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Plastering, Claddings & Coverings - 3.4

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    UNIT 1 - Floor Finishes

    • Subfloors

      COURSE 3 / MODULE 4 - CLADDINGS & COVERINGS / UNIT 1 - SUBFLOORS

    • This section provides a brief overview of floor layers, presenting the most commonly used floor finishes, paving and ceiling linings. The layers of flat roofs as terminal floor assemblies along with the available surface-covering options were discussed in detail in Course 3, Module 2. Similarly, in Course 1, Part 3, we covered the waterproofing of ground-bearing slabs although did not examine their floor layers.

      I. Subfloor for floor finishes

      Floor finishes or coverings are rarely applied directly onto the slab or the floor slab. Firstly, a solid, even-surfaced (flat and smooth) subfloor is prepared on the structure to provide a suitable base for the floor covering. The subfloor may consist of in-situ concrete, a reinforced concrete subfloor, a screed of mortar-like material or a dry floor system made of thermal insulation and building boards. 

      Between the subfloor and the slab / floor slab, there may be several additional layers to ensure proper technological construction. One example is the waterproofing layer on the foundation slab; in this configuration, the floor is classified as an unbonded screed. 
      Another example is the thermal insulation layer, which, when applied, results in a floating floor. The built-in thermal insulation layer can serve multiple functions simultaneously:

      • For intermediate floors, it provides impact sound insulation.

      • For floors on grade, the thermal insulation function is more important, and the layer thickness is designed accordingly.

      In addition, other layers may be present in floor structural layers such as waterproofing against service water in facilities, separating membranes, or sheet drains that function as a drainage system.

      Subfloor Construction

      The subfloor concrete is a 5–7 centimetre thick monolithic reinforced concrete layer, which must be dilated every 40 square metres to prevent cracking.

      Here are  the steps to construct a floating floor concrete subfloor:

      1. Install a 1-centimetre-thick edge insulation strip along walls to accommodate thermal expansion and prevent stress-induced deformations.

      2. Install expansion joints to divide the subfloor into smaller sections if any surface length exceeds 8 metres, or if the area is larger than 25–40 square metres, or if the side ratio exceeds 3:1.

      3. Lay expanded thermal insulation boards for impact sound insulation in a staggered pattern.

      4. Install a polyethylene (PE) foil as a separating layer to protect the insulation, sealing the overlaps with adhesive tape.

      5. Establish the top level of the concrete or reinforced concrete subfloor, measuring from the pre-levelled and marked reference line positioned exactly 1 metre above the finished floor level.

      6. Install reinforcement mesh. For lighter loads, reinforcement may be omitted.

      7. Prepare fresh concrete of minimum C12 strength, either through on-site mixing or by using dry concrete mix.

      8. Using straightedges, form 15–20 centimetre-wide guide strips spaced 1.5–2 metres apart, ensuring they are level.

      9. Fill spaces between the guide strips with concrete, levelling the surface to match the top of the guide strips.

      10. Keep the finished concrete surface moist to prevent cracking.

      Construction of other subfloors:

      • The procedure is similar when constructing a cement screed. The main difference is that the fresh mix is prepared on-site using a mechanical mixer and applied with a pump. The typical layer thickness in this case is 2–5 centimetres.

      • For a heated subfloor concrete, a 6–8 centimetre minimum concrete or smooth cement screed will ensure that the heating pipes covered by at least 3–4 centimetres of concrete above. A special PE foil, laminated with a reflective heat barrier, is laid beneath the concrete layer to reduce heat loss.

      • A dry subfloor can be constructed using either factory-produced building boards combined with thermal insulation or separate insulation boards and building boards. The building boards may be made of gypsum fibre, OSB, MDF, or plasterboard. They are laid as two layers on top of the thermal insulation surface.

      The surface of a finished subfloor may not always be perfectly even. In such cases, a self-levelling compound can be used to create a completely flat and uniform screed suitable enough for covering. The flowing, fine-grained self-levelling layer typically has a thickness of 2 to 10 millimetres, up to a maximum of 20 millimetres.  First, a primer must be applied with a roller; when it has dried, the levelling compound is poured onto the surface and then spread evenly using a trowel or spiked roller.


  • UNIT 2 - Floor & Ceiling Coverings

    • Floor & Ceiling Coverings

      COURSE 3 / MODULE 4 - CLADDINGS & COVERINGS / UNIT 2 - FLOOR & CEILING FINISHES

    • 1. Pavements

      Pavements around buildings, terraces, parking areas, and public spaces are often constructed using small-sized paver blocks. For higher-quality applications, such small-sized block pavements may be made of stone tiles or Klinker-quality fired bricks. Lower requirements or domestic use may utilise concrete paver blocks instead.

      Areas with low traffic and lighter loads are prepared with a 25–40 centimetre thick compacted gravel or crushed stone subbase which serves as a load-distributing, draining, and frost-protection layer. This base is laid in 2–3 layers and compacted using a plate compactor. On its surface, a 3–5 cm thick layer of sand is placed, into which the paver blocks are laid. The joints are filled with sand and, if necessary, slurried with water. Finally, the completed pavement can be compacted using a rubber mat compactor.

      For heavier loads, a concrete or reinforced concrete slab is required.

      2. Hard flooring

      a) Tile coverings

      Tile coverings are available in a wide variety of materials and sizes. Their advantages include easy cleaning, high wear resistance, and moisture resistance. The thickness of various ceramic tiles - glazed ceramic tiles, porcelain tiles, stoneware (Mettlach) tiles, and stone, artificial stone, or cement tiles - ranges between 0.8 and 2.5 centimetres. The width dimensions of the tiles may vary from small mosaic pieces of a centimetre to large panels up to one meter.

      Tiles can be laid in different layouts, such as running bond, stack bond, or even custom designs cut from individual pieces. Furthermore, tiles of different colours, patterns, and materials can be freely combined to create a unique appearance for each interior space.

      Nowadays, tiles are no longer installed using the traditional mortar bed method; instead, they are fixed using thin-bed adhesive bonding. Practically, this means a 2–4 millimetre-thick cement-bonded layer of adhesive is spread beneath the tiles. Resin-bonded flexible adhesives are preferred when there is higher mechanical stress or greater temperature fluctuations - for example, with exterior floor tiles.

      1. On a level subfloor concrete or screed, the dry-mix adhesive is prepared on-site and spread using a trowel or a plasterer’s trowel.
        A notch trowel is used to ensure  even distribution of the adhesive and uniform thickness.

      2. For an aesthetic finish, uniform grout joints ranging from 2 to 5 millimetres must be maintained between tiles. Tile spacers are used to keep the joints even, which must be removed once the adhesive has set.
        Throughout the laying process, care must be taken to maintain the designed levels and slopes and to avoid uneven surfaces.
        Alignment is adjusted using a spirit level and a rubber mallet.
        At wall edges, floor transitions, or where custom patterns are created, tiles must be cut to size using a circular saw, angle grinder, or tile cutter.
        Along the walls, skirting tiles can be installed, glued to the wall above the edge of the floor tiles.

      3. The finished covering and grout joints must be cleaned of adhesive residues; the spacers are removed, and the grout joints are moistened.

      4. Pre-coloured grout is mixed with water on site and spread over a section of the surface and pressed into the joints using a grout float.
        The filled joints are compacted with a damp joint smoothing tool. Gradually processing, joints should be filled across the entire surface. 

      5. Once all joints are evenly filled on the entire surface, the tiles must be thoroughly cleaned to remove any dried grout residue.

      b) Poured Floors

      In low-traffic areas such as garages, a simple, approximately 2-centimetre-thick smooth cement floor (cement screed) can be created on the surface of the subfloor concrete. A higher-quality version of this poured technology is terrazzo, where a 2–3 centimetre thick cement or resin-bonded poured layer is machine-polished to achieve a perfectly smooth surface. Resin-based coatings are thinner, ranging only from 1 millimetre to 5–10 millimetres. For their application, a precisely levelled or properly evened subfloor is required, on which a system-specific primer must first be used to create an adhesion bridge. After that, the slowly self-levelling coating must be evenly spread with a trowel.

      3. Soft Flooring

      a) Plank Flooring and Solid Wood Flooring

      Plank flooring consists of hardwood planks that are 3–6 metres long, 80–150 millimetres wide, and 19–22 millimetres thick. Solid wood flooring features higher-quality workmanship and smaller dimensions: 0.9–1.5 metres in length, 70–120 millimetres in width, and 16–22 millimetres in thickness.

      Planks or floorboards are laid on softwood battens that are 5 centimetres wide, and the boards are connected with tongue-and-groove joints. The spacing between battens varies between 45–50 centimetres and 50–80 centimetres, depending on the size of the boards or planks.

      Under the battens, thermal and sound insulation batts are placed, provided that the floor is not already built on a floating subfloor. Between the battens, fibrous thermal insulation or expanded clay aggregate is used as a sound and heat-insulating material.

      The planks are placed 1 centimetre away from the wall. On top of the finished floor, joints between the wooden floor and the wall are covered with floor trims which are nailed or glued to the painted wall.

      b) Parquet Flooring

      Parquet floors are made of small hardwood elements or strips that form a continuous floor covering.
      Parquet flooring come in a variety of designs. Individual pieces typically range from 15 to 50 centimetres in length, 15–25 millimetres in thickness, and 25–65 millimetres in width.
      The floor surface can be covered in a variety of laying patterns, the most common of which are the herringbone, basket weave, the strip pattern, and inlaid pattern.

      Among the traditional solutions, the most common is the tongue-and-groove system, in which the parquet elements are nailed to a loosely laid subfloor resting on wooden battens, creating tongue-and-groove joints between the parquet elements.
      The finished surface has to be sanded and is typically coated with lacquer.

      Modern parquet strips are glued directly to a continuous and even subfloor.
      These elements may be connected by butt joints, tongue-and-groove joints, or assembled into panels that are known as mosaic parquet.

      The three-strip engineered parquet floor is a factory-made, cost-effective version of the traditional parquet floor. Only the upper layer, known as the wear layer, is made of hardwood rather than the entire board.
      The boards are typically 1.8–2.5 metres long, 120–208 millimetres wide, and 10–16 millimetres thick.

      Each board is pre-lacquered and features either a tongue-and-groove or a click-lock joint system.
      Thanks to these properties, an engineered parquet floor is easy and quick to install, requiring no adhesive; instead, it simply involves fitting the boards together.
      It is sufficient to lay the staggered patterned floor over a continuous impact sound insulation layer.

      c) Laminate floor

      The modern, further developed and even more economical version of the three-strip engineered parquet floor is laminate flooring. Here, boards are typically around 20 centimetres wide, 7–12 millimetres thick, and 1–1.4 metres long. The elements are typically connected with a self-locking (click-lock) joint system, and the installation is completed in a staggered pattern, with offsets of half or one-third. Laminate floorboards are multi-layered structures, with a high-strength HDF core layer providing the base. On the underside, a levelling or rigid melamine-resin sound-damping layer is bonded to the core. On the top, an impregnated UV-resistant, colourfast decorative layer is protected by a wear- and scratch-resistant melamine-resin protective layer.
      Typically, a vapour-barrier PE foil and a 2–4 millimetres thick impact-sound insulation foam underlay are laid beneath the laminate flooring, which is assembled over the subfloor concrete.

      d) Plastic and linoleum floor coverings

      PVC or linoleum sheets create an easily-cleanable warm soft flooring from plastic. The sheets are laid from rolls 1 to 4 meters wide and glued either in strips along the edges or across the entire surface. Sheet  thickness ranges from 0.8 millimetres to 7 millimetres.

      e) Carpet flooring

      Carpet flooring is composed of two layers: a strong backing layer made of rubber, foam, or jute, and an upper wear layer. The upper carpet-like surface can be either natural or synthetic. Carpets are available in large rolls measuring 4–5 meters in width. They can be fixed by full-surface adhesion, edge-only adhesion, or by stretching them with tack strips.

      4. Raised Floor and Drop Ceiling

      a) Hollow floors and raised floors – Hollow floors are shell structures built on adjustable pedestals with heights ranging from 20 to 220 millimetres, forming the flooring subfloor.

      For soft flooring types, the floor finish is applied directly onto the gypsum or gypsum-fibre construction boards of the shell. For hard flooring solutions, a gypsum screed is first installed on a PE separation foil.

      Unlike hollow floors which are non-demountable, raised floors are constructions that can be dismantled without damage - so elements can be removed individually at any time.The 60 × 60 centimetre floor panels rest on height-adjustable metal pedestals and can be finished with any desired covering, either factory-applied or installed on site. For heavier loads or greater heights, metal bracing rods connecting the pedestals provide additional reinforcement. In the hollow space beneath the raised floor - ranging from 35 to 1,200 millimetres in height - mechanical services, cables, ventilation systems, and other components can be accommodated.

      b) Ceiling coverings and drop ceilings - Ceiling coverings and drop ceilings can be part of the floor and ceiling layer structure. Ceiling coverings refer to claddings attached either to the underside of the ceiling or to a supporting framework, while their construction technology is similar to that of wall claddings.

      Drop ceilings are suspended self-supporting shell structures composed of a metal framework suspended on metal rods with the cladding attached to it. The typically two-way grid system may be a simple, multi-level design or a single-level system consisting of main runner and cross tee beams. Cladding can generally be installed as a non-removable, homogeneous surface, for example, by using ceiling boards.

      Another frequently used technology is the ceiling tile system, where the cladding surface is created from square-shaped ceiling boards inserted between T- or Z-profile tee bars, typically arranged in a 60-centimetre grid. The grid may be designed with exposed or concealed tee bars. In both cases, the ceiling can be constructed so that it is fully dismountable.

      Linear metal ceilings with a single-direction support framework are commonly used in industrial applications. Long metal sheets are slid transversely into the longitudinal carrier profiles, giving the cladding a characteristic strip-like appearance.


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  • UNIT 3 - Renders & Plasters

    • Renders & Plasters

      COURSE 3 / MODULE 4 - CLADDINGS & COVERINGS / UNIT 3 - RENDERS & PLASTERS

    • Interior plasters and exterior renders create seamless, continuous coatings on the surface of walls and ceilings. The purpose of these wet-applied coatings is to protect the structures, create smooth finishes, and serve as a base for paints or various claddings. These mortar-like coatings typically use lime, cement, or gypsum as binders and can be mixed entirely on-site or prepared from pre-manufactured dry mixes.

      1. Plaster

      The typical thickness of interior plaster is 1 to 1.5 centimetres. After skim coating, the surface is typically painted or wallpapered. The plaster is usually applied in several layers:

      1. First, a spatterdash surface is created, or a primer is applied.

      2. Next, a gypsum or lime-cement base coat of plaster is applied with a thickness of 10–12 millimetres and a grain size of 0–4 millimetres.

      3. Finally, a finer, 2–5 millimetre thick finishing coat is applied with a grain size of 0–1.5 millimetres.

      For a lower standard of finish, or where the plaster will be covered by cladding, it is sufficient to apply the plaster in a single layer, completing the smoothing process on that one layer.

      2. Render

      Unlike plasters, render must also withstand weather conditions such as sunshine, wind, temperature fluctuations, precipitation, and frost. Rendering follows the same principles and steps as plastering, but in this case, the top coat is a much durable, coarser or textured finish. The finishing coat can be a traditional aggregate render, a thick or thin-coat decorative render, or a silicate, silicone resin, or synthetic resin-based thin-coat render.

      a) Thin-coat render

      Nowadays, the most common solution is a thin-layer render, whose finishing coat with a maximum thickness of 5 millimetres, is simultaneously weather-resistant, water-repellent, washable, and vapour-permeable. To apply the thoroughly mixed primer of the thin-layer render, a temperature above 10 °C is required, and the application is carried out with a brush or paint roller. The rendering mortar is a factory-prepared wet mixture which when it has been thoroughly stirred, can be applied 24 hours after the primer has dried. The building facade should be divided into sections so that each surface can be plastered in a single, uninterrupted operation. Application is done using a trowel or plastic float, working from top to bottom. The finished surface can be textured with a dragged or scraped pattern by mixing the aggregate into the render using a hard plastic or wooden float.

      b) Dryvit render

      A special type of render called the dryvit render is applied to walls with façade insulation. Thermal insulation made of expanded polystyrene or rock wool is mechanically fixed directly onto the raw surface of the wall structure using adhesive and dowels. A smoothing layer is created on the insulation surface with adhesive mortar, into which a reinforcing mesh is embedded. A smoothed surface is formed using a trowel. The primer of the thin-layer render and then the render itself are applied onto this surface, as described earlier.

      c) Plinth render

      Plinths require special protection, for which resin-based thin-coat renders are excellent. These renders contain coloured aggregates to provide greater resistance. If thermal insulation is needed, waterproof extruded polystyrene insulation is used beneath the render, with the thin-coat render applied on top of it. Above the plinth, a drip edge aluminium profile must be installed, and waterproofing sheets must be fixed either behind or above the plinth insulation.


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  • UNIT 4 - Wall Claddings

    • Wall Claddings

      COURSE 3 / MODULE 4 - CLADDINGS & COVERINGS / UNIT 4 - WALL CLADDINGS

    • Primarily in the case of public buildings, but often also in residential buildings, it is possible to create façade cladding from high-quality materials in addition to or instead of a simple render.

      1. Bonded wall claddings

      The claddings can be installed by glueing them directly onto the wall. Common coverings include:

      • klinker tiles, that is, bonded brick coverings

      • ceramic tiles, or

      • stone tiles

      The cladding is installed in a similar way to ceramic floor coverings: 

      First, the factory-made dry mix is diluted with water and stirred.  Then the elements are affixed to a thin adhesive bed applied to the wall with a notched trowel.  The cladding is installed from the bottom up, using tile spacers to maintain an even distance between the tiles. External wall corner profiles are used at the outside edges  corners. Flexible adhesive must be used outdoors, and the appropriate expansion joint requirements must consider how to eliminate stresses caused by thermal movement. The coverings can also be installed on thermally-insulated wall structures; in this case, we use the same method as rendered thermally-insulated walls to install the thermal insulation.

      2. Masonry wall claddings

      Brick cladding is a masonry structure independent of the wall; that is, the cladding must be built in the same way as if we were erecting a separate brick wall. As per the rules of bricklaying, horizontal and vertical mortar joints should be created.

      However, the area behind the cladding can be constructed as a mixed structure, typically with a 4-centimetre-thick cement mortar backing and the brick wall built directly in front of the load-bearing structure.
      It is more common - especially in multi-storey buildings - for the supporting structure and the cladding to be completely separate from each other. In this case, there are three options:

      1. Simple air gap cladding

      2. Thermally insulated cladding without an air gap  

      3. Multi-layer thermally insulated cladding with an air gap – the latter is the most common solution.

      To start, we build a one-brick wide wall for the brick cladding on a common foundation with the load-bearing wall. Alternatively, we can begin from steel support brackets which we attach to the base of the walls with dowels or anchor bolts. This is only feasible if the lower wall consists of reinforced concrete, and this section is appropriately dimensioned as a ring beam to support this load.

      The connection between the wall structure and the brick cladding is achieved by steel wall ties, whose hooked ends are placed in the horizontal joints of the cladding. These must be placed every third row, 50-70 cm apart. The hanger bracket attached to the ring beam supports the brick cladding from below and supports the bricks above wall openings, which are also held in place by the metal rods.

      3.  Mounted wall claddings

      a) Wooden claddings

      Mounted wooden cladding can be created in various ways. One less common option is shingle cladding, made from spruce or Scots pine and nailed onto a wooden sheathing or batten frame to form a double lap cladding.

      A more common solution is horizontal panelling made of tongue-and-groove boards, which are attached to a batten frame with hidden nails. Board cladding is usually applied vertically in two rows that partially overlap and is also fixed to a batten frame.

      A modern solution is an impregnated, 15-20 mm thick laminated veneer lumber (lvl) cladding, with a metal support frame constructed for the large panels. When installing the cladding, care must be taken to ensure that the area behind it is ventilated and that there is space for the required thermal insulation (rock wool is advised). It is recommended to protect the thermal insulation layer with a vapour control layer on the outside.

      b) Metal cladding

      Similar to flat-sheet covering of the roofing, metal cladding can be installed on façade walls in conjunction with the roofing system. Aluminium, zinc, or stainless steel sheets are commonly used. To create traditional flat metal cladding, continuous sheathing is required, onto which double-lock standing seam or single-lock (angle) standing seam metal cladding is formed from pre-profiled sheets. Metal cladding can be made from corrugated, trapezoidal, or other profiled sheets, which are typically available in large panels for order or purchase. The sheets can be fastened to a wooden or metal support frame using exposed screws, rivets, or concealed fasteners.  Finally, metal cladding can be made from panels or cassettes, with interlocking flanges and made of solid or even perforated sheets. For metal cladding, the metal support frame must also be designed in a way that ensures sufficient space for thermal insulation and an air gap.

      3. Ceramic tile cladding

      There are two known types of mounted ceramic panels. Solid panels are around 1 cm thick, while hollow-core panels are around 3 cm thick. The difference is also reflected in the method of fastening:

      • Solid panels are fastened using steel hooks protruding from vertical support members which grip the four corners of the square or rectangular panels.

      • Hollow panels have vertical support members which carry horizontal mounting rails, onto which we clip the fastening profiles. The flanged design of the panels allows the fastenings to remain hidden and the horizontal joints to be invisible. Joint closure profiles are used for vertical joints.

      Thermal insulation is fitted between the support members in the case of ceramic cladding.

      4. Fibre cement slate cladding

      Small-element fibre-cement slate cladding is only 4 millimetres thick, while large-format, meter-long fibre-cement slate slabs are 8-12 millimetres thick. The panels or slabs can be fixed to vertical timber battens or metal support rails, between which a few centimetres of air gap provide thermal insulation for the wall. The fixing method can be exposed (riveted or screwed) or concealed (bonded or hooked).  

      5. Stone panel cladding

      Mounted stone cladding is typically made of standard, sawn stone panels, 3-6 centimetres thick, with open-joint installation. The stone type can vary: limestone, granite, sandstone, or even marble panels. The surface finish of the panels can also vary: For example, polished, honed, or split-faced etc.

      There are two basic types of fixing methods:

      • Point-load bracket fastening can be achieved with tongue-and-groove elements at the top and bottom.
        The head of the bracket is located in the horizontal joints, from where the pins extend into the pre-drilled holes in the stone panels.
        In certain cases, only side fastening is possible (e.g., above openings).

      • In the metal frame version, pin fasteners are applied to horizontal mounting rails supported by vertical metal support profiles.

      Thermal insulation requires a minimum air gap of 3 centimetres to be maintained between the thermal insulation batts and the back of the cladding.

      6. Cast stone cladding

      Cast stone tiles are often used as plinth claddings. The plinth cast stone panels typically start from the same strip footing as the clad wall; behind them are concealed extruded polystyrene thermal insulation, as well as vapour or waterproofing membranes. The panels are typically fixed using adhesive bonding or mechanical hangers.


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  • UNIT 5 - Types of Roof Coverings

    • Types of Roof Coverings

      COURSE 3 / MODULE 4 - CLADDINGS & COVERINGS / UNIT 5 - TYPES OF ROOF COVERINGS

    • Roof truss coverings come with varying pitches to ensure the appropriate drainage of precipitation from the roof and the protection of the structures beneath. The coverings themselves can be implemented using a variety of materials and element sizes.

      I. Traditional Coverings

      1. Bundle Coverings (Thatch)

      Ancient traditional coverings include bundle coverings made of reeds or straw, as well as the pressed straw covering. A thatched roof is constructed by tying the straw into bundles, and making a continuous braid from smaller, rolled-up bundles of the sheaves' own fibers around the battening supporting the given course. This can be made with a smooth surface or in a stepped solution; in both cases, battening placed every 30-40 centimeters is necessary. Coverings tied according to the stepped solution can be made smooth by driving up (compacting) the ends of the courses; this is called the driven thatched roof.

      When making a reed roof, the reed bundles are tied to the battening placed every 50-80 centimeters, and these are driven up row by row, moving from bottom to top.

      2. Wooden Coverings

      The small-element solution for wooden coverings is the shingle roofing. The 40-80 centimeter long shingle elements are made by splitting, typically from pine blocks. The elements are formed with a grooved joint; one long side is sharp (a feathered edge), and the other has a groove (a rebated edge). The shingles fit next to each other, creating a single-layer, scale-like covering.

      For board roofing, one-meter, 10-15 cm wide elements made of hardwood are fixed by nailing or hanging. Elements made of softwood are wider, between 20-25 cm.

      3. Slate and Tile Coverings

      Slate can be used to make a roof covering by splitting and carving the square slate tiles to form a scale covering. It is fixed to the battening by nailing. However, the most successful traditional solution is the fired clay tile covering. It is a suitable small-element solution which meets modern requirements. Clay tiles are made in varied shapes, sizes, surface appearances, and colours. Two well-known solutions are:

      • The monk-and-nun covering (widespread in the Mediterranean areas of Europe). Truncated cone-shell-shaped monk tiles and flanged flat nun tiles create vertical channels within the roof surface. The advantage of this type of covering is that it provides adequate water sealing even at a lower pitch angle.

      • The beaver-tail tile covering is another widely-used form, allowing varied roof surfaces to be created due to the covering pattern. For adequate water sealing, a double lap covering or crown covering is necessary from the 35-40 centimeter long, 18-20 centimeter wide, lugged elements. In a double lap covering, a minimum of two layers of tiles cover each other over the entire surface at any point of the roof. This requires dense batten spacing (usually around 15 centimeters), providing an overlap of 22-25 centimeters between the layers of the scale covering.

      II. Types of Modern Coverings

      1. Small-Element Coverings

      In modern practice, countless improved versions of ceramic tile coverings have been developed in recent decades. Among these, interlocking tiles are worth mentioning, which make the lateral connection of the elements more watertight. Pressed clay tiles represent a further step towards less material usage and more secure water sealing. In this case, interlocking connections can be formed all around. All these tile forms, including the traditional shapes, are also increasingly gaining ground in concrete form and are available in various colors. A special type of concrete tiles is the corrugated interlocking tile, which in appearance, evokes the monk-and-nun covering. Through the interlocking connections, modern tile coverings function as a single covering. Moreover, the necessary degree of overlap is reduced to a minimum.

      Fibre-reinforced cement coverings are another small-element covering that has 4-5 mm thick elements which form a single or double covering depending on the element shapes.

      Likewise, small-element bituminous shingle covering has a multi-layered structure with a coloured slate or basalt grit surface on glass, or plastic fabric-reinforced modified bitumen sheets.
      Its construction requires full-surface sheathing or boarding.
      The covering’s underlayment is a type of bitumen sheet.

      2. Large-Element Coverings

      Large-element coverings include tile-effect sheets, corrugated fibre cement sheets, or profiled metal sheet coverings.

      Galvanized steel tile-effect sheets, 0.5 mm thick, imitate clay tiles by varying in dimensions from single or double-course panels to large format sheets covering 6-8 square meters. A major advantage is the low dead weight; its laying is done with the help of boarding (sheathing).

      Corrugated fibre cement sheet covering is made of fibre-reinforced cement (asbestos-free slate). The 1.5-2 square meter corrugated fibre cement sheets are installed, element by element, to 2-3 wooden or steel purlins, in a grid arrangement, with 15-20 cm overlap in both directions. The sheets are generally fixed at the wave crests using fastening screws.

      The characteristic material of the profiled metal sheet coverings can be aluminium, galvanized steel, or copper, which can be formed with wave, trapezoidal, or rare-rib profiling, with variable dimensions. Sheet size can range from 1.5 square meters up to 12 square meters, with a typical width of 1 meter. The coated, coloured, or material-patterned sheets are arranged in a grid, and these are screwed on steel or wooden purlins.

      3. Flat-Sheet Coverings

      Flat sheets from various metals can form a cohesive covering system with other flashings and gutters. Materials can be galvanized iron, galvanized steel sheets, aluminium, or copper sheets, similar to the roof's other flashings. Flat-sheet coverings require boarding in all circumstances, laid closed (tightly butted) or with gaps (spaced sheathing). Particular attention must be paid to ventilation; thus it must be designed as a two-layer (cold) roof in all cases. For non-absorbent, closed substrates, it is necessary to lay a ventilated underlay mat. The sheets or strips are connected watertight to each other using standing seam systems, either double-lock or single lock seams, or batten roll joints.


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  • UNIT 6 - Installation Of A Roof Covering

    • Installation Of A Roof Construction

      COURSE 3 / MODULE 4 - CLADDINGS & COVERINGS / UNIT 6 - INSTALLATION OF A ROOF CONSTRUCTION

    • A general rule in modern roof covering practice is that beyond the primary layer of covering, there is a secondary line of defence. This is the underlayment, which may consist of roofing membrane and waterproofing sheets, though roofing membrane is the more common solution. The roofing membrane is laid from meter-wide rolls directly over the rafters, with a 20-centimeter overlap, progressing from bottom to top. This membrane ensures that if precipitation penetrates the primary covering due to extreme weather conditions or cover damage, the underlayment directs the water away from the structure. The membrane is secured to the rafters by nailing counter-battens over it. The roofing battens or decking, onto which the final covering will be placed, are then attached to the counter-battens. The free airspace (cavity) created between the counter-battens plays an important role; allowing the area between the primary covering and the underlayment to be ventilated. The benefit of this ventilation is twofold: it serves to dry out water that has penetrated from the outside and moisture that has condensed from the interior space, and provides thermal protection against the overheating of the structure and the interior space.

      It is also important to consider the vapour permeability of the roofing membrane. Based on this property, we differentiate between vapour-permeable and vapour-barrier membranes.

      • For simple attics or undeveloped roof spaces, a vapour-permeable membrane can be used, led over the ridge. This allows the vapour generated in the attic space to diffuse through the membrane into the ventilated cavity. This configuration is called a singly ventilated roof system.

      • If a vapour-barrier membrane is used, the membrane must be interrupted near the ridge, and a strip of membrane must be led over the ridge and secured to the upper side of the counter-battens with a 10-15 cm overlap onto the lower membrane layer. This configuration provides additional ventilation for the interior space. This is the model of a doubly ventilated roof.

      For modern inhabited attics or converted roof spaces, only the simpler, singly ventilated version with a vapour-permeable membrane is used. Here, we can choose to completely fill the available space between the rafters with fibrous thermal insulation, which is essential for the thermal protection of the interior space. We must also ensure that the thermal insulation between the rafters is protected from the vapour of the interior space; thus, a vapour-barrier membrane is necessary on the interior side, typically in the layer beneath the plasterboard lining.

      Another essential element of modern roof coverings is professionally-executed flashing at critical points for the roof covering, such as:

      • Valleys

      • Verges

      • Around roof structures, skylights, and chimneys

      • Along the eaves

      • Along wall junctions

      A further key task at the eaves is to collect  runoff water in the gutter and direct it away using a downpipe. Gutters and downpipes can be made of zinc sheeting, galvanized steel sheeting, aluminium, or copper sheeting. The flanged sheets of the semi-circular or square-profile gutter are attached to the rafters with gutter brackets. From the gutter, collected precipitation flows to the downpipe through outlet connectors, from which a swan neck is formed beneath the eaves and secured to the wall with clamps and threaded rods. Finally, the underside of the eaves must be enclosed, typically achieved using boarding, tongue-and-groove paneling, or boxing in the eaves.

      Installation of small-element coverings:

      1. Create space for the eave boarding at the ends of the rafters;

      2. Install the eave-line boarding and verge flashing (gable boarding);

      3. Install the underlayment by layering roofing membrane and securing it with counter-battens, creating ventilation near the ridge.

      4. Secure the eave board and roofing battens;

      5. Install the guttering with gutter brackets, at a 2.5-3% slope, assemble the gutter downpipes, form the swan necks.

      6. Form the verge flashings and penetrations;

      7. Place and secure the tiles. Ventilating tiles are placed near the ridge, and ridge tiles are fixed on the ridge.

      8. Position the ridge battens with ridge batten brackets.

      9. Lay the ridge underlays and secure the ridge tiles.


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