BASEMENTS

Definition of basement: It is that part of the building which is Elements of Basement:

partly or fully below ground level and used for uses other than 1. Raft Slab
human habitation. 2. Retaining walls/ Diaphragm walls
3. Water proofing treatment
Uses of basement: 4. Intermediate columns and floors
1. Parking of Vehicles 5. Ramps
2. A/C plant room and electrical services 6. Rainwater disposal system
3. Strong rooms for banks 7. Ventilation system
8. Fire fighting system
Design of basement 9. Lighting system
1. How deep should be the excavation? 10. Parking system
2. How big should be the basement?
3. What should be floor to floor height?
4. What should be the problems if subsoil water is present?
SCHEMATIC SECTION FOR MULTI BASEMENTS
BYE-LAWS FOR BASEMENTS
DEFINITION

“Basement or cellar” means the lower storey of a building below or partly

below the ground level.

No basement shall be constructed within the prescribed setbacks and prescribed building lines and
shall not exceed in area the maximum
coverage of floor 1 (entrance floor):

Basement may be put to only the following uses –

(a) Storage of house-hold or other goods of ordinarily non combustible material
(b) Strong rooms bank cellars etc.
(c) air-conditioning equipment and other machines used for services and utilities of the building.
(d) parking spaces

The basement shall not be used for residential purposes.

Commercial purposes: The government allows you to build offices in basements.
However, the space will be included in the calculation of FAR usage in this case.
DESIGN REQUIREMENTS FOR BASEMENTS
The basement shall have the
SKETCH
following requirements :
(a) every basement shall be in every part at
least 2.4 m in height from the floor to
the underside of the roof slab or
ceiling:
(b) adequate ventilation shall be
provided for the basement. The standard of
ventilation shall be the same as required by
the particular occupancy according to
Rules. Any deficiency may be met by
providing adequate mechanical
ventilation in the form of blowers,
exhaust fans, air-conditioning
system etc.
(c) the minimum height of the ceiling of any
basement shall be 0.9 m and maximum
of l.2 m above the average surrounding
ground level.
DESIGN REQUIREMENTS FOR BASEMENTS

The basement shall have the following requirements :

(d) Adequate arrangements shall be made such that surface drainage does not
enter the basement.

(e) The walls and floor of the basement shall be water-tight and be so designed
that the effect of surrounding soil and moisture , if any, are taken into account in design
and adequate damp roofing treatment is given.

(f) The access to the basement shall be separate from the main and alternate
staircase providing access and exit from higher floors. Where the staircase is
continuous in case of building served by more than one staircase the same shall be of
enclosed type serving as a fire separation from the basement floor and higher floors.
Open ramps shall be permitted if they are constructed within the building line
BASEMENTS IN PRACTISE
BASEMENTS IN PRACTISE
STAIRCASE AND LIFTS FOR BASEMENTS
In case of single staircase it shall terminate at the ground floor level and the access
to the basement shall be by a separate staircase.

Wherever the building is served by more than one staircase one of the staircases may
lead to basement level provided the same is separated at ground level by either a ventilated
lobby or a out off screen wall without opening having a fire resistance of not less than
2 hours with discharge point at two different ends or through enclosures.

It shall also be cut-off from the basement area at various basement levels by a protected
and ventilated lobby/lobbies.

The staircase shall be lighted and ventilated and the minimum size of opening on walls
abutting to open spaces shall be 0.3 sq.m. per landing.

Lift shall not normally communicate with the basement. However, one of the lifts
may be permitted to basement level is pressurised and separated from the best of the basement
areas, by smoke actuated fire resisting door of two hours fire resistance.

These doors can also be kept in hold-open position by an Electromagnet devise to be linked
with smoke detector.
FIRE PROTECTION FOR BASEMENTS
Each basement shall be separately ventilated. Vents with cross sectional area
(aggregate )not less than 2.5% of the floor area spread evenly round the perimeter of
the basement and shall be provided in the form of grills or breakable stall boards lights
or pavement light or by way of shafts.
Alternatively, a system of air inlets shall be provided at basement floor level and smoke
outlets at basements ceiling level. Inlets and extracts may be terminated at ground
level with stall boards or pavement lights as before but ducts to convey fresh air to the
basement floor level have to be laid.
Stall-boards and pavement lights should be in positions easily accessible to the Fire
Brigade and clearly marked “SMOKE OUTLET” or “AIR INLET” with an indication of
area severed at or near the opening.

FIRE PROTECTION FOR STAIRCASES

The staircase of basements shall be of enclosed type having fire resistance of not
less than two hours and shall be situated at the periphery of the basement to be
entered at ground level only from the open air and in such positions that smoke from
any fire in the basement shall not obstruct any exit serving the ground and upper
storeys of the building and shall communicate with basement through a lobby provided
with fire resisting self closing doors of one hour fire resistance.
FIRE PROTECTION FOR BASEMENTS
FIRE PROTECTION FOR BASEMENTS

FIRE PROTECTION IN MULTI- STOREY BASEMENTS

In multi-storeys basements, intake ducts may serve all basement levels but each basement and
compartment shall have separate smoke outlet duct or ducts.

Mechanical extractors for smoke venting system from lower basement levels shall also be
provided. The system shall be of such design as to operate on actuation of heat sensitive detector
of sprinklers if installed and shall have the standard units.

It should also have an arrangement to start it manually and shall be designed to function at a
temperature not less than 50ºC.

Kitchens working on gas fuel, departmental stores, and shops shall not be permitted in basement/
sub-basement.
FIRE PROTECTION FOR BASEMENTS
FIRE PROTECTION FOR BASEMENTS
Transformers :
a) If transformers are housed in the building below the ground level it shall be necessarily in the first
basement in separate fire resisting room of 4 hours rating.
The rooms shall necessarily be at the periphery of the basement. The entrance to the room shall be
provided with a steel door of 2 hours fire rating.
A curb (sill) of a suitable height shall be provided at the entrance in order to prevent the flow
of oil from ruptured transformer into other parts of the basement. The direct access to the transformer
room shall be provided preferably from outside. The switch gears shall be housed in a separate room
separated from the transformer bays by a fire resisting wall with fire resistance not less than four
hours.

b) The transformer if housed in basement shall be protected by an automatic high pressure water
spray system (Mulsifyre System).

c) In case the transformer housed in the basements totally segregated from other area of the
basements by 4 hours fire resisting wall/walls with an access directly from outside it may be protected
by carbon-dioxide or B.C.F. fixed installation system.
RAMPS FOR BASEMENTS
(a) Ramps with as slope of not more than 1 to 10 may be substituted for and
shall c omply with all this applicable requirements of required stairways as to enclosure,
Capacity and limited dimensions, Ramps shall be surfaced with approved non-slipping material.
Provided that in the case of public office, hospitals,assembly halls etc. the slope of the ramp shall not
be more than 1 in 12.

(b) The minimum width of the ramps in hospitals shall be 3.0 m.

(c) Handrails shall be provided on both sides of the ramp.

.
(d) Ramps shall lead directly to outside open space at ground level or
courtyards

In the case of parking spaces provided in basement at least two ramps of adequate width and slope
(not less than 1:8 or more than 1:12) shall be provided, located preferably at opposite ends.
WATERPROOFING FOR BASEMENTS
WATERPROOFING FOR BASEMENTS
WATERPROOFING FOR BASEMENTS
WATERPROOFING FOR BASEMENTS
WATERPROOFING FOR BASEMENTS
UPLIFT WATER PRESSURE IN BASEMENT
BASEMENT SECTION

Methods of Construction of basement:

Conventional method -First excavate and then make walls

Diaphragm wall method -First make walls then excavate

A. Construct floors after excavation
B. Construct floors as excavation proceeds
BASEMENT SECTION
DIAPHRAGM WALL BASEMENT
DIAPHRAGM WALL BASEMENT
DIAPHRAGM WALL BASEMENT
DIAPHRAGM WALL BASEMENT
DIAPHRAGM WALL BASEMENT - GROUND ANCHOR
WATER BAR FOR CONSTRUCTION JOINT
WATER BAR FOR CONSTRUCTION JOINT