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Lecture 8 a.pptx
1. W0ll0 University
Department of Architecture
KIOT
Building Construction
(ARCH 3161)
Lecture - 8
Reading Assignment
Preparedby :Fiker Mk.
2. Scaffoldings
• Scaffolding is temporary framework of timber
or steel elements, having platforms at
different levels, to enable the masons to work
at different heights of a building.
• They are usually required when the working
height or level is 1.5m or more above the
ground level.
• Scaffolding can be divided in to two groups
depending on the material they construct. These are
• Timber/ Wooden scaffold
• Steel/Tubular scaffolds
3. Besides providing access, the Scaffoldings are also used for
(i) centering for formwork and
(ii) for supporting heavy loads at great heights.
4. Terminology
• Standard: This is the name given to the
uprights which carry the total load of the
scaffold including any men and materials on
plat form.
• Ledger: The horizontal tubes connecting the
standards together and providing support for
transoms.
• Transoms: horizontal tubes across the scaffold
connecting parallel sets of standards and
ledgers. At the required level the transoms will
support a working platform.
5. Cont’d…
• Put logs: Similar to transoms but one end is
flatted or fitted with special end piece so that
the end may be placed in a slot left in the
construction usually a gap in the mortar joint
of a brick wall.
• Base plate: A square metal plate welded to a
short length of tube and fitted to the bottom
of a standard. Its purpose is to spread the load
from the standard over a large area and this
helps to avoid settlement or displacement of
the standard bearing on the ground.
6. Cont’d…
• Guard rail: An additional ledger connected
between standards where ever there is
working plat form to form rail at a suitable
heights to prevent a man falling from the plat
form.
• Scaffolding board (Boarding): Timber boards
placed across the transoms or put logs to
create the working plat forms.
7. Cont’d…
• Coupler: There are many types of coupler and
their purpose is to hold together the various
structural components of the scaffold.
• Brace: Diagonally placed connections either in
a vertical or horizontal plane to ensure the
stability of the whole scaffold by removing the
possibility of movement.
8. Scaffold Types based on usage
Scaffolds
Timber
Scaffold
Metal
Scaffold
Heavy Duty Medium Duty Light Duty
Single Pole Double Pole
9. 1. Timber scaffold
• Timber has been used for building scaffolds
from time immemorial and continues to be
used even at present.
2. Metal Scaffolds:
• The designs of metal scaffolds that are
currently in vogue are broadly of two types:
– Tube and fitting type, and
– Pre-fabricated unit- frame type.
10. A. Tube and fitting type
• The tube and fitting type generally consists of
plain tubes which are used for making uprights,
ledgers, transoms and putlogs.
B. Prefabricated Unit-Frame Type Scaffolds
Various proprietary designs of unit frame
type scaffolds are also available according
to manufacturers’ specification to suit
various scaffolding/ centering/ supporting
needs.
11. 1. Putlog Scaffolds:
• These are scaffolds which have an outer row
of standards joined together by ledgers which
in turn support the transverse putlogs which
are built into the bed joints or perpends as the
work proceeds; they are therefore only
suitable for new work in bricks or blocks.
Scaffold types based on type of
construction
13. 2. Independent Scaffolds:
• These are scaffolds which have two rows of
standards each row joined together with
ledgers which in turn support the transverse
transoms. The scaffold is erected clear of the
existing or proposed building but is tied to the
building or structure at suitable interval.
15. 3. Mobile Scaffolds:
• Otherwise known as mobile tower scaffolds.
They can be assembled from pre-formed
framing components or from standard scaffold
tube and fittings.
• Used mainly for property maintenance.
• Must not be moved whilst occupied by
persons or equipment.
17. 4. Patent Scaffolding:
• These are systems based on an independent
scaffold format in which the members are
connected together using an integral locking
device instead of conventional clips and
couplers used with traditional tubular
scaffolding.
• They have the advantages of being easy to
assemble and take down using semi-skilled
labor and should automatically comply.
19. 5. Suspended Scaffolds:
• These consist of a working platform in the form of a
cradle which is suspended from cantilever beams or
outriggers from the roof of a tall building to give
access to the facade for carrying out light
maintenance work and cleaning activities.
• The cradles can have manual or power control and be
in single units or grouped together to form a
continuous working platform.
• Many high rise buildings have a permanent cradle
system installed at roof level and this is recommended
for all buildings over 30m high.
21. 6. Cantilever Scaffolds:
• These are a form of independent tied scaffold
erected on cantilever beams and used where
it is impracticable, undesirable or uneconomic
to use a traditional scaffold raised from
ground level.
• The assembly of a cantilever scaffold requires
special skills and should therefore always be
carried out by trained and experienced
personnel.
23. 7. Truss-out Scaffold:
• This is a form of independent tied scaffold
used where it is impracticable, undesirable or
uneconomic to build a scaffold from ground
level. The supporting scaffold structure is
known as the truss-out.
• The assembly of this form of scaffold requires
special skills and should therefore be carried
out by trained and experienced personnel.
