Choose plaster for leveling walls, ceiling

One of the methods of leveling walls is plastering. It is used most often. How to choose plaster for each room, which brands are better, how to make cement mixtures with your own hands – read on. 

Types of plaster

Any plaster consists of a mixture of a binder, sand of different fractions and additives that give the composition specific properties. First of all, they are distinguished by the type of binder. It could be:

• gypsum;
• cement;
• lime;
• clay.

Most often, gypsum and cement plasters are used. They are the most practical, with their help it is easier to get a flat surface. Since the cement-sand mixture (CPS) is very hard and it is not very convenient to work with it, lime is added to the solution. Such plasters are called cement-lime. To choose plaster, you need to know exactly where the walls will be leveled – outside or inside the room and what conditions are in this room (more on this below).

Cement-based plaster sweeps can be done independently. This saves money but takes more time. You can buy ready-made – dry mix, packed in bags. Gypsum plaster is rarely made by hand, more often they buy it ready-made.

Plaster and putty are often confused. The processes are somewhat similar – both are used to level the walls. But the walls and ceiling are plastered with a large curvature – from 5 mm or more. After plastering, the surface is even, but grainy (less grainy when using gypsum compositions) and needs to be smoothed down. And smoothing is done with putties. They contain more finely ground components, which is what gets a smooth surface. The maximum layer of putty is 5 mm, plasters – 50-80 mm in one layer, and several of them can be applied.

Which is better – gypsum or cement plaster

It is necessary to decide which plaster is better to buy – gypsum or cement – based on their qualities. What is a plus in one room is a minus in another. Therefore, we first consider the properties of cement and gypsum plaster.

Let’s start with economic feasibility. If we compare only the price per kilogram of dry composition, then cement-based compositions are cheaper by about 1/3. But since their consumption is about the same amount, the total amount spent on plastering will be approximately the same. So there are no priorities here and it will not work to choose plaster for the price.

The easier it is to work

If we compare cement and gypsum plaster in terms of ease of use, then the gypsum composition is easier to lay down. It is more elastic, better “sticks” to the base. But there is one “but” – it seizes faster. On the one hand, this is good – it dries faster to a state where you can apply the next layer and the work moves faster. On the other hand, this is bad – you need to close small portions at one time: in order to have time to put everything in 30-40 minutes. It is better not to use the seized mixtures, since the addition of water changes its state only externally. This material will no longer gain normal strength.

Cement compositions remain elastic for 2 hours, so that large volumes can be closed at a time. But such plaster also dries longer, so the process takes longer – you have to wait for the composition to dry.

Application area

When choosing between gypsum and cement plaster, everything usually depends on the area of ​​uXNUMXbuXNUMXbapplication – gypsum is not used outside because of its fear of moisture. In this case, choosing a plaster is simple: for outdoor work we use cement.

The same property determines its scope in interior spaces: for the bathroom and kitchen it is better to use cement plaster, which is not afraid of moisture. In all other, “dry” areas, they prefer to level the walls with gypsum compounds. They “lay down” better and, with some experience, you don’t need to putty the walls under the wallpaper – you just need to level the grout layer well.

There are, of course, gypsum moisture-resistant plasters. Their moisture resistance is increased through the use of hydrophobic additives, but this is reflected in the price – it is much higher than for conventional formulations. It is also worth mentioning that in the bathroom the walls are leveled with gypsum non-moisture resistant compounds. Tiles will then be laid on it, and if the seams are carefully rubbed with moisture-resistant grout, then moisture will not reach the plaster. But this, after all, is not the best way out, since gypsum and cement are very different in characteristics, and tile adhesive is always made on the basis of cement. If tiles are laid on gypsum plaster, in most cases it lags behind the base, as they say, “bumps”, and maybe falls off.

If you choose the better to plaster the ceiling, in dry rooms the choice is clear – gypsum plaster. It is lighter, has better adhesion, and is easier to level. And even in wet rooms it is better to use a moisture-resistant gypsum composition – it is very difficult to work with cement on the ceiling. This is the case when it is better to overpay a little. So it’s easy to choose plaster for the ceiling: it’s a gypsum composition.

Do-it-yourself plaster mixture

With a limited budget for construction or repair, you have to think about saving. It’s easy to choose plaster here: you can save on finishing if you make cement-based compositions yourself. It is really cheaper, although it requires additional time and effort. But remember that additives have been added to the finished compositions that improve the properties of the plaster. For example, antifungal additives are added to wetroom formulations to prevent mold growth. In compositions for plastering external walls, an additive is added to antibacterial ones that increases frost resistance. There are also plasticizing additives that make application easier. In principle, these additives can also be added to homemade plaster. You can find them in construction markets or in specialized stores, the norms are written on the packaging. And even taking into account the cost of additives, the savings in self-production will be solid – about 30%.

It is not difficult to make cement-sand or lime-cement plaster with your own hands. The components are mixed in certain proportions in a dry form, then liquid components are added (if any, and water), brought to a certain consistency. You can knead manually with a shovel in a large basin, trough. You can mechanize the process if you have a drill – using a special nozzle. The easiest way is with a concrete mixer. With it, things go faster, but large volumes are difficult to produce, especially if there is little experience.

Cement-sand mixture: proportions

The cement-sand mixture is made up of 1 part of M400 or M500 cement and 3-5 parts of sand. Cement must be fresh, sand – dry, sifted through a fine sieve with a grain of no more than 1,5 mm. Waters take 0,7-0,8 parts. As you can see, the proportions are approximate. Sand can be of different humidity, the mortar can be used for plastering walls in different rooms, cement can be of different grades. When choosing the amount of water, the main guideline is the convenience of work. It is necessary to choose the composition so that it is not so thick that it falls off the wall, but not so liquid that it slides off. This is determined experimentally.

There is also a difference in composition depending on the application. For plastering walls outside, 1-3 parts of sand are taken for 4 part of cement. To level the walls inside the sand, add more – 5 parts or even more.

Although the DSP is much cheaper than ready-made mixtures, it is more difficult to work with it – it does not adhere very well to the wall, it dries for a long time, and almost always cracks when it dries. But it is not afraid of moisture and for this reason it is recommended for plastering walls in damp rooms, which will subsequently be finished with tiles or wall panels (PVC, MDF or any others). For other types of finishing – painting, decorative plaster and wallpaper – it is better to use a cement-lime mortar or gypsum.

Do-it-yourself cement-lime plaster mortar

Cement-lime plaster is made with the addition of lime paste. Parts of lime are measured in the form of a dough, then diluted with water to a liquid state and added in this form to thoroughly mixed dry cement and sand.

The proportions of cement-lime plaster are as follows: for 1 part of cement, take from 1 to 2 parts of lime paste, 6-9 parts of sand. Water is added to bring the solution to the desired consistency. The sand is the same as for the CPS – with a grain of no more than 1,5 mm, the water is clean, without pollution. Lime dough is better purchased. With home extinguishing, there are still particles that have not reacted. Later, when the wall gets wet, they react, increase in volume, which causes pieces of plaster to fall out. Therefore, it is better not to save on this.

The exact selection of proportions is determined experimentally: the mass should hold well on the wall. You can plaster with cement-lime composition walls in any room. The composition is softer, it is more convenient to work with it, it does not crack when it dries. But the strength of such plaster is much lower than the DSP, and this must also be borne in mind.

Choosing ready-made compositions

Choosing the type of plaster – gypsum or cement – is just the beginning. Next, you will have to choose the manufacturer and the composition itself – there may be several products that have slight differences.

Good gypsum plasters

The most popular gypsum plaster Rotband (Rotband) company Knauf (Knauf). This is a really high-quality product that is easy to use even for beginners. The same company has other products – Goldband (Goldband) and HP Start (HP Start). They are cheaper, the quality is quite decent.

HP Start is a gypsum-lime composition, Goldband is gypsum. The difference between Rotband and Golduand is in the thickness of the minimum layer. In Rotband it is 5 mm, in the second – 8 mm. Otherwise, the technical characteristics are very close – and the consumption (8,5 kg / m³ at a layer thickness of 1 cm), and a maximum layer (50 mm), and compressive and flexural strength. Slightly different hardened density: ~980 kg/m³ at Goldband and 950 kg/m³ at Rotbabd. Scope – any residential and non-residential heated premises, including kitchens with bathrooms.

Not bad also speak about the gypsum plaster Volma Sloy, Found Gipswell, Eunice Teplon, Prospectors. They cost less, give a good result, but it’s still easier to work with Rotband and the “company”. Based on the results of working with these brands, there are both positive and negative reviews, but in general, the quality is not bad.

Finished cement plasters

Cement plasters are hand and machine applied. We will talk about compositions for manual application. For interior work, Forward, Weber Vetonit, Startvell, Weber Stuk Cement are good. They adhere well to a clean, pre-moistened surface. For better adhesion, it is better to pre-prime the walls, after drying, start the plastering process itself.

If you choose cement-based plaster for outdoor work (including for plastering an open loggia or balcony), you need facade compositions. They differ from ordinary ones in an increased number of freezing / thawing cycles. Facade cement plasters – Yunis Silin facade, Founded by Profi Startvell, Knauf Unterputz (Knauf Unterputz), Bergauf Bau Putz Zement. Ceresit CT 24 Light plaster is suitable for both facade and interior work.

Aerated concrete walls require a special plaster. It has increased vapor permeability to prevent moisture from being trapped inside the wall. This is Ceresit CT 24, Knauf Grundband (it contains the smallest particles of expanded polystyrene, which increases its thermal insulation properties, reduces consumption).