Soft roofing – technology

Soft roofing represents a modern and technological type of roof covering characterized by a high degree of waterproofing, flexibility, and aesthetic diversity. The general term “soft roofing” today encompasses a whole group of materials united by a common installation principle and key components. Its installation technology differs significantly from working with traditional rigid materials such as slate, metal tiles, or corrugated sheeting, and requires special knowledge, base preparation, and the use of specific tools. The foundation for most types of soft roofs is a solid, level, and rigid base, onto which waterproofing materials are laid or glued in layers. Key advantages of this technology include the ability to cover roofs with complex architecture featuring numerous breaks, valleys, and abutments, excellent sound-absorbing characteristics, as well as low weight, reducing the load on the truss system. Historically, soft roofs have evolved from simple felt coverings to high-tech multi-layer systems with warranties lasting several decades. Today, this market segment is rapidly developing, offering solutions for both multi-story civil and industrial construction and private housing.

The development of soft roofing technology is directly linked to the improvement of materials. If in the mid-20th century the main material was roofing felt on a cardboard base with bitumen impregnation, known for its short lifespan and brittleness, modern materials use durable synthetic bases made of polyester or fiberglass, modified bitumens with polymer additives (SBS or APP), and various protective surfacings. This has dramatically increased the service life of the coatings, their resistance to temperature fluctuations, ultraviolet radiation, and mechanical damage. Installation technology has also changed: methods using open flames for torching have been replaced by methods utilizing self-adhesive layers, improving safety and simplifying work for private builders. Thus, modern soft roofing is a complex engineering system where every element, from base preparation to the finishing layer, plays a crucial role in ensuring the durability and reliability of the entire roof structure.

The scope of application for soft roofing is extremely wide. It is used for covering residential houses, cottages, multi-story buildings with flat and pitched roofs, industrial structures, shopping centers, garages, and outbuildings. It is particularly in demand for roofs with slopes ranging from 12 to 90 degrees, as well as on objects with complex geometry where the use of large-format rigid sheets is difficult or results in significant waste. The technology allows for the creation of an almost hermetic covering, which is critically important for regions with high precipitation. Furthermore, the low weight of the materials enables the reconstruction of old roofs without reinforcing the load-bearing structures. The aesthetic component also plays a significant role: the variety of cutting shapes (rectangle, hexagon, brick, dragon tooth), a rich palette of colors and textures (imitating wood, slate, stone chips) allow soft roofing to fit organically into any architectural style, from classic to high-tech.

The economic aspect of soft roofing technology also deserves attention. Despite the seemingly high cost of the material itself, the total cost of installing a roof often turns out to be comparable or even lower than when using premium types of tiles or metal. This is achieved due to less waste during cutting, the ability to use a lighter and, therefore, less expensive sheathing, as well as reduced labor costs for installation, especially in complex areas. The durability of modern soft roofing, reaching 50 years or more, provided proper installation and operation, makes it an economically viable long-term investment that does not require frequent repairs. Thus, a comprehensive analysis of the technology shows that it combines functionality, aesthetics, reliability, and economic feasibility, which explains its growing popularity in the construction market.

Classification and Types of Soft Roofing Materials

Soft roofing materials constitute a vast group that can be classified according to several key criteria: structure, form of release, type of base, type of binder, and protective coating. Based on form of release and installation method, rolled materials, flexible (bituminous) shingles, and mastic (poured) roofs are distinguished. Each of these types has its own specific application, installation technology, and performance characteristics. Rolled materials, such as euro felt, membranes, and self-adhesive waterproofing sheets, are traditionally used for flat and low-slope pitched roofs, as well as underlayment. They are supplied in rolls typically 1 meter wide and 10 to 20 meters long, allowing for quick coverage of large areas with a minimal number of seams. Modern rolled materials often have a multi-layer structure with a reinforcing base, coated on both sides with bitumen-polymer binder, and the top layer is protected by coarse mineral surfacing.

Flexible shingles, also known as bituminous or soft shingles, are the most popular material for pitched roofs in private construction. They consist of small flat sheets (shingles) with shaped cutouts along one edge, imitating the laying of natural tiles. The shingle’s base is fiberglass or polyester, impregnated and coated on both sides with modified bitumen. The lower part has a self-adhesive layer protected by a film before installation, and the front side is covered with mineral (basalt or slate) granules, which provide color, texture, and UV protection. The advantage of flexible shingles is the ability to cover roofs of the most complex shapes, minimal waste during cutting, and high decorative appeal. Mastic roofs belong to seamless technologies and represent liquid compositions based on polyurethane, acrylic, or bitumen-rubber compounds, which are applied to a prepared base by spraying, pouring, or spreading. After polymerization, they form a monolithic, elastic membrane that perfectly follows all the irregularities of the base.

No less important is the classification by the type of base, which provides the material with tensile strength and dimensional stability. Fiberglass mat is a non-woven material made from randomly arranged glass fibers bonded together. It has high tensile strength, is not susceptible to rotting, but has low elasticity. Polyester is a synthetic non-woven base made from polyester fibers, characterized by high strength and, critically, excellent elasticity and resistance to deformation. Materials based on polyester are considered higher quality and more durable, especially under conditions of significant temperature expansion of the base. Cardboard base, used in traditional roofing felt, is practically not used in modern high-class materials due to its tendency to rot and low strength. Combined bases are also present on the market, combining the advantages of different materials to achieve optimal price-to-quality characteristics.

The type of binder determines the main performance properties of the material: heat resistance, flexibility, durability. Oxidized bitumen is a traditional bitumen improved by air blowing, which raises its softening point. However, such materials remain brittle in the cold. Modified bitumens are a modern solution. The two most common types of modifiers are SBS (styrene-butadiene-styrene) and APP (atactic polypropylene). SBS-modified bitumen acquires pronounced elastic, rubber-like properties, maintaining flexibility at temperatures down to -50°C. Materials based on it are ideal for regions with harsh winters and for roofs with complex shapes. APP modification, conversely, increases the heat resistance of bitumen (up to +160°C) and UV resistance, but the material becomes more rigid. Such roofing performs well in hot, sunny climates. The protective coating on the material’s front side serves two functions: decorative and protective. Most often, this is mineral (basalt, slate) surfacing of various fractions and colors. It protects the bitumen from UV rays, mechanical damage, and gives the material color and texture. There are also materials with a coating of copper or aluminum foil, increasing durability and providing a unique appearance.

For clarity, let’s compare the key characteristics of the main types of soft roofing in a table:

Preparing the Base for Soft Roofing

The quality and durability of a soft roof depend 90% on the correct preparation of the base. Unlike rigid coverings, which can smooth out minor irregularities, soft materials exactly replicate all surface imperfections, which can lead to premature wear, sagging, and loss of watertightness. The base for a soft roof must be solid, level, dry, clean, and have sufficient rigidity. For pitched roofs, the base is a solid deck, which can be made of moisture-resistant plywood (WBP), oriented strand board (OSB-3), or tongue-and-groove edged boards. The choice of material depends on budget, climatic conditions, and base requirements. Moisture-resistant plywood is considered the most stable and high-quality option, as it has high bending strength, does not warp, and provides a perfectly level surface. Its recommended thickness is 9-12 mm for a rafter spacing of 600 mm and 12-18 mm for a spacing of 900 mm.

Oriented strand boards (OSB-3) are also widely used due to their affordable price and good performance characteristics. It is important to use specifically OSB-3 grade, intended for use in high humidity conditions. The boards are laid with a 3-5 mm gap between them to compensate for thermal expansion and are attached to the rafters with galvanized screws or ring-shank nails. The seams between the boards should not coincide with open spaces between the rafters; the board must rest on at least two supports. Tongue-and-groove edged boards are a traditional but more labor-intensive option. The boards must be dry (moisture content no more than 20%), 100-150 mm wide and 20-25 mm thick. They are laid with a gap of 1-3 mm to compensate for swelling due to moisture changes. Each element of the deck must be fixed to at least two rafters. Regardless of the material, the surface of the base must be thoroughly cleaned of dust, dirt, oil stains, and protrusions that could damage the lower layers of the roofing system.

For flat and low-slope roofs, the base is often concrete floor slabs, screeds, or profiled sheets. In this case, the critical stage is creating the correct slope for water drainage (at least 1.5-2%) and carefully leveling the surface. Irregularities exceeding 5 mm over a 2-meter length are unacceptable. A concrete base must be dry (residual moisture no more than 5%), strong, and cleaned. Often, a cement-sand screed is laid over the concrete, which is then primed with bituminous primers to improve adhesion to rolled materials. When installing roofing over insulation (e.g., extruded polystyrene foam), a screed or flat asbestos-cement sheets must be laid over it to distribute the load and create a rigid plane. An underlayment is an integral part of the base for flexible shingles and serves as additional waterproofing, protecting the deck from possible leaks and smoothing out minor irregularities. It is rolled out over the entire roof area or, depending on the slope and manufacturer’s recommendations, only in the most vulnerable places: along eaves overhangs, in valleys, around pipes and other penetrations, on the ridge and hips.

The technology for laying the underlayment requires care. In valleys (internal corners), the material is laid along the entire length, and if the roof slope is small (less than 18°), a special valley sheet is used or a regular one is laid in two layers. Along eaves overhangs, gable overhangs, and abutments to walls, the underlayment is overlapped and additionally secured. The underlayment sheets are rolled out horizontally, starting from the bottom, with a longitudinal overlap of at least 100 mm and an end overlap of at least 150 mm. Overlap areas are thoroughly glued with bitumen mastic or, if the underlayment is self-adhesive, the protective film is removed from them. The underlayment is attached to the base using roofing nails with wide heads spaced 200-250 mm apart along the edges and in a staggered pattern over the entire area. After installing the underlayment, the base is considered fully ready for laying the finishing flexible shingle covering. Neglecting this stage or performing it poorly can negate all the advantages of expensive finishing material, as it is the underlayment that takes the first blow from leaks caused by mechanical damage or strong wind-driven rain.

Installation Technology for Flexible Shingles: Step-by-Step Process

The installation of flexible shingles is a meticulous process that requires adherence to technology at every stage. Work should be carried out in dry, windless weather at an air temperature not lower than +5°C. If installation is necessary in colder conditions, the material should be kept in a warm room before laying, and the self-adhesive layer and mastic should be warmed with a construction heat gun. Installation begins with the installation of metal eaves and gable drip edges (drip edges). The eaves drip edge, usually made of galvanized steel with a polymer coating, is installed on top of the underlayment along the eaves overhangs. It protects the deck from moisture running off the roof and gives the edge a finished look. The drip edge is fastened with roofing nails spaced 100-150 mm apart in a staggered pattern. Gable drip edges are installed similarly on the end (gable) edges of the roof to protect the deck from wind and rain.

The next stage is the installation of the starter (eaves) course. For this, special eaves/ridge shingles are often used, or regular shingles are trimmed by removing the tabs. The starter shingles are laid along the overhang, end-to-end, stepping back 10-20 mm from the bend of the eaves drip edge. They are fastened with nails across the entire width, and the joints are additionally coated with bitumen mastic. After this, the installation of the regular shingles begins. Installation starts from the center of the slope towards the ends, which ensures pattern symmetry. The first row is laid so that its lower edge is 10-20 mm above the lower edge of the starter course, and the “tabs” overlap the joints of the starter shingles. Each regular shingle is fastened with 4-6 nails (depending on the region’s wind load) in the places specially marked by the manufacturer – usually above the tab slots. The nails must be galvanized, with wide heads, and driven strictly perpendicular to the plane so that the head does not damage the shingle’s top layer but also does not protrude above it.

Subsequent rows are laid with an offset so that the joints of the tabs do not coincide. The offset amount depends on the shingle pattern (usually half or a third of a tab). A key technological nuance is the use of the self-adhesive layer. Before laying, the protective polyethylene film is removed from the lower part of each shingle. Under the influence of solar heat, the bitumen adhesive melts and permanently fuses the shingles together, creating a monolithic covering. This is why a slight smell of bitumen may be noticeable on the roof for the first few weeks after installation. Special attention is required for complex roof elements: valleys, hips, ridges, and abutments. In valleys (internal corners), it is recommended to use a special valley sheet of a contrasting or matching color. It is laid over the underlayment and has high strength characteristics. The edges of the shingles approaching the valley do not reach its axis by 50-100 mm, are trimmed in place, and carefully glued with mastic with a minimum overlap of 150-200 mm.

The ridge and hips of the roof are finished using special ridge/cap shingles or by cutting regular shingles into three pieces. The elements are laid overlapping in the direction of the prevailing winds and fastened with nails on each side. Abutments to vertical walls, chimneys, and ventilation shafts are made using metal flashing and sealants. At the junction, a triangular batten is installed on the wall and roof, then an underlayment is laid with an overlap onto the vertical surface of at least 300 mm. A metal flashing is mounted on top, which is fastened to the wall, and its upper edge is sealed with silicone or thiokol sealant. The shingle is brought onto the flashing and also glued with mastic. After installation is complete, it is necessary to remove any protective grit (if present on the self-adhesive layer) from the surface and check the quality of adhesion at all critical points. A properly installed flexible shingle forms a continuous, elastic, and watertight sheet capable of withstanding significant thermal deformation, heavy rain, and strong gusts of wind.

Installation Technology for Rolled Soft Roofs

The installation technology for rolled roofing, used primarily on flat and low-slope roofs, has its own specifics and is divided into two main methods: torch-applied and mechanical (ballasted, using mastics or special fasteners). The torch-applied method is the most common in Russia and the CIS for new and repaired roofs. It involves using gas burners to heat the lower bitumen-polymer layer of the roll and subsequently glue it to the base. Work begins with thorough surface preparation: cleaning, leveling, priming with a bitumen primer for dust removal and improved adhesion. The primer is applied with a roller or brush and left to dry completely (loss of tackiness). Rolls are delivered to the roof and unrolled for acclimatization and straightening.

Torch-applied roofing is usually laid in two or three layers, depending on the project and roof slope. The lower layers can be made of material with fine or granular surfacing, the top (finish) layer – necessarily with coarse or flake surfacing for UV protection. Installation starts from the lowest areas of the roof, near the water drains. The first sheet is unrolled, carefully aligned. Then one edge (usually 100-150 mm wide) is fixed by heating it with a burner and pressing it to the base. Next, the roll is gradually rolled back towards the start, simultaneously heating both the sheet itself and the base underneath it with the burner. The heating zone should be directly in front of the roller, which is used to forcefully roll over the already glued section, ensuring tight adhesion without air bubbles. The optimal heating temperature is determined by the appearance of a slight sheen and a thin film on the bitumen surface; overheating (charring, blackening) is unacceptable.

Subsequent sheets are laid with an overlap: longitudinal (side) 80-100 mm and transverse (end) at least 150 mm. When installing a multi-layer coating, the seams between sheets in different layers must be offset by at least 300 mm so they do not coincide. Particular care is taken to seal abutments to parapets, pipes, and ventilation shafts. Here, the material is brought onto the vertical surface to a height of at least 250-300 mm, additionally reinforced, and covered with clamping metal flashing. Internal corners (junctions) are reinforced with additional layers of material, cut and glued as inserts. The mechanical (ballasted) method is more often used for roofs with a slope of up to 10°. It involves freely laying a roll membrane (most often PVC, TPO, or EPDM) on a prepared base with subsequent fixation along the perimeter, at abutments, and along seams. The main area of the membrane is weighted down with ballast: gravel, paving slabs, or soil with vegetation (in the case of a green roof). Seams between sheets are welded with hot air using a special apparatus, creating a strong, hermetic connection.

Another method is adhesive, where the material is glued to the base with cold or hot bitumen mastics. This method is less fire hazardous than torching and is suitable for bases where open flame cannot be used (wooden, steel). The mastic is applied to the base with a trowel or roller, after which the roll is unrolled and rolled with a roller. The quality of the rolled roof installation is controlled visually (absence of blisters, poorly welded seams) and by tapping (the sound should be uniform, without dull areas indicating delamination). The final stage is the installation of the final protective layer, if provided (application of reflective paint on bitumen roofs, installation of tiles on a ballasted system). A properly installed rolled roof serves as a reliable waterproofing barrier for many years, requiring only periodic inspection and minor repairs.

Installation of Abutments, Valleys, and Other Complex Details

The reliability of a soft roof is determined not so much by the quality of installation on the slope planes, but by the correct execution of complex details: abutments to vertical surfaces, valleys, eaves, ridges, and penetration points for utilities. These elements are the most vulnerable to leaks, as they experience the greatest loads from water runoff, snow accumulation, and thermal deformation. The structural solution for each detail must ensure the continuity of the waterproofing sheet and moisture drainage. Let’s start with the eaves detail. The main task here is to organize the unobstructed drainage of water from the waterproofing sheet into the gutter system and to protect the wooden elements of the deck and fascia board from getting wet. For this, eaves drip edges are used, installed on top of the underlayment. Under it, on the very edge of the eaves overhang, a drip edge for collecting condensation from the under-roof space is often installed. It is important that the underlayment and finishing shingle overlap the eaves drip edge, and that the gutter is installed with the correct slope and securely fastened.

The gable (end) detail protects the roof edge from being lifted by the wind and from rainwater being driven under the covering during sideways rain. The gable drip edge is mounted on top of the underlayment at the ends of the slopes. The edges of the flexible shingles that reach the end are carefully trimmed at a distance of 10-15 mm from the edge of the drip edge and thoroughly glued with bitumen mastic. This creates a watertight and mechanically strong edge. The valley (internal corner) detail is one of the most critical. Here, water flow from two adjacent slopes converges, so waterproofing must be reinforced. There are two main methods for installing a valley under flexible shingles: open and closed (woven). With the open method, a special valley sheet of a contrasting color is laid along the center of the valley, on top of the underlayment. Shingles from both slopes are trimmed so that a gap 50-100 mm wide remains to the valley center. The edges of the shingles along this gap are glued with mastic. With the closed method, shingles from one slope overlap the valley, and shingles from the second slope are laid on top of them, after which both layers are carefully trimmed along the valley line. Regardless of the method, the base in the valley must be solid and level.

The abutment of the roof to vertical walls and parapets requires the creation of a waterproofing apron. The technology includes several operations. At the junction of the roof plane and the wall, a wooden triangular batten is installed, creating a smooth transition (cove). An underlayment or special abutment sheet material is laid on it and on the adjacent surfaces with an overlap of at least 250-300 mm. Then, on top of the sheet, a metal flashing is installed (one of its edges is fastened to the wall with dowels, the other lies on the roof). The upper edge of the flashing is sealed with polyurethane or silicone sealant, and the lower part is covered from above by the finishing roofing material, which is brought onto the flashing and glued with mastic. Similarly, but using special penetration elements (roof jacks), abutments around chimney pipes, ventilation outlets, and antennas are arranged. These elements are metal or polymer flanges with a rubber or silicone gasket that tightens around the pipe. The flange base is integrated into the roofing sheet.

The ridge detail serves to ventilate the under-roof space, which is a mandatory condition for the durability of the wooden structure and preventing ice formation on the eaves. Ventilation is carried out through a gap that remains under the ridge elements. Before installing the ridge, the shingle is cut along both sides of it so that a groove about 150 mm wide is formed. The ridge itself is finished with special ridge/cap shingles or elements cut from regular shingles. They are laid overlapping in the direction of the prevailing winds and fastened with nails. It is important that the nails of each subsequent element overlap the fastening point of the previous one. Air passes freely through the ridge elements, drawing moisture out of the insulation and wooden structures. Thus, careful and technologically correct elaboration of each complex detail, taking into account manufacturer recommendations and building codes, is the key to absolute watertightness and many years of trouble-free service for a soft roof under any weather conditions.

Ventilation of the Under-Roof Space and Thermal Insulation

Effective ventilation of the under-roof space is a critically important element of soft roofing technology, without which it is impossible to ensure the durability of both the roofing structure itself and the entire building. The main task of ventilation is to remove excess moisture that inevitably accumulates under the roofing covering. Sources of moisture include: diffusion of water vapor from interior spaces through ceilings and insulation, residual moisture in building materials, and possible minor leaks. Without constant air exchange, this moisture condenses on cold surfaces (deck, metal fasteners, underside of the roofing material), leading to rotting of wooden structures, corrosion, wetting and loss of insulation effectiveness, and in winter – to the formation of ice jams and icicles on the eaves.

The ventilation system for a pitched roof under a soft covering is an organized airflow from the eaves overhangs to the ridge. Fresh air intake occurs through ventilation openings in the eaves soffits. These openings can be made in the form of perforation in soffit panels, special ventilation grilles, or slot gaps. It is important that the total area of intake openings complies with regulations (usually at least 200 sq.cm per 100 sq.m of roof projection). Air entering under the roof moves upward through a ventilation gap, which must be provided between the thermal insulation and the base under the roofing. The size of this gap should be at least 50 mm. To ensure it, either counter-battens (50×50 mm battens) are mounted on top of the rafters after laying the insulation and waterproofing membrane, or special ventilation boxes are used. Exhaust of moist air occurs through ridge or point (pitched) roof vents, as well as through gaps under the ridge elements of flexible shingles. A ridge vent is a continuous plastic part with perforation, installed along the entire ridge and covered from above with ridge shingles.

Thermal insulation, in combination with a soft roof, serves not only to retain heat in the house but also to protect the attic or mansard space from overheating in summer. The choice of insulation and its installation technology depend on the type of room under the roof (cold attic or heated living space). For a cold attic, the slope is not insulated; instead, the ceiling of the top floor is insulated. In this case, ventilation of the attic space itself must be intensive; dormer windows or ventilation grilles in the gables are often provided. If a living space is set up under the roof, insulation is placed directly between the rafters. The material most often used is mineral (basalt) wool, less often extruded polystyrene foam or polyurethane foam. Mineral wool is preferable due to its non-combustibility, vapor permeability, and excellent thermal insulation properties. The insulation boards should fit tightly, without gaps, between the rafters, but should not be compressed, as this worsens their properties.

On top of the rafters, directly on the insulation, a special hydro-windproof vapor-permeable membrane is laid. This is a key element of the “pie” that protects the insulation from fiber blow-out and possible moisture ingress from the outside, while allowing internal vapor to escape freely. The membrane is rolled out horizontally with an overlap of sheets of 100-150 mm, starting from the lower part of the slope. It is fastened to the rafters with a construction stapler. Overlap areas must be taped with special tape to ensure airtightness. Counter-battens are nailed on top of the membrane, creating the necessary ventilation gap, and then the solid base for the soft roofing. The vapor barrier layer, on the contrary, is installed on the inner side of the insulation (from the room side) and serves as a barrier against water vapor from the house. It is fastened to the rafters, and all joints are also carefully sealed with tape. Thus, a well-designed and installed “roofing pie,” including vapor barrier, insulation, ventilation gap, hydro-wind protection, and finishing coating, creates a balanced system that ensures a comfortable microclimate in the house and the maximum service life of all structural elements of the roof.

Operation, Maintenance, and Repair of Soft Roofing

Soft roofing, despite its durability, requires regular and proper maintenance to preserve its performance qualities throughout the entire manufacturer’s stated service life. Operation begins from the moment installation is completed. In the first weeks, under the influence of solar heat, the final sintering of the shingles’ self-adhesive layers and mastics occurs, forming a monolithic sheet. During this period, walking on the roof without urgent need is not recommended. Subsequently, the main tasks of maintenance are: regular inspection, cleaning of debris, monitoring the condition of safety elements and gutters, and timely elimination of minor damage. Roof inspections should be conducted at least twice a year: in early spring, after the snow melts, and in late autumn, before the onset of winter. It is better to conduct the inspection using binoculars or a drone to minimize direct impact on the covering.

During the spring inspection, attention is paid to the consequences of the winter period: checking for blisters or delamination on flat areas of rolled roofing, checking whether the surfacing and the shingles themselves of flexible shingles are damaged from falling icicles or ice, and whether valleys are deformed. Particular attention is paid to all abutments, areas around pipes, and ventilation outlets – signs of compromised watertightness most often appear here. The autumn inspection is aimed at preparing for winter: it is necessary to clean the roof and gutters of fallen leaves, pine needles, and branches, which can retain moisture and impede normal water drainage. Clogged gutters in winter lead to ice formation on the eaves and increased load on the roofing system. The fastening of snow guards is also checked; they are a mandatory safety element on pitched roofs with flexible shingles, especially if there is a living space underneath. Snow guards prevent snow masses from sliding down in an avalanche, which is dangerous for people, property, and the gutters themselves.

Cleaning a soft roof should be done as gently as possible. Metal shovels, scrapers, or stiff brushes should not be used for this purpose, as they can damage the protective mineral surfacing and expose the bitumen layer. Fallen leaves and small debris are swept away with a soft broom or blown off with air. If it is necessary to clean moss or lichen, which may appear on roofs in shaded, damp places, special soft roof cleaners based on oxygen-active components that do not damage the bitumen and surfacing are used. High-pressure water from a pressure washer is also contraindicated, as it can wash the granules out of the top layer. The repair technology for soft roofing depends on the type of damage and material. The most common type of repair for flexible shingles is the replacement of individual damaged shingles. To do this, the edges of the adjacent shingles are carefully pried up, the old nails are removed, and the damaged element is taken out. A new shingle is slipped into place, having previously applied bitumen mastic under its edges, and nailed, after which the edges of the adjacent shingles are also glued with mastic.

For rolled roofing, typical problems are blisters and minor leaks. Blisters form due to local delamination of the material from the base due to residual moisture or poor adhesion during installation. To repair a blister, it is cut crosswise, the flaps are folded back, the base is thoroughly dried with a construction heat gun, coated with bitumen mastic, and the flaps are glued back, placing a patch of the same material on top with an overlap over the edges of the cut of at least 100 mm. Leaks at seams are eliminated by re-torching these areas with a gas burner or gluing with special butyl rubber-based tapes. In case of serious damage or natural aging of the material (appearance of numerous cracks, massive loss of granules), a major repair is carried out, which consists of installing a new layer of rolled material over the old covering or completely replacing the roofing sheet. Timely and high-quality execution of even minor repairs prevents the development of damage and significantly extends the life of the entire roofing system, protecting the building from more serious and costly problems associated with leaks.

Comparative Analysis with Other Types of Roofing Coverings

To fully reveal the technological and operational aspects of soft roofing, it is necessary to conduct an objective comparison with other common types of coverings: metal tiles, natural tiles, corrugated sheets, and standing seam metal roofing. Each of these materials occupies its niche in the market, and the choice depends on many factors: building architecture, budget, climatic conditions, requirements for durability and aesthetics. Soft roofing, in the form of flexible shingles, has an undeniable advantage when working with complex roofs. Due to the small size of the shingles and their flexibility, it allows for covering domes, towers, curved surfaces, and roofs with many valleys, hips, and abutments with minimal waste. While metal tiles and corrugated sheets, being large-sheet materials, generate a huge amount of waste on such objects, and their installation requires high skill to seal numerous joints.

Sound absorption is another critical parameter for living comfort, especially in mansard floors. Soft roofing, consisting of multi-layer bitumen-based materials, effectively dampens the sound of falling rain, hail, or wind. In this aspect, it outperforms all types of metal roofs, which, despite the use of sound-absorbing underlayments, remain quite “loud” during heavy rain. Natural ceramic or cement-sand tiles also have good acoustic properties, but their enormous weight (40-60 kg/sq.m) requires a powerful, and therefore more expensive, truss system and foundation. The weight of flexible shingles is only 8-12 kg/sq.m, which is comparable to metal tiles and significantly lower than natural analogues. This allows for savings on load-bearing structures and often enables the use of the roofing for reconstructing old buildings without strengthening them.

In terms of watertightness, soft roofing, forming a continuous sheet without through holes (nail fastening occurs in the overlap and is covered by upper rows), has a minimal risk of leaks through the slope plane. The main risks are concentrated in abutment details, which, however, are carefully designed. Standing seam roofing, although very reliable, has many transverse and longitudinal seams, the quality of sealing of which depends entirely on the roofer’s skill. Metal tiles are fastened with screws, which over time can lose the watertightness of their rubber gaskets, especially with poor installation. Regarding durability, modern soft roofing with polymer modifiers (50+ years) is comparable to natural tiles (100+ years) and significantly surpasses metal coatings without a polymer layer (20-30 years), which are susceptible to corrosion. However, it loses to metal in fire safety: bitumen materials belong to flammability groups G3-G4, while metal does not burn.

The economic component of the analysis is ambiguous. The cost of the material itself for mid-class flexible shingles is comparable to high-quality metal tiles and significantly lower than natural tiles. However, the total cost of a soft shingle roof must include the cost of solid decking, underlayment, and mastics, making the “square” of the finished covering in the estimate more expensive than that of metal tiles installed on spaced battens. But on complex roofs, savings on materials due to minimal waste and reduced labor costs for fitting can offset this difference. Operating costs also vary: metal roofs may require touch-up painting of scratches and replacement of gaskets, while soft roofing may require periodic cleaning and monitoring of detail watertightness. Thus, soft roofing is a technological, aesthetic, and durable choice, optimal for complex architectural forms, regions with high noise loads (rain, hail), and for projects where the lightness of the structure and a wealth of design solutions are important.

Conclusion and Development Prospects of the Technology

Soft roofing has come a long way from simple and short-lived roofing felt to high-tech, durable, and aesthetically pleasing roofing systems. Modern technology combines deep knowledge in polymer chemistry, building physics, and design, enabling the creation of coatings that last half a century or more. Key drivers of its development have been the improvement of bases (transition to polyester), modification of bitumen with polymers (SBS, APP) to impart elasticity and heat resistance, and production automation ensuring consistently high material quality. Today, soft roofing is not just waterproofing, but a comprehensive system that includes vapor and waterproofing membranes, insulation, ventilation systems, safety elements, and, of course, a finish coating with wide design possibilities.

Development prospects are seen in several directions. The first is further improvement of environmental friendliness. Developments are already underway to reduce the share of fossil bitumen, use recycled materials (recycled polymers in the base, secondary bitumen) and create fully recyclable roofing systems at the end of their life cycle. The second direction is “smart” roofing. Integrating photovoltaic elements (flexible solar shingles) into or under flexible shingles allows turning the roof into an energy source without compromising its appearance. The integration of sensors for monitoring humidity, temperature, and coating integrity, transmitting data to the owner’s smartphone, is also possible. The third direction is the improvement of performance characteristics: creating materials with an even wider operating temperature range (e.g., for arctic conditions), with increased resistance to biological damage (moss, lichen) and to UV radiation for color retention.

The growing popularity of green (vegetated) roofs also stimulates the development of soft waterproofing technologies that serve as the basis for such systems. Requirements for root resistance, mechanical strength, and durability under a layer of soil and vegetation are extremely high, leading to the emergence of new types of membranes and mastics. Finally, the development of the construction industry towards industrialization and fast-track installation leads to the creation of new forms of release and installation methods. For example, the emergence of flexible shingles in the form of large-format panels on a soft base, which speeds up installation while preserving all the advantages of a piece material. In conclusion, it can be confidently stated that soft roofing technology, combining proven reliability and constant innovation, remains and will remain one of the leading solutions in the global roofing market, offering an optimal balance of price, quality, aesthetics, and durability for a wide variety of construction tasks.