dampness in structure by umar khan

PRESENTATION
OF
DAMPNESS IN BUILDINGS
From : M KAMRAN GUL, UMAR HAMEED, MUHI-U-DIN,
ATIF ZIA
ROLL NO : 71-FET/BTCE/F-15,

 What is Dampness?
 What are the difference between Dampness and
Condensation
 Define
 Types of Dampness
 Causes of Dampness
 Effects of Dampness
 Define
 Which materials used for damp proofing
 Methods of damp proofing
PURPOSE OF THE PRESENTATION

The excess entry or penetration of moisture inside a
building through its Floors, Walls and Roofs is called
Dampness.
Dampness is dangerous both for
Inmates
Building
 Due to dampness the building become unhygienic.
 Dampness in buildings is a risk factor for health effects.
WHAT IS DAMPNESS

 Dampness is due to entry or penetration of moisture in
side a building.
 Condensation is the change of the physical state of
matter from gas phase into liquid phase, and is the
reverse of evaporation.
 Condensation Comes from human activities in the
building, cooking, bathing, etc.
DIFFERENCE BETWEEN DAMPNESS
AND CONDENSATION

DAMP AND CONDENSATION
DAMPNESS CONDENSATION

 Based on the movement of moisture the dampness can
be of the following three types.
 Rising or capillary dampness.
 Falling or penetrating dampness.
 Condensation dampness.
TYPES OF DAMPNESS

 Rising or capillary dampness
 Rising damp is a condition caused by ground moisture rising up
a masonry wall by capillary action. It occur where there is no
DPC or where the DPC has damaged.
 Where present, moisture can rise up the wall to a height of a
meter and it will often leave a characteristic horizontal tide
marks.
TYPES OF DAMPNESS (Continue)..

 Deterioration of the DPC material leads to failure in the
barrier and allows moisture to rise, and if the DPC is
bridged, for example by external soil being placed against
the wall above the DPC level, then the DPC is rendered
ineffective.

RISING DAMP

 Signs of rising damp:
 Mostly, damp signs are only visible for a maximum of
1.50m from the ground level.
 Paint does not adhere to the wall.
 Wallpaper lifts.
 Tide marks and stains appear on the walls.
 Plaster flakes away, feels soft and spongy, bubbles and
white powder or crystals appear.

 Falling or penetrating dampness
 Falling or Penetrating damp occurs when water
penetration reaches inside masonry walls. There is a large
array of different issues that can cause penetrating damp.
 Penetrating damp shows up when moisture is in regular
contact with the masonry wall, resulting in a saturation
of the wall with water.
 Alternatively, penetrating damp can also be caused by
building defects or bad quality building products.

FALLING OR PENETRATING DAMPNESS

 Signs of falling or penetrating damp:
 Mostly, damp signs are only visible for a maximum of
1.50m from the ground level.
 Paint does not adhere to the wall.
 Wallpaper lifts.
 Tide marks and stains appear on the walls.
 Plaster flakes away, feels soft and spongy, bubbles and
white powder or crystals appear.

 Condensation dampness.
 Condensation is caused by two main reasons.
 Firstly, damp air due to a lack of ventilation within the building;
especially old buildings must be allowed to breathe.
 Secondly, condensation can occur through extreme
temperature fluctuations inside the house. The moist air
condensing on cool surfaces such as walls and windows,
particularly from wet areas such as kitchens and bathrooms
and can then condense on the coldest walls.

CONDENSATION DAMPNESS

 Signs of Condensation damp:
 Mold on walls and ceilings particularly in corners, window
reveals or along edges- Musty smell
 Fogged up windows
 Damp patches on plaster
 Peeling wall paper
 Blackened window frames

 Following are the main causes of dampness in a building
 Rain penetration
 Level of site
 Drain ability of the Soil
 Climatic conditions
 Defective Orientation
 Entrapped moisture in the building
 Defective construction material
 Defective construction
 Moisture originates in the building.
CAUSES OF DAMPNESS

 Rain penetration:
 It is the main source of dampness. Heavy rain of short duration
is less dangerous. rain water enters through joints, cracks and
porous bricks or stones.
 Level of site:
 Low laying building sites are effected by the depositing surface
water and underground water.
 Drain ability of the Soil:
 Course grained soils like Sandy or gravely soils provides good
drain ability conditions and fine grained soils like clay retain
water and cause dampness.
CAUSES OF DAMPNESS (Continue)..

 Climatic conditions:
 In cold climatic condition dampness causes due to
condensation of water vapors.
 Defective Orientation:
 If building is exposed to direct rain showers and less sun
rays then it cause dampness.
 Entrapped moisture in the building:
 Due Over soaked bricks and use of salty or alkaline water
results dampness in building.

 Defective construction material:
 Porous bricks, soft stones, alkaline water etc. cause
dampness of building.
 Defective construction:
 Through defective joints of parapet, copping and masonry
joints moisture can enter in the building.
 Moisture originates in the building:
 It is due to the leakage through water supply or sanitary
system of building.

 Following are the harmful effects of dampness in buildings.
 Ugly patches on walls and ceilings.
 Plaster softens and crumbles.
 It cause corrosion of metals used in building.
 Materials used for wall decorations are damaged.
 Tiles disintegrate due to efflorescence.
EFFECTS OF DAMPNESS

 Holes and pits are formed in topping of floors.
 Efflorescence occurs and bricks disintegrate and turn in
to powder.
 Un hygienic conditions in building.
 Paint blistered and bleached and the surface disfigured.
 Electrical fittings are damaged.
 Dampness leads to breeding of mosquitoes, growth of
termites and germs carrying diseases such as tuberculosis,
it also aggravates asthma.
EFFECTS OF DAMPNESS (Continue)..

 Hot bitumen :
 Hot bitumen,3mm thick may be applied on bedding of
mortar or concrete.
MATERIALS FOR DAMP PROOFING

 Mastic asphalt :
 Semi rigid material obtained by heating asphalt with sand
and mineral fillers. It is laid on mortar or concrete bed.
(Continue)..

 Metal sheets :
 Sheets of lead, copper and aluminum may be used
membranes in damp proofing. Lead is the most ideally
suited material.
(Continue)..

 Bituminous felt:
 Flexible material available in rolls. It is laid on flat mortar
finished surfaces.
(Continue)..

 Combination of sheets and felts :
 Economical and durable damp proofing sheet is obtained
by sand witching a lead sheet and bituminous felt.
(Continue)..

 Plastic sheets:
 A relatively cheap method of damp proofing is by laying
0.5-1.0mm thick plastic sheets made of black polythene.
This is not a permanent method.
(Continue)..

 Mortar:
 Cement mortar in the ratio 1:3 is used for bedding layers
over damp proofing course. It may be mixed with slaked
lime to improve its workability.
 Cement concrete course:
 A cement concrete course of proportion 1:2:4 and
thickness 75-150mm is laid on masonry at plinth level.
(Continue)..

Different types of treatments are used for preventing dampness
in different parts of the building.
 Treatment for Foundations:
 This is method of protecting foundations of outer walls. An air
drain is constructed parallel to the wall. The drain is covered
with RCC slab, and gratings are provided at regular intervals,
horizontal and vertical damp proof courses are also provided.
METHODS OF DAMP PROOFING

(Continue)..

 Treatment for floors:
 If there is no damp soil, a layer of coarse sand,75-100mm
thick is provided over entire area under the flooring.
Then 1:4:8 concrete of 100mm thickness is laid. This
layer serves as DPC. the usual flooring is provided over
this, If soil is wet, a membrane DPC is provided over the
floor area, over which a layer of flat bricks is laid. The
usual flooring is then provided.
(Continue)..

 Treatment for walls:
 The plinth level should preferably be 450mm above
ground level. DPC should be provided over a concrete bed
of thickness 100-200mm.the top of the parapet should be
provided with capping over the DPC. the wall also needs
DPC at the edge of the roof slab.
(Continue)..

dampness in structure by umar khan

dampness in structure by umar khan

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dampness in structure by umar khan