Critical Evaluation of Practice

This critical evaluation of practice discusses the use of glass in building facades and the demand for new technologies for glass installation and mounting. It covers the different types of glazing systems, components of a structural glazing system, types of structural glazing, advantages of structural glazing, and professional knowledge, problems, and solutions. The document also includes an interview with a glazing professional and an architect's role in mechanical mounting of glazing.

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CRITICAL EVALUATION OF PRACTICE
By (Name)
Course
Professor’s name
University name
City, State
Date of submission

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TABLE OF CONTENT
CHAPTER ONE:INTRODUCTION...........................................................................................3
CHAPTER TWO : TECHNOLOGICAL AREA: CONVENTIONAL MECHANICAL
MOUNTING..................................................................................................................................3
CHAPTER THREE – PROFESSIONAL KNOWLEDGE, PROBLEMS AND
SOLUTIONS................................................................................................................................11
INTERVIEW WITH MR JONES A GLAZING PROFESSIONAL..............................................11
ARCHITECT..............................................................................................................................12
MAIN CONTRACTOR...............................................................................................................13
CURTAIN WALL SUPPLIER....................................................................................................13
STRUCTURAL SILICONE SUPPLIER.....................................................................................14
CHAPTER FOUR :QUALITY CONTROL.............................................................................16
CHAPTER FIVE:CONCLUSION.............................................................................................17
REFERENCES............................................................................................................................18

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CHAPTER ONE: INTRODUCTION
Glass is a very popular building material with architects and engineers. This is because of the
ability to transmit light and provide a linkage between the interior and exterior spaces while still
presenting a modern sophistication. In the beginning of the twentieth century the ability to bring
light into the interior while, capturing the exterior environment was very limited. This however
changed with the introduction of steel and concrete. With technological advancements and
structural solutions, the use of glass on small openings advanced and it glass was used
structurally and covered larger openings. Later on glass was used on full building facades and
sometimes formed the entire building envelopes. This shift in the use of glass has precipitated a
demand in new technologies for glass installation and the mounting of glass systems.
Figure 1: Building glass facades in Sri Lanka
Source: google images

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CHAPTER TWO: TECHNOLOGICAL AREA: CONVENTIONAL MECHANICAL
MOUNTING
Glazing
This refers to the facades of a building comprising of glass. It is derived from the word glass.
Some of the common glazing systems on accounts of explicit knowledge include:
1. Structural glazing
2. Curtain walling
3. Bolted glazing
4. Fin supported glazing
5. cable stayed glazing
6. suspended glazing
Structural glazing
Structural glazing refers to the utilization of a silicone sealant that exhibits strength and
high performance to bond glass to the structural members of a building (Aiello, et al., 2011). The
sealant used in this case has to undergo thorough testing for structural glazing purposes. This
type of technique can be utilized with most of the glass types.
Some of the components of a structural glazing system include:
1. Location blocks
2. Silicone sealant
3. Setting blocks, gaskets and spacers
4. Structural framing
5. Glass

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Figure 2: Actual site installation of panels’ beings handled from inside
Source: design drawing by BES
According to Kelly, his mental development on personal construct theory meant to improve or
construct new technology and ideas that improve the quality of life and by giving us different
experience and observations. The glazing system has not been left out by the personal construct
theory to create or construct new technological components to improve the operation of the
structural glazing system. There are different parts of the structural glazing system have to be
assembled together either in shop or on site to form the structural glazing system with the help of
constructs work mechanism. This can be done either manually by glazing professionals or
mechanically. Mechanical mounting and bonding of the structural systems and components
involves the use of machines and specialized building information modelling software to fit the
different parts together. It allows for easy and fast assembly of the entire system. Some of the
components of a Structural glazing System include:
Location blocks- these are glass edges that help restraining the glass units location in the
structural frame for the efficient transmission of loads imposed on the glass.

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Silicone sealant: This special adhesive is strong and compatible and is used to block the
penetration of unwanted elements including water, air, dust, or heat through the joints of the
structural system (Bennison, et al., 2008). They are based on the polymers of silicon and exist in
three types including oxime cure, acetoxy cure and alcoxy cure (Arasteh, 2008). For internal
applications, the acetoxy cure is recommended while for external use the oxime and alcoxy
cures, which are neutral in nature, are recommended since they possess better waterproofing
capabilities as well as adhesive properties (Bennison, et al., 2008). The neutral silicones (oxime
cure and alcoxy cure) are recommended for surfaces where acetic acid cannot be used.
There are different factors considered in the selection of the sealant:
1. The glazing system type being used
2. The parameter of the design to be achieved
3. Glazing contractor requirements
Setting blocks, gaskets and spacers – these provide the required support for the glazing material
in relation to glass size, techniques of glazing and the conditions in the use of the glazing
(Koccaz, et al., 2008). Some of the factors considered in the choosing of these elements by the
glass manufacturer include:
1. The size of the glass installation
2. The location within the building envelope or structural frame
3. The hardness of the element as a factor of its ability to resist loads
4. The compatibility of the elements or fabricated materials of the parts with the sealant to
be used in the fixing and the preformed rubber parts. It is important that the materials
used do not react with the silicon sealant and result in a color change (Konstantin and

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Konvin Assoc Ltd, 2011). A change of color is therefore proof that there is a chemical
reaction which may in the end lead to the total loss of adhesive force between the
structural silicon sealant and the members it is joining, either glass or metal upon
exposure to ultraviolet light. For example, neoprene and EPDM (ethylene propylene
diene monomer rubber) which are organic rubbers change in color upon exposure to
ultraviolet light leading to a resultant loss in the adhesive force of the sealant (Konstantin
and Konvin Assoc Ltd, 2011). The two rubbers are therefore not to be used in a structural
glazing system since they are not compatible
Types of structural glazing
1. Four sided framed glazing
2. Two sided framed glazing
3. Slope glazing
4. Frameless glazing
5. Glass fin glazing
Four sided framed glazing:
This is the most wide used system of structural glazing mainly because it is economical
In this system of structural glazing, a pre-fabricated frame that is made of horizontal and vertical
support members is installed on the building. Glass is supported by a frame that is fabricated on
the four sides and anchored in the frame. In this system glass is used as an infill panel (Serpico,
et al., 2010).

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Figure 3: four sided framed glass Source: (Serpico, et al., 2010)
Two sided framed glazing
In this type of structural glazing the glass is fabricated on two sides for support in either the
vertical or the horizontal direction while on the other two sides silicone is used. This system of
glazing also involves prefabrication of the members before they are assembled on site
(Strickland, et al., 2012).
Figure 4: two sided framed glazing Source: (Serpico, et al., 2010)

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Slope glazing
This is structural glazing done on slanted surfaces of building. Special glass is used in these
systems with the European standards approving only splinter proof laminated glass for use in
these kind of systems (Suarez, et al., 2012). The glass weight is also a major issue of
consideration in these systems.
Tooth shape glazing
Tooth shape glazing involves specialized glass panels. They are manufactured in stages with the
exterior panels being produced first followed by an internal panel (Suarez, et al., 2012). The
inner surface of the internal panel houses a structural joint for each glass unit.
Figure 5: Tooth shape glazing Source: (Suarez, et al., 2012)
Frameless glazing
Also referred to as bolted or spider glazing system. In this type of structural glazing, the glass is
tied to the structural frame using hardware like spider fixtures (Woelfert & Engr, 2007). This
kind of glazing gives a seamless look to the facade of the glass. The joint sealant in these
systems has a structural function

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Figure 6: frameless glazing Source: (Woelfert & Engr, 2007)
Glass fin glazing
Glass fin glazing involves the placing of perpendicular sheet of glass on the façade of the
building to add strength to the glass façade (Suarez, et al., 2012). The bonding to the building
structure is done using special sealants and hardware.
Advantages of structural glazing
1. Allows for wider flexibility in the design of buildings.
2. Prevents breakage of glass as a result of extreme thermal conditions
3. Prevents the infiltration of water and unwanted air
4. Contributes to the overall increase in the thermal efficiency of buildings. This is due to
the reduction or total elimination in the exposure of the exterior metal framing.

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It is also important to address lateral and horizontal floor movement in the design due to wind
movement and imposed load. This aspects can induce racking in façade panels causing panel
deformation.
Figure 7: panel mode of movement due to building sway
Figure 8: floor bracket and curtain wall profile Source:
Rajan at BES consultant
CHAPTER THREE – PROFESSIONAL FACTUAL KNOWLEDGE, PROBLEMS AND
SOLUTIONS
Most of the experts gave their opinion on accounts of tacit knowledge of what they have learnt
throughout their profession. The interviewed professionals included glazing expert, architect and
main contractor.
INTERVIEW WITH MR JONES A GLAZING PROFESSIONAL
INTERVIEWER: what are the major constraints you face in the application of the sealant?
JONES; The main factors that affect the strength of a sealant after application include
The shelf life of the sealant: this refers to the duration that the sealant has been stored before use
The substrate and structural sealant compatibility, effectiveness in preparation of the surfaces for
the application of the sealants. This is done by priming or cleaning of the surface. The quality of

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application of the sealant tom the surfaces. Proper application should ensure good contact
between the surfaces and not have air voids, the duration allowed for the curing of the units that
are assembled in the factory and on site before movement of the units or removal of temporary
stops in the field (Kinowski, et al., 2016). The conditions of the environment at the time of
applying the sealants. These weather elements may include rain, temperatures, dust, and air and
they affect the quality of the application. Variation in the finishes of the metal used in the
structure, which may vary between different patches. The varying affects the ultimate strength of
the assembled members.
Caution should be exercised in the use of sealants to be used in structural glazing. Only tested
silicone sealants that possess adequate strength for the resisting of the loads imposed on the
structure should be used (Haldimann, et al., 2008). They are referred to as structural sealants.
General or multipurpose sealants if are not fit for structural glazing for a variety of reasons
detailed below:
- Exhibition of low cohesive strength
- Use of these sealants may result in deflection of glass edges when exposed to high wind
load (Kinowski, et al., 2016). The deflection could lead to the displacement of the spacer
bar and eventual rupturing of the primary seals in insulating glass units resulting in
breakdown of the unit.
In accounts of reflective knowledge, it is important to note that various glass types have special
considerations in their installation and use. For instance in the use of insulating glass a
verification of the compatibility of the edge seal of the insulating glass and the sealant to be used
must be done (Scandlyn, et al., 2010). In addition to that, the glass to be used must be high
quality insulating glass with a dual seal and a secondary silicone seal.

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In the use of clear vision glass with an opacifier or a reflective coating, the compatibility of the
structural silicone and the adhesion of the silicone adhesive to the coating used should be
established through tests before installation (Scandlyn, et al., 2010).
ARCHITECT
In the project what are the roles of the architect in the mechanical mounting of the glazing?
An Architect is the lead professional in the projects and undertakes a variety of roles in the life of
the project on behalf of the owners of the building. Some of the major roles played by the
architect include; Interpretation of the owners brief and development of the concepts .Provision
of the construction drawings as well as the detail drawings to be used on site by the contractors
on site. Checks the adequacy of the structure to resist different loads over its lifetime allowing
for a safety factor as per the requirements of the regulations in the zone of the site. Checks the
conformity of the shop drawings to the requirements of the structural design of the project.
Supervision of the other professionals on site and general administration work including
inspection of the quality of work done
MAIN CONTRACTOR
What is the responsibility of the main contractor in achieving the project goals?
An interview with the main contractor on his roles on site and knowledge in the field of
structural glazing. The main contractor also referred to as the general contractor bears the full
responsibility for the undertaking of the project. Some of their main roles include;
1. Interpretation of the architectural plans to enable realization of the project

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2. The selection of competent sub-contractors to undertake various aspects of the projects.
The selection of the sub-contractors should be based on the quoted sums
3. Management of the work force on site for timely completion of the work
4. Controlling of costs of the various work in accordance with the bill of quantities provided
at the onset of the project
5. Coordination of the activities on site and management of the schedules and time frames.
They also help in the inspection of the works on site.
6. Oversee the sub contactors and other skilled laborers on site to ensure that the
specifications given by the architect are complied with.
During the interviewing process most of the expert gave accounts by mainly depending on
reflective knowledge about the experiences they had or learnt about the glazing technology with
none of the experts having embraced their reflection to form new ideas in the glazing
technological area to gain reflexive knowledge.
Common problems faced in glazing and their solutions
1. Infiltration of air and water – this may result in the damage of interior spaces. The
solution to this problem is the undertaking of a water test to confirm the source in
readiness for repairs
2. Failure of the aluminum coating – this is because of poor application of the finish, to
solve this problem a survey of the glazing is taken and collection of samples for testing in
the laboratory is done. The repairs can then be done accordingly
3. Noise from the exterior – in a case where there is infiltration of noise into the building the
glazing can be retrofitted with laminated glass to reduce the noise penetration

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4. Failure of the IGU (insulated glazing unit) - This is as a result of the failure of the
sealants in keeping moisture outside. It can be solved by the application of the sealant
CHAPTER FOUR: HOW KNOWLEDGE IN CONSTRUCTION OPERATES
Personal Construct Theory was invented in 1955 by George Kelly who is an American
psychologist to help in the analysis of individual’s character and explain their actions. According
to George Kelly theory, it explain that we create our own way of viewing the world we live in.
just like research scientist, we explore the world around us using our own theories and
hypotheses created through the experiences we encounter in our lives, which are then deemed as
personal constructs. This are created constructs in our mental maps or model which gives us a
view or a frame through which we interpret the world and deal with new challenges that come
along our lives. It’s a common knowledge to use that we have different life experiences,
therefore this means that we have different constructs that are meant to understand our situations
which act on them differently. Our constructs help us to predict and control our own world which
eventually leads to a course of events. However, those constructs may not necessarily solve the
problems in the real world but to some extend makes the world to be a differentiated
heterogeneity that we can be able to at least make a sense out of it.
Generally, in most cases we seek to make our constructs better by improving our repertoire of
mental maps and changing them to provide better fits. For example in construction, when a
problem is faced in design and installation of equipment’s such as the structural glazing, the
construct theory can be used to consolidate the situation by resolving the mechanism used and
when it works to save the situation, it will be reused in future until the test fails in the coming

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projects. However, if the construct fails in solving a problem, it will be termed invalid and can be
revised or replaced to accommodate the future events. As such, we experience a life cycle of
events in our life that makes our construct to undergo a progressive evolution which makes us to
consistently revise the already existing construct in the direction that will improve the level of
our predictive efficiency.
Effectively managing knowledge is critical to the survival of construction companies. However,
grabbing the knowledge in the construction industry is not an easy task, since knowledge is
usually tacit, more experienced based and hard to pass to other design team members. This
makes personal construct theory to come to play since every project is unique on its own in terms
of how the different professions in the design team manage knowledge.
Construction stakeholders should have a cooperative behavior in order to share their tacit
knowledge on the design solutions ideas. Design and construction being a critical field, requires
collaboration in all stages of construction. The architect need to update all the other professions
in the design team on the progress and changes made in the design to achieve the desired
outcome. With effective communication, the constructs theory will play a very big part in
solving the design solutions. This means that in order to improve the performance of the design
teams, constructs must be explored. More research on construction solutions need to be carried
out to fill the gap by using psychological perspective that is linked to the personal construct
theory.

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Figure 9: A generic process model showing the flow of information and resources needed to
perform Task A on the construction site. (Adapted from CIB78 1997 by Persson & Hansson
2008)
Knowledge management of construction sector and the information available on site for different
design team members is not always well arranged to enable the transfer of explicit knowledge to
implicit knowledge as illustrated in SECI model created by Nonaka and Takeuchi as indicated in
the figure below. The figure shows the process of socialization which involve tacit knowledge to
tacit knowledge; on the left hand side is externalization which involve tacit knowledge to
explicit knowledge; at the top part is combining explicit knowledge to explicit knowledge, and
on the right is one of the important process of internalization involving explicit knowledge to
tacit knowledge.

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Figure 10: The SECI model of knowledge transfer with the process of internalization (adapted
from Nonaka & Takeuchi 1995)
CHAPTER FIVE: CONCLUSION
As discussed technology plays an important role in the implementation of projects today. It is
also helps reduce the occurrence of human error and aides in the faster and efficient completion
of work. Mechanical mounting is therefore a field that needs more research and development for
better performance in the mounting of structural glazing systems. Many buildings today are
tending towards the use of glass and curtain wall systems due to the advantages they bring in
terms of floor plan flexibility and natural lighting, it is therefore evident that the demand in
structural glazing technology is bound to increase.

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