Although a flat roof has a sleek and contemporary appearance, it also presents certain difficulties, particularly in selecting the correct materials and making sure there is enough coverage. In contrast to sloped roofs, flat roofs require extra care to avoid leaks and water buildup.
This post will discuss several materials that can be used to cover a flat roof, ranging from more contemporary materials like EPDM rubber to more conventional ones like bitumen. Every material has advantages and disadvantages, so it’s critical to select one based on your needs for durability, climate, and affordability.
We’ll also talk about coatings, which are essential to prolonging the life of your roof. For your flat roof to continue being dependable and waterproof for many years to come, proper installation can make all the difference. Knowing these fundamentals will help you make an informed choice, regardless of whether you’re a do-it-yourself enthusiast or intend to hire a professional.
Effectively covering a flat roof necessitates selecting the appropriate materials and being aware of the installation procedure in order to guarantee weather resistance and durability. Bitumen, EPDM rubber, and PVC are just a few of the options available; their costs, lifespans, and maintenance requirements vary. Knowing these materials and how to apply them will help you make an educated choice to keep leaks and damage out of your house.
- Requirements for roofing
- Laying methods
- Welded
- Self-adhesive
- Self-leveling and spraying
- Kinds
- Bitumen rolls
- Polymer membranes
- Liquid and coating mastics
- What is better to choose for outbuildings and a private house??
- How to cover a roof?
- Welded roll
- Mastic
- Profiled sheeting
- Video on the topic
- Alternative to built-up roofing. Flat roof covering
- Flat roof installation: connection arrangement
- Fused roofing. Should I remove the old coating or not??
- HOW TO COVER A FLAT ROOF WITH YOUR HANDS + WITHOUT fire + WITHOUT fasteners!
- Flat Roofing from DSP. Construction and Installation of a Flat Roof.
Requirements for roofing
The outside layer of these structures’ pie should:
- Be as airtight as possible (ideally seamless) and resistant to atmospheric and external influences, including UV radiation, moisture, temperature changes and mechanical loads. The latter is especially important for exploited flat roofs, which wear out intensively due to constant mechanical influences.
- Comply with fire safety standards.
- Retain their useful properties for at least 4-5 years, better more.
Only when arranging green and exploited roofs does external attractiveness matter; in other situations, any kind of coating can be used. Apart from performance indicators, other crucial selection criteria are material cost and ease of installation technology; for do-it-yourself projects, types that don’t require specialized equipment are preferred.
Appropriate features include multi-layer composite coatings, specialized roofing membranes, and rolled, sprayed, and coating materials based on bitumen and polymers.
It is crucial to understand that conventional roofing materials (flexible tiles, ondulin, seams) that have been shown effective in covering low-slope slopes on flat roofs must be installed under a number of additional restrictions. They specifically need reinforced joint sealing, waterproofing carpet, or continuous flooring.
Combining the aforementioned materials is feasible, but it would not be financially advantageous because flexible tiles or seams on typical flat slopes don’t look nice and aren’t made to support loads for pedestrians or vehicles. Rather than being an external covering, rigid grades of corrugated sheeting are frequently used as a base.
Laying methods
Typically, roll and liquid materials are separated out of all materials appropriate for flat roofs; if needed, both types are combined. Glued, fused, and liquid-distributed materials form continuous coatings with few seams, and are currently superior to mechanical fastening systems.
Welded
After heating the lower layers to 200 °C, bitumen, polymer, and mixed roll materials are placed on bases to represent this group. Gas burners are used for heating, and worker safety is given particular consideration. The method’s main drawbacks are its limitations when handling flammable substrates; otherwise, it is praised for its simplicity, speed, and dependability.
Watch the video to learn how to construct a built-up roof using only your hands:
Self-adhesive
There are two methods for "cold" safe fixation of rolled materials: applying adhesive mastics to the panels and applying self-adhesive markings following the removal of the protective film. The second approach is thought to be more practical and efficient, while the first approach can only be used if the glue and the roll coating are completely compatible. However, self-adhesive coatings cost more for obvious reasons.
Self-leveling and spraying
While liquid compositions work best in situations where a seamless pie is required, they are not applied as a stand-alone coating on commercially exploited flat roofs.
Materials can be applied with a roller, brush, or specialized equipment—the latter of which is costly and exclusive to expert teams.
Kinds
The variety of coatings available for flat roofs is always expanding, partly due to advancements in conventional roll materials or to the blending of various coating types. Maximum moisture resistance polymer materials and bitumen lead the top sales.
Bitumen rolls
This category is exemplified by long-lasting roll coatings that are up to 30 meters long and 1 to 1.2 meters wide, and are impregnated with modified or oxidized bitumen. The following types are distinguished based on the material and structure of the base:
- Ruberoid – budget coating based on bitumen-impregnated cardboard with non-flammable mineral bedding on the outside. The advantages of this material are well known – roofing felt is cheap, airtight and easy to install. But due to their low resistance to temperature changes, coatings based on roofing felt have a limited service life (5-10 years), after which the roof must be renewed. The average price of a 1×15 m roll is 490 rubles.
- Rubemast – an improved version of roofing felt with a thicker layer of bitumen on the bottom side and a reinforced topping layer on the outside. The coating is installed hot, the durability of the fused carpet reaches 15 years. Starting prices for a roll of 10 m² – 530 rubles.
- Stekloizol – durable, flexible, heat- and wear-resistant coatings, reinforced with glass cloth or fiberglass, protected on the outside with polymer films or coarse-grained non-flammable bedding. The coating is hot-fused onto flat roofs and retains useful properties for up to 20 years at a material price of 70 rubles/m².
- Euroroofing material – modern coatings impregnated with modified bitumen, characterized by increased flexibility and resistance to moisture and any external influences. But with all the advantages in comparison with conventional brands, euroroofing material costs 2-3 times more expensive.
Polymer membranes
Although it was a relatively new product on the market, this kind of coating for flat roofs rose to the top.
Its unique properties (durability up to 30-50 years, increased elasticity and strength, ability to remove condensate at almost 100% tightness, reinforcing and self-supporting properties) and variety of sizes (membrane width reaches 20 m, length – 60, if desired) explain this.
Diffusion soldering or mechanical installation are the two methods used for installation; many roofing membranes can tolerate being directly backfilled with gravel or other ballast.
- Rubber-based membranes, reinforced with polyester fibers and fiberglass. On sale there are both regular EPDM membranes and combined brands with a bottom layer of bitumen-polymer mixture, sold at a price of 290 rubles/m².
- PVC varieties, presented by membranes with different shades and thicknesses with a cost of 280 rubles/m². PVC membranes look attractive and are characterized by increased strength and resistance to stress. Maintenance-free service life reaches 20-30 years, after which the coating fades, but can maintain integrity and tightness.
- TPO membranes based on thermoplastic rubber and polypropylene with modifying additives that improve resistance to UV, aggressive environments, low temperatures and wear. This type of roofing membrane is recommended for installation in northern latitudes or under unfavorable operating conditions. Starting price – 285 rubles/m².
You can learn about the technology used to install PVC membranes on a flat roof from the following video:
Liquid and coating mastics
When laying a seamless coating, bitumen, polymer, and combined mastics are applied to substrates in liquid form and are thought to be the best choice.
Mastics are actively used in flat roof repairs and sealing, where they not only form the primary protective layer but also combine with other materials, specifically reinforcing and bulk layers. However, they are usually incompatible with roll coatings that have been hot-fused.
Elasticity, seamlessness, resistance to temperature fluctuations between -50 and +120 °C (and up to 200 °C for certain brands), strength and wear resistance (maximum when paired with reinforcing canvases), and good resistance to moisture and precipitation are some of the benefits of mastics.
The drawbacks include the comparatively low UV resistance (per convention, mastic surfaces are painted with protective coatings every two to three years or covered with gravel) and the reliance of the formed layer’s tightness on the caliber of the base and the uniformity of the mastic distribution. Thinner carpet deteriorates and leaks more quickly in certain areas.
In this group, TechnoNIKOL mastics (Eureka No. 41, Technomast No. 21, No. 33, and No. 31, AquaMast) have the best reviews. Processing costs range from 60 to 200 rubles/m², with an average consumption of 2-4 kg/m² (from 6 for multilayer systems). Buying mastic in bulk in large quantities can result in savings.
What is better to choose for outbuildings and a private house??
The decision is based on the intended use of the flat roof; there is no ideal material in terms of cost and longevity.
- There is no point in covering the surfaces of secondary buildings (for example, a garage, barn) with expensive membranes or euroroofing felt. Fused roll materials, such as roofing felt, are quite suitable for these purposes.
- When arranging the roofs of residential buildings and industrial buildings, the situation is the opposite, since the requirements for withstanding loads will be much greater. For these purposes, it is better to use modern membrane roofing or mastics.
Generally speaking, built-up bitumen or combined coatings, mechanically laid membranes, or mastics are preferred when doing tasks independently. Diffusion-connected polymer membranes triumph with an infinite budget and rising load-bearing specifications.
How to cover a roof?
No matter what kind of coating is selected, the formation, fortification, and preparation of the base come first. The surfaces are first examined for flaws, cleared of any debris and outdated, leaky layers, dried, primed, or impregnated with soil.
Note: Sometimes the base needs to be leveled, dried, heated artificially, or cleared of concrete deposits.
Welded roll
Laying requires dry, wind-free conditions with an air and base temperature of +5°; if this is not met, the burner will use more gas or the adhesion quality will suffer. Additionally:
- In addition to the standard preparation of the base before installing fused coatings, sanding of vertical adjoining areas and installation of dumbbell-shaped moldings is performed.
- Starting from the lower sections of the flat roof, the first underlayment layer is laid with a mandatory overlap of at least 15 cm on the walls. The entire roll is unrolled, the edges and the bottom layer are heated with a burner, after which the coating is pressed tightly to the base with a roller.
- The second and subsequent sheets of the first row are laid with a 10 cm overlap at the joint. Each strip is glued after checking the quality of the adhesion of the previous seam, the areas at the joint should not peel off or bubble.
- With the joint offset, the second and subsequent layers of the fused coating are installed.
Fused roll roofing is attached over existing coatings in a similar order. The preparation is the only difference: all peeling and bubbling areas are removed without hesitation, and all previous layers are thoroughly dried.
It’s important to remember that when using wooden bases, the first layer is attached in different ways and doesn’t require burning the coatings!
This article will teach you about the layout and characteristics of installing a flat roof on wooden beams.
Mastic
The process varies depending on the type of roof: the number and arrangement of layers differ for combined soft, unreinforced, and reinforced roofs. Either way, after priming and cleaning the base, work is done during dry weather. In the event that the cake has lining layers, which is the most typical design:
- Areas adjacent to the parapet and walk-through vertical structures are protected.
- A lining layer of rolled perforated fiberglass is laid on a flat and clean base.
- Mastic is spread over the lining in an even layer (if necessary, after heating). The composition should completely saturate the glass sheet through the holes and harden. Some manufacturers offer the opposite scheme of action, namely, applying hot mastic to the base and then covering it with rolled reinforced canvas.
- The vapor barrier layer and insulation are being installed. After this, the cake is covered with another layer of mastic and a waterproofing carpet.
The aforementioned plan isn’t applicable to all bases; for example, bitumen cardboard is used to cover board decks, which are then reinforced with wire mesh and covered with mastics and rolled materials. Alternatively, a continuous layer of bitumen-latex mastic is applied to the base, along with mineral or gravel chips, to create an unreinforced cast pie.
Generally, two layers of reinforcement or one gravel are added to the surface of at least three layers of composition when creating a mastic roof with a slope of two to ten degrees.
The manufacturer’s flow chart specifies the precise amount of time that the cake must be kept dry throughout the entire process in order for all mastic layers to fully solidify.
Profiled sheeting
This is not the best material for a finishing coat; it works better for setting up the bases of a lightweight flat roof. Installing such roofs is a straightforward technological process: vapor barrier, insulation, and roofing membranes are placed over the waves once the rigid sheets have been fixed. Disc-shaped dowels are used to secure the slabs; in certain instances, insulation pieces are also inserted into the corrugation (how to build a flat roof for a private home by hand, including the frame?).
Though manufacturers set the minimum acceptable slope at 11–12°, and less frequently at 8°, corrugated sheeting is rarely laid as an external covering. However, these instances do happen. Furthermore, corrugated sheeting works best for these uses out of all the sheet metal material types. This is because different sizes are available; a single sheet up to 12 or 13 meters long can cover a roof with a small area.
Discharged sheathing is prohibited; on flat roofs, corrugated sheeting is only fastened to solid decking by means of a sealant application at the roofing screws’ screw-in locations. With the insulation tucked away inside the pie, this design works better on wooden roofs.
It is necessary to fasten the sheathing beneath the corrugated sheet to concrete bases using anchors, but this procedure is regarded as cumbersome and is rarely used.
Material | Covering Method |
EPDM Rubber | Installed in large sheets, adhered or mechanically fastened |
TPO/PVC | Heat-welded seams, lightweight and reflective |
Modified Bitumen | Layers torch-applied or self-adhered, durable and flexible |
Built-Up Roofing (BUR) | Multiple layers of asphalt and reinforcing fabrics |
Green Roof | Vegetation planted on top with drainage and root barrier layers |
Metal Roofing | Panels or sheets installed with seams or standing seams |
Selecting the appropriate materials and being aware of installation techniques are essential when covering a flat roof in order to guarantee longevity and functionality. Rubber made of EPDM is one of the most popular options because of its durability and simplicity of installation. It is the perfect membrane for flat roofs because it is flexible and resistant to UV rays and harsh weather.
PVC membrane, which provides outstanding waterproofing and durability, is another well-liked choice. PVC roofs require little upkeep, are long-lasting, chemical-resistant, and lightweight but robust. Additionally, because they reflect light, they lower cooling expenses in warmer climates.
TPO (thermoplastic polyolefin) membranes are an option to think about if you’re looking for something greener. TPO roofing is tear-, dirt-, and puncture-resistant, recyclable, and energy-efficient. They can be an affordable choice for flat roof coverings and offer good UV resistance.
Appropriate planning and installation methods are essential when installing any type of flat roof material. Prior to applying the membrane or coating, make sure the roof is clear of debris, dry, and clean to help avoid problems later on, such as leaks or premature wear. To keep the integrity of the roof intact, edges, vents, and penetrations must all be properly sealed.
In conclusion, a flat roof’s intended lifespan, budget, and climate all play a role in selecting the appropriate material for the job. Every material type, including EPDM, PVC, TPO, and others, has special benefits in terms of maintenance, longevity, and environmental effect. Homeowners can make sure their flat roofs offer dependable protection and longevity for many years to come by choosing a trustworthy contractor and adhering to manufacturer installation guidelines.