The document discusses the importance of foundations in architecture, detailing shallow and deep foundation types, their functions, and various methods for constructing them. It also explains damp proof courses (DPC), their necessity in preventing moisture ingress in buildings, and different methods and materials utilized for effective DPC installation. The document emphasizes the need for proper foundation design and moisture prevention to ensure structural integrity and hygiene in buildings.

1. Foundation and DPC

2. ◾ A foundation is the element of
an architectural structure which connects it to
the ground, and transfers loads from the
structure to the ground.
◾ The soil which is located immediately below
the base of the foundation is called the sub-
soil or foundation soil, while the lowermost
portion of the foundation which is in direct
contact with the sub-soil is called the footing.

3. ◾ Foundation is the most important part of a building,
since it remains below the ground level, the signs of
failure of foundation are not noticeable till it has
already affected the building.
◾ A foundation shall
be sufficiently
strong to prevent
excessive settlement
as well as
unequal settlement.

4. ◾ Weak sub-soils
◾ Shrinkable and expansive soil (CLAY)
◾ Frost action
◾ Movement of ground water
◾ Slipping of strata on sloping sites
◾ Excessive vibrations

5. ◾ Reduction of load intensity
◾ Even distribution of load
◾ Provision of level surface
◾ Protection against soil movements
◾ Safety against undermining
◾ Lateral stability

6. ◾ Foundations are broadly classified under two
heads:-
A.SHALLOW FOUNDATION
B. DEEP FOUNDATION

7. • Depth is less or sometimes equal to its width.
• It is placed immediately beneath the lowest
part of the superstructures.
• It is spread more horizontal than vertical.
• It transfers the loads to subsoil at a shallow
depth, close to the ground level.
• Shallow foundations are of the following
types:-
1. Spread footings
2.Combined footings
3. Strap footings
4.Mat foundation

8. • Spread footings are those which spread the super-
imposed load of wall or column over a larger area. This
footing is also known as pad foundation.
• In this type of foundation, the base is made wider than
the top to distribute the load from the superstructure
over a large area.
• These foundations are constructed after opening the
trenches to the required depth.
• It is economical for a maximum depth of 3 m.
• Spread footings support either a column or wall.
• Spread footings may be of following kinds:
1. Single footing for a column
2. Stepped footing for a column
3. Sloped footing for a column
4. Wall footing without step
5. Stepped footing for wall
6. Grillage foundation

12. ◾ A spread footing which supports two or more
columns is termed as combined footings.
◾ The combined footings may be of the
following kinds:
◾ Rectangular combined footing
◾ Trapezoidal combined footing
◾ Combined column-wall footing

14. ◾ If the independent footings of two
columns are connected by a beam,
it is called a strap footing.
◾ A strap footing may be used where
the distance between the columns
is so great a combined trapezoidal
footing becomes quite narrow, with
high bending moments.
◾ In this case, each column is provided
with its independent footings and a
beam is used to connect the two
footings.
◾ The strap beam does not remain in
contact with the soil, and thus doest
not transfer any pressure to the soil.

15. ◾ A raft or mat is a combined footing that
covers the entire area beneath a structure
and supports all the walls and columns.
◾ When the building loads are heavy, the use of
spread footings would cover
more than one half the
area and it may prove
more economical to use
mat or raft foundation.

16. ◾ Deep foundations are of the following types:
1.Deep strip, rectangular or square footings. 2.Pile
foundation
3.Pier foundation
4.Well foundation

17. ◾ Pile foundation is that type of deep foundation in which the loads are taken to a
low level by means of vertical members which may be of timber, concrete or steel.
◾ Pile foundation may be adopted:-
1. Instead of a raft foundation
where no firm bearing strata
exists at any reasonable depth
and the loading is uneven
2. When a firm bearing strata
does exist but at a depth such
as to make strip or spread
footing uneconomical.
3. When pumping of sub soil
water would be too costly or
timbering to excavations too
difficult to permit the
construction of normal
foundations.

18. DPC (Damp ProofCourse)

19. ◾ “Dampness is the
presence of gravitational
moisture”
◾ Building should remain
dry or free from moisture
travelling through walls,
roofs and floors.
◾ Dampness gives
unhygienic conditions apart
from reduction in strength
of structural components.
◾ Provision of damp
proof courses prevent
entry of moisture in the
building

20. 1. Moisture rising up the walls
from ground.
a) All structures are founded on
Soils and soil has moisture
d) This moisture rise up into wall &
floor through capillary action.
e) Ground water rise also result in
moisture entry into the building
through walls
2. RAINTRAVELTROUGHWALLTOPS:
A. If the wall tops are not properly
protected from rain penetration, rain
will enter the wall & will travel down.
B. Leaking roofs will also permit water to
enter.

21. 3. Rain beating against external
walls :-
A. Heavy showers of rain may beat
against the external faces of walls
& if the walls are not properly
treated, moisture will enter the
wall causing dampness in the
interior.
B. If balconies and chhajja projections
do not have proper slope, water
will accumulate on these & will
enter the walls through their
junctions.
C. Moisture will completely damage
interior paints of walls.

22. 4. CONDENSATION
A. Due to condensation of atmospheric moisture, water is
deposited on the walls, floors & ceilings.
B. This moisture causes dampness

23. Following are ill effects of entry
of dampness:
3.
1. Dampness gives rise to
breeding of mosquitoes &
create unhealthy conditions.
2. Travel of moisture on wall
causes unsightly patches.
It may cause softening &
crumbling of plasters.
4. Wall decoration or paint is
damaged.
5. Continuous presence of
moisture in wall may cause
florescence which result in
disintegration of bricks,
stones, tiles

24. 6. Flooring gets loosened due to reduction in adhesion
when moisture enters through the floor.
7. Timber fittings such as doors, windows almirahs etc
coming in contact with damp walls, damp floors get
deteriorated because of warping etc.
8. Electrical fittings get deteriorated, giving rise to
leakage of electricity & danger of short circuiting.
9. Floor coverings are damaged.
10. Dampness promotes & accelerated growth of
termites.
11. Dampness breeds germs of disease like tuberculosis,
neuralgia, rheumatism.
12. Moisture causes rusting & corrosion of metal fittings.

25. 1. Membrane Damp Proofing (Use of DPC)
2. Integral Damp Proofing
3. SurfaceTreatment
4. CavityWallConstruction
5. Guniting
6. PressureGrouting

26. 1. In this method water
repellent membrane or
damp proof course (DPC)
between the source of
dampness and part of
building adjacent to it.
2. DPC may be bitumen,
mastic asphalt, bituminous
felts, plastic sheet, metal
sheets, cement concrete
3. DPC may be provided
horizontally or vertically in
floors, walls etc

27. Following general principles should be applied while
providing DPC:
a) DPC should cover full thickness of wall.
b) Mortar bed supporting DPC should be levelled &
even and should be free from projections, so that
DPC is not damaged.
c) At junctions & corners of walls, the horizontal DPC
(on floor) should be laid continuous.
d) When a horizontal DPC is continued to vertical face,
a cement concrete fillet of 7.5 cm radius should be
provided at junction.
e) DPC should not be kept exposed on wall surface
otherwise it may get damaged during finishing.

28. ◾ This consists of adding certain water proofing
compounds of materials to the concrete mix, so that
it becomes water proof.These water proofing
compounds may be in three forms:
1. Compounds made from chalk, talc, fullers earth,
which may fill the voids of concrete.
Compounds like alkaline silicates, aluminum
sulphate, calcium chlorides etc which reacts
chemically with concrete to produce water proof
concrete.
Compounds work on water repulsion principle. like
soap, petroleum, oils fatty acid compounds such
asStearates of calcium, sodium, ammonia etc.
When they are mixed with concrete becomes
water repellant.
Commercially available compounds like Publo,
Permo,Silka etc.
2.
3.
4.

29. 1. The surface treatment consists of application
of layer of water repellant substances on the
surface through which moisture enters.
2. The use of water repellant metallic soaps
such asCalcium &Aluminium Oletes and
Stearates are effective against rain water
penetration.
3. Pointing & plastering of the exposed surfaces
must be done carefully using water proofing
agents like Sodium or Potassium silicates,
Aluminium orZinc sulphates, Barrium
hydroxide and magnesium sulphate.
4. Surface treatment is successful when
moisture is superficial.
◾ In this method of damp prevention in which
main wall of building is shielded by an outer
skin wall, leaving a cavity between the two

30. ◾ This consists of depositing layer of rich
cement mortar by pressure to the
exposed surface of wall, pipes.
◾ Cement mortar is 1:3 cement sand mix.
◾ Mortar is shot on clean surface with
cement gun under 2 to 3 kg/cm2
pressure.
◾ Nozzle of machine is kept at a distance
about 75 to 90 cm from wall.
◾ Curing of mortar is done for 10 days.
◾ In this method, cement grout is filled in cracks,
voids in the structure of building by pressure.
◾ Foundation of building are subjected to grouting
to make water-penetration- resistant.
◾ This method is effective to control entry of
ground water through foundations

31. Ideal DPC should have following quality:
• Should be perfectly impervious
• Should not permit moisture penetration
• Material should be durable with life equal to
building life.
• Material should be strong to resist superimposed
load/ pressure.
• Material should be flexible to accommodate the
structural movements without any cracks.
• Material should not be costly.
• Material should remain steady in its position.

32. Hot bitumen:
◾ This is highly flexible.
◾ Can be applied with a minimum thickness of 3 mm.
◾ It is placed on bedding of concrete in hot condition
MasticAsphalt
◾ It is made by mixing bitumen &
sand & mineral fillers
◾ It is semi rigid material
◾ It is squeezed out in hot climate or
under pressure.

33. ◾ BituminousAsphalt
1. It is ready made roll of dry
asphalt sheets
2. It is laid on leveled flat layer
of cement mortar.
3. An overlap 10 cm provided
at joints.
4. The laps is sealed with
bitumen.
5. It can not resist heavy load.
6. It can accommodate slight
movement.

34. ◾ MetalSheets
1. Sheets of lead,copper,aluminium is used as DPC
2. Lead sheet is more flexible.
3. Thickness of sheet should be such that its weight is not less than 20
kg/m2.
4. They are laid similar to bituminous felts.
5. Lead sheet is completely impervious, resistant to atmospheric
corrosion, can take complex shape resistant to sliding action.
6. Lead will have corrosion if comes in contact with
cement/lime. It is covered by bitumen.
7. Copper Sheets of 3 mm thickness are embedded in cement/lime
mortar.
8. It has high resistance to dampness, sliding and pressure.
9. Aluminum sheets is also used for DPC but not better than copper
& lead

35. ◾ Combination of sheets & bituminous felts
1. Lead foils sandwiched between asphaltic or bitumious
felts can be used as DPC.
2. The combination known as LeadCore can be laid easily,
is durable, efficient,economic & resistant to cracks

36. ◾ Stones
1. Dense & sound stones, such as granite, trap,slates etc
are laid in cement mortar 1:3 in two layer to form
effective DPC.
2. Stone should be extended to full width of wall.
◾ Mortar
1. Cement mortar 1:3 is used as bedding layer for housing
other DPC.
2. Small quantity of lime may be added to increase
workability of mortar.
3. In water used for mixing, 75 gm soap is dissolved per liter
of water
4. This Mortar can be used for plaster of outer walls

37. ◾ CementConcrete
1. Concrete 1:2:4 mix or 1:11/2:3 mix is provided at plinth level
to work as DPC.
2. The thickness may vary from 4 cm to 15 cm.
3. This layer prevent water rise in wall by capillary action.
4. Where dampness is more two layer can be made.
Plastic sheets
1. This is new type of DPC material made
of black polythene sheet of 0.5 mm to 1
mm thickness.
2. Available in 30 m length in market.
3. The treatment is cheaper but not
permanent.

38. ◾ TREATMENTTOWALLS
◾ TREATMENTTO FLOORS

39. ◾ DPC TREATMENTTOBASEMENT
When the foundation soil is in damp condition then basements are
structures on the three methods:
a) Provision of foundation drains and DPC
b) Provision of RCC raft and wall slab
c) Asphalt tanking
Provision of foundation drains and DPC:
It is better to provide trench all around the basement, up to foundation
level, and fill it with gravel, coke, and other previous material when the
foundation soil is not properly drained.

40. Provision of R.C.C. raft and wall slab
In this system, floor slab, as well as walls, are
constructed in a rigid RCC structure. At least 3
layers of bitumen felts are used as DPC.
Horizontal and vertical DPC treatment is also
provided there. The outer surface of the RCC
wall slab is protected by a half brick thick
outer wall. This type of system is better from
the above systems because it can solve the
problem effectively when the underground
water pressure is severed, and it can also so
less expensive because of not pumping water
continuously.
DPC as Asphaltic tanking
When the subsoil water table is not very high Asphalt
tanking is adopted for DPC course. In the figure below we
can see all detail about the section in which horizontal DPC
in the form of an asphaltic layer of 30mm thick coats over
the entire area of the basement floor and then extending
it in the form of vertical DPC on the external faces of the
basement walls. The vertical faces make the same function
as a waterproofing tank in which the sequence of the
vertical asphaltic layer maybe 20 mm that layer keep all
the system dry. Generally, vertical DPC is Laid on at least 15
cm above the ground with one half (1 and ½) brick thick
outer protection wall.