ROLL ROOFING MATERIALS: TYPES OF MATERIALS, MARKET, DEVELOPMENT TRENDS

The roof is one of the most important and responsible structural elements of the building, performs protective functions and at the same time provides a certain thermal regime and comfort of the room, participates in creating the architectural appearance of the city. Such a multifunctional purpose of the roof can be fulfilled only if high quality, durable materials and modern technologies of waterproofing works are used.

Among all the variety of roofs (single-piece, mastic, roll, metal, etc.), roll roofs are the most widespread, as they have obvious advantages.  As a rule, these include: control of material consumption (thickness, width is set by the manufacturer at the factory) and labor costs, speed and year-round range of installation work, environmental friendliness and safety, mechanical and deformation resistance.  As for disadvantages, these are: the number of joints and operations to be made.

Historically, roll roofing materials based on bituminous binders are most widespread in Russia [1].  They are easy to manufacture, cheap and create a layer with a guaranteed thickness regardless of the production conditions and the state of the insulated surface.

The first roll roofing materials based on bituminous binders were roofing felt, paper roof covering and their analogues.  However, such materials had a significant drawback – low durability (from 1 to 57 years).  The reason for the decline in performance over time is the low strength and low water resistance of the roofing board, aging and increased fragility of bitumen, lack of stability of the rheological properties of the structural coating as a whole. 1998 was a turning point in the history of roofing materials – that is when the decision was made to ban using it for roof waterproofing purposes.  Design and construction organizations of the Russian Federation stopped using it.

The second generation of roofing coatings, which are widely used at present, are roll materials based on uncured bitumen-polymer and polymer binders (Table 1).  The polymer content is 812% by weight of bitumen.  This makes it possible to expand the operating temperature range by reducing the brittleness temperature and increasing the softening temperature, to increase adhesion to the base and improve adhesion in the construction of a multi-layer carpet.

A small amount of polymer serves as a modifier of the properties of bitumen.  Common polymers for these purposes are atactic polypropylene (APP) and synthetic thermoplastic elastomers, in particular styrene butadiene styrene (SBS).  Compared to conventional oxidized bitumen, bitumen modified with APP are characterized by high heat resistance, good flexibility in cold (up to 20 ° C) and high resistance to weathering.  Bitumen modified by SBS have even higher flexibility in cold conditions (up to 30 ° C), but are more sensitive to UV radiation [2].

To increase the strength and the possibility of mechanical installation, roll materials are reinforced with glass or synthetic fibers in the form of canvas fabrics, nets and non-woven fabrics, as well as by dispersed reinforcement with short lengths of fibers.  For protection from solar radiation, armor dressing is used from specially prepared and painted mineral (slate, ceramic, basalt) or plastic chips [3].

The desire to increase the service life leads to an increase in the polymer content in bitumen.

Composite binders contain up to 2025% polymer in their composition.  In regions with a warm climate, preference is given to bitumen modified with APP, due to its good resistance to UV radiation. Compositions based on bitumen and SBS have

high elasticity and are indispensable in regions with cold climates.  It is believed that SBS and bitumen are more susceptible to aging under the influence of UV radiation; therefore, protection (covering with powder, foil, or paint coating) is mandatory for such materials.

According to the latest data, polymer-bitumen materials are the leader among roofing and waterproofing materials, occupying about 45% in the world, and according to the National Roofing Union (NRU), the share of bitumen materials in the European market is more than 60% (Table 2) [4].

Year	Single-layer membranes, share%	PVC membranes, share%	Bitumen materials, share%
2008	24.6	14.9	75.4
2011	27.9	17.1	72.1
2014	29.9	18.2	70.1
2019	35.6	21.1	64.4

In Russia, according to data for 2015, bitumen and bitumen-polymer materials together occupy 82% of the market (Fig. 1) [5].

 

Figure 1.  Russian market of roll roofing materials

 

Most of the materials of the first and second generations do not meet modern requirements for reliability and durability in terms of the life cycle of buildings and structures, which leads to huge labor and material costs (Fig. 2).  In this regard, there is a clear trend towards a shift towards materials of the third generation, where the life cycles of both the material and the building itself coincide, which is confirmed by the NRU data (Fig. 3) and research carried out by the marketing agency “IndexBox Russia” (Fig. 4), where it can be seen that 47% of respondents prioritized durability over other parameters of roofing materials.

The third generation of materials, the durability of which is 3050 years, are materials based on

 

Figure 2. Estimated cost of 1 m2 of flat roofing in the calculation of the life cycle of a building in 50 years (according to LLC “Bikom”)

 

Russia	Europa
The share of polymer membranes is not growing at all. Redistribution of the market is associated with the transition from roofing material to rolled bitumen materials	The share of polymer membranes is gradually but continuously growing. Almost all growth is taken up by polymers, bitumen is stable

 

Figure 3. Russian and European market of roofing and waterproofing materials

Figure 4. Requirements for roofing materials [6]

 

extremely saturated polymers: chlorosulfonated polyethylene (CSPE), polyisobutylene (PIB), ethylene propylene rubber (EPR), butyl rubber (BR), polyvinyl chloride (PVC). The absence of double bonds in the polymer backbone provides high resistance to UV radiation, oxidation stability and increased atmospheric and ozone resistance.  The coatings retain their highly elastic properties in the range from 60 to + 100 ° C.  The nonpolarity of the polymer base also determines the high resistance to the action of polar media, including water.  Typically, the elastomers used are capable of high filling.  Elastomeric coatings are generally single-layer construction.

The main advantages of single-layer carpets over multilayer ones are that they allow you to perform roofing work all-season, reduce labor costs when installing a roof by 200-300%, reduce the mass of the roof (in accordance with SNIP, polymer roofing is allowed to be used in one layer, and bitumen-polymer – in two layers) and reduce transport costs by more than 1020 times, eliminate hot processes when installing roofs.

Elastomer-based roll roofs can be glued with uncured elastomer-based sealants such as butyl rubber and EPR.  Such mastics are compatible with the roofing material and have good adhesion to various substrates [712].

The reasons for the growth of the market of roll roofing materials in Russia and in neighboring countries:

1. Depreciation of residential buildings in the multi-apartment sector. More than 50% of multi-apartment buildings in Russia are in need of overhaul of the roof and foundations.  The existing demand was supported by the creation of capital repair funds, therefore, we can speak of an economically supported demand for roof repair and waterproofing in this segment.
2. Improving the energy efficiency of buildings. Due to the constant increase in the cost of housing and utility services for all segments of consumers, there is an increase in demand for application of energy efficient technologies and materials
   for reduction of the consumption of energy resources (heat and electricity).This assumption is supported by Russia’s transition to the use of international certification standards to confirm the energy efficiency of buildings in the residential and commercial sectors.  The most popular and effective certification systems include the following systems: Energy Star, LEED, Cool Roofing, Building Codes, Regulatory & Environmental Considerations.
3. Tightening of environmental regulations and rules of disposal.  An additional stimulus for the growth and changes in the market of roofing materials and technologies is the tightening of environmental rules and regulations for disposal (especially construction waste).  The costs of these items in the estimate should become more and more significant – to motivate the entire chain (owner – customer – performer) to optimize these processes.

Today, the main direction of development of the roll roofing materials market is to increase their service life.  It should be noted that an increase in the service life leads, among other things, to a decrease in waste during major repairs.  Tightening of environmental requirements for roofing materials is, according to the National Roofing Contractors Association of America (NRCA), one of the trends in the development of the roofing industry.

The desire for energy conservation is also relevant (for example, painting roofs in white), as well as installing solar panels on roofs, an increase in the construction of green roofs (municipal buildings should have “green” roofs).

In general, summarizing all of the above, the future lies with third generation of roll roofing materials and a planned transition to the fourth generation (smart home, smart roof, where indicators of reliability, energy efficiency, environmental friendliness, alternative energy and comfort are harmonized). The use of roofing coatings based on rubbers and TPP allows, with the use of new vulcanizing systems, if necessary, to regulate their properties in a wide range by using the principle of pre-vulcanization of rubber after coating, which is of interest from the point of view of operation.