1. Ducted Distribution of Services
QUS 3206 / MDM NURUL AINI

2. Ducted Distribution of Services
• Service duct require careful planning and should be considered at
an early stage in the design of a building.
• Accommodation of the plant and the layout of services are the two
essential factors in design.
• It is usual to need some 7 – 10% of the total floor area for plant
spaces and ducts.

3. Ducted Distribution of Services
• The purpose :
• conceal the services and to facilitate
inspection, repair and alterations.
• Helps to reduce noise
• Protects the services from damage

4. Terminology
• Plant space – area required for the
accommodation of mechanical or electrical
equipment or control gear required for the
operation of services
• Storage space – area required for the
accommodation of storage containers required
for particular services
• Duct – space within a building specially
enclosed for the accommodation of services
and allowing facilities for working and
inspection.

5. Terminology
• Subway – a horizontal passage for the
conveyance of services underground or
below the bottom floor of the building which
allows walking headroom for access.
• Crawlway – passage for services similar to a
subway but where there is insufficient
headroom to stand upright.
• Trench – horizontal passage for services
below floor level where the access is by
removable covers in the floor.

6. Terminology
• Wells – vertical space used for the
accommodation of stairs or lifts or
to allow natural light or ventilation
• Casing – an enclosure formed over
pipes or cables running on the
surface of a wall or ceiling. Casing
are usually for decoration but can
also provide protection from
impact or corrosion.

7. Terminology
• Chase – a recess cut in a wall or
floor when building is over; it
accommodates pipes or cables and
is screed or plastered over
• Void – space may used for the
accommodation of services but
which is not primarily for this
purpose

8. Ducts for Small pipes or cables
• These may be formed in the floor or wall, or on
the surface of the wall.
• The size of ducts depends upon the outside
diameter of the pipe or cable and the number
of services installed.
• Normally the outside diameter not exceeding
64mm

9. • Casing & Chase

10. Terminology
• Sump – pit for seepage, leakage and draining
down of pipework that cannot be discharge by
gravity to the drain and must be collected and
pumped.
• Trunking – lightweight, usually sheet metal
enclosure for the passage of air or cables

11. Terminology
• Flue – builders’ work or metal passage to
convey the products of combustion to an
acceptable point for discharge to the
atmosphere
• Service core – zone extending vertically
through high rise building containing vertical
circulation, service ducts and other utility
and sanitary provisions.

12. Importantof unifiedsystemof services
distribution
• Most services can be run in common ducts except flammable
liquids and gases
• The pattern of distribution of services is considered as a whole in
relation to the building planning
• 3 different categories of services run having different requirements
for patterns of distribution:
• Wells and flues
• Pipes and ventilation trunkings
• Electrical cables
• Stair and lift wells run vertically through buildings. They do not
required linkage with services at each floor level but prevent an
obstacle to horizontal distribution of other services

13. Locationand approximatesizingof plant
spacesand ducts
• Different building functions will imposed different priorities on the
service
• Electrical cables do not normally imposed serious limitations on
planning however the length of cables may be a dominant factor

14. Locationandapproximatesizingofplantspacesand
ducts–Planningconsiderations
Air trunking
• large and essential to consider
them at the outset of any design
• They must be take into
consideration first before other
services due to the space
requirement
Waste and soil installation
• Are not as large as air trunking but
need to be design in the early stage
due to space requirement

15. Locationand ApproximateSizingof Plant Spaces
andDucts
Heating pipes
• May be larger than waste and soil pipes in
large buildings due to the insulation but
generally they are smaller in size.
Water supply pipes
• Are very often smaller than heating supply
pipes and do not require heavy insulation.
• They are equal flexible in their detailed layout
and may be taken up and over or under
obstruction without any major problems.

16. Locationand ApproximateSizingof Plant
Spacesand Ducts
Electrical cables
• Very small in most buildings and they can
very easily be accommodate in
comparatively small trunking
• They are disposed within the thickness of a
floor screed

17. Approx.sizingof ducts:
Several factors to consider in deciding the size of ducts and recess:
• Number & size of pipes, cables & trunkings to be accommodated
• Any critical spacing or fixing position which must be followed for certain
pipe types
• Clearance required for placing the pipes in position, which must also allow
for ease of removal should it become necessary during maintenance
• Clearance to allow for position of fixings and to permit jointing

18. Approx.sizingof ducts:
Several factors to consider in deciding the size of ducts and recess (cont’d):
• Allowance for additional services which may be needed
• Space for access in the case of ducts
• Space of valve, dampers
• Space for expansion bands in long, straight horizontal or vertical ducts
• Space for branching and service junctions, and to carry these branches
past adjoining services

19. Vertical ducts & Undergroundducts
• Vertical ducts – dimensions are often
found varied due to lack of planning in the
design process
• Underground ducts – would conflict with
columns and foundations in construction

20. Vertical Duct

21. Underground ducts

22. Ceiling voids
• Space to accommodate services within the ceiling void but near the
points at which branches leave the primary vertical ducts to enter
secondary ceiling recesses, the trunking and pipes will be at their
maximum diameter and the necessity for crossing will be relatively
high
• Headroom on the various floors will be normally have been reduced
to the acceptable minimum
• Space available above suspended ceiling will also kept as low as
possible, in order to avoid increasing the overall height of the
building.

23. Service distribution above ceiling

24. Floorvoids
• Increasing use of electrical, telecommunications and computer
equipment in office has led to the use of suspended floors to
contain wiring and provide flexibility for additional and alterations.

25. Crossingservices& Spacearound trunking
Crossing services – where services cross it is
possible to have a great deal of wasted space
in ducts
Space around trunking – cable trays suspended
from ceilings should have minimum clearance
of 250mm at each side and similar distance
above each edge of the tray

26. Locationand ApproximateSizingof Plant
Spacesand Ducts
Ventilation trunking
• Ventilation trunking should have 250mm clearance of the
sides and at least 300mm clearance above the trunking
• The clearance above the trunking should be increase up to
500mm for 2m wide trunking

27. Firehazards
• Vertical ducts should have vents at the top so that smoke and
flame can be dissipated
• Ducts must be sealed where they pass through fire resisting
construction
• The walls and doors of the ducts must have adequate fire
resistance
• Pipes run through fire-resisting walls should have gaps tightly
packed with fire stopping material and depending on the
movement of pipe

28. Ductdetails
• All major underground ducts should provided with channels to carry
away seepage and leakage
• Vertical duct – simply a recess in corridor wall covered by ply facing

29. Duct details
• Some have to laid to fall – drainages
• Firmly support – heating/ or water pipe with pressure to avoid
movement
• Long and straight lengths pipes – adjustable level pipe clip
• Underground ducts – provide with channel to carry away
seepage or leakage
• Access to the services – maintenance

30. TUTORIAL
1.Choose any one (1) department/building/faculty in Inti IU
e.g. library. Provide photographic evidences to identify
various ducting system in Inti IU Building.
2. Explain the important of adopting unified system of
service distribution.
3. Explain the factors that must be considered in deciding
the size of the ducts and recesses.
Due Date : …………………………………
Task :