Interior Fnishes

Question 1

True or False:
The installation of interior finishes
begins after a building has been
enclosed, once the interior is
protected from the weather.

Answer 1

True

Question 2

Interior finishes

Answer 2

– Roofing works must be finished
– Cladding installed, and doors and windows set.
– The electrical and mechanical trades can begin installing electrical, communications,
telephone, and computer systems, as well as waste and potable water lines; automatic
sprinkler systems; and heating, cooling, and ventilation systems.
– Installation of transportation systems, such as elevators, escalators, and moving walks and ramps, can also commence.

Question 3

What are the Performance Criteria for Interior Finishes?

Answer 3

• Environmental concerns
• Appearance
• Cost
• Code Requirements
• Durability
• Maintenance
• Acoustical Considerations

Question 4

Materials made from rapidly renewable natural resources, those containing post-consumer or post-industrial recycled content, and materials that are themselves readily recycled.

Answer 4

Environmental concerns

Question 5

Products that off-gas volatile organic compounds (VOCs) and other toxins that reduce indoor
air quality should be avoided.

Answer 5

Environmental concerns

Question 6

Interior finishes are chosen according to their appearance to set the mood and atmosphere of a space.

Answer 6

Appearance

Question 7

Finish systems generally hide the structural, mechanical, and electrical systems and provide quality interior surfaces.

Answer 7

Appearance

Question 8

Consideration of material costs and the labor to install them, including a contractor’s overhead and profit

Answer 8

Cost

Question 9

Other cost factors include the expected life- cycle of materials before replacement is required, regular maintenance, minor repairs, and the possibility of increased
replacement costs years later because of inflation and increased labor costs

Answer 9

Cost

Question 10

Building codes, and local regulations must be consulted when selecting interior finish materials.

Answer 10

Code Requirements

Question 11

of interior finishes includes the ability of exposed material (and any protective or decorative coating) to resist damage from abrasion or dirt. In areas where wear and tear is expected, hard-surfaced materials provide considerable protection.

Answer 11

Durability

Question 12

requirements and the effort required to preserve the appeal of finishes is considered during materials selection.

Answer 12

Maintenance

Question 13

Consideration must be given to the ability of a finish to control sound created within an
area, as well as restrict its flow through walls, ceiling, and floor to adjoining areas.

Answer 13

Acoustical considerations

Question 14

It is the process of covering rough surfaces of walls, columns, ceilings and other building components with thin coat of mortars to form a smooth durable surface.

Answer 14

Plastering

Question 15

It is a mixture of cement and sand along with the required quantity of water.

Answer 15

Plastering

Question 16

Objectives of Plastering

Answer 16

• To protect the external surfaces against penetration of rainwater and other atmospheric agencies
• To give smooth surface in which dust and dirt cannot lodge
• To provide a satisfactory base for decorating the surface by white washing, color washing, distempering or painting
• To conceal inferior materials or defective workmanship

Question 17

Types of Plasters used in Plastering Work

Answer 17

• Gypsum Plaster
• Lime Plaster
• Mud Plaster
• Cement Plaster

Question 18

is a paste formed by mixing the gypsum powder and water in a suitable proportion

Answer 18

Gypsum Plaster

Question 19

No sand is used in this type of plaster. Only mixing of gypsum powder and water is done to prepare this.

Answer 19

Gypsum Plaster

Question 20

The setting of unmodified plaster
starts about 10 minutes after
mixing and is complete in about
45 minutes; but not fully set for 72
hours.

Answer 20

Gypsum Plaster

Question 21

When lime is mixed with the sand
in the presence of the proper
quantity of water

Answer 21

Lime Plaster

Question 22

The proportion of lime and sand for
lime plastering is generally taken
as 1:3 to 1:4 and has a curing time of
about one month.

Answer 22

Lime Plaster

Question 23

This plaster is prepared by mixing
an adequate percentage of clay
and sand content. A small amount
of cow dunk is added to this
plaster to receive a better surface

Answer 23

Mud Plaster

Question 24

This plaster is environmentally
friendly, and repairing work is
easy and inexpensive.

Answer 24

Mud Plaster

Question 25

The generally used mixed proportion of cement and sand

Answer 25

Cement plaster

Question 26

The generally used mixed proportion of cement and sand for cement plaster are

Answer 26

1: 4, 1:5, and 1:6

Question 27

Internal plaster External plaster Ceiling plaster

Answer 27

– 1:6 or 1:5 – 1:4 – 1:3

Question 28

Procedure of Plastering Work

Answer 28

1. Preparation of Surface for Plastering 2. Groundwork for Plastering 3. Applying Under Coat or Base Coat 4. Applying Finishing Coat 5. Curing of Plastering works

Question 29

Plastering Problems and Solutions

Answer 29

- Slow set - Quicksetting - Dry-out - Sweat-out - Cracking - Loosening

Question 30

Spraying the unset surface with a solution of zinc sulfate, followed by a brisk floating of the surface.

Answer 30

slow set

Question 31

Accelerating unmixed plaster can be remedied by the addition of accelerators as approved by the specification

Answer 31

slow set

Question 32

Because plaster never should be re-tempered, this material should be discarded

Answer 32

quicksetting

Question 33

If atmospheric conditions prove to be the reason, a retarder can be added as approved by the specifications

Answer 33

quicksetting

Question 34

Water should be added with a soft spray, and openings should be closed to reduce wind through the building and cut down the rate of evaporation

Answer 34

dry-out

Question 34

Addition of artificial heat in cold weather, or opening of doors and windows in warmer weather.

Answer 34

sweat-out

Question 35

* Areas to be investigated include deflection of the structural frame and shrinkage of unseasoned lumber. * Settlement of the foundation walls also can cause cracking. * A thickness of less than 1/2 in. may make the plaster vulnerable. * Ratio of mixture should be reviewed * Thermal Shock through either application of too much heat or sudden applications of cold.

Answer 35

cracking

Question 36

(When plaster has been properly mixed and applied)

Answer 36

cracking

Question 37

May be due to the use of an inappropriate surface, which is too dense, glazed, or made of a material that will not accept bonding of the plaster

Answer 37

loosening

Question 38

(Excess water has not evaporated, and walls remain damp for an extended period.)

Answer 38

sweat-out

Question 39

(The surface is soft and crumbly with a light chalky appearance)

Answer 39

dry-out

Question 40

(Sometimes caused by using water in which hardened plaster has been allowed to drop from tools or atmospheric conditions)

Answer 40

quicksetting

Question 41

(Plaster should set within two to three hours after having been mixed with water, and always within four)

Answer 41

slow set

Question 42

Preparation of Surface for Plastering

Answer 42

– Keep all the mortar joints of wall rough, so as to give a good bonding to hold plaster. – Roughen the entire wall to be plastered. – Clean all the joints and surfaces of the wall with a wire brush, there should be no oil or grease etc. left on wall surface. – If there exist any cavities or holes on the surface, then fill it in advance with appropriate material. – If the surface is smooth or the wall to be plastered is old one, then rake out the mortar joint to a depth of at least 12 mm to give a better bonding to the plaster. – Wash the mortar joints and entire wall to be plastered, and keep it wet for at least 6 hours before applying cement plaster. – If the projection on the wall surface is more than 12 mm, then knock it off, so as to obtain a uniform surface of wall. This will reduce the consumption of plaster. – Hacking must be made on all concrete surfaces such as columns, beams, ceiling, and retaining wall before plastering to ensure proper bonding between mortar and surface. – Ensure all the electrical conducting work is complete. – Cover groove cutting by chicken mesh to avoid cracks developed by groves in the future.

Question 43

Groundwork for Plastering

Answer 43

– In order to get uniform thickness of plastering throughout the wall surface, first fix dots on the wall. A dot means patch of plaster of size 15 mm * 15 mm and having thickness of about 10 mm. – Dots are fixed on the wall first horizontally and then vertically at a distance of about 2 meters covering the entire wall surface. – Check the verticality of dots, one over the other, by means of plumb-bob. – After fixing dots, the vertical strips of plaster, known as screeds, are formed in between the dots. These screeds serve as the gauges for maintaining even thickness of plastering being applied.

Question 44

Applying Under Coat or Base Coat

Answer 44

– In case of brick masonry the thickness of first coat plaster is in general 12 mm and in case of concrete masonry this thickness varies from 9 to 15 mm. – The ratio of cement and sand for first coat plaster varies from 1:3 to 1:6. – Apply the first coat of plaster between the spaces formed by the screeds on the wall surface. This is done by means of trowel. – Level the surface by means of flat wooden floats and wooden straight edges. – After leveling, left the first coat to set but not to dry and then roughen it with a scratching tool to form a key to the second coat of plaster.

Question 45

Applying Finishing Coat

Answer 45

– The thickness of second coat or finishing coat may vary between 2 to 3 mm. – The ratio of cement and sand for second coat plaster varies from 1:4 to 1:6. – Before applying the second coat, damp the first coat evenly. – Apply the finishing coat with wooden floats to a true even surface and using a steeltrowel, give it a finishing touch. – As far as possible, the finishing coat should be applied starting from top towards bottom and completed in one operation to eliminate joining marks.

Question 46

Curing of Plastering works

Answer 46

– After completion of the plastering work, it is kept wet by sprinkling water for at least 7days in order to develop strength and hardness. – Improper curing may lead to cracks formation or efflorescence in plaster work