Different types of defects occur in plastering such as
blistering, cracks, efflorescence, flaking, peeling, popping, softness and
uneven surfaces. These defects in plastering need to be repaired as soon as
they are observed.
Types of Defects in Plastering
1. Blistering of Plastered Surface
Blistering of plastered surface occur when small patches swell
out beyond the plane of the plastered surface. Blistering is seen in case of
plastered surface inside the building.
2. Cracks in Plastering
Cracks are formed on the plastered surface. These cracks can
be hair-line cracks which are difficult to notice, or it can be wider cracks which
are easily seen. The development of fine cracks is known as crazing.
Cracks on plastered surface can be due to thermal movements,
discontinuity of surface, structural defects in the building, faulty
workmanship, excessive shrinkage etc.
3. Efflorescence on Plastered Surface
Efflorescence is formed on plasters when soluble salts are
present in plaster making materials as well as building materials such as
bricks, sand, cement etc. Even water used in the construction work may contain soluble
When a newly constructed wall dries out, the soluble salts
are brought to the surface and they appear in the form of a whitish crystalline
substance. Such a growth is referred to as efflorescence and it seriously
affects the adhesion of paint with the wall surface.
Efflorescence gives a very bad appearance and can be removed
to some extent by dry bushing and washing the surface repeatedly.
The formation of a very small loose mass on the plastered
surface is known as flaking and it is mainly due to bond failure between
successive coats of plaster.
The plaster from some portion of the surface comes off and a
patch is formed. Such formation is termed as peeling and it is mainly due to
bond failure between successive coats of plaster.
Sometimes the plaster mix contains particles which expand on
being set. A conical hole in plastered surface is formed in front of the particle.
This conical hole is called as blow or pop.
7. Uneven Plaster Surface
Uneven surface defect become prominent only due to poor
workmanship of the plastering work.
8. Softness of the Plaster
The excessive dampness at certain points on the plastered
surface makes that portion soft. The main reason for such softness are undue
thinness of the finishing coats, presence of deliquescent salts, excessive
suction of the undercoats etc.
9. Rust Stains on Plastered Surface
Rust stains are sometimes seen on the plastered surface
specially when plaster is applied on metal lath.