Plastering in construction | Usage and Types of Plastering | Types of Plaster Finishes and External Rendering for Buildings | Plastering Techniques |
Plaster can be cellulose, cement based, mud-based, stucco plaster, lime based or acrylic. Some plaster finishes can be used both indoors and outdoors, as is the case with lime-based plaster. Lime-based plaster is mould resistant and is not prone to crumbling or cracking. You will not have to worry about the light changing the plaster’s colour or outdoor weather conditions making it change form.
This Article is the Part of 8 Essential Construction and Building Materials in India. You can read about Plaster Calculator here. Must read about Non-Erodible Mud Plaster With Bitumen Here.
What Is Plastering In Construction ??
Plastering is a process of covering tough surfaces and uneven surfaces with a plastic material called plaster or mortar to obtain an even smooth, regular, clean & durable surface.
In other words, Plastering is a process by which coarse surfaces of wall or ceiling roofs are changed or turned or rendered to provide smoothness. In the beginning, wet materials are spread over the block or brickworks and then suitable equipment is used to make the surface smooth level.
This is the Definition Of Plastering In Construction. You can use the same words for Explaining in general terms.
What is the Objective/Purpose of Plastering ??
- To provide even, smooth, regular, clean and durable finished surface with improved appearance.
- To preserve and protect the surface.
- To cover up the use of porous materials of the masonry work.
- To conceal defective workmanship.
Properties Of Plastering
In this section, we discussed the properties of plastering. We will read the properties of surface for plastering and properties of plastering sand. Here are some properties of good plaster:-
- It should be hard and durable.
- It should be possible to apply it during all weather conditions.
- It should adhere to the background and it should remain to adhere during all climatic changes.
- It should be cheap and economical.
- It should offer good sound insulation.
- It should be highly resistant to fire.
- It should effectively check the penetration of moisture from the surface.
Types of Plastering
Generally, people ask What are the different types of plastering commonly used for cement plaster works? Types Of Plaster Pdf or Types Of Plastering In Building Construction Pdf can be downloaded from here.
We Can Divide Whole Plastering process into Two Broad Category.
- Category 1. Types of Material Used in Plaster
- Category 2. Types of Finishing
Types of Plaster based on Material Used
There are different types of plasters are available such as:
Lime mixture consists of sand and line that are mixed by 1 sand to 3 of lime by volume. Not only this mixture is used for undercoat but also used as a finish coat. Lime plaster might be shrink after drying so animal hair of about 5 Kg is used for 1 m2 to avoid lime plaster cracking and shrinking. Lime plaster could be used for ancient structure restoration and rehabilitation.
- When lime is used as a binding material it is called lime plaster.
- Lime plaster is a type of plaster composed of hydrated lime, sand and water.
- Lime plaster is similar to lime mortar, the main difference is based on use rather than composition.
- Mortar for lime plaster is usually prepared by mixing sand and lime in equal proportions, to improve the strength small quantity of cement is added to it.
Grey powder Portland cement is mixed with water by the ratio of 1cement to 3 or 4 clean washed sand by volume as an undercoat for hard background, for example, brick blocks walls and partitions.
Cement-based plaster is durable and resistant to most types of weather and related moisture. It creates a visually interesting look as well. It is best to use when an area will have a lot of exposure to weather.
The mixture of sand and cement might be plastic and require experienced and skilled labour, therefore, plasticizer or lime is added to the mixture usually by volume ratio of 1cement:0.25 lime: 3 sand or 1 cement to 4 sand with a plasticizer.
The plasticizer is a liquid that added to the mixture to ease plaster spreading over the surface.
- When cement is used as a binding material it is called cement plaster.
- It is especially suited for the damp condition.
- Cement plaster is usually applied in one coat.
- The thickness of the coat can be 12 – 15mm or 20mm depending upon site conditions and type of building.
- 6mm thickness of plastering of 1:3 or 1:4 Ratio is recommended for cement plastering of RCC surfaces.
Types of Plaster Finishes :
Here is the list for Types of Plastering & Finishing for construction. Different types of plaster finishes with different appearances are available as follows. Types of Plaster Finishes used in Building Construction are
Smooth cast finish
Sand faced finish
These are the Different Types Of Plaster Finishes which is generally used in Construction.
Smooth-Cast Plaster Finish
To obtain a smooth cast finish, the mortar used should be in the ratio 1: 3 [cement: sand]. Fine Sand should be taken to prepare the mortar. For spreading the mortar, skimming float or wood float is a best suitable tool. Hence, the smooth and levelled surface is obtained finally.
- It is a finish which presents levelled and smooth surface.
- The mortar for the finish is made by mixing of cement and fine sand in the ratio of 1:3.
Rough Cast Plaster Finish
Rough cast finish is also called as spatter dash finish. Mortar used to get rough cast finish consist coarse aggregate along with cement and sand. Their ratio is about 1: 1.5: 3. The size of coarse aggregate used is 3mm to 12mm.
Large quantity of mortar is taken by trowel and it is dashed into the surface and levelled using wooden float. Usually this type of plaster finish is preferred for external renderings.
- It is a finish in which the mortar for the final coat contains a proportion of fairly big size coarse aggregates.
- The mortar for finishing is made by mixing cement, fine sand and coarse aggregate in the ratio of 1: 1/2:3
Sand Faced Plaster Finish
To get sand faced finish two coats of plastering is required. For first coat, 12mm thick layer of cement sand mortar in 1: 4 ratio is preferred. The first coat should be provided in zigzag lines. And then it is allowed for curing for 7days.
After that 8mm thick layer of second coat with cement and sand in 1:1 ratio is applied. Level the surface using sponge. Finally take some sand and screened it to obtain uniform grain size. The screened sand is applied on the second coat using skimming float or wooden float. Finally, sand faced finish with uniform grain size of sand is obtained.
Pebble Dash Plaster Finish
Pebbledash finish requires a mortar layer of 12mm thickness with cement and sand in the ratio of 1: 3. After plastering pebbles of size 10mm to 20mm are dashed on to the plastered surface. Then press them into the plastered surface using wooden float slowly. After hardening, they provide an aesthetic appearance to the structure.
- It is a finish in which the small pebbles or crushed stones of suitable size are thrown on to a freshly applied finish coat of plaster and left exposed.
- The mortar finish is made by cement and coarse aggregate of 1:3 ratio.
Scrapped Plaster Finish
To obtain scrapped finish, apply the final coat of 6 to 12 mm thickness and allowed it to dry. After some time using steel blade or plate scrap the plastered layer up to 3mm depth. The scrapped finish is less liable to cracks.
Depeter Plaster Finish
This is also similar to pebble dash finish. But in this case pieces of gravel or flints are used in place of pebbles.
Textured Plaster Finish
The textured finish is obtained from the stucco plastering in which different textures or shapes are made on the final coat using suitable tools.
Defects In Plastering
In this section, we discussed Defects In Plastering. You can also Download Defects In Plastering Ppt from our website.
We listed some common Defects in plastering:-
Falling out of plaster
Blowing of plaster
Cracking:- Appears on the plastered surface in the form of hair cracks or wider cracks, it is due to the old surface is not properly dressed, bad workmanship or due to expansion and shrinkage in the plaster during drying.
Efflorescence:- It is soluble salts are present in the plaster making materials or bricks. They appear on the plastered surface in whitish patches and produced ugly appearance.
Blistering:- Small patches well out beyond the plastered surface like boils.
Falling out of plaster:- Due to excessive thermal variation in plaster, inadequate bonds between the coats of plaster and due to imperfect adhesion of the plaster to the background
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F.A.Q. in Plastering in Construction
- Crazing In Plastering ??
- Flaking Of Plaster ??
- Grinning In Plastering??
- Methods Of Plastering Application And Curing??
- Plaster Defects And Remedies ??
- Prevention Of Defects In Plastering?