This document provides information on fireplace construction, including the functions and requirements of fireplaces and flues. It discusses the components of a fireplace including the hearth, recess, lintel, fireback, throat, surround, and flue. It describes the regulations governing fireplace construction and the materials used for flue linings. Additionally, it covers chimney design considerations like damp prevention, flashings, and chimney outlets.

1. FIREPLACE CONSTRUCTION
CHAKAMBA J

2. FIREPLACE CONSTRUCTION
• A FIREPLACE: is a space in a wall, or formed in
a freestanding position, to accommodate an
open fire from which the smoke and gases
pass to the open air through a duct or flue.
(Jack Stroud Foster)
• Is a special designed area where the
combustion of fuel takes place. ( Mugari and
Pekeyo)

4. FUNCTIONS OF A FIREPLACE AND FLUE
• Primary function
• Is to regulate thermal comfort levels in a
building during cold winter months.
• Secondary functions
• To burn fuel efficiently and safely transfer the
heat generated into the room effectively.
• Provides a focal point in the living room or
lounge.

5. FLUE
• A passage or duct within the chimney to carry
smoke and gases (combustion fumes) away
from the fire.
• Is the working part of the chimney, conveying
the products of combustion safely to the
atmosphere.

6. FUNCTIONS OF A FLUE
• To convey products of combustion into the
atmosphere.
• To ventilate the room in which the fire is
situated.

7. FUNCTIONAL REQUIREMENTS OF A
FIREPLACE
1 Provision of adequate strength and stability
• Must resist wind pressure and must be
properly bonded to the main wall.
2 Weather resistance
a properly constructed fireplace should
prevent penetration of wind and rain especially
where the stack passes through the roof.
Flashings and damp proof courses are required
at the junction of the two.

8. FUNCTIONAL REQUIREMENTS CONTI..
• The top of the stack must also be protected to
prevent saturation of the chimney.
3. Thermal insulation
provision of adequate thermal insulation to
the flue avoids cooling of the flue gases and the
consequent slowing down of the upward air
flow and draught (condensation of flue gases).

9. FUNCTIONAL REQUIREMENTS CONT…
4. Fire resistance
A properly constructed fireplace should not end up
igniting combustible materials within and outside
the building.
Material for the fireplace should be non-
combustible (this is ensured by the provision of
adequate thickness of non- combustible material
around flues and fireplaces and by keeping all
combustible materials a sufficient distance away
from a flue or fire place).

10. REQUIREMENTS CONTI…
• Suitable materials for walls should be 100mm
of brick, stone, concrete ( a temperature 70
degrees Celsius is considered to be a safe
maximum which should not be exceeded).
• Outlet of a flue should be well above the roof,
especially if the roof covering is combustible,
in order to avoid danger from sparks.

11. DIAGRAM SHOWING FIREPLACES
TERMINOLOGY

12. TERMINOLOGY OF VARIOUS
COMPONENTS OF AN OPEN FIREPLACE
• Chimney- a structure, which contains the flue
through which smoke and other gases may
escape.
-A structure enclosing a flue.
• Flue pipe- means a pipe forming a flue but does
not include a pipe built as a lining into either a
chimney or an appliance ventilation duct.
• Chimney stack- a structure enclosing a flue which
rises above the roof.

13. TERMINOLOGY CONTI…
• Chimney breast – a structure enclosing a flue
from fireplace to the roof.
• Constructional hearth – a hearth forming part
of the structure of the building.
• Hearth – the platform on which the fuel is
burnt.
• Superimposed hearth – a hearth not forming a
part of the structure of the building.
• Fireback -

14. TERMINOLOGY CONTI…
• Recess – is part or space set back from the line
of a wall or a room.
• Throat – part of a flue immediately above the
fireplace opening.
- a slot like opening part of the flue.
• Party wall – it is a wall which separate two
families.
• Mantel/Surround – part of a fireplace around
an opening often incorporated for aesthetic
reasons or to increase the effective depth of
the fireplace.

15. TERMINOLOGY CONTI..
• Surround – is the finish to the fireplace and
generally consists of a precast ceramic tile slab
or in-situ built brick, slate, or stone.
• R.C lintel – a horizontal member supporting
the brickwork over the opening ( should be of
precast or in-situ reinforced concrete).
• Gathering over – bringing together the sides
of the smoke chamber by means of corbelling
to form the flue.
-formed by corbelling brickwork to reduce
the size of the throat to flue size.

16. CROSS-SECTION AND PLAN OF RECESS

17. TERMINOLOGY CONTI..
• Reduction of the fireplace opening to flue size.
• Smoke shelf – is constructed between the throat
and flue, used to prevent downdraft and help
divert cold air into smoke chamber.
• Rendering/ Pargetting a 10-13mm coat of plaster
applied to the inside of the flue during
construction.
• Flaunching/Weathering – a sloping of the
chimney pot to shed off rain water.
• Chimney pot and cap – the termination of a
chimney.

18. FIREPLACE TERMINOLOGY CONTI…
Damper
1. Controls air flow/shut off when
not in use
Smoke Shelf
1. Prevent downdraft
2. Help divert cold air into smoke
chamber
Smoke Chamber
1. Transition from the firebox to the
flue
2. Responsible for controlling &
regulating burning and eliminating
smoke & combustion gases

19. TERMINOLOGY CONTI…
• Withes – dividing walls between the flues of
minimum thickness 100mm.
-properly bonded into the outer walling of the
stack so as to obtain the greatest amount of
stability.
• Jamb- protruding vertical side of a fireplace
opening.

20. Apart from blockage of the flue by
soot or debris, there are conditions
which render a fireplace ineffective:
• Insufficient air entering the room to replace
that passing up the chimney.
• Poor design of passages through which smoke
passes ( throat, flue and the gathering ).
• Down-draught caused by the build-up of
pressure at the chimney pot/top influenced by
the building itself, neighboring buildings, trees
and the general topography of the area.

21. PRINCIPLES OF FIREPLACE DESIGN
• To promote the efficient combustion of fuel
the shape of the fireplace must be designed to
allow an adequate but not excessive supply of
primary air to the fire bed and secondary air
to the flue.
• All fires require sufficient air for combustion
purposes, and as air is drawn into the flue
from the room, further air is needed to
replace it.

22. REGULATIONS GOVERNING THE
CONSTRUCTION OF FIREPLACES AND
CHIMNEYS
• A brick flue should have a minimum size of
225 by 225mm or 175mm diameter.
• Every flue must be surrounded by at least
100mm thickness of properly bonded
brickwork.
• Every chimney must be built on a suitable
foundation forming part of the building
foundation.

23. REGULATIONS CONTI..
• The inside of every chimney/ flue must be
rendered or lined with non-combustible
materials (fireclay, heavy duty asbestos,
vitrified clay pipes).
-this is done to protect brickwork from acids
and products of combustion.

24. CONSTRUCTION REQUIREMENTS OF:
1. HEARTH
• The construction begins with the constructional
hearth.
• Every fireplace must have a hearth extending
both under and in front of the opening.
• The hearth shall project not less than 500mm in
front of the jambs.
• It shall extend not less than 150mm beyond each
side of the opening between the jambs.
• The minimum thickness of the hearth shall be
125mm.

25. HEARTH
• Be constructed of such size as to contain a
square of 840mm side, if there is no recess.
• Have no combustible material placed
underneath the hearth within 250mm of the
top surface unless there is a minimum
separate air gap of 50mm, or it provided
support to the edge of the hearth.
• Hearth in suspended timber ground floors
may be supported by fender walls

26. HEARTH
• In upper floor construction use reinforced
concrete.
• If such a hearth is being supported by the wall, it
is a cantilevered slab, therefore, the
reinforcements must be placed within the top
part of the slab, about 25mm from the upper
surface.
• If timber formwork is used between trimmer joist
and the fireplace recess so that the concrete
hearth may be cast in-situ, such timbering must
be removed if it is within 250mm of the upper
surface of the hearth.

27. HEARTH

28. FIREPLACE RECESS
• The fireplace opening is the recess housing
the fire grate.
• The jamb on each side of the opening is not
less than 200mm thick (of either bricks, in-situ
concrete, or concrete or clay blocks).
• The back of the recess if a solid wall shall be
not less than 200mm thick, or if a cavity wall
shall be not less than 100mm thick, extending
for the full height of the recess.

29. RECESS
• With the exception of a cavity wall or an
outside wall with no combustible cladding
where respectively two 100mm leaves or a
single 100mm leaf will satisfy the regulations.
• No opening shall be made in the back of a
fireplace recess which does not communicate
with a flue.
• No combustible material other than timber
supporting the sides of the hearth where it
joins the floor shall be placed under the
hearth.

30. THE LINTEL
• Should be constructed in such a way that it
support the brick over the opening and it
should be of precast or in-situ reinforced
concrete to BS 1251.

31. LINTEL

32. CONSTRUCTIONAL REQUIREMENTS OF
THE FIREBACK
• It is sloped forward in order to direct or
transmit maximum heat into the room and
raise the temperature of fire, thus assisting
combustion.
• It must prevent the heat of the fire from
damaging the wall behind it as such the space
is left behind the fire back.
• The space behind the fire back is filled with a
width as 1:2:4 mix of lime sand and broken
bricks or a light weight aggregates ( this takes
care of heat).

33. DIAGRAM OF A FIREBACK

34. FIREBACK
• The fire back should be preferable in two parts
since the lower half will become hotter than
the other.
• It should be lined rear with corrugated paper
which will eventually smolders away leaving a
small expansion gap.

35. THROAT
• It should be 100mm wide, 200-250mm long
and 150-200mm deep.
• It is restricted in order to accelerate the flow
of flue gases and to ensure enough draught.
• The throat restricts down-draught by reducing
the amount of air down the flue and it also
reduce excessive heat loss into the flue.
• It is formed by corbelling brickwork to reduce
size this called GATHERING.
• It can also be made from concrete or an
adjustable metal throat restrictor.

36. SURROUND
• Is the finish to the fireplace and generally
consists of a precast ceramic tile slab or in-situ
built brick, slate, or stone.
• It is securely fixed to the brickwork of the
chimney breast by lugs cast in the back at
each side of the surround.

37. TYPES OF FIREPLACES
1. Single Breast
• Fireplace opening on one side of the wall by
inserting jambs or attached piers.
• The opening can be formed internally or
externally.
• If the breast is formed externally the
advantage is that the large room area is
available into the room.
• The minimum depth of the fireplace opening
338mm.

38. SINGLE BREAST FIREPLACE

39. TYPES CONT…
2. Double Breast/ Back to back fireplace
• It is usually formed on semi-detached type
dwelling.
• The fireplaces are formed on the party wall
which is sometimes called a double breast
party wall (the wall that separate two
properties).

40. DOUBLE BREAST OR BACK TO BACK
FIREPLACE

41. TYPES CONTI..
• 3. Interlacing fireplace/Side by side fireplace
• These fireplaces are usually built on internal
walls and placed side by side.
• This arrangement has a tendency to increase
the chimney breast and the projection of
jambs into the rooms is reduced to give
greater room area.

42. INTERLACING FIREPLACE

43. TYPES CONTI..
• 4. Angle fireplace
• The fireplace is formed at an angle and
construction is complicated because it entails
a number of twist of the flue in order to
obtain the correct position.

44. ANGLE FIREPLACE

45. FLUES AND CHIMNEYS

46. FLUES AND CHIMNEYS
• Flue is a passage for conveying the smoke or
discharge gases from an appliance to the
external air.
• The minimum internal diameter of metal flue
175mm.
• Minimum cross sectional area of a brick flue is
225mm2
• The flue must be pargetted or rendered to
ensure a smooth surface and seal any cracks in
the joints.

47. FLUE CONTI..
• Sides of the flue to be smooth to avoid the
accumulation of soot not to block the passage
and reduce its size.
• The flue must be lined to provide a chimney
that is resistance to acids and combustible
products.
• Materials used for lining a flue are acid
resisting clay pipes, rebated or socketed flue
linings made from kiln, burnt aggregate clay
flue linings and high alumina cement.

48. FLUES CONTI…
• Substances obtained when burning coal-
carbon dioxide, sulphur dioxide and water.
• Water + carbon dioxide = carbonic acids.
• Water + sulphur dioxide = sulphurous acids.
• When either the two oxides are mixed with
water acids can be produced.
• These acids are not concentrated but
continuous application in the flue will
eventually harm the bricks.

49. CHIMNEY FLUES
• Area through which the combustion gases and
smoke travel
Flue liners
• used to prevent deterioration to mortar joints
• produces a better downdraft & requires smaller
flue (smoother surface)
Unlined Flue
• Chimney must be thicker walls than with chimney
with flues liners

50. MATERIALS USED AS FLUE LININGS
1.Parging with mortar
• As construction progresses the sides of a flue
are rendered with the 12mm thickness of
mortar mix 1:3 or 1:3:10 if you add a bit of
lime.
2.Pipes either made from clay or concrete.
• These must be placed with sockets facing
upwards to prevent dislodgement of
components.

51. MATERIALS CONTI…
3.Precast concrete blocks (425×102×215)
• These are sized to bond to the brickwork.
• The block contain opening which were aligned
or lined to form smooth way.

52. DAMP PREVENTION OF THE CHIMNEY
• Chimneys are vulnerable to dampness
because they are exposed at their junction
within roof is exposed.
• At the point where the chimney meets the
roof dampness can be prevented by:
a) Flashings are often used on pitched roof
junction between roof and the chimney
stack.

53. DAMP PREVENTION CONTI..
• Flashings- are pieces of metal specially made
to waterproof the gap between the roof and
chimney stack, roof and the vent pipe or a
parapet wall.
• Building regulations make it mandatory that
dampness must be prevented at valleys,
chimney stack and roof junctions, parapet
wall.

54. REQUIREMENTS FOR FLASHINGS
• The material selected for use as flashings must
be rust proof.
• Dissimilar materials which may cause
electrolytic corrosion should never be used.
• Certain situations like chimney stacks require
double layered flashings, that is, under and
cover flashings. The flashings should be
properly secured and bonded in mortar.
• The material should be damp proof.

55. MATERIALS SELECTED FOR USE AS
FLASHINGS
• Galvanized sheet metal.
• Aluminium
• Asbestos cement
• copper

56. DAMP PREVENTION CONT…
• d.p.c;
• cover flashings (lead or steel);
• tilting fillet;
• chimney back gutter;
• stepped cover flashing;
• line of soakers;
• front apron;

57. FLASHINGS AROUND THE CHIMNEY
STACK

58. DAMP PREVENTION CONTI…
• The flashing is stepped along the slope. On
the upper end, a gutter and stepped flashing
are provided while on the sloping lower end, a
flashing apron is provided.

59. Chimney outlets or stacks
• The top of the chimney should not be less
than one meter(1m) above highest point of
contact between the chimney and the roof. If
it is not within 600mm from the ridge.
• If roof pitch is not less than 10 degrees on
either side of the ridge and the chimney
passes within 600mm from the ridge, the top
chimney may not be less than 600mm above
the ridge.

60. CHIMNEY OUTLETS
• The chimney stack should not be less than
(1m) above the top of a window or sky light
which can not be opened.

61. CHIMNEY STACK OUTLETS

62. CHIMNEY POTS

63. CHIMNEY POTS
• These are structures put at the top of a chimney
stack to lessen the possibility of down draught
and also preventing the wind from blowing down
the flue. To prevent rains from falling into the
flue.
• It can be made from: clay, bricks, metal, concrete.
• The chimney pot must be securely fixed at the
top of the chimney stack to prevent dislodgement
by wind.

64. CHIMNEY POTS AND CAP CONTI..
• It may be circular or circular with a square
base. A circular chimney pot is used with a
circular flue lining. A circular with a square
base used with a circular square lining.
• The chimney pot must be weathered to shed
off rain.
• The chimney pot must project 100mm-
175mm above flaunching or weathering.

65. ceramic or clay differently designed
pots

66. CERAMIC CHIMNEY SYSTEMS

67. Cowl (Crow Guard)
-Decorative
-Helps protect
chimney from
forming nests

68. TEE-CHIMNEY POT
• decorative;
helps protect the
upward flow of
flue gases in windy
or exposed areas

69. CAUSES OF SMOKING CHIMNEYS
• Failure to provide a restricted throat (poor
design of the throat).
• A blocked flue.
• Insufficient air supply.
• Unsatisfactory gathering of the flue.
• Overshadowing of the flue outlet by tall trees
or buildings.

70. SOLUTIONS TO SMOKEY CHIMNEYS
• Ensure that the chimney is swept regularly to
remove excess soot.
• Open windows and doors of the room, if
smoking ceases then the fire is starved from
the air.
• Provide ventilators or under floor or ducts. If
the height of the fire opening is too much
reduce it by a permanent canopy.

71. SOLUTIONS CONTI..
• Determine the effect of increasing the height
of chimney stack with pieces of sheet metal
pipes of varying lengths.
• Where desirable results are achieved fit a long
chimney pot.

72. By-laws controlling fireplace and
chimney construction.
• are concerned with stability, fire hazards and
escape of noxious fumes into the building,
which might constitute a danger to health and
property;
• for domestic fireplace construction, the
assumption is that heat producing appliance
will not exceed 30 kW (London) 45 kW
(Building Regulations) output rating.

73. BY-LAWS CONTI…
• a resulting flue should not exceed 225 mm x
225mm;
• a chimney may be defined as a solid material
surrounding a flue;
• flue is a duct through which smoke and other
combustion products pass;
• a chimney is a single flue surrounded by at
least 100 mm of brickwork;

74. BY-LAWS CONTI..
• a stack consists of two or more flues surrounded
by the requisite amount of brickwork, if the
withes of the stack are ½ brick in thickness;
• every flue must be surrounded by at least 100
mm thickness of brickwork, properly bonded and
exclusive of the flue lining thickness;
• a gas flue thickness is reduced to 225 mm,
exclusive of plastering, but the mortar joints must
not project into the flue;

75. BY-LAWS CONTI…
• every chimney or stack consisting of two or more
chimneys must be built to a height of at least 900
mm above the last point of contact emerging
from the roof;
• in no case must a chimney or stack be built up to
a height greater than 6 times its least width at
the last point of leaving the roof;
• the top of a chimney carried up through the ridge
must be at least 600 mm above the ridge;

76. BY-LAWS CONTI…
• but in all other cases at least 1 m measured from
the highest point in the line of junction with the
roof;
• every chimney must be built on a suitable
foundation approved by the District Surveyor;
• the twelve highest courses of every chimney or
stack must be built in cement mortar, or cement-
lime mortar can be used, provided there is 1 part
of cement to every 6 parts of sand;

77. BY-LAWS CONTI…
• a chimney stack passing through a roof must be
properly protected against the adverse effects of
moisture, achieved by inserting a damp course in the
brickwork as the stack emerges from the roof;
• chimneys inclining at an angle less than 45 degrees to
the horizontal must be provided with a soot door not
less than 0.026 square metres in a proper frame.
• the inside of every chimney must be rendered or lined
with non-combustible materials (e.g. fireclay,
diatomaceous earth, heavy duty asbestos) as building
proceeds.

78. BY-LAWS CONTI…
• non-combustible linings are purpose-made
units either square or circular in section to fit
1 brick by 1 brick flue;
• the outer surface of every chimney within a
building constructed of a material less than
200 mm thick must be properly rendered up
to the level of the outer surface of the roof or
gutter.

79. BY-LAWS CONTI…
• woodwork must not be placed under any
fireplace opening within 225 mm (London) or
250 mm (Building Regulations) from the upper
surface of the hearth except for fillets or
bearers supporting the hearth, unless an
airspace of not less than 50 mm between the
underside of the hearth and any combustible
material is provided;

80. BY- LAWS CONT…
• woodwork must not be built within 225 mm to
any flue or to the inside of any fireplace
openings;
• wooden pegs must not be driven into any wall or
chimney nearer than 150 mm to any flue or the
fireplace inside;
• if fireplace surrounding is constructed of wood or
any other combustible materials, must be at 150
mm measured horizontally and 300 mm
measured vertically from fireplace opening, being
backed with solid incombustible material;

81. BY-LAWS CONTI…
• line the chimney with insulating brick (e.g. fosasil)
or by the cavity provision where a chimney is
adjacent to constructional steelwork or
reinforced concrete;
• a flue must not be used for more than one
fireplace unless: it is impracticable to meet
building requirements erected before the by-
laws were approved and enforced, or there are
two fireplaces in the same room;
• jambs of every fireplace opening must be at least
200 mm wide;

82. BY-LAWS CONTI…
• the back of every fireplace opening in a party
structure must be at least 200 mm thick from
the hearth up to 300 mm above the top of the
fireplace;
• all thickness may not be less than 100 mm
where a chimney breast is not on a party wall
(Hodge, 1987).

83. REFERENCE
• Chudley, R. (1987). Construction Technology-V.L. 1 (2nd ed).
England: Longman Group UK Limited.
• Chudley, R. and Greeno, R. (2001). Building Construction
Handbook (4th ed). Great Britain: Keywood Typsetting
Services Ltd.
• Grundy JT. (1984). Construction Technology-Vol 3. London.
Edward Arnold Ltd.
• Hodge, J.C., (1987). Brickwork for Apprentices. London:
Edward Arnold (Publishers) Ltd.
• Mugari, K. and Pekoyo, I. (2010). O’Level Building Today.
Harare, Zimbabwe: ZPH Publishers (Pvt) Ltd.
• Nash, W.G. (1989). Brickwork 2. London: Stanley Thornes
(Publishers) Ltd.