When starting to renovate an apartment, keep in mind that even in modern panel houses, the walls are quite uneven. Often, concrete slabs and panels have a wavy surface, and this waviness is quite deep and therefore clearly visible. The putty can “remove” only minor irregularities (up to 5 mm), but if they exceed this limit, you will have to use a solution and do small plastering work. Or, for example, if vertically installed doors protrude significantly beyond the plane of the wall due to its strong inclination, you should also use plaster to “bring” such protrusions. To reduce the cost of renovating an apartment (renovation) (and plastering work is quite expensive), it is not necessary to plaster all walls that have irregularities. You can restrict yourself to those walls, the irregularities on which are clearly visible, or their small pieces. These include:
-walls on which oblique light falls, located at right angles to the plane of the window. If they are not cluttered with furniture, then it is better to align them;
-places where the skirting boards will be attached, especially those that should be in plain sight.
Attach a flat bar or level to the bottom of the walls where the plinths will be attached, and if the gaps between the bar or level are large enough (more than 5 mm), then, when making apartment renovations (renovation), it is best to level them with plaster, and you can plaster with mortar only a small strip 10-15 cm high, and the rest of the irregularities later on it is enough to “reduce” the putty to nothing. In order for this small layer of mortar to hold reliably and in the future during cosmetic repairs it does not fall off the wall, you need to prepare its surface well by cleaning it from layers of old putty and priming with PVA glue diluted with water.
Other not striking defects are often enough to smooth out with a putty to make them invisible.
Sometimes plastering work is performed not with mortar, but with plaster. It should be borne in mind that the plaster solution is attached to the wall (concrete or brick) not only mechanically, but also due to a chemical reaction. Gypsum has only a mechanical connection with the wall surface. Therefore, if the walls are subjected to vibrations, the plaster of paris can peel off the wall and fall off. Example: if a door is transferred and part of the doorway is covered with bricks. This brick wall, especially if it is laid out in a quarter of a brick (on the edge), is subjected to vibration due to the slaps of the door, and if it is plastered with plaster, then over time this plaster peels off. Plaster is best used only on gypsum walls and partitions..
The most common mistakes in plastering work, or rather it will be said, is the saddest result of plastering work: peeling, cracking of the plaster and changing the geometry of the premises, due to the “thick” layer of plaster. This “rake” hit every season of renovation and finishing works. We do not aim to tell in such a short article about all the problems and defects that arise during plastering work. At the same time, we would like to draw your attention to the most typical imperfections and defects of plaster.
Let’s start with the requirements of building codes and rules for plastering and stucco work when renovating apartments:
3.15. When plastering brick walls at an ambient temperature of 23 ° C and above, the surface must be moistened before applying the solution.
3.16. Improved and high-quality plaster should be carried out on beacons, the thickness of which should be equal to the thickness of the plaster coating without a cover layer.
3.17. When installing single-layer coatings, their surface should be leveled immediately after applying the solution, in the case of using trowels – after it has set.
3.18. When installing a multi-layer plaster coating, each layer must be applied after the previous one has set (the covering layer – after the mortar has set). Leveling the soil should be carried out before the mortar begins to set..
3.19. Sheets of gypsum plaster must be glued to the surface of brick walls with compositions corresponding to the design ones, placed in the form of marks, 80×80 mm in size on an area of at least 10% along the ceiling, floor, vertical plane angles every 120-150 mm, in the intervals between them at a distance of no more 400 mm, along the vertical edges – in a continuous strip. Sheets should be fastened to wooden bases with nails with wide heads.
3.20. Installation of plaster molded products should be carried out after setting and drying of the base from plaster solutions. Architectural details on the facade must be secured to the reinforcement embedded in the wall structure, previously protected from corrosion.
Technical requirements Control (method, volume, type of registration)
Allowable thickness of one-layer plaster, mm: when using all types of solutions, except for gypsum – up to 20, from gypsum solutions – up to 15 inspection, work log
Allowable thickness of each layer when installing multi-layer plasters without polymer additives, mm: spraying on stone, brick, concrete surfaces – up to 5 spraying on wooden surfaces (including the thickness of the shingle) – up to 9 soil from cement mortars – up to 5 soil from lime, lime gypsum mortars – up to 7 top coat of plaster coating – up to 2 top coat of decorative finishing – up to 7 Measuring, at least 5 measurements per 70-100 m2 of the coating surface or in one room of a smaller area in places identified by continuous visual inspection, work log.
Do you make repairs in a panel, monolithic or brick house in any case with the help of an architect, designer, foreman, foreman or directly with the craftsmen, you need to measure, hang surfaces: floors, walls, ceilings. Look at the diagrams of hanging walls and ceilings with a plumb line.
This and only this will show what their curvature, slopes and differences are..
These measurements will make it possible to calculate the consumption of the selected material..
And determine the complexity, timing and cost of work.
The peculiarity of plastering work is also that they, ultimately, form the geometry of the room, be it a room, kitchen, bathroom or study..
Only slight irregularities (up to 5 mm) can be “removed” with the putty. The thickness of the plaster layer can be up to 5 cm. And some big drops will probably have to be hidden under decorative structures or drywall. At this stage, you need to work hard and carefully make all measurements and weigh whether you need all the angles at 90 or, so as not to reduce the area and not to increase the cost of repairs, and give up something? But it must be taken into account that the irregularities left are not striking only at the beginning of the repair. All the slopes, all the curvature will subsequently be emphasized by non-matching wallpaper, gaps between the wall and the baseboard, geometrically uneven parquet, a slope over the cabinet, crooked furniture, etc. We ask our customers not to buy or order furniture before fixing the surfaces. This is especially true for kitchens and bathrooms, where even 1-2 cm will not allow you to insert a refrigerator, cabinet or leave a gap.
And more about defects: Violation of technical rules and regulations during the preparation of solutions and the production of plastering works is the cause of defects.
Large and small cracks when plastering
Large and small cracks appear on the surfaces of the plaster because either greasy (with a high content of binding substances) or poorly mixed solutions are used, in which a lot of binding materials or fillers accumulate in places. Cracks can also appear as a result of the rapid drying of the applied plaster under the influence of strong drafts or high temperatures. Cracks are also formed from the application of a thick layer of a slow-setting mortar at one time or because the mortar is applied, albeit in thin layers, to the previous layer of mortar that has not yet set. To avoid the appearance of cracks, it is necessary to strictly dose binders and aggregates when preparing the solution and mix it thoroughly. The applied plaster must be protected from extremely fast drying, drafts, by closing windows and doors in plastered rooms..
Defined directional cracks form on brick surfaces along the seams of the masonry. On brick walls, cracks appear as a result of the application of very thin layers of plaster mortar without first wetting the surfaces with water. Alkalis emitted from the seams of the masonry can also cause cracks. Flares and bulges during plastering
Flakes and swelling of the plaster occur when plastering damp surfaces or with constant moistening of the plastered surfaces. Most often this happens on lime and lime-gypsum plasters. In order to avoid flaking and swelling of the plaster, damp places must be dried and only then plaster.
Plaster flaking is caused by the mortar being applied to an excessively dry surface or dry layers of a previously applied mortar. Peeling can also occur as a result of the fact that subsequent layers of the mortar were applied to weaker previous ones, for example, a more durable cement mortar was applied to the lime mortar. Plaster also peels off if a lime or lime-gypsum mortar without transition layers is applied to the concrete base or cement plaster.
Colored and decorative covering layers peel off when they are applied on very strong or, conversely, very weak soils, when the covering layer is much stronger and denser than the soil itself, or they cover soils with an insufficiently rough surface.
Cracks in husks during plastering
Cracks in husks appear as a result of the fact that the corners of the walls or the joints of dissimilar surfaces made of different materials were not sufficiently prepared or because the solution was applied to overdried wooden surfaces. Cracks also appear if the structures to be plastered were not firmly fixed. Before plastering, the corners and joints of dissimilar surfaces should be covered with mesh strips, and dry wooden walls, partitions, ceilings should be well moistened with water. A defect such as insufficient strength mainly occurs if there was an insufficient amount of binder in the solution or the sand is heavily contaminated. Insufficiently strong plaster is detected by tapping. Having found this defect, you should beat off the fragile plaster from the surface and re-plaster it with a more durable solution.
We hope that knowledge of the requirements of building codes and the reasons for possible defects in plaster, which we presented to you, albeit in a very abbreviated material, will still allow you to avoid at least obvious, but very annoying defects when plastering your walls and ceilings.