7 Things You Need To Know About Plaster

When it comes to building or renovating a home, plaster will play a central role, both from an aesthetic point of view and in terms of protection. But before you apply it, there are things you should know, whether you’re just supervising the work or you want to do it yourself. In order not to get caught on the wrong foot, here is some useful information. 


In order to be able to decorate, but also to protect and smooth the ceiling and the walls, the plaster will be applied, this consisting of a layer of mortar. After insulation, it will level the walls and prepare them for the next specific finishing steps, namely painting, whitewashing or wallpaper. It is suitable for use on different types of surface, from concrete to brick, the specific process being adapted to this feature. 

In general, plastering is a central step, which can not be missing from a correct and durable construction, protecting the walls and building elements, largely, from the effects of humidity, cold and other climatic elements. After drying, it will also have a sound insulating effect, not letting the outside sounds pass, maintaining the thermal comfort, to a certain extent. 


Where the plaster is applied

Depending on the location and application conditions, there are specific versions for interior and exterior. 

The ones for the interior will have a smaller class and will be applied first on the ceiling, after which the walls will be covered, the movement being from top to bottom, so that the excess is useful and does not form too thick areas. 

Exterior variants use a higher grade mortar, but the application technique is maintained. 


How to process mortar

Depending on the technique used, it can be about:

Raw plaster – which is used in bridges, turf or basement, the processing being slightly superficial, not requiring a flat finish to perfection, the purpose being to protect the wall;

Simple plaster – the most common, specific to homes, office buildings, shops or ordinary rooms, the visible face being smoothed very well with a trowel;

Polished plaster – specific for well-finished surfaces, with smooth and glossy walls, subject to high humidity (basins, bathrooms, laundries), the primer is processed with cement milk and smoothing is done with steel trowel, for a glossy and smooth result;

Plastered plaster – where the simple plaster is covered with a layer of lime or plaster, after which it will be smoothed with a metal trowel (offices, houses, social buildings). 


Differences between execution formulas

There may be:

– dry variants, which are made in advance in boards that are simply attached to the wall by using plaster, nails or bituminous mastics, being used in places that will be subject to high humidity; 

– wet options, which involve the use of fresh mortar made on the surface to be plastered; it is applied using cancioc, mala and trowel, or in mechanized format by using special equipment (plastering machine, mortar pump, injector);

– plaster applied on prefabricated materials, which is made in the workshop or factory and is mounted during their construction, then the construction materials are already plastered. 


Finishes and functions of plaster

These materials can be divided according to their destination, as well as the function they have. There is:

Antacid plasters that do not deform and are not affected by the action of chemicals, being obtained by adding special and resistant materials;

Waterproof plasters that are used especially on the outside, being made by crushing the face with cement mortar, by adding in the mortar some special elements that confer impermeability or by shotcreting, which is a specific method of application;

Acoustic plaster has the effect of absorbing sounds, being used in performance or sports halls. 


The number of layers required for a durable wall

Usually, the plaster is applied in two layers, the first being the primer and the second the plaster. The base (primer) will give a regular surface because it corrects and levels. 

It can be added manually or mechanically, using a plastering machine  , from top to bottom, in uniform storage. The plaster will be added after the primer has dried, in a thin layer, it being the visible level of the plaster. It will be placed first on the ceiling and then on the walls. 


Tips to follow before starting work

Because any homeowner wants a clean home, a few precautions are needed before you can actually start plastering. If you have a client who wants the work to be done as cleanly as possible, you will comply, taking care that the horizontal surface (floor, parquet, tiles, etc.) is protected by plastic or nylon sheets. You will mask the functional parts of the wall, such as sockets and switches, so that they do not get dirty. 

Before starting this stage, make sure that the masonry is completely completed, that there are no more necessary retouches and that the masonry frames and waterproofing have already been installed. 


How to apply

To choose with well-insulated walls, protected from moisture and ready for whitewashing, you will first clean the surface that will be plastered. It should not be covered with dust, traces of grease or oil or impurities, as there may be weak spots where it does not stick. 

The working temperature is usually between 5 degrees Celsius and 30 degrees Celsius. 

First, you will apply the primer on the support, it will be the one that will ensure the efficient and accurate gripping of the plaster, having to be spread over the entire surface. It is left for up to two days, after which it will proceed to the practical process. 

The primer is made and will be applied without smoothing, the surface being more adherent if it remains rough, so that the plaster adheres more easily. 

The last step is to prepare the plaster for the exterior or interior, as the case may be, applying it with a trowel, then resorting to its processing until the face becomes smooth, uniform and straight. 

By taking note of the information and applying the above steps, the plaster has great chances to acquire a final appreciated aspect and to fulfill its attributions, the result being a durable one and ready to add aesthetic elements such as paint, lime or wallpaper. 


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