UNIT 04_BTM_ALL.pptx

Sanjivani Rural Education Society's
Sanjivani College of Engineering, Kopargaon
-Department of Civil Engineering-
By
Prof. V. S. Chaudhari (Assistant Professor)
Mail ID- chaudharivishalcivil@sanjivani.org.in

UNIT 04
DOOR, WINDOWS,
ARCHES AND LINTELS

CONTENTS
>Introduction
>Location of Doors
>Components of Door,
>Technical Terms of a Door
>Sizes of Door

What is Door?
> A door is defined as a movable barrier,
s e c u r e d i n a n o p e n i n g , k n o w n a s a d o o r w a y
th r o u gh a b u ild ing wall or partition for the
p u r p o s e o f p r o v id i n g a n a c c e s s t o t h e i n s i d e
of a building or rooms of a building.
>Door is provided to give an access to the
inside of a room.
>Serves as a thermal, acoustic and fire barrier,
also as a weath er b arrier as part of an external
wall.
>Location of Door: Preferably door is located
near the corner of a room.
>A door is held in position by a door frame,
t h e m e m b e r s o f w h i c h a r e l o c a t e d a t t h e s i d e s
and top of the opening or doorway.
Introduction

Location of Doors
The designer or the planner should observe the following rules
while deciding the location of door
>The number of doors should be minimum for a room for better movement
and for no obstruction in the room.
>From view point of utility of the accommodation and privacy of the
occupants, doors should preferably be located near the corner of a room.
>The location, number and size of the windows are decided considering
various factors.
>From view point of good ventilation and free air circulation inside the room,
the doors should be located opposite walls facing each other.
>The sill should be located about 70 to 80 cm about floor level of the room.

Parts of a Door
It consists of two parts:
1. Door frame 2. Door shutter
1. Door Frame:-
> It is an assembly of horizontal and vertical members, forming an enclosure,
to which the shutters are fixed.
> A door frame is made of timbers of sufficient cross section to support the
weight of door and to serve as surround to the door into which it closes .
> The majority of door frames are rebated to serve as stop for one way swing
doors.
> Width of door frame depend on thickness of wall
2. Shutters :-These are the openable parts of a door or window.

-Door
Shutter
(main part)
Door frame
(sub part )

TECHNICAL TERMS:
• HEAD:- This is the top or uppermost horizontal part of frame.
• SILL:- This is the lowest or bottom horizontal part of a window frame, not
provided indoor frames.
• HORN:- These are the horizontal projections of the head and sill. The length of
the horn indoor is kept about 10 to 15cm.
• STYLE:- It is the vertical outside member of the shutter of a door or window.
• TOP RAIL:- This is the top most horizontal member of the shutter.
• LOCK RAIL:- It is the middle horizontal member of the shutter where locking
arrangement is provided.

• BOTTOM RAIL:- This is the lower most horizontal member if the shutter.
• PANEL:- This is the area of shutter enclosed between the adjacent rails.
• HOLD FASTS:- It is a mild steel flats, generally bent into Z-shape, to fix the
frame to the opening. The horizontal length of hold fast is kept about 20cm
and is embedded in the masonry.
• JAMB :- This is vertical cross wall face of a door or window opening which
supports the frame and against which the shutters rest when they approach.
• REVEAL :- This is external jamb of a door openings which is at right angles
to the face of the wall.
• REBATE :- This is a cut or recess made inside a frame all round on one
side into which the door shutters are received by means of hinges.

Sizes of Doors:
>In general, a door should be of such dimensions that it allows the movement of the
largest object likely to be passed through the door.
>In case of residential buildings it should be aimed that two persons walking
shoulder to shoulder can freely move through the door; while in public buildings,
bigger sizes are used.
>Normally, the sizes of doors provided in different locations in the buildings areas
follows :
(1) Internal doors for residential buildings : 0.9 m x 2.0 m to 1.0 m x 2.1 m
(2) External doors for residential buildings : 1.0 mx 2.0 m to 1.2 mx 2.1 m

(3) Doors for bathrooms and water closets in residential buildings : 0.7 mx 2.0 m to
0.8 m x 2.0 m
(4) Doors in public buildings, viz. hospitals, libraries, cinemas, etc. : 1.2 mx 2.25 m
(5) Doors in garages : 2.5 mx 2.25 m
• Note : Minimum height of a door should not be less than 1.80 m.
• Common criterion for sizes of doors used in India is as follows :
Width = 0.4 to 0.6 x Height
or
Height = Width + 1.2 m

Designation of doors
>The size of an opening is indicated by number of modules where each
module is of 100 mm.
e.g. 10 DS 20 OR 10 DT 20
size of opening = 1000 x 2000 mm
• D – Door opening
• S – Single shutter
• T – Double shutter

CONTENTS
>Door Frames
>Method of Fixing Door & Window Frames
>Types of Doors

Materials used for door frames
• Timber
• Steel
• Aluminium
• Concrete
• Stone
DOOR FRAMES

1. Timber door frame
General specifications:
•All members of frames are of same species of
timber and be straight without any warp.
•The frames are smooth, well planed surfaces except
the surface touching wall lintelsill etc.
•The thickness of rebate is 15 mm and the width is
equal to the thickness of shutter.
•Nominal size of door frame for single shutter is 75
x100 mm and for double shutter 75 x 125 mm.

• The back portion of door frame which in contact with walls, lintels sill
etc. is painted with bitumen or any anti termite chemical.
• To protect door frame during construction priming coat is done before
fixing.
• A minimum of 3 holdfasts shall be fixed on each side, one at the centre
and the other two at 300 mm from top and bottom of the frame.
• Holdfasts and other parts, which go into the masonry wall and thus not
accessible for maintenance, shall be protected against moisture and
decay, with a coating of coal tar or other suitable protective material.

Method of fixing Door and Window frames:-
>The fixing place of Door and Window frames need special attention.
>It will depend on the way the shutters are to open usually the front doors open
inside.
>The door of shutters are planned to swing 90ºor 180º or and parallel to the wall.
>In modern building construction where concrete lintels are used over opening
door and window frames are fixed after the roof construction and before plastering
of masonry is taken.

Types of Doors:-
Doors are mainly classified on the basis of-
>Arrangement of components
>Method or manner of construction
>Working operations
>Metal doors

On the basis ofArrangement of Components
This includes four types:-
1. Battened & ledged doors
2. Battened, ledged and braced doors
3. Battened, ledged and framed doors
4. Battened, ledged, braced and framed doors

Battened & ledged doors
> These doors consist of vertical boards
called battens which are nailed or screwed
to the horizontal members, called ledges.
>Often the battens are about 15 to 18 cm
wide and 2 to 3 cm thick.
>Doors made with narrow battens like
these have a better appearance.

Battened, ledged and braced doors
>This is aledged and battened door to which
braces have been added to prevent sagging.
>These braces must slope upwards from the
h i n g e e d g e o f t h e d o o r , an d t h ey ar e h o u sed
with askew notch into the ledges.
>Battens : 100- 150 mm wide and 20-30 mm
thick.
>Ledges : 200 mm wide and 25 – 30 mm thick.
>The door is hung to the frame by T-hinges of
iron.
>The door is commonly used for narrow
openings for internal use where it is not subject
t o h a r d u s e , o r w h e r e e c o n o my i s o f ma i n
consideration than the appearance..

Battened, Ledged & Framed Doors
>It is improved version of battened and
ledgeddoors with provision of frame.
>Two vertical members known as styles are
provided

Battened, Ledged , Braced &
Framed Doors
>It is improved version of battened and
ledgeddoors with provision of frame.
>Two vertical members known as styles
are provided with extra braces.

Framed & Paneled Door
>These doors consist of a frame made up of
stiles, a top rail, a bottom rail and
sometimes an intermediate rail. Into this
framework a plywood panel is fitted.
>This panel may fit into a groove or a
rebate.

CONTENTS
>Types of Door continues…

• Hinged doors
• Glazed/Sash
• Flushed
• Louvered
• Wire- guage
• Revolving doors
• Sliding doors
• Swing doors
• Collapsible
doors
• Rolling
shutter
On the basis ofworking operations

Hinged doors
• Most doors are hinged along one side to allow the door to pivot away
from the doorway in one direction but not in the other. The axis of
rotation is usually vertical.
• The most common door type. It is a simple & rigid.
• The panelswings, opens and closes, on hinges.
• Hinged doors require a minimum amount of maintenance and
cleaning, they are not expensive, and have an excellent insulating ability.
• However, they take up precious room space to swing in.

Glazed or sash door
• This type is used in residential and public buildings.
• They supplement the natural lighting provided by windows or to make
the interior of the room visible from adjoining rooms.
• They can be made fully glazed or partly glazed.
• Fully glazed doors are recommended where sufficient light is required
through the door openings like in shopping malls, entrance halls etc.
• Incase of partly glazed, the bottom 1/3 rd part is usually paneled and
upper 2/3 part is glazed.

• They can be glazed fully or partly. Fully glazed doors are
recommended in situations where sufficient light is
required through the door opening as in the case of
shopping or display centres, lobbies, entrance halls etc.
• In case of partly glazed doors, normally the bottom one-
third height of the door is panelled and the remaining two-
third is glazed. In case of partly glazed doors, the styles are
sometimes diminished at the lock rail to improve the
elevation and to permit more area of glazing in the process.

Partly Glazed Door
Fully Glazed Door

Plastic doors:-
• Plastic doors are used in different types of building such as residential,
commercial, institutional, and many more.
• This doors are used in interiors as it is available in many designs and
colors.
• These are stable material doors, so it is sea water resistant , pollution
resistant.
• Plastic doors needs only regular cleaning it doesn’trots or fades.
• Such doors are chemically proof, dust proof, sound proof.
• These doors have good strength and high durability.

• With the large scale production of plywood and face veneers, use of flush
doors has become very popular these days.
• Flush doors have pleasing appearance, simple construction, high strength,
durability, and these doors cost less as compared with panelled doors.
• These doors are commonly used in residential as well as public buildings.
• Flush door shutter consists of a solid or semi solid framed skeleton(core)
covered on both faces with either plywood or a combination of cross bands
and face veneers giving perfectly flush and joint less surface.
• Flush door shutters are manufactured in standard thickness of 25,30,35
and 40 mm
Flush doors:-

• 25 mm thick shutter is considered suitable for door openings upto 800 mmx 2100 mm
in size; 30 mm to 35 mm thick shutter is used for opening of 900 mmx 2100 mm in
size whereas 40 mm thick flush door shutter is recommended for door openings ranging
from 1000 mmx 2100 mm to 1200 mmx 2100 mm in size.
Types of Flush Doors
Flush doors can be broadly divided into following three types :
(a) solid core type,
(b) Cellular core type, and
(c) Hollow core type

a) Solid core
>Door consist of the framework of vertical stiles and
top rail and bottom rail.
>The core consists of wooden strips (width not more
than 25 mm) glued together under high pressure OR
block board or particle board.
>Plywood sheets /cross bands/face veneers are glued
under high pressure to the assembly of core on both
faces.
>Such doors are quite strong but heavy and require
more material.
>Solid-core doors provide better sound insulation and
have less tendency to warp.

b) Hollow core:
• The frame consists of styles, top rail, bottom rail
and two intermediate rails, not less than 75 mm in
width.
• The space between the styles and rails is filled by
equally spaced battens each of minimum width 25
mm, such that voids are equally distributed and
limited to 0.5 sq. m.
• Plywood/veneers and cross bands can be glued
from both sides. The thickness of plywood should
not be less than 6 mm.

CONTENTS
>Types of Doors based on working operation continues…

Louvered doors:-
• Louvered door permits free ventilation through them and at the same
time maintain privacy of the room.
• The door may either be louvered to its full height or it may be partly
louvered and partly panelled.
• However these doors liable to the dust which is very difficult to be
cleaned.
• These doors are generally used for w/c and bathrooms of residential
and public buildings.
• The louvers are arranged at such an inclination that vision is
obstructed while they permit free passage of air.

PARTLY LOUVERED AND PARTLY PANELED
DOOR

Collapsible doors:-
• These doors consists of a mild steel frame which is made up of
light steel channel sections.
• They are provided with rollers at bottom and top to roll on
rails when they open or collapse.
• These doors work without hinges and can be opened or closed
by aslight pull or push, and are extensively used for residential
buildings, public building's, sheds. schools godowns etc.

>Such doors are used in garages, workshops, public buildings etc. to provide
increased safety and protection to property.
>The doors do not require hinges to close or open the shutter nor the frame to hang
them.
>It acts like a steel curtain.
>The door is made up from vertical double channels (20x10x2 mm), jointed
together with the hollows on the inside to create a vertical gap.
>These channels are spaced at 100-120 mm apart and braced with diagonal iron
flats.
>These diagonals allow the shutter to open or closed.
>The shutter operate between two rails, one fixed to the floor and other to the lintel.
>Rollers are mounted at the top and bottom.

• These doors are extensively used where frequent opening and
closing of a door is to be avoided due to heavy foot traffic, e.g.
public buildings, banks, hotels, stores, theatres, hospitals, etc.
• Such door provide entrance to the one and exit to the other
person simultaneously and close automatically when not in use.
• This door also suitable for air conditioned buildings or for
building situated at a place where strong breeze flow through out
the year.
• The door consists of centrally placed mullion to which four
radiating shutters are attached as shown in fig.
Revolving doors:-

>A revolving door normally has four wings/leaves that hang on a center shaft and
rotate one way about a vertical axis within around enclosure.
>The central shaft is fitted with ball bearing arrangement at the bottom, which allows
the shutters to move without anyjerk and making noise.
>The radiating shutters may be fully paneled, fully glazed or partly glazed. The glass
doors allow people to see and anticipate each other while walking through.
>Vertical rubber pieces are provided at the rubbing end of the shutter to prevent
drought of air. Revolving doors are energy efficient by eliminating drafts, thus
reducing the heating or cooling required for the building.
>The door may be motorized, or pushed manually using push bars. Revolving doors
therefore create a good seal from the outside and help to reduce A/C and heating
costs for climate control from the building.
>Revolving doors typically have a "speed control" to prevent people from spinning
the doors too fast.

• Rolling doors area modification over sliding doors.
• These doors are generally made of steel or slats of sheet
metal which can be easily closed or opened by slightly
pulling or pushing the shutter.
• They do not require much space and are commonly used
for garages, showrooms, shops, godowns, factory buildings
etc.
Rolling steel doors:-

>The door shutter acts like a curtain and thus provides adequate protection and
safety against fire and thefts.
>The shutter is made up of thin steel slabs called laths or slates about 1.25 mm thick
interlocked to each other and coiled upon specially designed pipe shaft called drum
mounted at the top.
>The shutter moves in two vertical steel guide channels installed at their ends.
>The channel is made up of steel sheets and deep enough to accommodate the
shutter and to keep it in position.
>A horizontal shaft and spring in the drum which allow the shutter to coiled in or
out.
>These may be manually operated for smaller openings (upto 10 sq.m.).
>Above 10 sq. m., they may be operated manually.

Folded doors
>Made of many narrow vertical strips or
creases that fold back to back into a
compact bundle when doors are
pushed open, these strips or creases
will be hanged from the top, and run
on a track.
>They save space as they do not swing
out of the door opening, though their
sound and weather isolation is poor.
Folding doors are usually pretty noisy,
and considered not so durable.

Sliding Doors
>In these doors, the shutter slide horizontally along tracks with the help of runners
and rails. often for space or Sliding glass doors are common in places where there
is no space to swing the door.
>Such doors are very popular for use for the entrances to commercial structures and
also in residential buildings for aesthetic considerations.
>Sliding doors consist of either one, two or three doors that slide by each other on a
track depending upon the size of opening and space available for sliding.
>They are pretty easily cleaned and maintained.
>These doors sound insulation is pretty poor usually, and they must be of high
quality and fitted exactly in their tracks or else they may slide out of them.

>When fully open these doors will allow half
the space of the opening in double sliding
doors, or one third if triple.
>Sliding doors move along metal, wood, or
vinyl tracks fitted into their frames at the top
and bottom. To ease their movement, sliding
doors often have plastic rollers attached to the
top and bottom or to the bottom only.
>The door is hung by two trolley hangers at the
top of the door running in a concealed track
while at the bottom, rollers are provided to
slide the shutter in a channel track.

Contents
• Introduction to Windows
• Criteria for Selection ofwindows
• Thumb Rules for deciding Area ofwindows
• Types of Window

WINDOWS - INTRODUCTION
• A window may be defined as an opening made in a wall for the
purpose of providing day light,vision and ventilation.
• The construction of window is identical to that of door.
• Window consists of a window frame and shutters.
• The frame consists of two vertical members called jambs, one flat, i.e.
horizontal member connecting the jambs at top, known as head and another
flat member connecting the jambs at their feet, known as sill.
• The shutter can be fully glazed, panelled and glazed or only panelled type.
Windows are normally provided with two shutter leaves.

The selection of size, shape, location and the number of windows to be provided in
a room depends upon the following considerations :
(a) Size of room to be lighted.
(b) Location of the room and its utility.
(c)Architectural treatment to be given to the building.
(d) Direction of wind and its speed.
(e) Climatic factors prevailing at the site such as humidity & temperature variation.

Following thumb rules have been framed to determine the area requirements for windows in a
room; and the size and hence the number ofwindows can be worked out once the total area
required for the window opening is known:-
• The total area of window openings should normally vary from 10 to 20% of the floor
area of the room. In hot and arid regions it could be 10 to 15% of the floor area. When
the building is to be located in hot and humid regions, the area of window openings
should vary between 15 to 20% of the floor area.
• In case of public buildings like, schools, offices, factories, hospitals etc, the minimum area
of windows should be 20% of the floor area.
• For adequate natural Iight the total area of glass panels in windows should be at least 8%
of the floor area.

• Casement window • Bay window
• Double hung window • Corner window
• Pivoted window • Dormer window
• Sliding window • Gable window
• Louvered or venetian window • Skylight window
• Sash or glazed window • Circular window
Types of windows:-

• Windows having shutters which opens like door are called as
casement windows.
• These are the main and common types of window usually
provided in the buildings.
• This has a frame consisting of styles, top rails, bottom rails
and intermediate rails,thus dividing into panels.
• The window frame is made in the same manner as a door
frame except that it has a sill at the bottom.
Casement window:-

Double hung window:-
• This type of window frame consists of frame and pair of shutters,
arranged one above the other.
• The shutters can slide vertically within the grooves provided in
window frame.
• By provision of sliding, the window can be cleaned effectively and
at the same time ventilation can be controlled effectively since
the window can be opened at top and bottom at desired extent.

Pivoted window:-
• This type consists of a frame and a shutter which is
pivoted to allow it to open with the top rail swinging
inside.
• The pivots are fixed slightly higher than the horizontal
central line of the shutter so that the shutter can be
self closing.
• The fittings used are pivots, cleats, latches and
ventilating gear etc.

• These windows are made of shutters which move horizontally
or vertically on small roller bearings.
• The shutters are of usual size.
• Suitable openings in the frame are left to accommodate the
shutters
Sliding window:-

Louvered or venetian window:-
• In this type of window the stiles of shutter are grooved to receive a series
of louvers which may be of glass or wood.
• The louvers are set with the grooves in inclined position so that
they slope downward to the outside in order to run off the
rain water and obstruct the horizontal vision at the same time.
• For economical construction the angle of inclination of the louvers or
blades to the vertical stiles should be 45".
• This type of window provides ventilation and light even when the opening is
closed.
• Such windows are commonly recommended for bathrooms, WCs and other
areas where privacy is the main consideration.
• It is difficult to maintain them clean as the dust gets easily deposited on louvers.

Sash or glazed window:-
• A sash window is a type of casement window in which the panels are
fully glazed.
• The frame of each shutter consists of two vertical stiles, top rail and
bottom rail.
• The panel space between the stiles and the rails is suitably divided by
small timber members or bars placed both horizontally and vertically
or only horizontally to suit the design requirements. These bars are
known as sash bars or glazing bars.
• Thus the sash bars divide the total panel space of a window shutter
into panels of small size.
• The glass panes are secured in position either by putty or by small
fillets known as glazing beads

Bay window:-
• Bay window projects outward from the face line of the
wall or a building.
• The projection may be triangular, circular, rectangular or
polygonal in plain.
• This gives extra floor area to the room and at the same
time provides an additional space for admitting light
and air into the room.
• A number of these windows might increase the
architectural beauty of the entire house.

• As the name suggests this type of window is
essentially located in the comer of a room.
• This window has two faces in two perpendicular
directions, due to this light and air is admitted from
both directions.
• In addition such window serves as an architectural
feature for improving the elevation of the building.
• However special lintel has to be casted over the
window opening in case of these windows.
Corner window:-

Dormer window:-
• A dormer window is a vertical window built in the
sloping side of a pitched roof.
• This window is provided to achieve proper
ventilation and lighting of the enclosed space below
the roof.
• Dormer also provides architectural feature for the
building.

A vertical window provided in the gable end of a pitched
roof is known as a gable window.
Gable window:-

Skylight window:-
• Skylight window is a fixed window provided on the sloping surface of a
pitched roof,the window being parallel to the sloping surface.
• Sky lights are provided with a view to permit the room below to be
fully lighted with natural light.
• The opening for the sky light is made by cutting the common rafter suitably.
• The framework of sky light supporting the glass panels consists of an arrangement of
trimming pieces, curb frame, bottom rail and top rail.
• The opening made for accommodating the sky light is properly treated by lead flashing
so as to ensure complete water proofing of the roof surrounding the opening.

Contents
• FIXTURES AND FASTENING FOR DOORS AND
WINDOWS

FIXTURES AND FASTENING FOR DOORS AND WINDOWS
• The fixtures and fastenings for doors and windows can be of Iron, Brass or Aluminium.
• Fixtures and fastenings are provided for doors and windows to provide operating
facilities, security for rooms and ease of opening and closing etc.
• The fixtures and fastenings are manufactured in different shapes and sizes to suit
the requirements of different sizes and types of doors and windows.
• The fixtures and fastenings can be broadly grouped as under :
(1) Hinges, (3) Handles, and
(2) Bolts, (4) Locks

Hinges:-
• Hinge is a fixture which helps the door to rotate freely along its axis.
Types of Hinges:-
(1) Butt Hinge
(2) Strap Hinge
(3) Garnet Hinge
(4) Parliamentary Hinge
(5) Nar-Madi Hinge

• This is the most common type of hinge used for doors and
windows.
• It has two flanges made of cast iron, malleable iron, or steel
with countersunk holes.
• One flange of hinge is screwed to the door or window and
other one screwed to the rebate of the frame.
Butt Hinge:-

Strap Hinge:-
• This type of hinge is normally used with ledged braced
doors,garage doors, boundary wall gates etc.
• The hinges have long arms which are fixed to the shutter
and the rebate in the frame.

Garnet Hinge:-
• This type of hinge is also known as T-hinge and is commonly used for
battened orledged and braced doors.
• The long arm of the hinge is screwed to the shutter whereas the short
armor plate of the hinge is screwed to the door frame.

Parliamentary Hinge:-
• When the opening is very small or narrow, then it is better to provide
parliamentary hinges to provide more space of opening as well as to avoid
obstruction while moving furniture etc.
• Parliamentary hinges permit the shutters when open to rest parallel to the wall
clear of the opening.

Nar-Madi Hinge:-
• Nar-madi hinge is used for heavy doors, but it consists only one flange which is
fixed to the door.
• Pin is fixed to the frame to which flange is attached whenever is needed.

Bolts:-
• Door or window bolts are used to provide security for the rooms.
Types of Bolts:-
(1)Aldrop Bolt
(2) Hook and Eye type Bolt
(3) Barrel Bolt andTower Bolt

Aldrop Bolt:-
• Aldrop bolt is olden type and most common type bolt.
• To lock this bolt padlocks are used.

Hook and Eye type Bolt:-
• This type of bolt is used to keep the windows shutter in required position when
it is opened.
• Hook is fixed to the shutter frame and eye is fixed to the window rail.

Handles:-
• Handles are used to open or close the door or windows.
Types of Handles:-
(1) Bow type handle
(2) Lever handle
(3) Door handle
(4)Wardrobe handle

Locks:-
• Locks used for doors and windows are of many types and some of them are :-
(1) Padlock
(2) Mortise lock
(3) Rim lock
(4) Cupboard lock
(5) Lever handle lock

Pad lock:-
A detachable lock hanging by a pivoted hook on the object
fastened is called as padlock.

Mortise lock:-
A mortise lock is a lock that requires a pocket- the mortise- to be cut
into the door or piece of furniture into which the lock is to befitted.

Rim lock:-
A lock that is fitted to the surface of a door as opposed to
a mortise lock is called as rim lock.

BuildingTechnology and Materials
UNIT-IV (B) LINTELS AND ARCHES
By
Prof.V S. Chaudhari
Assistant Professor
Civil Engineering Department
SRES’s Sanjivani College of Engineering
(An Autonomous Institute Affiliated to SPPU, Pune)
Kopargaon-423603

LINTEL:- INTRODUCTION
• A lintel is defined as a horizontal structural member which is
placed across the opening.
• A lintel is thus a sort of beam, the width of which is equal to
the width of the wall, and the ends of which are built into the
wall.
• The bearing of lintel should be the minimum of the following:
(1) 10cm
(2) Height of lintel.
(3) 1/10th
to 1/12th
of the span of lintel.

Classification of Lintel
Lintels are classified into the following types according to the materials of
their construction:
(1) Timber lintels
(2) Stone lintels
(3) Brick lintels
(4) Steel lintels
(5) Reinforced cement concrete lintels

 Timber Lintels:-
• Timber lintels are oldest type of lintels, though they are not commonly used now-
a-days, except in hilly areas.
• Timber lintels are relatively costlier, structurally weak and vulnerable to fire.
• They are also liable to decay if not properly ventilated.

 Stone Lintels:-
• Stone lintels are the most common types. specially where
stone is abundantly available.
• A stone lintel consists of a simple stone slab of greater
thickness.
• Stone lintels can also be provided over openings in brick
walls.
• Dressed stone lintels give good architectural appearance.
• Stone lintels may be used in the form of either one piece
or more than one piece along the width of the wall.

 Brick Lintels:-
• Brick lintels are not structurally strong and they are used
only when the opening is small (less than 1m) and loads are
light.
• A brick lintel consists of bricks placed on end or edge.
• The depth of brick lintel varies from 10 to 20 cm, depending
upon the span.
• It is constructed over temporary wooden centering.
• The bricks with frogs are more suitable for the construction
of lintel since the frogs, when filled with mortar, form joggles
which increases the shear resistance of end joints.

 Steel Lintels:-
• Steel lintels are provided where the opening is large and
where the super-imposed loads are also heavy.
• It consists of rolled steel joints or channel sections either
used singly or in combination of two or three units.
• When used singly, the steel joist is either embedded in
concrete, or cladded with stone facing, so as to increase
its width to match with the width of the wall.
• When more than one units are placed side by side they
are kept in position by tube separators.

 Reinforced Cement Concrete Lintels:-
• Reinforced cement concrete lintels have replaced practically all other types of
lintels because of their strength rigidity, fire resistance, economy and ease in
construction.
• These can be used on any span.
• Its width is kept equal to the width of the wall.
• The depth of R.C.C. lintel and the reinforcement depends upon the span and the
magnitude of loading.
• Longitudinal reinforcement, consisting of mild steel bars, are provided near the
bottom of lintel to take up tensile stresses.

• Shear stirrups are provided to resist transverse shear.
• R.C.C. lintels are also available as pre-cast units.
• For cast-in-situ units,which are quite common,formwork is required for
construction.

Lintel with chajja projection Wooden lintel

Ventilators :
• Ventilators are provided for the purpose of ventilation in the room.
• These are small windows provided at a greater height than windows nearer to roof
level,generally about 30 to 50cm below roof level.
• Horizontally pivoted shutters are provided for the ventilators.
• The shutters can be opened or closed by means of two
cords one attached to the top rail and other to the bottom rail of the
shutter.

BuildingTechnology and Materials
UNIT-IV (B) LINTELS AND ARCHES
By
Prof.V. S. Chaudhari
Assistant Professor
Civil Engineering Department
SRES’s Sanjivani College of Engineering
(An Autonomous Institute Affiliated to SPPU, Pune)
Kopargaon-423603

• An arch may be defined as mechanical arrangement
of wedge-shaped blocks of stones or bricks
mutually supporting each other and supported at
end by piers or abutments.
• Arch is a structure that spans a space and supports
structure and weight below it.
ARCH :- INTRODUCTION

Function of anArch:-
• The function of an arch is to carry weight of the structure above the
opening.
• Because of their shape, the blocks support each other by mutual
pressure of their own weight.
• Hence the structure remains in the position by the resistance from
the support.

Technical Terms:
The various technical terms used in arches are as follows:-
• Intrados:This is an inner curve of the arch.
• Extrados: It is the outer curve of an arch.
• Voussoirs:The voussoirs or arch stone are the wedge shaped units forming the arch.
• Crown: It is the highest part of the extrados.
• Keystone:This is the highest central wedge-shaped block of an arch.
• Haunch: It is the lower half of the arch between the crown and skewback.
• Springing points:These are the points from which the curve of the arch springs.

• Spandril: This is the curved triangular space formed between the extrados and the
horizontal line through the crown.
• Rise: It is the clear vertical distance between the highest point on the intrados and
springing line.
• Abutment:This is the end support of an arch.
• Pier:This is an intermediate support of an arcade .
• Springing line: It is an imaginary line joining the springing points of either end.
• Skewback: It is the inclined or splayed surface on the abutment which is so prepared
to receive the arch and from which the arch springs.
• Span:This is the clear horizontal distance between the two supports.

A) Classification ofArches Based on Shape:
Flat arch:-
• In this type of arch the intrados is apparently flat and it acts as a base of
equilateral triangle which was formed by the horizontal angle of 60° by
skewbacks.
• These flat arches are generally used for light loads, and for spans up to 1.5m.

 Segmental Arch:-
• This is the basic type of arch used for buildings in which centre of arch lies
below the springing line.
• In segmental arch, the thrust transferred to the abutment is in inclined
direction.

 Semi-circularArch:-
• The shape of arch curve looks like semi-circle and the thrust transferred to the
abutment is perfectly in vertical direction since skewback is horizontal.
• In this type of arch,the centre lies exactly on the springing line.

 Horse ShoeArch:-
• Horse shoe arch is in the shape of horse shoe which curves more
than semi-circle.
• This type of arch is provided mainly for architectural consideration.

 PointedArch:-
• In this type of arch two arcs of circles are met at the apex hence triangle is
formed.
• This may be either isosceles or equilateral.
• It is also known as Gothic arch.

 VenetianArch:-
• This type of arch is another form of pointed arch.
• Venetian arch has deeper depth at crown than springings.
• It contains four centre's , all located on the springing line.

B) Classification of arches based on number of centres:
One Centred Arches:-
• Segmental, semi-circular, flat, horse-shoe arches and silted arches are one centred
arches.
• In some cases, perfectly circular arch is provided for circular windows which is
called as bull’s eye arch also comes under these category.

Two Centred Arches:-
Pointed or gothic or lancet arches comes
under this category.
Three CentredArches:-
Semi-elliptical arch and Florentine arches comes
under this category as they have three centres.

Five Centred Arches:-
A good semi-elliptical shape arch
Comes under this category.
Four Centred Arches:-
Venetian arch is a typical example
for four centred arch.

2. Brick arch –
(a) Rough arch
(b) Axed or rough cut arch
(c) Gauged arch
(d) Purpose made brick arch
3.Concrete arch –
(a) Precast concrete arch
(b) Monolithic arch
1.Stone arch –
(a) Rubble arches
(b) Ashlar arches
C) Classification of arches based on Material andWorkmanship

(1) RubbleArches:
• Rubble arches are very weak and used only for inferior work,
these are used for spans up to 1m.
• These are made of rubble stones which are hammer dressed,
roughly to shape and size and fixed in cement mortar.
• Sometimes these are also used as relieving arches up to a
depth of 37.5cm, but these are constructed in one ring.
• If the depth is more,we can go for two rings in alternate
course of headers and stretchers.
(1) Stone Arch

(2) Ashlar Arches:
• In this type of arch the stones are cut to proper shape of voussoirs (a
wedge-shaped or tapered stone used to construct an arch) and fully
dressed,joined with cement mortar.
• Ashlar stones are also used to make flat arches.

(1) Rough Brick arches:
• This type of arch is constructed with ordinary bricks
without cutting these to the shape of voussoirs.
• The arch curve is provided by forming wedge shaped
joints with greater thickness at extrados and smaller
thickness at intrados.
• So, it looks unattractive. That's why it is not
recommended for exposed brick works.
(ii) BrickArches

(2)Axed Brick arches:
• The bricks are cut into wedge shape with the help of brick axe.
• So,these are roughly dressed in shape and size.
• Arch formed by these axed bricks is not very pleasant.

(3) Gauged Brick arches:
• This type of arch is constructed with bricks which are prepared to exact size and
shape of voussoirs cutting it by means of wire saw.
• The surface of bricks are fine dressed with the help of a file.
• For gauged brick arches only soft bricks are used.
• The joints formed in gauged brick arch are fine, thin (1 to 1.5 mm) and truly radial.
• Lime putty is used for jointing.

(4) Purpose Made BrickArch:
• These arch are made with special bricks which are manufactured in exact
shape and size of voussoirs.
• This is very fine workmanship.
• Lime putty is used as binding material.

(1) Precast Concrete Block Arches:
• Such arches are made from precast concrete blocks, each block
being cast in the mould to the exact shape and size of voussoirs.
• For keystone and skewbacks special moulds are prepared.
• Because of exact shape and size of blocks, good appearance of
the arch is achieved also joints made of cement mortar are
quite thin.
• However, casting of blocks is costly and such work is
economical only when the number of arches is quite large.
• Cement concrete of 1:2:4 mix is usually used.
(iii) Concrete Arches

• Monolithic concrete arches are cast-in-situ concrete, either
plain or reinforced depending upon the span and magnitude of
loading.
• These arches are quite suitable for larger span.
• The arch thickness is 15cm for arches up to 3m span.
• Formwork is used for casting the arch, and is removed only
when concrete has sufficiently hardened and gained strength.
• The curing is done for 2 to 4 weeks.
(2) Monolithic Concrete Arches:

The construction of arches, of all types of materials (i.e. bricks, stones,
concrete) is carried out in three steps:
(1) Installation of centring or formwork,
(2) Laying or casting the actual arch and
(3) Striking or removal of centring as formwork.
Construction ofArches

Step 1 – Installation of Centring:
• Centring is the temporary structure required to support brick, stone or concrete
arch during its construction till it has gained sufficient strength.
• The centring is installed in such a way that its upper surface corresponds with the
intrados of the arch.
• For minor works centring may be made of mud masonry constructed to match
with the inner soffit of the arch and then plastered.
• This masonry is dismantled later when the arch has been constructed and cured.
• The usual centring is made of timber or steel.
• Wooden centring is simplest and cheapest one which is used for moderate spans.

• It is easy to construct and easy to dismantle and it can be used several times.
• The centring made of wooden piece is known as turning piece.
• They are supported by props and a pair of folding wedges is provided at the top
of the props under the centring to tighten or loosen the centring.
Centring for wide soffits and bigger spans

Step 2 – Laying ofArch:
• After the erection or installation of centring, skewbacks are first prepared and
placed very carefully in the correct angles.
• Voussoirs are then arranged in proper and required forms, starting from
skewbacks and proceeding towards the crown from both ends.
• Finally, keystone is inserted so that all voussoirs are locked in position.
• It is important that the masonry above the skewback at the haunches should be
loaded by filling up the spandrels upto the level of the crown of the arch or at
least 2/3 of the height of the arch to counteract the thrust, this should be done
on both the sides

• Before the mortar hardens the centring is slightly slackened by means of easing
the wedges on the top of props by only 2 to 3 mm to permit the voussoirs to sit
on their beds properly.
• Such a process is an essential requirement in stone arches, since it permits the
voussoirs to settle upon their beds properly.

Step 3 – Removal of Centring:
• When the arch has developed sufficient strength,the centring can be removed.
• No load should be placed on the arch unless the centring has been removed.
• For small spans, removal of centring is done by loosening the folding wedges.
• When the span is more than 7 m, sandbox method can be used for loosening, so
that shocks are avoided.
• A sandbox as shown in fig is placed below the prop.
• Sand is filled in box with a plugged hole at its bottom.

• Prop rests on the steel plate placed on the top of sand.
• In order to lower the centring, plug is taken out due to which the sand flows out
and lowers the prop gradually.
Sand Box Method

UNIT 04_BTM_ALL.pptx

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