Floors divide buildings horizontally and support activities within. They must withstand loads, prevent dampness and growth, meet insulation standards, and have durable, acceptable surfaces. Ground floors prevent damp and growth while upper floors restrict fire/sound transmission. Floors require strength, stability, durability, fire resistance, heat/sound resistance. Roofs protect from rain and sun with parapets, spouts, and coverings. Underpinning reinforces foundations while shoring supports structures during dismantling or construction. Common underpinning methods are mass pour, mini piles, and beam/base.

1. Definition
• A floor is a structure formed of beams, girders and other members with
proper covering, which divides a building horizontally into stories.
• It can also be defined as the base or surface of a building on which all
activities in the building take place.
• Floors maybe stone, wood, metal, or any other material that can
support the expected load.
• Two types: Ground floor and upper floors.

2. Functions of floors
Floors need to satisfy a number of functional requirements as listed below;
GROUND FLOORS
I. To withstand the loads that will be imposed upon them, with domestic
buildings they are normally confined to persons and furniture but in other
classes such as factories floors maybe subjected to much heavier loads and
must be sufficient to carry them.
II. To prevent growth of vegetable matter inside the building by provision of
concrete over site.
III. To prevent damp penetrating the building by inserting a damp proof
membrane in or below the floor. Suspended floors also require under floor
ventilation to prevent stagnant, moist accumulating below them.

3. iv. To meet certain prescribed thermal insulation standards by incorporating a
layer of insulating material to reduce the heat loss into ground below.
V. To be reasonably durable and so reduce the amount of maintenance or
replacement work to a minimum.
VI. To provide an acceptable surface finish which will meet the needs of users
with regard to appearance, comfort, safety and cleanliness.

4. UPPER FLOORS
The functional requirements of upper floors include;
i. To support their own weight, ceiling and super imposed loads.
ii. To restrict the passage of fire, this is particularly important in high rise
buildings or where large amounts of combustible goods are stored.
iii. To restrict the transmission of sound from one floor to other.
iv. To posses an adequate standard of durability.
v. To accommodate services readily.
vi. To provide an adequate surface finish in the manner described for ground
floors.

5. Functional requirements of floors
 Strength
The strength of a floor depends on the material used for the structure of the floor
such as concrete, timber or steel. The floor must be strong enough to support safely
the dead load of the floor and finishes, fixtures, partitions and services and
anticipated imposed loads of occupants and furniture.
 Stability
A floor is designed and constructed to serve as a horizontal surface to support people
and their furniture. The floor should have adequate stiffness to remain stable and
horizontal under the dead load of the floor structure and such partitions and other
fixtures it supports and the anticipated static and live loads. The floor should also
support and accommodate services either in its depth or below or above the floor
without affecting the stability.

6.  Durability and freedom from maintenance
All floors should be durable for the expected life of the building and require little
maintenance or repair. The durability of floor finishes will depend on the nature
of materials used and the wear to which they are subjected to.
 Fire resistance
Suspended upper floors should be constructed to provide resistance to fire for a
period adequate for the escape of the occupants from the building. The notional
periods of resistance of fire range from ½-4 hours depending on the size and use
of the building set out in the building regulations.

7.  Resistance to passage of heat
A floor should provide resistance to transfer of heat where there is normally a
significant air temperature difference on the opposite sides of the floor. This
would include any building which was heated but would not include some
external buildings, such as garages.
 Resistance to passage of sound
Upper floors that separate noisy from quiet activities, should act as a barrier to
the transmission of sound. airborne sound more readily than a high mass
concrete floor.

8. Components of roof
The structure forming the upper covering of a building is known as roof.
There are some common components of roof which are usually
provided such as:
• Parapet
• Rainwater spouts
• Stair case
• Roof covering
• Overhead water Tank

9. Components of roof
There are some other components that may also be seen on a roof:
• Plumbing lines
• Lift machine room
• Telecom Tower
• Garden
• Community Centre

10. Parapet
• To ensure safety.
• Parapet walls in roofs help to distribute the wind evenly over the roof.
It resists load coming from wind.
• Fire protection.
• In case of brick parapet, placement of brick should occur before the
slab concrete is hardened to ensure proper bonding.
• If future extension of building is required, brick parapet is favourable.

11. Parapet

12. Rain Water Spouts
• To ensure fast removal of rain water from rooftop
• The number of spouts and their positions, placement should be
accurate.
• Must have adequate diameter to avoid clogging.
• Poor reinforcement of rain spout may lead to structural failure.

13. Rain water spouts

14. Stair Case
• Stair case is the room which covers the stair landing towards roof .
• It protects the inner opening of the building through stairs from
entering rain water and direct sun light.
• It can also contain overhead water tank over it.

15. Roof Covering
• To protect dampness.
• To ensure movement of rain water towards the spout.
• Damp proof materials: lime concrete, bitumen etc.

16. Plumbing Lines
• These are water pipes which supplies water from overhead tank to all
the floors.
• These also uplift water through them from reservoir to overhead
tank.

17. Lift machine room
• It’s a room where lift machine is placed.
• It situated on the room just beside stair case.
• Lift control machine is placed here with proper electric arrangement.

18. Overhead Water Tank
• It’s a water container which usually placed on the roof of a building.
• It’s usually placed over stair case so that the water pressure is
sufficient for the top floor people.
• It can be constructed by RCC or it can be ready made tank like GAZI
tank, RFL tank etc.

19. Overhead Water Tank

20. Underground Water Tank
• In an underground water tank there should be minimum reserved
water for 2 days.
• The height of an underground water tank should be foundation level
to plinth level or less than plinth level.

21. Shoring
• The term “shoring” is applied to construction of the temporary
structure required to support an unsafe structure.

22. Main objectives of shoring
• When the walls of a building develop signs of bulging or leaning
outwards, shoring is necessary to prevent further development of the
defect.
• When defective walls of a building are to be dismantled and rebuilt,
shoring is resorted to for supporting the floors or roofs connecting to
the walls.
• Shoring is necessary to support the super structure when large
openings are required to be made in the main walls of two adjacent
buildings when the intermediate building is to be pulled down and
rebuilt.

23. Underpinning
Underpinning is the process of strengthening and reinforcing the
foundation of an existing building or other structure. Underpinning may
be necessary when defective foundation of a wall is to be replaced with
new foundation or when the existing foundation of a wall is required to
be strengthened to enable it to carry more loads.

24. Necessity of underpinning
Structure might require underpinning if –
• The original foundation isn’t strong/stable enough to support the
existing structure
• The initial use of the structure has changed, requiring foundational
reinforcement
• The soil is not competent to withstand the weight of the structure
• It is cheaper to repair/reinforce than buy new
• Seismic activity, drought, flood have compromised the structure’s
structural security

25. Methods of Underpinning
1. Mass Pour
• Most widely used method of underpinning.
• The greatest advantage of this method is its low cost and ability to
handle heavy foundation loads.
• In mass pour method a concrete foundation is poured beneath the
existing foundation in sections.
• It is a simple method of underpinning and does not require any heavy
machinery.

26. Methods of Underpinning
2. Mini Piled
• Mini Piled method is best for those sites where soil condition are
variable and the access areas around the foundation are limited.
• In this method, ‘piles’ or deep vertical structural elements are
screwed into the ground holes deep enough to allow the piles to rest
on stable soil.
• While this method is best suited for any adverse soil condition, the
process can be quite expensive due to the expertise involved.

27. Methods of Underpinning
3. Beam and Base
• Beam and base method is a technically advanced method.
• In this method, a reinforced concrete beam is constructed below the
foundation to replace the existing footing.
• The new concrete beam is responsible for transferring the load to a
mass concrete base which spreads the load evenly across the soil.

28. Underpinning