necessary Fewer down pipes Short underground pipes The Geberit Pluvia System is fully approved by the BBA. This includes outlets, pipes & fittings, and the dedicated design software. All installations carry a minimum of a ten year product and design guarantee, and are carried out by a Geberit Syphonics approved installer. The product range includes outlets to suit most roof designs and finishes, with a comprehensive range of contact foils to suit the majority of roof membrane materials currently on the market. RIBA approved CPD seminars are available. Please contact Geberit for more information. 1
Software Geberit Pluvia DLS software The highly advanced software package easily allows the calculation of the most complex roof projects. It offers distinct advantages: convenient to operate considerable time savings very easy to use provides - Isometric drawings - Hydraulic calculations - Material list incl. fixing components - Cost calculation with ready to mail tender documents The Geberit HDPE range of pipes and fittings accompanies the Pluvia outlets for total drainage. Geberit HDPE is available 40mm - 315mm, and can be jointed in a variety of different methods including electrofusion, butt welding and mechanical coupling. The outstanding material characteristics of Geberit HDPE allow specifiers and contractors to design and pre-fabricate pipe runs away from the site of the installation. Pipe runs can be created in a safe, clean environment ensuring secure and accurate fabrication as well as considerable material and labour savings. Drawings and calculations available from the Geberit Technical Department or Geberit Syphonic approved installers. The Geberit Pluvia Outlets are developed for all types of roof structures. Due to the different discharge rates of the outlets (6 l/s, 12 l/s or 25 l/s) an economical layout of the roof drainage system can be reached. The wide range of contact sheets and accessories allows connection to most roof finishes. Geberit Pluvia should only be installed by a Geberit Syphonics approved installer. The Geberit rail fixing system The Geberit Pluvia fastening system was developed for the installation of exposed, horizontal roof drainage piping. The expansion and contraction of the piping, which occur after installation are absorbed by the system itself. For this purpose, all mechanical forces are transmitted to the square steel rail routed parallel to the pipe. Geberit rail fixing features Large spans between beams can be bridged. Fewer brackets on roof structures Pre-assembly on the floor is possible: - alignment of clamps on the rail, or - alignment of clamps and of HDPE pipes on the rail The clamps are conveniently secured with wedges. Only very simple tools are required for the assembly of the system. The clearance required to install insulation against condensation is accounted for in the design. The system overcomes fixing constraints on steel profile roofs. The forces associated with changes in length as a result of temperature fluctuations are absorbed by the rail fastening. 2
Methodology for Designing a Pluvia System Step 1 Determine the roof(s) drainage patterns. Step 2 Calculate the areas of roof(s) draining to each outlet (see capacities on page 7) Step 3 Determine the rainfall intensity rate Method A Geberit recommend using 108 mm/hr (0.03 l/s per sq.m.) In the UK this figure provides a frequent return rate for a 2 minute storm which ensures the systems self cleansing routine is activated. Method B Use the method and data provided in BS EN 12056 part 3. We do however advise against using the very high rainfall intensity rates that can be generated if long life spans for the building and high safety factors (categories) are used in the calculations. Example: Project located in London requiring 25 year life span protection, Category 3 Safety Factor. This will result in a rainfall intensity rate of 236 mm per hour. In reality this will mean that once every 112.5 years for 2 minutes there may be a storm with a rainfall intensity of 236 mm/hour. Using this high rainfall rate will result in the systems pipework being massively oversized, which will result in the system not operating syphonically frequently, requiring a high level maintenance programme to check for silt build up in the pipes. Geberit recommend using the rainfall rate mentioned in Method A and allowing any potential higher rate rainfall to temporarily accumulate on the roof (for valley gutters this may require some over sizing of the gutter to provide additional storage capacity). Example: If the 236 mm/hrs protection is required, design a primary system to cope with 108 mm/hr. The build up from the excess over 2 minutes would be 236-108 128 30 = 4.3 mm If the above mentioned temporary storage method is not acceptable then one of the three options below may be used: Option 1 Weir overflows in the parapet walls. Option 2 A secondary syphonic overflow system. Option 3 A separate internal overflow system (gravity). (See page 6 for detail) In all roof designs an emergency/warning overflow must be provided to indicate a blockage within the system. Step 4 Contact the Geberit Technical Department or Geberit Syphonics approved installer to design and calculate a system. 3
Typical Roof Types (12l/s capacity) Steel Profile Roof Deck (without Clamping unit) Steel Profile Roof Deck (with Clamping unit) 359.551.00.1 Roof Thermal Insulation 359.550.00.1 Roof Thermal Insulation Steel Roof Profile Decking 90 0 Bend Electroweld Coupling and Brackets (Creating on Anchor Point) Geberit Pluvia Rail System Steel Roof Profile Decking Clamped Seal Unit 90 0 Bend Electroweld Coupling and Brackets (Creating on Anchor Point) Geberit Pluvia Rail System Steel Gutter using a Clamping Ring Steel Gutter using a Contact Sheet/Foil Min 380 mm 359.551.00.1 359.636.00.1 Flange to be riveted, soldered or welded depending on gutter finish Gutter Gutter Geberit Clamping Ring 359.568.00.1 Min. 350 mm 4
Typical Roof Types (12l/s capacity) Concrete Roof (no ) Detail Showing Two Roof Finishes Concrete Roof (with a ) Detail Showing Two Roof Finishes Gravel Paving Gravel Paving Roof Insulation 359.551.00.1 Geberit Contact Sheet to be Bonded to Roof Roof 359.550.00.1 Insulation Geberit Contact Sheet to be Bonded to Roof Concrete Slab Concrete Slab 90 0 Bend Electroweld Coupling and Brackets (Creating on Anchor Point) Geberit Pluvia Rail System Clamped Seal Unit 90 0 Bend Electroweld Coupling and Brackets (Creating on Anchor Point) Geberit Pluvia Rail System Promenade Outlet (with a ) Timber Roof Construction Paved Area Roof Insulation 359.550.00.1 (Remove top grating Geberit Contact Sheet to be Bonded to Roof Promenade top 359.635.00.1 50mm Ventilation Gap 359.551.00.1 Geberit Contact Sheet to be Bonded to Roof Timber Roof Deck Roof Concrete Slab Clamped Seal Unit 90 0 Bend Electroweld Coupling and Brackets (Creating on Anchor Point) Geberit Pluvia Rail System Timber Joists 12mm Plasterboard Insulation 5
Typical Roof Types and Overflow Series 7+ Outlet (25l/s capacity) 25 Litre Outlet Series 7 Overflow Adaptor Pluvia Grating Held in place by a wing nut Geberit PVC Coated Outlet Flange to be bonded to PVC Roof (This outlet is also available without PVC coating 359.573.00.1 for other roof finishes Remove and discard function disc from outlet Adaptor* Ref: 6147/DVW Series 7 outlet cover holds unit in place 50mm high standpipe Concrete Slab 90 280 Pluvia Outlet 359.502.00.1 *Flow capacity of outlet with adaptor similar to standard outlet but with water depth 90mm (normal 40mm) Pushfit joint Roof deck Series 5 Outlets (6l/s capacity) PVC Roof Finish Asphalt Roof Finish Pluvia Grating Geberit PVC Coated Outlet Flange to be bonded to PVC Roof Stones or paving Slabs Pluvia Grating Pluvia Gravel/Clamping Ring 359.511.00.1 (Fixing extension Rods and nuts extra 240.816.00.1) Concrete Slab 15mm max 56 214 Pluvia Outlet 359.501.00.1* *359.500.00.1 Stainless Steel Finish Concrete Slab Insulation 15mm Max 56 Pluvia Outlet 359.500.00.1 214 Mastic Asphalt 6
Technical Specification of Outlets Series 5 Outlet (Small) Min. flow capacity 1l/s + Max. flow capacity 6l/s Discharge capacity (outlet in gutter) 1-5l/s Outlet spigot diameter 56mm Standard Min. flow capacity 1l/s + Max. flow capacity 12l/s Discharge capacity (outlet in gutter) 1-10l/s Outlet spigot diameter 56mm High Capacity Series 7+ Outlet Min. flow capacity Max. flow capacity Discharge capacity (outlet in gutter) Outlet spigot diameter 8l/s 25l/s 20l/s 90mm Design Parameters Min. pipe diameter 40mm Max. pipe diameter 315mm Min. flow velocity 0.7m/s Min. water to air ratio 60% Max. negative pressure 40-160mm (PN4)* -800mbar Max. negative pressure 200-315mm (PN3.2)* -450mbar Max. negative pressure 200-315mm (PN4)* -800mbar Min. 2 outlets to be installed on a system Emergency warning overflows must be provided on all roofs Pluvia outlets should be spaced no further than 20 metres apart Pluvia outlets should be spaced no further than 10 metres from end of gutter All horizontal pipes must be laid level (no gradient) + This equates to 33m 2 based on 0.03l/s (108m/hr) *PN4 denotes a thicker wall pipe 7
Maintenance Geberit recommend that a maintenance programme is always implemented on completion of the project. The intervals between inspection will depend on the location of the building. The maintenance programme should include:- 1 2 3 Clearing of all outlets of any debris or silt as shown in figure 1. a Remove lid b + c Remove function disc d Rinse function disc with water Check that no pipes connecting to outlets are blocked with silt etc, if blockages are found they can be removed by using a water jet through the outlet after removing the top unit and function plate (a, b & c in figure 1) Ensure all outlets have gratings and tops in place. Order spares from Geberit if necessary. e Wipe outlet with cloth d a c b b e Figure 1 8
A D V A N C E D P L U M B I N G T E C H N O L O G Y Other Geberit Syphonic literature available: Product and price guide Other innovative products available within the Geberit Ltd. product portfolio include: Geberit Terrain UPVC & HDPE soil, waste and underground drainage systems Geberit Mepla water supply Geberit Terrain Rainwater Systems Geberit Duofix wall hung sanitaryware installation systems, WC and urinal flushing systems, electronic washroom solutions and shower toilets Please call 0700 4323748 or visit www.geberit.co.uk for more information. Geberit Ltd. New Hythe Business Park New Hythe Lane Aylesford, Kent ME207PJ Tel:+44 (0)1622 717811 Fax:+44 (0)1622 716920 www.geberit.co.uk Registered office as postal address Registration Number 761885 SYPHONICS