Syphonic Roof Drainage

T E C H N O L O G Y
A D V A N C E D
P L U M B I N G
Syphonic Roof Drainage
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
Conventional System
Syphonic System
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
Fall 1 - 3 %
No fall necessary
Many down pipes
Fewer down pipes
Long underground pipes
Short underground pipes
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
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 Geberit HDPE range of pipes and fittings
The highly advanced software package easily allows
accompanies the Pluvia outlets for total drainage.
the calculation of the most complex roof projects. It
Geberit HDPE is available 40mm - 315mm, and can
offers distinct advantages:
be jointed in a variety of different methods including
■ convenient to operate
electrofusion, butt
■ considerable time savings
welding and
■ very easy to use
mechanical coupling.
■ provides
The outstanding
- Isometric drawings
material
- Hydraulic calculations
characteristics of
- Material list incl. fixing components
Geberit HDPE allow
- Cost calculation with ready to mail tender
specifiers and
contractors to design
documents
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.
The Geberit rail fixing system
The Geberit Pluvia fastening system was developed for
the installation of exposed, horizontal roof drainage
Drawings and calculations
piping.
available from the Geberit
The expansion and contraction of the piping, which
Technical Department or
occur after installation are absorbed by the system
Geberit Syphonic approved
itself. For this purpose, all mechanical forces are
installers.
transmitted to the square steel rail routed parallel to
the pipe.
The Geberit Pluvia Outlets are developed for all
types of roof structures. Due to the different discharge
Geberit rail fixing features
rates of the outlets (6 l/s,
■ Large spans between beams can be bridged.
12 l/s or 25 l/s) an
■ Fewer brackets on roof structures
economical layout of the
■ Pre-assembly on the floor is possible:
roof drainage system can
- alignment of clamps on the rail, or
be reached. The wide
- alignment of clamps and of HDPE pipes on the rail
range of contact sheets
■ The clamps are conveniently secured with wedges.
and accessories allows
■ Only very simple tools are required for the assembly
connection to most roof
of the system.
finishes.
■ 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
Geberit Pluvia should only be installed by a Geberit
result of temperature fluctuations are absorbed by
Syphonics approved installer.
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
Series 7 Outlet (12l/s capacity)
Steel Profile Roof Deck
(with Vapour Barrier Clamping unit)
Steel Profile Roof Deck
(without Vapour Barrier Clamping unit)
Roof Membrane
Series 7 Outlet
359.551.00.1
Series 7 Outlet
359.550.00.1
Thermal Insulation
Roof Membrane
Thermal Insulation
Vapour Barrier
Vapour Barrier
Steel Roof
Profile Decking
Steel Roof
Profile Decking
Vapour Barrier
Clamped Seal Unit
900 Bend
900 Bend
Electroweld Coupling and Brackets
(Creating on Anchor Point)
Electroweld Coupling and Brackets
(Creating on Anchor Point)
Geberit Pluvia Rail System
Geberit Pluvia Rail System
Steel Gutter using a Clamping Ring
Steel Gutter using a Contact Sheet/Foil
Min 380 mm
Series 7 Outlet
359.636.00.1
Series 7 Outlet
359.551.00.1
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
Series 7 Outlet (12l/s capacity)
Concrete Roof (no Vapour Barrier)
Concrete Roof (with a Vapour Barrier)
Detail Showing Two Roof Finishes
Detail Showing Two Roof Finishes
Paving
Gravel
Roof
Membrane
Insulation
Series 7 Outlet
359.551.00.1
Gravel
Paving
Roof
Series 7 Outlet
Membrane
359.550.00.1
Insulation
Geberit Contact Sheet
to be Bonded to Roof
Membrane
Geberit Contact Sheet
to be Bonded to Roof
Membrane
Vapour Barrier
Concrete Slab
Concrete Slab
Vapour Barrier
Clamped Seal Unit
900 Bend
Electroweld Coupling and Brackets
(Creating on Anchor Point)
900 Bend
Electroweld Coupling and Brackets
(Creating on Anchor Point)
Geberit Pluvia Rail System
Geberit Pluvia Rail System
Promenade Outlet (with a Vapour Barrier)
Series 7 Outlet
359.550.00.1
(Remove top grating
Roof
Membrane
Insulation
Vapour Barrier
Paved Area
Timber Roof Construction
Series 7 Outlet Geberit Contact Sheet
359.551.00.1 to be Bonded to Roof
Membrane
Geberit Contact Sheet
to be Bonded to Roof
Membrane
50mm Ventilation Gap
Timber Roof
Deck
Roof
Membrane
Promenade top
359.635.00.1
Concrete Slab
Vapour Barrier
Clamped Seal Unit
Timber Joists
900 Bend
12mm Plasterboard
Electroweld Coupling and Brackets
(Creating on Anchor Point)
Geberit Pluvia Rail System
5
Insulation
Typical Roof Types and Overflow
Series 7+ Outlet (25l/s capacity)
25 Litre Outlet
Series 7 Overflow Adaptor
Geberit PVC Coated
Outlet Flange to be
bonded to PVC Roof
Membrane (This outlet is
also available without PVC
coating 359.573.00.1 for
other roof finishes
Pluvia Grating
Held in place by
a wing nut
Adaptor* Ref: 6147/DVW
Series 7 outlet
cover holds unit
in place
Remove and discard
function disc from
outlet
50mm high standpipe
Concrete Slab
90
*Flow capacity of outlet with
adaptor similar to standard outlet
but with water depth 90mm
(normal 40mm)
Pluvia Outlet
359.502.00.1
280
Roof deck
Pushfit joint
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 Membrane
Pluvia Grating
Stones or paving Slabs
Pluvia
Gravel/Clamping
Ring 359.511.00.1
(Fixing extension Rods
and nuts extra
240.816.00.1)
Concrete Slab
Concrete
Slab
15mm max
56
Pluvia Outlet
359.501.00.1*
Insulation
15mm Max
214
*359.500.00.1
Stainless Steel Finish
56
214
6
Pluvia Outlet
359.500.00.1
Mastic Asphalt
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 Series 7 Outlet
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
8l/s
Max. flow capacity
25l/s
Discharge capacity (outlet in gutter)
20l/s
Outlet spigot diameter
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 33m2 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
Check that no pipes connecting
Ensure all outlets have gratings
or silt as shown in figure 1.
to outlets are blocked with silt etc,
and tops in place. Order spares
if blockages are found they can
from Geberit if necessary.
a
Remove lid
be removed by using a water jet
through the outlet after removing
b + c Remove function disc
the top unit and function plate (a,
b & c in figure 1)
d
Rinse function disc with
water
e
Wipe outlet with cloth
d
c
a
b
b
e
Figure 1
8
T E C H N O L O G Y
P L U M B I N G
A D V A N C E D
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