Tapl Knowledge Center

Location of Leakage / Seepage

S.No.Location of Leakage or SeepagePossible Causes
I.underside of roofs (such as flat roof, Podium roofs) and Bottom of light wells
  • Damage or deterioration of waterproofing layer
  • Leakage at access doors or top hatch doors
  • Deterioration of corrugated steel roofing materials and joints
  • Defective enclosure for water tanks
  • Cracks of parapet walls affecting the waterproofing membrane
  • Inadequate protection /improper installation of sleeve around opening through roof slab
  • Excessive movements of constructions joints
II.ceiling with internal Areas above
  • Leakage from bathroom or kitchen above usually caused by seepage from fitments, bathtubs, shower Trays ,buried pipes or drains due to improper construction of joints installation of sealants of occurrence of cracks
  • Waterproof cement rendering underneath floor tiles for the floor above not installed /specified or such waterproofing features damaged by installation of sockets or conduits
  • Mal-function of waterproofing in nearby external features such as balconies or external walls above
  • Water penetration through external wall defects such as cracks, joints, honeycombs, spalling, weak points, holes, punctures, leftovers of debris, and movement of external wall components
  • Water penetration through defective external wall finishes such as loosened mosaic tiles, cracked ceramic tiles & paint surface; through poor cladding or curtain walls constructions; or weaknesses in water-resisting components
  • Water leakage through party walls between units of pre-fabricated elements, or between buildings
  • Seepage from defective pipe works or sanitary fitments
  • Temporary floods and overflows
  • Defective bathroom fitments such as bathtubs, shower trays or hand wash basins, or the improper Installation of pipe works or necessary sealants
  • Improper fillings around frames
  • Deformation of frame and sashes, defective gasket, sealant or putty for window glass setting or frames
  • Air conditioning box or platform tilting inwards
  • Insufficient sealant around air conditioning units
  • Inadequate or damaged waterproofing tanking (may be due to movements or punctures)
  • Deterioration of water stops at construction/movement joints
VII.Buried or underground drains or pipes
  • Seepage through defective joints or pipes caused by poor installation or differential movements / settlements, movement of building structures or ground or water table
  • Corrosion of pipes at junctions with floors or walls
  • Invasion of water into conduits and distribute throughout the network
  • Blockage leading to excessive pressure built up
  • Attack by rodents or roots of plants
VIII.Exposed(or in pipes ducts) supply pipes or drains
  • Inadequacy in design of drains such as insufficient diameter of drains, bends being too sharp, etc.
  • Blockage of drains by rubbish/sand collected in the system especially in bends or traps
  • Insufficient number or deterioration of brackets leading to hammering and breakage of supply pipes
  • Blockage of open joints such as hoppers of down pipes by plants or rubbish
  • Unauthorized additions overloading the drainage system

Common Defects

S.No.Common DefectsSymptoms / PhenomenonPossible Causes
I.Defective concrete, spalling or loose plaster in ceilings.
  • Surface with water/rust staining, water leakage
  • Patterned cracking
  • Bulging, failing off of concrete patches with Reinforcement exposed, often rusty
  • Failing off of plaster/tiles
Defective concrete as a result of ageing is commonly found in old buildings. Persistent water leakage may affect the steel reinforcement. Weak concrete caused by the use of salty water in concrete mix , or overloading are also common causes in spalling
II.Water seepage from external wall, window,roof,or from ceiling.
  • Water staining
  • Peeling off of paint of wall paper
  • Water dripping
  • Growth of fungus
  • Defective concrete, plaster or tiles
  • Rust staining
External water seepage could be due to variety of reasons including cracks on external wall, honey comb concrete, defective sealant at window, defective water-proofing membrane at roof ,defective external water and drainage pipes ,etc.
III.Structural cracks in walls.
  • Cracks that penetrate through finishes into the concrete or bricks
  • Long, continuous crack across width of wall
  • Diagonal cracks at corners of window or door
  • Cracks with rust staining
Structural cracks may be caused by many factors,e.g. excessive movement of the building structure ,unwanted ground settlement, serious overloading, weakness caused by corrosion/deterioration of materials or damage by accidents, or poor design/ construction, etc detailed investigation must be carried out to identify the cause(s) which must be removed or rectified before the cracks are repaired.
IV.Structural cracks in columns & beams.
  • Cracks that penetrate through finishes down to the concrete or bricks
  • Spalling
Same as item (III) as above.
V.Non-structural cracks (usually in plaster or other finishes with cement sand rendering as base).
  • Hairline cracks
  • Multi directional cracks (shrinkage cracks)
  • Cracks between panel walls and structural elements e.g. bricks wall and beams/ columns
Cosmetics shrinkage cracks in plaster or other forms of finishes will effect the appearance only and do not pose Any safety concern. They are small hairline cracks developed within the finishes layer not penetrating down to the reinforced concrete structure
VI.Defective external wall finishes/mosaic tiles/ceramic tiles/stone cladding/curtain wall
  • Debonding of finishes/tiles from wall structure resulting in “hollow sound” when tapped with a hammer
  • Cracking of wall surface
  • Bulging with hollow base
  • Falling off
  • Cracks
  • Loosening of parts
The defects could be due to ageing , structural movements, defective workmanship during installation, thermal movement, defective or missing expansion joints, damage by external factors(e.g. falling objects during typhoon), ingress of water into the gap between the finishes or tiles and the structure, etc.
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