Plastering the walls allows you to make them smooth and neat, as well as protect against adverse environmental factors. Before starting work, it is important to correctly calculate the amount of dry mix required. Finished plaster hardens very quickly after adding water. Therefore, it is necessary to correctly calculate the portioned volumes of the batch. All this will avoid unnecessary expenses and increase the performance of finishing work.
Varieties of plasters
There are several factors affecting the consumption of plaster per 1 m2. First of all, the amount of dry mix required depends on its variety. For wall decoration can be used:
- Gypsum plasters. This type of mixture is mainly used to align walls and ceilings from the inside. From the side of the street and for decoration of courtyard structures it is impossible to use them, since they do not tolerate too high air humidity and sudden changes in temperature. One of the most popular brands of this type is Rothband.
- Cement mixes. Such materials are used for decoration of rooms with high humidity or outdoor structures.
- Decorative plaster. They are usually applied in a thin layer and serve as a fine finish.
Wall curvature
This is another important indicator that affects the consumption of plaster. To finish absolutely even walls of the mixture you will need less. If there are deviations from the horizontal or vertical plane, the surface must be smoothed during plastering. Of course, in this case the mixture will need more. The consumption of plaster increases during decoration even if there are bumps on the walls: pits, large cracks, chips, etc.
Dry gypsum plaster consumption
This is a fairly economical type of mixture. To finish walls and ceilings with the same area of gypsum plaster, it is usually required 2-3 times less than cement. The recommended layer thickness when using this tool is 1 cm. In this case, the plaster consumption per 1 m2 will be about 9 kg. However, if there are no bumps on the walls, it is allowed to plaster them with a layer 0.5 cm thick. Consumption in this case, accordingly, will also be halved.
The most popular gypsum plaster today is the "Rotband" tool. The compositions of this brand are produced at domestic enterprises invested by the German company Knauf. The Rotband plaster, the consumption of which is 8.5 kg per 1 m 2 , is a high-quality product and at the same time quite economical.
Cementitious compounds
The consumption of plaster per 1 m2 in this case will be about 16-18 kg. These figures are true both for ready-made store products and for those made independently. The composition of such plasters usually includes cement and sand. Their volumetric ratio is 1: 3. Therefore, cement will need about 4.5 kg per m 2 . For plasters, it is better to take high-grade material, for example, M400. Sand per 1 m 2 will need 13.5 kg. Before kneading, it must be sieved.
Sometimes plasters are made on the basis of cement with the addition of a lime mixture. Usually they are bought ready-made. To obtain a smooth surface, cement-lime plaster is most often applied in two layers: preliminary spraying and coating. Therefore, its consumption is significant.
Decorative plasters
For surface finishing with an area of 1 m 2 of material of such a variety, an average of about 8 kg will be needed. But in this case, it all depends on the specific type of decorative mixture. Very popular at the moment is, for example, the tool "Bark beetle" intended mainly for finishing facades. Plaster (its consumption is somewhat less) of this brand is very high quality. For finishing 1 m 2 of the surface you will need about 2.5-3 kg of Bark beetle with a layer thickness of 1 mm.
Serving Size
The life time of gypsum solutions is very short: on average, the mass hardens in 20-25 minutes. Therefore, the batch must be done in such a way that during this time it has been fully worked out. Typically, gypsum plaster is prepared in a bucket of water - based paint. It is possible to develop such a capacity (incomplete) in just 20 minutes. Decorative plaster (the consumption of which is slightly less than gypsum and cement) of most types also hardens quite quickly. Therefore, you need to cook it in small portions.
Cement plasters do not harden for about two hours. Therefore, when using such funds, a rather large portion is prepared at a time (usually in a capacity of 10-15 liters, in the event that the work is performed by one person).
Calculation Method
To find out how thick the layer should be on the surface, you should first hang the walls, that is, check their deviation from the plane.
Blockage can be determined using the building level and plumb. Deviation should be measured at several control points. The more there are, the better. Further, the results obtained are added up and divided by the number of points. Thus, you can find out the required layer thickness. Knowing the consumption of plaster per quadrant meter, it will not be difficult to calculate the required amount of material.
Calculation example:
Suppose you have determined that the wall obstruction is 50 mm, and the deviation is at another two points: 30 and 10 mm. Add up the results 50 + 30 + 10 = 90 mm. Divide by the number of points 90/3 = 30 mm. That is, the thickness of the layer should be at least 3 cm. The consumption of plaster per 1 m2 in the event that it is made on the basis of gypsum is, as we have found, 9 kg. Therefore, for a layer of 3 cm it will need 9x3 = 27 kg. Cement - respectively 16x3 = 48 kg. The resulting figure is multiplied by the total area of the walls. For example, in a 6x4 m room with a ceiling height of 2.5 m, the area of two long walls will be 15 + 15 = 30 m 2 , two short walls - 10 + 10 = 20 m 2 . The ceiling area in such a room is 6x4 = 24 m 2 . As a result, we get the total figure of 50 + 24 = 74 m 2 . That is, for finishing all surfaces with gypsum plaster with a layer of 1 cm, 74x9 = 666 kg will be needed. Cement plaster needs more: 74x16 = 1184 kg.
What you need to know
The actual consumption of the mixture is always a little more than the calculated. Plaster may fall to the floor, remain in the container for kneading and on the tools. Therefore, it is worth purchasing material with a margin (approximately 5-10%). Plaster mixes are usually sold in bags of 30 kg. When calculating their number, rounding is worth doing up. That is, in our case, the consumption of gypsum plaster will be 666/30 = 22.2 bags. Therefore, you will need to buy 23 bags. Given the stock - 24. Cement plaster will need 1184/30 = 39.5, that is, 40-41 bags.
The minimum thickness of the beacons is 6 mm. A thinner layer is done without them. It is unlikely that it will be possible to plaster the surface exactly in this case without a certain experience. Therefore, with self-decoration of the walls, a layer of less than 6 mm is rarely made. An exception is only cement-lime plaster, which (by spraying) is often finished with walls of technical rooms.
If you don’t want to waste time on independent calculations, you can use the online calculator. All that will need to be done in this case is to enter the necessary numbers in the fields (length and width of walls, layer thickness, etc.).