RYMEC, BALLARI Page 1 Module -4:
Doors, Windows and Ventilators: Location of doors and windows, technical terms, Materials for doors and windows, Paneled door, Flush door, Collapsible door, Rolling shutter, PVC Door, Paneled and glazed Window, Bay Window, French window. Ventilators. Sizes as per IS recommendations Stairs: Definitions, technical terms and types of stairs, Requirements of good stairs. Geometrical design of RCC doglegged and open-well stairs.
Formwork: Introduction to form work, scaffolding, shoring, under pinning. STAIRS
“Stairs are the medium through which a person can travel from one horizontal level to another horizontal level”.
Or
“A stair is a set of steps leading from one floor to the other. It is provided to afford the means of ascent and descent between various floors of the building”.
STAIRCASE: The room or enclosure of the building, in which the stair is located, is known as staircase.
The opening or space occupied by the stair is known as a stairway.
In a domestic building the stairs should be centrally located to provide easy access to all rooms. In public buildings, stairs should be located near the entrance.
Stairs may be constructed by timber, bricks, stone, steel or reinforced cement concrete. Staircases provide access and communication between floors in multi-storey buildings. They are a path by which fire can spread from one floor to another.
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Staircase, therefore, must be enclosed by fire resisting walls, floors, ceiling and doors.
Another important aspect in the design of stairs is the strength aspect. It must be designed to carry certain loads, which are similar to those used for the design of floor.
The technical terms associated with the design and constructions of stairs are:
Tread: it is the upper horizontal portion of a step upon which the foot is placed while ascending or descending.
Riser: it is the vertical portion of a step providing a support to the tread. Flight: this is defined as an unbroken series of steps between landings. Landing: it is the level platform at the top or bottom of a flight between the floors. A landing facilitates change of direction and provides an opportunity for taking rest during the use of the stair.
Rise: it is the vertical distance between two successive tread faces. Going: it is the horizontal distance between two successive riser faces.
Strings and Stringers: these are the slopping members which support the steps in a stair. They run
along the slope of the stair.
Newel Post: newel post is a vertical member which is placed at the ends of flights to connect the ends of strings and hand rail.
Baluster: it is vertical member of wood or metal, supporting the hand rail.
Hand Rail: it is the surrounded or moulded member of wood or metal following generally the contour of the nosing line, and fixed on the top of balusters.
Nosing: It is the projecting part of the tread beyond the face of the riser. It is rounded to give good architectural effect.
RYMEC, BALLARI Page 3 Run: The total length of a stair in a horizontal plane is known as the run and it includes the length of landing also.
Head room: The vertical distance between the nosings of one flight and the bottom of the flight immediately above. It should be of sufficient value so as not to cause any difficulty to the persons using the stairs.
Scotia: This is an additional finish or moulding provided to the nosing or tread to improve the elevation of the step and to provide strength to the nosing.
Soffit: The under surface of a stair. It generally covered with ceiling or finished with plaster.
Types of Landings Half Space Landing:
• Change stair direction 180⁰
• Landing width = width of stair (min 750mm) • Used in Dogleg Stairs
RYMEC, BALLARI Page 4 Quarter Space Landing:
• Change Stair Direction 90⁰
• Landing Width & Length = Stair Width • Forms Quarter Turn Stair (min 750mm)
Three quarter turn stairs:
A stair turning through three right angles. In this case, an open well is formed. This type of stairs is used when the length of the staircase is limited and when the vertical distance between the two floors is quite large.
Intermediate Landing:
• Allows the Stair to continue in same direction • Required where more than 18 Risers
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• Width = Stair Width
• Length = Stair Width or greater Types of Staircases
Based on type of Material: 1. Wooden Stair
2. Stone Stair 3. Steel Stair
4. Reinforced Cement Concrete Stair 5. Brick stair
TIMBER STAIRS:
These stairs are light in weight and easy to construct. They are very poor in resisting fire.
They are used only for small rise residential buildings.
Sometimes, fire resisting hard wood of proper thickness (45mm) may be used. The strings supporting the ends of wooden steps may be a cut string or a close string. The scotia blocks may be provided to give a additional finish to a wooden step.
A metal strip may be provided on a nosing of a wooden step to increase its resistance against wear and tear.
The landing in case of a wooden stair may be formed by providing wooden bearers or beams of suitable sizes.
The timber used should be free from fungal decay, insect attack and other defects. STONE STAIRS:
The stones to be used for the construction of stairs should be hard and non absorbent and they should possess enough resistance to the action of fire.
They are widely used for warehouses, workshops etc.
These are widely used at places where ashlar stone is readily available.
Stone used for construction of stairs should be hard, strong and resistant to wear. The simplest form of stone stairs is those supported on both the ends.
They can be constructed either of rectangular step with rebated joints or spandrel steps or tread and riser step or cantilever tread slab step or built up step.
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Stones can be supported and fixed at the both the ends of the wall. The bearing in wall should be at least 100mm for stairs up to 1.20m width and 200mm for width greater than 1.20m. The steps may be supported at one end only and the other end may be left unsupported, such
cantilevered step should not have length of more than 1.20m. METAL STAIRS:
Stairs of mild steel or cast iron are used only as emergency stairs.
The common metals used in metal stairs are cast iron, bronze and mild steel. The treads and rise may be of one unit or may be separate units.
The stingers are normally of channel sections.
The treads and risers are supported on the angles which are connected to the stringers. For metal stairs the metal balusters with handrail of pipe is used.
They are not common in residential and public buildings, though they are strong and fire resistant.
These are commonly used in factories, godowns, workshops, etc. R.C.C:
These are the stairs widely used for residential, public and industrial buildings. They are strong, hard wearing and fire resisting.
These are usually cast- in – situ and a wide variety of finishes can be used on these.
The steps can be provided with suitable finishing material such as marble, terrazzo, tile etc. These stairs can be easily maintained clean and they are strong, durable and pleasing on
appearance.
They also can be easily rendered non slippery and can be designed for greater widths and longer spans.
The steps may be can in situ or pre cast.
The details and placing of reinforcement will naturally depend on design of RCC stairs.
BRICK STAIRS:
These are not very common, except at the entrance.
However, brick stairs of single straight flight are often made in village houses.
The stairs consist of either solid wall, or also, arched openings may be left for obtaining storage space. The latter arrangement reduces the total quantity of materials and gives some additional space.
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The tread and riser of a brick stairs are finished with suitable flooring material.
The treads and risers are generally made equal to length of 1 ½ bricks and height of 2 layers of bricks respectively.
GLASS STAIRS:
This type of stairs is not commonly used.
It is usually used in places were appearance is of utter importance. It can be easily damaged.
Glass is brittle in nature, hence harmful.
Tread edges are sharp, which may hurt while ascending and descending. They are not strong.
Types of Stairs: 1. Straight Stair 2. Dog legged Stair 3. Quarter turn Stair 4. Open newel Stair 5. Three quarter turn Stair 6. Bifurcated Stair
7. Geometrical Stair 8. Circular Stair Straight stairs:
All steps lead in one direction
This may be continuous with two flights with an intermediate landing Adopted when staircase is narrow and long
RYMEC, BALLARI Page 8 Dog-legged Stairs:
Consists of two straight flights running in opposite directions There is no space between the flights in plan
Landing is provided at level where direction of flight changes.
This type of stair is useful where the width of the staircase hall is just sufficient to accommodate two width of stair.
Quarter Turn Stairs:
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Quarter turn stairs run straight in a flight and after reaching the landing changes its direction. This stair turns either to left or right at 90° degree.
It runs again till it reaches the consecutive horizontal level.
Open Newel Stairs:
Popularly known as open well stairs.
In these types of stair there is a well or opening between the flights in plan. This well may be rectangular or of any geometrical shape
A well or opening is left between forward and backward flight The opening is generally used for installation of lift
RYMEC, BALLARI Page 10 Three Quarter Turn Stair:
A stair turning through right angles is known as three quarter turn stair. This has its direction changes to 270°.
In this case an open well is formed.
Some flights have very few risers (only 3-4).
Bifurcated Stairs:
These stairs are so arranged that there is a wide flight at the start which is further sub-divided into two narrow flights at the mid-landing.
The two-narrow flight starts from either side of the mid-landing. These stairs are suitable for modern sub building.
RYMEC, BALLARI Page 11 Geometrical Stairs:
These stairs may have any geometrical shape and they require no newel post.
This type of stair is similar to open newel stair except the well formed between forward and backward flight is curved.
Change of direction in such stairs is achieved by winders and not by landings.
Circular or Spiral Stairs: It is known as spiral stair.
When viewed from top it appears to follow a circle with a single centre of curvature. The spiral stairs are provided where space available is limited and traffic is low. These stairs can be constructed in R.C.C., Steel or Stone
RYMEC, BALLARI Page 12 Essential Requirements of good Staircase:
Location of the staircase should be such as to provide easy access to the occupants. It should be well ventilated, especially at turns.
Width of the stair should be adequate for the users. 1. Minimum 1000mm for Residential Buildings. 2. Minimum 1350mm for Public Buildings.
The slope of the stair should not exceed 40° and it should never be less than 25°.
The number of steps in a flight should be restricted to a maximum of 12, from comfort point of view and a minimum of 3.
Headroom of desirable height, 2300mm should be provided. Width of the landing should not be less than width of the stair.
Materials used in the construction of stairs should be sound and fire proof. All the risers and treads should be of uniform dimensions.
Winders should be avoided as far as possible. However, if winders are unavoidable, they should be given at the bottom rather than at the top of flight.
It’s not desirable to provide Flight with more than 12 or at most 15 steps and not less than 3 steps
When flight consists of more than 3 steps, a hand rail at least on one side is considered to be necessity. The wide stairs, should be provided with handrails on both the sides.
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Type of Building Maximum Riser Minimum Tread
Public Building 150mm 300mm
Domestic Building 190mm 250mm
Geometrical Design :
The height of floor is generally known. The procedure for determining the number of treads and risers is as follows
1. The position of first and last risers is determined with regard to the position of doors, window or varandahs etc.
A convenient height of the riser is assumed
Number of risers = total height of floor / Height of riser Number of treads in a flight =number of risers-1
This is due to the fact that the surface of the upper floor forms the tread for the top step Ex. Suppose that the height of floor is 3.50m Assume a riser of 0.14mm Then No of risers = 3.50 / 0.14 =25
No. of treads for stair with single flight = (25-1) = 24 No. of treads for stair with double flight =25-2=23
Depending upon the space available for staircase the type of stair is selected.
Treads and Risers:
For comfortable ascent and descent, the rise and tread of a step should be well proportioned. The following thumb rules are followed
(Rise in cm) + (going in cm) =40 to 45
(Rise in cm) x (going in cm) =410 to 450 approximate (2 x rise in cm)+ (going in cm) =60 approximately
RYMEC, BALLARI Page 14 Problems:
1. The inside dimensions of a staircase in a residential building are 2.00m x 4.60m. The height of floor is 3.30m and the roof consists of RCC slab of 120mm thickness. Design a proper layout of an RCC stair for this building.
Solution: Adopt a dog-legged stair
Assuming a convenient height of riser=180mm
Then, Number of risers = Total height of floor/Height of riser = (3.30 +0.12) /180 =19
In order to provide suitable headroom below landing level, provide 12 risers in the first flight and 7 risers in the second flight.
Assume a tread of 230mm
No. of treads in the first flight = No. of risers -1 = (12-1) =11 Width left for landings = (4600-11 x 230) =2070mm
2. Plan a doglegged stair for a building in which the vertical distance between the floor is 3. 6m. The stair hall measures 2.5m x 5.5m. Draw the plan. Solution
Solution: Let the rise be 15cm =150mm and tread = 25cm = 250mm Let the width of each flight =1.3m
Width of landing =width of stairs=1.3m
Number of risers= Total height of floor / Height of riser = 3600/150=24 Provide 12 risers in each flight
No. of treads in each flight =12-1=11
Space occupied by treads=11 x 250=2750mm Space
DOORS, WINDOWS &VENTILATORS Definition of door:
“A door may be defined as “an openable barrier or as a framework of wood, steel, aluminum, glass or a combination of these materials secured in a wall opening”.
Function of door:
It is provided to give access to the inside of a room of a building.
It serves as a connecting link between the various internal portion of building. They admit ventilation and light into the buildings.
Controls the physical atmosphere within a space by enclosing it, excluding air drafts, so that interiors may be more effectively heated or cooled.
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They act as a barrier to noise.
Used to screen areas of a building for aesthetic purposes Keeping formal and utility areas separate.
Location of door and windows in a building:
The number of doors in a room should be kept minimum due to the fact that more number of doors will cause obstruction and reduce the effective usable carpet area of the room.
It should not be located in the centre of the length of a wall. A door should preferably be located near the corner of a room, nearly 20cm away from the corners. It should meet the interior decoration. If there are two doors in a room, the doors should preferably be located in opposite walls, facing each
other, so as to provide good ventilation and free air circulation in the rooms.
The factors such as distribution of light, control of ventilation, prevalent direction of wind, privacy etc should be considered in the location of windows.
The sill of a window opening should preferably be located at a height of 700mm to 800 mm from inside of the floor level.
It should meet the interior decoration.
The location of a door should meet functional requirements of room. Components of a door:
a) Door frame b) Door shutter
Materials used for frames Timber Steel Aluminum Concrete Stone Materials for shutter
Timber Plywood Glass Steel PVC
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The use materials for doors and windows are wood, glass plywood and metals. That is the most common materials for doors and windows as it can be folded in a variety of shapes and can thus present a decent appearance. The glass is used for parents to admit more light the plywood can be used as a covering material the materials such as aluminum from St Anna commonly used especially for Windows. At places if it is likely to be attacked by vermins, the RCC frames may be provided for doors and windows. The traditional wooden door shutters inevitable problems of warping, rotting, painting and maintenance. They cannot therefore be considered suitable for bathrooms toilets and kitchens with water contact are continuous. Polyvinyl chloride or PVC is the wonder metal from the plastic family and it is used as to shutter is becoming popular because it provides total protection against corrosion, moisture, termite and chemicals.
The use of PVC for doors and windows is also going to be popular because of the following advantages offered.
1. They are totally rust proof, termite proof and water proof.
2. They are unaffected by coastal Saline air, dry heat, sub zero temperatures or Tropical rain 3. They provide an alternative to the wood
4. They do not fade, corrode, flake or warp and consequently require no maintenance.
5. They provide better thermal insulation and may be considered as Idol for air condition and heated rooms.
6. They restrict dust penetration through openings and hence prove ideal for operation theatres and computer rooms
Timber: Widely used for the construction of doors. Most of the people prefer timber because of its appearance. Doors can be constructed with solid planks or timber pieces. To increase the lifetime of doors various preservatives are added o Timber is seasoned
Plywood: Plywood is very useful, for flush doors. It takes good polish and provides smooth and plain appearance.
Glass: Glass pieces are fixed in door panels to admit light inside the room. Large openings in doors fitted with thick glass panels impart a beautiful appearance. The glass may be of various types frosted glass or beaded glass or ribbed glass
Metals: Steel and aluminum framed doors are widely used due to the pleasing appearance .If properly maintained, their life is very long. Hollow metal doors fabricated of a metal frame, covered with metal sheet are selected for greater strength, life and fire resistance.
Concrete: Reinforced cement concrete frames are used in areas where doors are exposed to vermin, fungus, white ants etc.
Technical terms used in connection with doors and windows:-
1) Frame:- A door frame consists of two vertical members called jambs and a horizontal member called head provided at the top.
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A window frame consists of two of more vertical member called jambs and two horizontal members provided at top and bottom. The top horizontal member is called head and the bottom horizontal member is called sill.
2) Hold fast:- It is generally made from mild steel. Holdfasts are provided on each sides f the door and window frame. They keep the frame in position.
3) Horn :- This is a horizontal projection of head or sill beyond the face of the frame. They keep the frame in position.
4) Rebate: - The depression made inside the frame to receive the shutter is called Rebate. 5)Transom:- It is the horizontal member used to divide a window frame.
6) Shutter:- The entire assembly of styles, panels and rails is known as shutter. Shutters are provided inside the door or window frame.
7) Style:- Out side vertical members of a shutter are known as styles. 8) Top rail:- The top most horizontal member of shutter is known as top rail
9) Bottom rail:- The lower most horizontal member of a shutter is known as bottom rail. 10) Lock rail:- This is the middle horizontal member of a shutter where locking arrangement is provided.
11) Frieze rail:- The rail which is provided between the top rail and lock rail is called frieze rail. 12) Mullion or Munting:- The vertical member running through a shutter and sub-dividing the shutter vertically is called mullion.
13) Panel:- The area enclosed between the vertical styles and horizontal rails is known as panel. 14) Sash or glazing bar:- It is a special type of frame made of light section and designed to carry glass fitted in a shutter.
15)Louver:- It is an inclined piece timber fixed within a frame. Louvers are provided in window where vision is required to be prevented without affecting the ventilation system.
16) Putty:- It is a mixture of whiting chalk and linseed oil. is used for fixing the glass panels. 17) Jamb: The vertical wall face of an opening which supports the frame of door and window 18) Reveal: The external jamb of a door or a window opening at right angles to wall face.
RYMEC, BALLARI Page 18 DOOR FRAME
• A door frame is an assembly of horizontal and vertical members forming an enclosure to which door shutters are fixed
• The vertical members are known as jambs or posts. • The top horizontal member is known as head.
• The horizontal projections of the head are known as horns.
• A rebate cut of about 12 mm is provided all-round the frame to receive door shutter. Types of Doors:
On the basis of working operations Hinged doors
Battened type Framed and paneled Glazed/Sash
RYMEC, BALLARI Page 19 Flushed Louvered Wire-gauge Revolving doors Sliding doors Swing doors Collapsible doors Rolling shutter 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 panel swings, 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.
Sliding doors:
In these doors, the shutter slide horizontally along tracks with the help of runners and rails. 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. Swing doors:
The shutter is fitted to its frame by special double action hinges.
The hinges permits the shutter to move both ways, inward as well as outward. The doors are not rebated at the meeting styles.
RYMEC, BALLARI Page 20 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. Their sound and weather isolation is poor.
Folding doors are usually pretty noisy.
They are considered as not durable type of roads.
Collapsible Door
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 shutter operates between two rails, one fixed to the floor and other to the lintel. Rollers are mounted at the top and bottom.
Rolling shutter:
These are commonly used for shops, godowns, stores etc.
The door shutter acts like a curtain and thus provides adequate protection and safety against fire and thefts.
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 is provided 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 operate mechanically. Battened & ledged doors:
These doors consist of vertical boards called battens which are nailed or screwed to the horizontal members, called ledges .
RYMEC, BALLARI Page 21 With Braces
This is a ledged and battened door to which braces have been added to prevent sagging. These braces must slope upwards from the hinge edge of the door.
Framed & Paneled Door:
These types of doors are widely used in all types of buildings since they are strong and give better appearance than battened doors.
Panel doors consist of vertical members called stiles and horizontal members called rails. Stiles and rails form the framework into which panels are inserted.
Panels may be solid wood, plywood, particleboard or louvered or
have glass inserts.
Additional vertical members called mullions are used to divide the door into any number of panels. Glazed Doors:
These are provided where the visibility of the interior of the room is required. These are generally provided for commercial shops, malls, etc.
Flush Doors:
The flush door with a framed core is a type of door that we frequently make in Rural Building. This door consists of a frame which has stiles, top and bottom rails, and narrow intermediate rails. It is covered on each side by a sheet of plywood Plywood-covered flush doors cannot be used where
they will be exposed to rain and sun. Louvered Doors:
These permits free ventilation through them and at the same time maintain the privacy of the room.
Wire gauged doors:
Wire gauge or fly proof door shutters are fixed to provide free air circulation and prevent mosquitoes, flies, insects etc. from entering into the building.
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shutters
double
with
opening
Door
=
DT
shutter
single
with
opening
Door
=
DS
1190 X 2090
X 2100
1200
12 DT 21
8
1190 X 1990
1200 X 2000
12 DT 20
7
990 X 2090
1000 X 2100
10 DS 21
6
990 X 1990
1000 X 2000
10 DS 20
5
890 X 2090
900 X 2100
9 DS 21
4
X 1990
890
2000
900 X
9 DS 20
3
790 X 2090
2100
800 X
8 DS 21
2
790 X 1990
800 X 2000
8 DS 20
1
frame(mm)
Size of Door
Size of Opening(mm)
Designation
Sl. No
Recommended Dimensions for Doors
WINDOWS
A window may be defined as an opening made in a wall for the purpose of providing day light, vision and ventilation. Construction of window is identical to that of door. It is comprised of two parts
1) Frame 2) Shutter
They are normally provided with two leaves.
The selection of size, shape, location and the number of windows to be provided in a room depends upon the following considerations.
i. Size of the room
ii. Location of the room and its utility iii. Direction of wind
iv. Climatic considerations of the site such as humidity, temperature, variation etc. Architectural treatment to the exterior of the building
RYMEC, BALLARI Page 23 1. Pivoted Windows 2. Double-Hung Windows 3. Sliding Window 4. Casement Windows 5. Glazed Windows 6. Louvered Windows 7. Metal Windows 8. Bay Windows 9. Corner Windows 10. Dormer Windows 11. Skylight 12. French window Fixed Window:
In this type, the glass pane is permanently fixed in the opening of the wall. The shutter can’t be opened or closed.
The function is limited to allowing light and or permit vision in the room. The shutters are fully glazed.
In homes, they are generally decorative windows near doors, stairwells and high-places. Pivoted windows
In this type of window, the shutter is capable of rotating about a pivot fixed to window frame. The frame has no rebate.
The shutter can swing horizontally or vertically. Double-hung windows
It has two panels, top and bottom that slide up and down in tracks called stiles.
These are the most commonly used windows today. When open, these windows allow air flow through half of its size.
The two parts are not necessarily the same size. It is possible to have controlled ventilation.
RYMEC, BALLARI Page 24 Sliding Window or Slider:
Has two or more sashes that overlap slightly but slide horizontally within the frame.
Suitable openings or grooves are left in the frame or wall to accommodate the shutters when are shutters are opened.
Casement windows
Casement windows are hinged at the sides.
When fully opened, offer the maximum amount of ventilation.
Operates like a hinged door, except that it opens and closes with a lever inside the window.
The panels may be either glazed, unglazed or partly glazed and are fixed in the grooves made in rails and styles.
Glazed window
This is a type of window where panels are fully glazed. The frame has styles, top rail and a bottom rail.
The space between top and bottom rail is divided into number of panels with small timber members called, sash bars or glazing bars.
Louvered window
They are provided for the sole function of ventilation and not for the vision outside.
The louvers are usually fixed at 450 inclination sloping downward to the outside to run-off the rain
water.
The windows provide light and ventilation even if closed.
Such windows are recommended for bathrooms, WC, workshops etc., where privacy is more important. Metal Windows:
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These are very popular in public buildings and can be made up of mild steel, stainless steel, aluminum, bronze etc.
Mild steel being cheapest of all, they are widely used.
The windows can be fabricated for the required size using light rolled steel sections. They can be fixed directly to the wall opening in a wooden frame or in the steel frame.
Bay window
The window projecting outward from the external walls . Wide and decoratively impressive allow for 180° view.
A multi-panel window, with at least three panels set at different angles to create an extension from the wall line.
They may be triangular, circular, rectangular or polygonal in plan. Corner window
These are provided at the corner of the room. Light and air is admitted from two directions.
The jamb post at the corner is made of heavy section. Dormer window and Gable window
The windows provided at the dormer end and gable end of the sloping roof to provide light and ventilation to the enclosed space below the roof.
Skylight
These are fixed windows on the sloping roofs.
Admit natural light and help distribute light more evenly throughout the room. Considered as an energy saver feature.
French window: French window: a pair of windows that have many small panes and that reach to the floor and open in the middle like doors
RYMEC, BALLARI Page 26 shutters double with opening Window = WT shutter single with opening Window = WS 12 WT 13 6 10 WT 13 5 6 WS 13 4 12 WT 12 3 10 WT 12 2 6 WS 12 1 Shutter (mm) Window Size of Window (mm) Size of Frame Opening (mm) Size of Designation No Sl
Recommended Dimension for windows:
VENTILATORS Ventilators are small windows of small height. They are generally fixed on top of doors or windows. The ventilators may also be movable.
They are provided with glass panels and steel grill for safety purpose.
Sometimes the ventilators are isolated from the door or window and they are provided at the top level of room or at any level between the top of the door or window and bottom of ceiling. Recommended dimensions for ventilators:
No. Designation Size of opening
(mm) Size of ventilators frame (mm) 1 6 V 6 600 X 600 590 X 590 2 10 V 6 1000 X 600 990 X 590 3 12 V 6 1200 X 600 1190 X 590
(6 V 6 stands for ventilator opening having width of 6 modules i.e 600 mm and height of 6 modules i.e 600mm
RYMEC, BALLARI Page 27 FORMWORK
“When concrete is placed, it is in plastic state. It requires to be supported by temporary supports and casings of desired shape till it becomes sufficiently strong to support its own weight. This temporary casing is known as Formwork or Forms or Shuttering”. The term moulds is sometimes used to indicate form work of relatively small units such as lintels. For circular works such as arch, dome, etc. the term centering is generally used.
Requirements of Formwork: Easy Removal:
Its design should be such that it can be easily removed with least amount of hammering. This prevents the possible injury to the concrete.
Further use of formwork becomes economical.
The process of removal of formwork is commonly known as Stripping.
Quality: The forms should be designed and built accurately so that the desired shape, size and finish of the concrete is obtained.
Economy:
The formwork material should be easily available. It should be such that it can be used several times.
As much as possible irregular shapes of forms should be reduced. Less Leakage:
There should be minimum leakage through the joints.
It is achieved by providing tight joints between adjacent sections of the formwork. Rigidity:
It should be rigid enough to retain the shape without any deformation. It should allow repeated use.
Smooth Surface:
The surface of the formwork should be smooth. It provides good concrete surface.
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This is normally achieved by applying crude oil. This also makes the removal of formwork easy.
Supports: The formwork should rest on sound and hard supports. Strength:
It should be sufficiently strong enough to bear all the loads coming on it like concrete, equipment's, labor etc. while placing the concrete.
Cost of Formwork:
It generally contributes to 30-40% of total cost of concrete in ordinary buildings and 50%-60% for special structures such as Dams, Bridges, etc.
Four things contributing to cost of formwork are: Cost of formwork material.
Cost of erecting, placing & removal of formwork. Cost of joining materials like nails, wires, etc. Cost of labor for fabrication of formwork
Timber Formwork:
Where formwork is required for fewer repetitions, timber formwork is preferred. It is cheap in initial cost.
It can be easily adopted or altered for new use.
Timber used for formwork should be well-seasoned, free from knots. Light in weight and easily workable with nails without splitting.
Important consideration for using Timber Formwork: Timber used should neither be too dry nor too wet.
Preferably its moisture content should be 20%. Minimum number of nails should be used.
Nails head should be kept projecting for easy removal. Cutting timber pieces should be minimum.
Steel Formwork:
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Initial cost of steel formwork is high. It is economical for large works.
Erection and removal of formwork is simple. It imparts smooth surface to the concrete.
Advantages over Steel Formwork:
It can be reused several times without much damage. It do not absorb water from concrete.
It does not shrink or swell. It is easy to install and dismantle.
Hence less labor cost compared to timber formwork. It gives excellent exposed surface to concrete. It possess more strength.
RYMEC, BALLARI Page 30 Removal of formwork:
Time of formwork removal mainly depends on the following factors 1. Type of Cement
1. Rapid hardening cements require lesser time as compared to OPC (Ordinary Portland Cement)
2. Ratio of concrete mix
1. Rich ratio concrete gain strength earlier as compared to weak ratio concrete. 3. Weather condition
1. Hydration process accelerates in hot weather conditions as compared to cold and humid weather conditions.
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10 Days
-8 21 Days
removal) (more than 6 m span)
Beams & Arches (Complete formwork
6
8 Days
-5 14 Days
removal) (up to 6 m span)
Beams & Arches (Complete formwork
5
5 Days 8 Days
remains intact)
Beams (Removal of Sheeting, Props
4
5 Days 10 Days
Slab (Complete Formwork removal)
3
3 Days 4 Days
Slab (Vertical Supports remains intact)
2
2 Days 3 Days
-2 Beam sides, walls & Columns
1
Cement
Hardening
Rapid
(Ordinary Portland Cement)
OPC
Structural Member
No Sr.
SCAFFOLDING
When the height above floor level exceeds 1.50m a temporary structure, usually of timber, is erected close to the work to provide safe working platform for the workers and to provide a limited space for the storage of plant and building materials.
“The temporary framework or the support system which is provided for the construction and maintenance purpose is known as a Scaffolding or simply Scaffold”.
It is generally useful in construction, maintenance, demolition and repair works. Components Parts of a Scaffolding:
Standards: these are the vertical members of the framework. They are either supported on the ground or embedded into the ground.
Ledgers: these are the horizontal members parallel to the wall.
Putlogs: these are the pieces of wood which is placed on the ledgers and which are supported on the wall at one end.
Transoms: these are the putlogs, but both the ends are supported on the ledgers. Braces: these are the diagonal or cross pieces fixed on the standards.
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Toe Board: this the board placed parallel to the ledgers and supported between the putlogs. Raker: this is an inclined support.
The various members of scaffolds are supported by means of devices such as nails, bolts, rope, etc.
Types of Scaffolding: 1. Single Scaffolding 2. Double Scaffolding 3. Cantilever Scaffolding 4. Suspended Scaffolding 5. Trestle Scaffolding 6. Steel Scaffolding 7. Patented Scaffolding Single Scaffolding:
Most common type of scaffolding.
It is widely used in construction of brick masonry.
It consists of single row of standards placed at a distance of about 1.2m from the wall. The distance between the successive standards is 2m-2.5m.
The ledgers are then fixed on the standards.
Putlogs are placed with one edge on the ledgers and other end on the wall. This type is sometimes called putlog scaffolding
RYMEC, BALLARI Page 33 Double Scaffolding:
This is stronger than single scaffolding. It is used in the construction of stone work.
The framework is similar to single scaffolding except that two rows of standards are provided. This type is sometimes called as independent scaffolding.
Cantilever or needle Scaffolding:
This type of scaffolding is useful under following circumstances: When proper hard ground is not available for standards to rest.
When construction is to be carried for upper parts of multi-storied buildings. Here frame work may be single or double scaffolding.
RYMEC, BALLARI Page 34 Suspended Scaffolding:
This is very light type scaffolding.
Generally used for maintenance works such as painting, pointing, whitewashing, distempering etc. The working platform is suspended by means of ropes.
It can be raised manually or mechanically. It doesn’t create any obstructions on the ground. It provides optimum level for working.
Trestle Scaffolding:
Here working platform is supported on movable things like ladders, tripods, etc. mounted on wheels. This type of scaffolds is generally used for minor repair and painting works.
RYMEC, BALLARI Page 35 Steel Scaffolding:
Steel can be used as a replacement to timber scaffolding.
The diameter of tubes is about 40mm-50mm and thickness is about 5mm. The tubes are available in standard lengths.
They can be used up to any height. It is strong and more durable.
It can be easily erected and dismantled. High scrap value and it is resistant to fire. Initial cost is high & require skilled labors.
Patented Scaffolding:
Now a days these are very much in use. They are made of steel.
It consists of special types of couplings and frames.
RYMEC, BALLARI Page 36 Points to be attended to in scaffolding:
Bedding of standards: If standards are not resting on the firm ground, the base plates of suitable size should be provided at their bottom end. Further, if required, a timber sole plate may be provided on which the base plate rests.
Loading: The scaffolding should never be loaded heavily mainly because it is temporary structure. Tying in scaffold: It is necessary to tie back the scaffolding with the building at suitable levels. Raising: As the work proceeds, the standards are lengthened and fresh ledgers and putlogs are
inserted. The working platforms are then shifted to new levels.
Finishing: After the scaffolding is removed, the holes of putlogs in the wall should be immediately filled up.
Spacing of standards: The loading of the scaffolding decides the spacing. It is less for heavy loading and more for light loading. The max spacing is about 3m.
Miscellaneous structures: The scaffolding of special types should be built for structures like chimneys, towers, domes, etc
UNDERPINNING
“Underpinning means the rebuilding or deepening of the foundation of an existing building to provide additional or improved support”.
Or
“Underpinning is the installation of temporary or permanent support to an existing foundation to provide either additional depth or an increase in bearing capacity”.
Purpose of Underpinning
To obtain additional foundation capacity To modify the existing foundation system
To create new foundations through which the existing load may be wholly or partially transferred into deeper soil
Underpinning is generally used for remedial purposes To arrest the excessive settlement
To improve the future performance of the existing foundations When Underpinning is Required?
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Underpinning is required when:
Construction of a new project with deeper foundation adjacent to an existing building. Change in the use of structure
The properties of the soil supporting the foundation may have changed or was mischaracterized during planning.
To support a structure which is sinking or tilting due to ground subsidence or instability of the super structure
As a safe guard against possible settlement of the structure when excavating close to or below its foundation level.
To enable the foundation to be deepened for structural reasons e.g to construct the basement beneath the building
To increase the width of the foundation to permit heavier loads to be carried e.g when increasing the story height of the building
REQUIREMENT OF AN UNDERPINNING DESIGN: The art of underpinning requires an engineer to:-
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Determine the loads
Determine the bearing capacity of the soils
Design an underpinning system to support the structure with minimum of settlement. Considerations Before Underpinning
Height of the building Column spacing Wall thickness
Type and material of construction Different loads acting on the building Condition of the building
Methods Used for Underpinning Pit Underpinning
Push Piers System Helical Pier System Pile Underpinning Other Methods • Chemical Grouting • Microfine Grouting Micro piles Pit Underpinning
The most common and oldest method of underpinning
Requires careful and skilled work as loss of ground will cause building settlement.
In this method, the existing wall is divided into suitable sections of width about 1.20m to 1.50m. The holes are then made in the existing wall. The needles with bearing plates are then inserted through
these holes and supported on jacks.
Columns/ walls above the affected footing should be braced as much as possible.
A pit of 3’ wide, 4’ long and 5’ deep is excavated in front of the footing to be underpinned. Pit is extended laterally to reach under the foundation to be underpinned
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Vertical formwork is built in the pit and then is concreted up to the foundation Dry packing operation is then carried out.
If the length of the wall is more, the underpinning is started from the middle and it is then extended in both the directions.
One section should be excavated at a time.
It is desirable to carry out the new foundation work in concrete. Push Piers System
Push Pier systems utilize high-strength steel pier sections that are hydraulically driven through heavy-duty steel foundation brackets to reach deep down to competent load-bearing strata.
The piers have the ability to reach far below the problem soils and do not rely on friction for capacity. Push pier systems are an easy, economical solution providing with a long-lasting result.
Push Pier Advantages:
Piers reach greater depth than other options
Long life span – galvanized steel is resistant to corrosion Does not require the use of invasive equipment
In most cases, can lift foundation back to level position Restores Property Value
Helical Pier System
Helicalpiersare used to support foundation of existing structures.
Piers are drilled under the affected foundations to a specified depth with the help of a hydraulic motor attached to a backhoe.
Difficult to use below water level. Pile Underpinning
In this method, the piles are driven along both the sides of the existing wall and then needles in the form of pile caps are provided through the existing wall.
The existing wall is relieved of the loads coming on it.
This method is useful in clayey soils and for water logged areas and for walls carrying heavy loads. This technique is used to overcome the extremely difficult working circumstances en countered when
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For underpinning very light structures, the piles are driven along the structures and then brackets or cantilever needles are provided to carry the structures.
Cement Grouting
This method is used to restore slab or pavement which has settled. The operation is simple.
The holes are drilled in the slab and the cement grout is forced under pressure through these holes. The pressure is maintained until the cement grout has set.
Chemical Grouting
In this method, soil under the existing footing is consolidated by using chemicals.
Perforated pipes are drilled into the ground in an inclined direction. The inclination slopes are so adjusted that the entire area under the existing footing comes under the command of the inclined pipes.
A solution of Sodium Silicate is pressure-injected into the ground and then Calcium or magnesium chloride is injected as the pipe is withdrawn.
The chemical reaction takes place between these two chemicals and the soil is consolidated. This method is useful when the soil consists of sand or granular materials and the cost of
consolidation depends on nature of soil, depth of consolidation, site of work etc. Microfine Grouting
A perforated pipe is drilled into ground and fluid grout mixture is injected by pressure The mixture consist of
water + Cement
water + cement + fly ash or lime Vibroflotation
In this method, the underpinning is carried out by vibrating the sand and thereby increasing its density which ultimately results in the increase of bearing capacity of soil.
This method is useful for granular and sandy soils.
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The vibrating equipment or soil to be compacted is to be isolated from the building and its shoring.
SHORING Definition
“It is the method of providing temporary support (shores) to an unsafe structure”. Shoring is required under following circumstances:
Adjacent structures are to be dismantled.
Cracks developed due to unequal settlement of foundation in a wall are to be repaired. Large openings are required to be made in the main walls of existing buildings.
Walls of buildings showing signs of bulging out or leaning outwards due to bad workmanship. Defective walls of a building are to be dismantled and rebuilt and supports are necessary to the
floors or roofs connected to the wall.
Materials: The shoring can be carried out either in timber or in steel tubes or in combination. The timber surfaces should be coated with a preservative so as to give protection against wet rot. Duration: There is no limit for the duration of shoring and it ranges from week to years.
Requirements: the loads coming on shoring vary widely in nature and hence the requirements of each case of shoring should be studied separately and designed accordingly.
Approval: the shoring should be carried out as per prevailing rules and regulations of the local authority and necessary approval should be obtaine.
Types of Shoring
• Horizontal shoring or flying shoring • Vertical shoring or dead shoring • Inclined Shoring or raking shoring Horizontal shoring
The horizontal supports are given to parallel walls which have become unsafe due to the removal or collapse of the intermediate building.
It consists of
Horizontal beam or strut Wall plates
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Straining beams
The flying shore should have depth not less than 1/30th of the clear span and width not less
than 1/15th of its length.
The large factor of safety should be adopted in the design of flying shores as it is difficult to assess the actual loads.
The struts are generally inclined at 45 degree and in no case; the angle of inclination should increase 60 degrees.
The centre line of flying shores and struts and those walls should meet at the floor levels. If the floor levels of the two buildings are at different levels, the framework may be suitably designed and made unsymmetrical.
The building operations on the ground are not obstructed by this type of shoring. Only one set of shoring strengthen two walls.
When span increase 9m double flying shore can be used.
Vertical shoring
In this arrangement, the horizontal members,, known as the needles are supported by vertical members known as dead shores.
The needles are driven at right angles to the wall through the holes made in the wall. A dead shore is used in following circumstances
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i. The lower part of the wall has become defective.
ii. The foundations are to be deepened.
iii. The lower part of the wall is to be rebuilt.
iv. The large openings are to be made in the existing walls.
It consists of
i. Dead shores
ii. Sole plates
iii. Needles
iv. Props
The floors are suitably supported inside.
The openings above and bear a dead shore are suitably strutted.
A raking shore may be provided as an additional safety especially in case of weal walls.
The sequence of removal should be needles, strutting from openings, the floor strutting inside and raking shores, if any.
Inclined Shoring It consists of Rackers Needles Cleats Braces Sole plate
The wall plate is placed against the wall and is secured by means of needles which penetrate into the wall for a distance of 150mm.
The wall plate distributes the pressure evenly.
The needles, in turn, are secured by cleats which are nailed to the wall plate. The rakers are interconnected by struts or braces or lacings.
The feet of struts are stiffened by similar braces and they are connected with the sole plate by the means of iron dogs.
The centre line of the raker and of the wall should meet at the floor level.
The rakers prevent the outward movement of the wall and partly deflect the roof and floor loads. A large factor of safety should be adopted in the design of inclined shores as it if difficult to assess
the actual loads.
RYMEC, BALLARI Page 44
It is not desirable to do wedging as it would damage the building which is already in an unstable condition.
The length of the top raker can be reduced by providing a rider raker.
The sole plate is usually embedded in the ground and the legs of rakers rest on the sole plate.
Questions from Old Question Papers:
1. With the help of a neat sketch explain paneled and collapsible doors. 2. With the help of a neat sketch explain bay and paneled glazed windows. 3. With the help of sketches explain types of stairs.
4. Write short notes on shoring and underpinning.
5. List the guidelines to be followed while locating doors and windows.
6. With the help of a neat sketch showing all the components of fully paneled and revolving doors.
7. With neat sketches differentiate fixed and pivoted window, corner and bay window. 8. Define stair. With neat diagram explain thread, riser, flight and landing.
9. Plan a doglegged stair for a building in which vertical distance between the floors is 3.6m. The stair hall measures 3m X 5m (internal dimensions).
10. Briefly explain classification of stairs. 11. Write the requirements of a good stairs.
12. With the help of a neat sketch explain partially paneled and glazed door, revolving doors. 13. With the help of a neat sketch explain corner and bay window.
14. With the help of a neat sketch explain ledged and braced doors, skylights. 15. Discuss the following provision of door and window w.r.t location and size.
RYMEC, BALLARI Page 45
17. Plan a doglegged stair for a building in which vertical distance between the floors is 3.3m. The stair hall measures 2m X 4.60m (internal dimensions).RCC slab is 120 mm.
18. Write short notes on formwork for columns.
19. Differentiate the following formwork and scaffolding. 20. List the factors affecting the location of doors and windows.
21. What do you mean by underpinning? When do you require it? Explain the pit method of underpinning.
22. What are the salient features of a framed paneled door?
23. Explain with neat sketches dog legged and open newel staircase. 24. Draw a neat section of a staircase and label the parts with definitions. 25. Explain the terms shoring, slip forming and guiniting.
26. What are the requirements of good formwork?
27. Explain with neat sketches ledge and braced door, sky light.
28. Explain briefly the parts of a stairs with a neat sketch baluster, newel post, hand rail, flight, riser and thread.
