Construction Technology Card: Installation of Plaster Coatings on Facades of Buildings and Structures

This technological process is applied during the construction, reconstruction, and repair of building facades. Before commencing finishing works on the site, roofing works, waterproofing installation, flooring on balconies, as well as the installation and secure fastening of all metal flashings for architectural details and fasteners for drainage systems must be fully completed. Execution of works is permitted only with an approved facade color passport.

Surfaces of factory-made precast smooth reinforced concrete structures (concrete class C20/25 and higher) are not subject to traditional plastering. The strength of the base to be plastered must obligatorily be not less than the strength of the plaster coating itself to prevent cohesive failure. For surfaces made of heavy, dense concrete or brick (compressive strength from 10 MPa / class C8/10 and higher), cement primers are applied.

The critical factor is the humidity and temperature regime. In dry weather at an ambient air temperature of +23 °C and above, wall sections made of small-sized masonry materials (bricks, cellular blocks) are subject to mandatory pre-wetting. The production process requires strict coordination: the installation of prefabricated scaffolding must be carried out taking into account the minimization of attachment points to the facade for their subsequent traceless sealing.

1Cylindrical handle or guide rod, length 200-250 units, used for holding and positioning the penetrometer cone during testing

1. Step 1: Conducting an expert assessment of the facade's condition and repairing all load-bearing structures of the building.
2. Step 2: Cleaning the facade from dust, dirt, efflorescence, bituminous, and grease stains using mechanical or hydrodynamic methods.
3. Step 3: Scoring and notching of smooth surfaces (if necessary), priming with a 7% aqueous solution of polyvinyl acetate emulsion.
4. Step 4: Washing complex areas with a 10% solution of technical hydrochloric acid followed by neutralization with water.

The choice of binders and mix proportioning directly depend on the operating conditions. For external walls, plinths, and cornices subjected to systematic wetting, cement and cement-lime mortars based on pozzolanic Portland cement, slag Portland cement, or standard Portland cement (grades M300-M400 / classes CEM I 32.5 - CEM I 42.5) are used. For surfaces protected from direct wetting, lime and lime-slag mixtures are optimal.

Lime mortars are prepared in proportions from 1:1 to 1:2.5 (lime:sand), while the lime putty must be aged for at least three weeks. Cement-lime mortars are formulated in proportions from 1:1:6 to 1:3:15; however, mixtures of 1:1:6 and 1:2:8 show the highest performance characteristics for facades. Pure cement mortars are mixed in a ratio from 1:1 to 1:6. To accelerate setting, gypsum can be introduced into lime mortars (1 part of gypsum to 2-3 parts of lime mortar).

The aggregate (quartz sand) must undergo strict granulometric control. The maximum permissible grain size for preparatory layers (splash coat and base coat) must not exceed 2.5 mm, and for the finishing coat — 1.2 mm. The workability of the prepared mortar is monitored by plunging a standard cone: for mechanized and manual application of splash and base coats, the penetration should be 8-12 cm. The finishing coat without gypsum requires a penetration of 7-8 cm, with added gypsum — 9-12 cm.

1Main operational block or production hall, rectangular layout, width 3660 mm, central focus of the facility

2Connecting corridor or transition area linking the main block to the auxiliary building

3Loading dock or vehicle access bay, dual-lane configuration, extending 3150 mm outwards from the main alignment

4Auxiliary building or utility room, separated from the main block, width 1600 mm, positioned at the left extreme of the layout

5Utility connection point or structural tie to the main boundary wall, indicating alignment with the site's perimeter

6Anchor point or utility entry at the boundary wall, securing the connection line from the main operational block

1. Step 1: Preparation of binding components (aging of lime putty, testing cement activity).
2. Step 2: Sieving aggregates through vibrating screens: 3x3 mm mesh for the base coat, 1.5x1.5 mm for the finishing coat.
3. Step 3: Mechanized mixing of components in a mortar mixer until a homogeneous consistency is achieved.
4. Step 4: Controlling mortar workability with a standard cone before loading into the plastering machine.

Before plastering begins, the substrate is subjected to strict instrumental control. Surfaces are checked using the plumbing method in vertical and horizontal planes with the mandatory installation of removable inventory marks (beacons). The thickness of the installed beacons must exactly match the design thickness of the plaster coating, excluding the finishing coat.

Permissible deviations of the base surface prior to the commencement of work are strictly regulated. Deviations of the surface and corners of brick or block masonry from the vertical must not exceed 10 mm per floor and 30 mm for the entire height of the building. Irregularities on vertical surfaces, detected when applying a 2-meter control straightedge, are allowed up to 10 mm. Deviations of masonry courses from the horizontal must not exceed 15 mm for every 10 meters of wall length.

In case of deviations exceeding normative limits, local leveling with base mixtures is performed. When walls are laid with unfilled joints, the depth of joints not filled with masonry mortar from the front side must not exceed 15 mm for wall planes and 10 mm for vertical joints of load-bearing pillars and pilasters.

1Perimeter fence delineating the construction site boundary, providing safety and security.

2Temporary site buildings or containers serving as site offices, welfare facilities, or storage areas.

3Control point or security cabin positioned near the site entrance to monitor access.

4Crane control cabin or operator's station, typically elevated for clear visibility of the site.

5Tower crane base section showing the structural mounting and support mechanism, ensuring stability.

6Counterweight system or base ballast of the tower crane, designed to balance the load during lifting operations.

7Main structural floor or slab of the building under construction, representing the primary load-bearing level.

8Secondary structural layer or finishing screed applied over the main slab, often serving as a leveling course.

9Crane track or rail system laid out parallel to the building facade to facilitate linear movement of the crane.

10Crane track foundation or ballast layer supporting the rails and distributing the heavy loads of the crane.

11Zone marker indicating the swing radius or operational reach of the crane's jib.

12Designated safe zone or restricted area within the crane's operating radius to prevent accidents.

13Material laydown or staging area within the crane's reach for efficient lifting and positioning.

14Another operational zone marker, possibly detailing a specific lifting sequence or safety buffer.

15Zone indicating the boundary of the crane's maximum lifting capacity or safe working load limit.

1. Step 1: Instrumental checking of wall verticality and horizontality using laser levels and plumb bobs.
2. Step 2: Checking substrate flatness using a 2-meter control straightedge.
3. Step 3: Setting up inventory mortar or metal beacons with a pitch corresponding to the working straightedge length.
4. Step 4: Fixing corner protection profiles on external corners (arrises) and reveals.

The installation of a multi-layer high-quality coating is a strictly regulated process. Mortar transportation is carried out by plastering machines (capacity up to 4-6 m3/h, delivery distance up to 250 m horizontally and 60 m vertically) through metal mortar pipelines. The first layer — the splash coat — is applied with a nozzle as a continuous layer up to 5 mm thick. The surface of the splash coat is not leveled to ensure maximum adhesion.

After the splash coat begins to harden (in 1-2 hours), the base coat is applied. The thickness of a single base coat is limited: no more than 5 mm for heavy cement mortars and up to 7 mm for lime mortars. Leveling of the base coat is performed with H-shaped straightedges or floats immediately after application. For improved and high-quality plastering, the base coat is screeded strictly along the beacons. The plane quality is continuously monitored with a straightedge during the work.

The finishing coat is applied with a thickness of up to 2 mm for standard smooth coatings and up to 7 mm for decorative textured finishes (terrazzo, stone plasters). Troweling of the finishing layer is carried out 30-40 minutes after application using rotary power trowels (disc diameter 280 mm, rotation speed 450-500 rpm). To significantly increase the strength of the troweled layer, it is recommended to add a 3.5-5% aqueous solution of PVA emulsion to the water supplied under the machine's working discs.

1. Step 1: Mechanized application of the splash coat ensuring 100% coverage of the substrate.
2. Step 2: Application of the first base coat (after a 1-2 hour technological pause) and leveling it with a straightedge along the beacons.
3. Step 3: Application of additional base coats (if necessary) after the setting of previous layers.
4. Step 4: Application of the finishing coat and its machine troweling with rotary equipment applying water or PVA solution.

Carrying out plastering works in the winter period requires a radical change in the technological regulations. Before applying the mortar, the base surface must be absolutely dry: snow, frost, and ice are removed mechanically. Ice that cannot be mechanically cleaned is pre-thawed. The use of hot water to accelerate the heating of frozen walls or to remove ice is strictly prohibited. Wetting the masonry before applying layers at sub-zero temperatures is not allowed.

At an outdoor air temperature in the range of -10 °C to -20 °C, anti-freeze additives must necessarily be introduced into the mixing water of the plastering mortar. The standard formulation includes adding 3% potash (potassium carbonate) by weight of the mixing water, or a complex mixture of 2% sodium chloride (NaCl) and 2% calcium chloride (CaCl2). Transportation of the mortar to the workplace is carried out exclusively in insulated containers, and outdoor mortar pipelines must be thermally insulated.

The sizes of work sections are calculated so that the full plastering cycle in the area is completed before a break in work, eliminating the risk of the mortar freezing prior to the machine troweling stage. If local heating is required, panel-linear portable electric heaters (capacity up to 6 kW) are used. In this case, the scaffolding must be enclosed with fire-resistant thermal insulation material (thermal enclosure). Regrouting and repairing old plaster in winter conditions are strongly discouraged.

1Unit of measurement for 'Surface preparation for plastering'

2Unit of measurement for 'Plumbing the surface and installing beacons'

1. Step 1: Cleaning the facade from ice and snow using heat guns (without using hot water).
2. Step 2: Mixing the plastering mortar with the introduction of 3% potash or 4% salt complex (NaCl + CaCl2) in a thermal enclosure.
3. Step 3: Delivery of the heated mortar through thermally insulated pipelines to the work section.
4. Step 4: Accelerated application and troweling of the layer within one work section before a critical drop in mortar temperature.

The quality system includes incoming, operational control, and conformity assessment. Dry building mixes must be supplied in factory packaging indicating the recipe, fraction, amount of mixing water, and expiration date. A laboratory test of the mortar is mandatory: it must completely pass through a 3 mm sieve (for the base coat) and a 1.5 mm sieve (for the finishing coat). Operational control includes checking the moisture of the substrate, the adhesion of the applied layer, and the thickness of each coat.

The finished plastered surface is subjected to strict flaw detection. The presence of shrinkage cracks, marks from the troweling tool, mortar sags, efflorescence, and voids on the facade is not allowed. To repair plastered surfaces, it is strictly forbidden to use mortars that have a higher compressive strength than the main (old) plaster (for example, repairing a lime facade with a cement mixture is unacceptable). Cracks wider than 1 mm are routed and filled with an elastic polymer-cement compound.

Acceptance tolerances are classified by quality level. For high-quality plaster: deviation from the vertical and horizontal — no more than 1 mm per 1 meter (max. 3 mm for the entire height of the element). Smooth surface irregularities when checked with a 2-meter straightedge — no more than 2 irregularities up to 2 mm deep. Deviations of window reveals, pilasters, and internal corners from the vertical/horizontal — 1 mm per 1 meter. The thickness of single-layer plaster is limited to 20 mm, multi-layer — according to the project.

1. Step 1: Incoming control of sand granulometry and mortar workability (cone test, 8-12 cm).
2. Step 2: Operational control of the applied layers' thickness (up to 5 mm splash coat, up to 7 mm base coat) using a probe.
3. Step 3: Checking the finished surface with a 2-meter control straightedge in various directions.
4. Step 4: Instrumental measurement of deviations of window reveals, radii of curved surfaces, and moldings.