DO YOU HAVE THE PROBLEM WITH GLAZE-WORK? HERE IS A DETAILED ACCOUNT GIVING YOU THE READER A CLEARER UNDERSTANDING OF THE TOPIC.

1. BY CHAKAMBA J.

2. This presentation consists the following:
 Definition of glazing
 By laws governing ventilation requirements
 By laws governing daylight admittance
 Tools and materials
 Types of glass and uses
 Preparation and procedure (steel windows
only)

3. DEFINITION
 Glazing is the process of fitting glass part of the window to
the frame which is essential to let in daylight and exclude
rain and elements of weather (Walton 1995).
 Glazing is the act or process of fixing glass into a frame or
surround in domestic work. This is usually achieved by
locating or placing the glass in a rebate and securing it with
putty or beading in accordance with the recommendations
contained in BS 6262: Glazing for buildings (Chudley and
Greeno, 2005).
 The fitting of glass into openings in doors and windows
(Fleming, 2004).

4. Definition continued
 The working definition for glazing is that it is the
process of fitting glass panes into door and window
frames using putty or beads.

5.  Model Building By-Laws 1977 state the
minimum ventilation requirements for a
habitable room as being 5% of the floor area
of the room.
 This means that the area for all the openings
in room that are capable of being open for
ventilation purposes should amount to 5% of
floor area of that particular room.
 These include windows which can be opened,
air vents, permavents and or service openings

6.  Circular No 6 of 1991 of the MPC&NH (Ministry of
Public Works and National Housing in Zimbabwe)
recommends that for all windows used on
residential construction, 50% of the area of the
window should be capable of being open to the
external air for the ventilation of the room.
 While glazing can be done, some windows may
have some glazing panel that is slightly smaller
than the rebate into which they are fixed to allow
for the fitting of a permavent.
 The area of the ventilation openings can be
calculated as; 5% x Area of the Floor=area of
ventilation

7. BY-LAWS ON DAYLIGHT
ADMITTANCE:
Daylight admittance table
 The Model Building By-Laws
specify the daylight areas in
accordance with the
following;
Type of
Habitable Room
Minimum
daylight area
as% of floor area
Any Habitable
room
10%
kitchen 12%
Workshop 15%

8. Daylight bye laws -continued
 The glazing used on the windows should be clear
enough to permit daylight or natural light into the
building.
 Barry specifies that such material should be
transparent or translucent so as to promote daylight
admittance.
 Calculation of the Daylight Admittance is also done on
the formula;
 Area of Windows ÷ Area of the Floor x 100%

9. MATERIALS USED FOR
GLAZING
 For a steel sash window frame, these
normally include;
 Glazing Panels
 Glazing Putty
 Turpentine and
 Paint.

10. Glazing panels-types of glass

11. Types of glass-continued
Drawn Sheet Glass/Clear Glass:
 This type of glass is normally 3.13mm or 4mm
thick and is used for general purpose work on a
building.
Obscured Glass:
 A type of glass that has patterns rolled on its
surface although obscured plain is also available.
Thickness range from 3.13mm to 6.25mm
depending on where they should be used. It is
used where aesthetics is of the glass
architectural work is important such as on
churches, halls and auditoriums where a
minimum amount of daylight shall be permitted
as a design.
 They can also be used on bathrooms

12. Glass types-continued
Tempered Glass is glass that is reheated and rapidly cooled,
which causes it to break into pea-sized pellets.

13. GLASS TYPES-CONTINUED
Wired Glass:
 Used where fire resistance is required such as
in factories, kitchens and other places where fire
is always used,
 contains some thin mesh reinforcement wires in
them.
 They are normally available in thicknesses
ranging from 4.69mm to 9.37mm depending on
where they are needed.

14. WIRED GLASS

15. GLASS TYPES-CONTINUED
 Toughened/Armored Glass
 This type of glass is normally used for
Aluminum sliding doors, French doors and
Wooden and Glass Paneled doors on public
places.
 Thickness includes dimensions from 4.69mm
to 9.37mm depending on where they shall be
used.

16. Glass types-Heat absorbing or
rejecting glass
Tinted blue glass Tinted grey glass

17.  Is tinted to absorb a high degree of solar
radiation and thus it transmits less solar heat
and glare into building.
 transmits most of the visible daylight
required in a building
 It is usually bronze, grey or blue green in
color

18. MATERIALS OF GLAZING-TYPES OF GLASS-
CONTINUED
Opaque Coloured Glass:
 A type of glass that is normally used for
interior and shop decorations. The thickness
is usually more than 4mm (Ezeji 1989).
 There are various other types of glass whose
list is exhaustive

19. GLASS TYPES-LAMINATED GLASS
 is made by sandwiching a transparent
polyvinyl butyric (PVB) interlayer between
sheets of glass bonding the three layers
together under heat and pressure.
 When laminated glass breaks, the plastic
sheet holds the broken glass in place, thus
reducing the risk of injury in case of
breakage

20. LAMINATED GLASS

21. Glazing Materials continued- Putty
Types of putty
Linseed Oil Putty
 This is traditional putty which contains a mixture of
linseed oil and inorganic fillers (BS 544: 1969). It sets
by a combination of aerial oxidation of the oil and
some absorption into the timber.
 A hardening skin is initially, produced but the mass
ultimately sets to a semi-rigid material later on. The
putty hardens faster in cold seasons than in hot.

22. Linseed putty-continued
 Application is done with a putty knife onto primed
timber or frame rebate. For application to steel
window frames, non absorbent hardwoods and water-
repellent preservative treated softwoods, non-linseed
oil putty is the most appropriate sealant compound.
 Linseed oil putty should be painted within two weeks,
whereas metal casement putty may be left for three
months before painting (Lyons 2007).

23. Types of putty- continued
Metal Casement Putty:
 A compound sealant suitable mostly for glazing on
steel casement window frames.
 It is made from refined vegetable drying oils and
finely ground chalk.
 It takes time about three months to harden but just
like the linseed oil putty, the hardening process is
faster in cold seasons than in hot seasons.

24. TURPENTINE:
 A solvent that thins and makes the putty workable.
PAINTS:
 Paints consist of a blend of components, each with
their specific function. Commonly these include the
binder (or medium), solvent, base, extenders,
pigments and driers, although other additives may be
incorporated into specialist paints to improve their
properties (Lyons 2007).

25.  When the putty is hardened to a certain degree, it
may need to be painted. From the various types
of paints that can be used in building
construction, gloss enamel paints are
recommended for painting both the steel window
frames and their putty.
 While the steel frames normally have their body
painted with a red metal alky or red metal oxide
priming coat on manufacture, the metal
casement putty will need to be painted with all
the three coats of gloss enamel paint namely the
priming coat, the undercoat and the finishing
coat of the required colour.

26. TOOLS FOR GLAZING
 Glass Cutter:
 A handy tool consisting of a handle with some teeth
and a cutting wheel. It is used for cutting glass to the
required size (Fig 1). The teeth are used for breaking
the glass in strips as it is cut.

27. Glass cutter

28. Fig 1: The Glass Cutter and Putty Knife.
Source: Mugari and Pekoyo (2008; 91)

30.  Mark on the glass the required size.
 Place the pane on a flat surface and make a
groove along the line marked.
 Use the teeth on the glass cutter for breaking

31. Tools of glazing-continued
Tee square Putty knife
 A tee shaped tool
consisting of a long
straight edge and a
stock. It is used for
describing a straight line
with a glass cutter during
the process of cutting a
glass. A metal tee square
or straight-edge is more
preferred than a plastic
or wooden straight-edge.
 Another handy tool
consisting of a steel
blade and a handle. It is
used for compacting and
cutting putty when fixing
it to a slope. See Fig 1.

32. PRE-GLAZING PREPARATION
 Estimate your usage of putty for the glazing job but do not
prepare more than you can use in 40 minutes.
 Set sufficient putty aside for the backing putty (no drying
compound added).
 Place any unused putty back in the liner and fold to seal.
 Shake the drying compound well before use.
 Split the putty required into four segments. Add an equal
portion of drying compound to each quarter. Sufficient
drying compound is provided for the whole bag of putty.

33. Pre-glazing preparation continued
 Replace the cap on the unused portion of drying agent.
 Mix each quarter and then the four segments together
to ensure that the drying compound is mixed into the
putty.
 Knead the putty and drying compound for ten
minutes.
 For optimum performance ensure that unused putty
(with drying compound added) is not kept for more
than 40 minutes.

34. PREPARATION AND
PROCEDURE FOR GLAZING
 Clean the steel frame rebate to
receive the glass pane to remove dust
oils and grit.
 The cleaning process should be done
with a damp rag dipped in turpentine
or paraffin.
 Take a ball of putty and knead until
soft until soft and pliable.

35. PROCEDURE OF GLAZING-CONTINUED
 Press the glass pane firmly and lightly into
the frame rebate while cutting off excess
putty from the inside. Take care not to break
the glass as you fit it into the rebate.
 The glass may be secured by springs or clips
if required.
 Apply front putty on the outside edge of the
glazing pane recently fit onto the rebate
using
a putty knife

36.  Apply some back putty around the rebate of
the frame. This will act as a shock absorber
when the glass is fit and when the window is
closed with a bang.
 Ensure that the glass pane to be fit is 2mm
or 3mm smaller than the rebate right round to
allow easy fixing.

37. GLAZING PROCEDURE-CONTINUED
 Press the glass pane firmly and lightly into
the frame rebate while cutting off excess
putty from the inside. Take care not to break
the glass as you fit it into the rebate as
shown below

38. GLAZING PROCEDURE CONTINUED
 Apply second layer of putty around the glass
as shown by the diagram below

39. GLAZING PROCEDURE-CONTINUED
 Hold the putty at an angle of about 60
degrees and cut excess putty as shown
below.

40.  Smooth the putty using putty knife as shown
by the diagram below

41. IMPORTANT GUIDELINES
 Ensure that the frames (new and existing) are free from dust,
rust, oil and dirt. Old putty should also be removed. Metal frames
should be painted with a primer (allow the primer to dry for at
least 16 hours). Wooden frames must be sealed with a suitable
wood sealer.
 Backing putty (the putty applied to the frame behind the glass)
should be 3mm to 4mm thick. Do not add drying compound to the
backing putty, as you need to allow for applying the putty by hand
using your thumb. This will ensure sufficient adhesion to the
frame.
 Upon placing the glass pane, apply a firm pressure at the edges
of the pane. Do not press in the centre of the pane.
 The holding putty (the putty applied to secure the glass in place)
must be finished off with a putty knife. A 60 degree angle is
standard.

42. GUIDELINES-CONTINUED
 Application is done with a putty knife onto
primed timber or frame rebate. For application
to steel window frames, non absorbent
hardwoods and water-repellent preservative
treated softwoods, non-linseed oil putty is the
most appropriate sealant compound.
 Linseed oil putty should be painted within two
weeks, whereas metal casement putty may be
left for three months before painting (Lyons
2007).

43. THIS WHOLE PROCESS OF FIXING THE GLAZING PANE IS
ILLUSTRATED IN THE DIAGRAM BELOW

44. Post glazing procedures
 As stated by Lyons (2007), allow the metal casement
putty at least three months to harden without
tampering with it or pressing it with your to feel its
state of hardening.
 Paint the putty as required in three days time applying
the priming coat on day one, the undercoat on day two
and the finishing coat of the required colour on day
three.

45. Post glazing procedures-continued
 As you paint, take care not to smudge or to mess up
the glazing pane with the paint brushes. Thin brushes
should be used in a firm and controlled movement of
the hand. Apply a universal undercoat to the frame and
putty.
 As specified apply the final layers of the paint

46. Conclusion
 This presentation was about glazing which is done in
buildings to improve its aesthetic value.
 The need for skilled glazier is highly called for, to
produce good workmanship and quality work.

47. REFERENCES:
 Barry R. (1999) The Construction of Buildings, Volume 2 Fifth Edition,
Blackwell Publishing (Pvt) Ltd, Oxford.
 Choga, F.,V. Mukova& B. Mushowo(2006) Focus on ‘O’ level Building
Studies. Harare: College Press
 Chudley R. and Greeno R. (2006) Building Construction Handbook,
Third Edition, Heinemann Butterworths Publishing, Oxford.
 Ezeji S. C. O. A. (1989) Building Construction, Longman, London.
 Fleming E. (2005) Construction Technology, Blackwell Publishing (Pvt)
Ltd, Oxford.

48.  Fleming E. (2005) Construction Technology, Blackwell
Publishing (Pvt) Ltd, Oxford.
 Lyons A. (2007) Materials for Architects and Builders,
Third Edition, Elsevier Heinemann Butterworths
Publishing, Oxford
 MPC&NH (1997) New Minimum Revised Standards on
Low Cost Housing Designs, Ministry of Public
Construction and National Housing, Harare.
 Mugari K. and Pekoyo I. (2007) O-Level Building
Today, Zimbabwe Publishing House (Pvt) Ltd, Harare.

49.  Lyons A. (2007) Materials for Architects and Builders,
Third Edition, Elsevier Heinemann Butterworths
Publishing, Oxford.
 Mugari K. and Pekoyo I. (2008) ZJC Building Today,
Zimbabwe Publishing House (Pvt) Ltd, Harare.
 Walton D. (1995) Building Construction: Principles
and Practices, Macmillan Education Ltd, London.

 Zimbabwe Government, Model Building By-Laws
1977, Government Printers, Harare