Correct proportions of mortar for wall plaster

Plaster or a layer of finishing material applied to the surface during construction work is an obligatory step preceding the finishing.

This is a specially prepared building mixture (mortar), which, after drying, hardens, forming a solid even surface, ready for final processing.

In most cases, with its help, walls are aligned, any defects are corrected, and technological channels formed during the repair process are closed, for example, when laying new wiring. The surface becomes even, smooth and aesthetically pleasing.

The exact proportions of the mortar for wall plastering allow the prepared mixture to fulfill its function after drying and not crumble over time. To choose it correctly, you need to have a general idea of ​​the types of building mixtures and their purpose. Knowing their main components and application possibilities will make it easy to navigate the existing assortment and correctly apply the solution for their use.

Types of plaster and their features

Wall decoration can be used outdoors or indoors and is divided into three main types:

• standard, as protection against the effects of the external environment (external walls) or correction of surface defects, including alignment, sealing of cracks, technological channels and preparation for final finishing with decorative finishes, usually thin layers;
• protective, acting as an insulator or screen, for example, suppressing noise, retaining heat or preventing the penetration of radiation;
• decorative, used during the finishing coating (colored, stone, Venetian, graphite).

Each type is characterized by a specific composition, the preparation of which requires an exact proportion of the mortar for plastering the walls.

What is a building mixture

To prepare the mortar for wall plaster, the proportions should include a cementitious element (cement, lime or gypsum), aggregate, usually sand and water.

Depending on the amount of astringent component, they are:

• skinny, characterized by the absence of cracks, but poor strength;
• fatty, capable of crumbling and sitting down.

Skinny mixes easily slide off the trowel, fatty, on the contrary, stick to it. The task of any builder is to prepare a mortar for plastering the walls, the proportions of which will be optimal.

In addition, a plasticizer is necessarily added to the finished solution, making it easier to work with the mixture. The easiest option is a regular liquid soap or laundry detergent, but there are also special industrial additives.

Number of layers

Application usually takes place in three layers, which have individual proportions of the mortar for plastering the walls:

• the first (spray) is applied with a layer of at least 5 and not more than 9 mm when filling all the irregularities and looks like sour cream;
• the second (primer) is the main layer, which can be applied several times and has a density of dough;
• the third (nakryvka), applied with a layer of not more than 4 mm, must be on a damp surface, similar in consistency to a spray.

When preparing a solution for wall plastering, the proportions differ in the amount of binder, most often cement. In the first layer it is very little, in the second the quantity increases and in the third it becomes maximum.

Types of Mixtures

When decorating walls, several basic types of compositions are used. Today, mainly three mixtures are used:

• cement, the most common and popular, is characterized by the greatest strength, but a long period of solidification;
• earthenware used during interior and exterior work when processing wooden surfaces;
• Lime, an inexpensive analogue of cement mix, often used with gypsum, accelerating the period of solidification and increase strength.

In addition, depending on the situation, other options may also apply:

• gypsum - the most rarely used because of the quick (within a few minutes) initial solidification and complete fixation in half an hour;
• mixed - characterized by the simultaneous use of several special components;
• special - used with a certain additive, depending on the goal.

One of the important indicators that determine the type of solution you need is the humidity level. Depending on the microclimate, the desired composition is selected. The most universal and common is cement mortar for plastering walls, the proportions of manufacture of which are known even to the amateur, and allow it to be used successfully both outside and indoors.

To better understand, the proportions of the mortar for plastering walls that are used today in any construction work will be discussed in detail below.

Cement mortar

The most reliable, simple and ubiquitous way. To do it, you must clearly follow the sequence.

Work begins with the preparation of all components and, first of all, sand. It must be dried, and then sieved. Then thoroughly clean all lumps, especially clay ones. Sand of red or red color is not advisable to use, this reduces the quality of the finished mixture and its operational properties, and it is impossible to use whole or uncleaned.

After sifting, you can begin to prepare a cement mortar for plastering walls. The proportions vary depending on the type of cement used. For example, applying the M400 brand, 4 components of sand are enough for 1 part of cement. If the M500 is used, the number of parts increases to five. Violation leads to a loss of quality finishes and is not allowed. Dry components are thoroughly mixed in a previously prepared container. This can be done using a mixer inserted in a hammer, shovel or concrete mixer.

The choice of method depends on the required volume. If you have independent work, it is enough to use a large building bucket of 15 or 20 liters, in which you can prepare a solution for plastering your walls with your own hands, the proportions remain the same. If the work is done by several people, it makes sense to use a large trough or concrete mixer.

Water is gradually added to the thoroughly mixed mixture, bringing the composition to a state of thick sour cream.

Features of lime mortar

In order to reduce costs, cement is sometimes replaced with slaked lime, which almost does not affect quality. Moreover, the proportions of lime and cement for wall plaster are almost the same.

Its feature is the use of slaked lime only . It is quite simple to do at home without much cost.

The acquired lime is poured with warm, but not hot water in a large container, and after the reaction is completed, it is filtered, usually through cheesecloth. It can be used no earlier than in a day.

Lime mixture

The preparation of the solution also involves compliance with the sequence.

First, lime is cleaned of lumps by stirring. Small amounts of water or sand are allowed. Having a homogeneous composition, we can proceed to the preparation of the mixture.

The necessary composition is obtained if three sand, previously sifted and cleaned, is put on one part of the calcareous mass. Along with the sand, water is gradually introduced. This continues until the solution resembles a thick, uniform mass. Then it can be used for 12 hours.

Features of mortar during outdoor work

Typically, the lime mixture is used only in dry climates. If the facade processing time is limited, the proportions of the mortar for plastering the exterior walls include a small amount of gypsum.

This allows her to begin to solidify within a few minutes, completely hardening in half an hour.

To make the solution, 1 kg of gypsum is added to 3 liters of the prepared lime mixture. But it is necessary to take into account the period of solidification and the amount of work, otherwise it will harden ahead of time.

Clay solution

The use of clay is still quite common in wooden houses. To prepare a strong clay mortar for plastering the walls, the proportions should include cement, lime or gypsum.

You will need alumina, preferably oily, which is soaked for several hours. The mixture is important to constantly mix and add water until it becomes thick.

The easiest way to cook is to add sifted sand in a proportion of one to three. But it is not very durable. This is corrected by adding to these components 1/5 parts of cement. In this case, cement and clay, that is, binders, are mixed first, and only then sand.

Sometimes cement is replaced by lime, but with a mandatory increase in part to 1/2. You can also add gypsum, but not more than 1/4.

Ratio of components

The proportions of different components in the finished solution always differ, depending on the task and the type of layer. Typical ratios are given in the table below.

The indicated proportions are not constant and can be adjusted in each case.

Ready-made dry mixes

Today, almost all manufacturers provide a wide range of ready-made dry mixes. All that is needed before starting work is to take the necessary volume of water and ready-made dry solution, after which everything is thoroughly mixed, usually twice. The mixture is ready to use. As a rule, they are always a little more expensive than the cost of incoming components, if purchased separately.

Their main advantage is the lack of the need to mix several different elements in the right proportions. In addition, the sale of bulk materials is carried out in large quantities, which is not always convenient. For example, it makes no sense to purchase a 25 kg cement bag if you need to close up a small hole in the wall. Therefore, with a small amount of work, a ready-made dry mixture will be a good alternative.

Work with plaster

Properly selected proportions of the mortar for plastering the internal or external walls are one of the key points of any repair. But even the ideal ratio will be useless if plastering is carried out in violation of the rules for applying to the surface. Therefore, attention must be paid to all stages without exception. Only in this case can a positive effect be expected.

The order, thickness and number of layers is as important as the composition. A mistake can lead to the most unpleasant consequences. Application is made with a special tool, with a mandatory time interval provided for each type of mixture.

With minimal experience in carrying out such work, a mandatory number of trial attempts in small areas is recommended in order to evaluate their own capabilities.

Tools and specifics of individual surfaces

If the work is done by yourself, you will need a certain construction tool:

• rule
• Master OK;
• level;
• spatulas of different sizes;
• cord;
• grout for grouting.

The application of the first and second layer is carried out with a trowel, the third - with a spatula. Typically, the first layers are applied to an auxiliary mesh for reinforcement. When applying the finish coating, a gypsum mixture is used.

Surfaces with large differences are processed using special building beacons that facilitate the process of applying and leveling the plaster.