What is bitumen mastic and how to use it

A common and adaptable material in roofing and construction is bitumen mastic. It is a viscous, thick material composed of bitumen, a naturally occurring petroleum product that is either dark brown or black in color. Because bitumen mastic has waterproofing qualities, it is highly valued for sealing and guarding against water damage to roofs.

Bitumen mastic sticks well to concrete, metal, and wood surfaces, creating a flexible, long-lasting barrier when applied. It can effectively seal gaps and cracks, stopping leaks and prolonging the life of roofs and other structures.

The process of using bitumen mastic is simple. Usually, a trowel or brush is used for application, which enables accurate placement and even covering. To guarantee good adhesion, surfaces should be dry and clean before application. Bitumen mastic needs time to cure after application in order to fully achieve its waterproofing properties.

Bitumen Mastic How to Use It
Bitumen mastic is a thick, sticky substance made from bitumen, a petroleum product. To use bitumen mastic, clean the surface thoroughly, apply the mastic with a trowel or brush, ensuring a thick and even coat. Allow it to dry completely for effective sealing and waterproofing.

What is bitumen mastic

Bitumen that has been oxidized is the primary ingredient in bitumen mastic. Solvents such as toluene, white spiteen, and solvent are added to bitumen to make it liquid. Volatile solvents rapidly evaporate after application, causing the bitumen coating to freeze. Other ingredients are added to bitumen mastic because it is difficult to use the mixture with just a solvent:

  1. For hardness and heat resistance: dust asbestos, ash, finely dispersed powders of brick, quartz, dolomite, talc, limestone.
  2. For density: chalk, ground asbestos, peat crumbs. Work with bitumen mastic with such fillers is facilitated. When applying, the composition retains its shape better and does not spread so much that it allows you to remove the coating on an uneven surface into the plane.
  3. For reinforcement and resistance to bends: mineral wool threads, fiberglass, fiber asbestos.

The thickener for bitumen mastic is added right before use in two-component mixtures. If the containers were sealed, two-component compositions can be used and stored for several months after opening. The thickener is poured into the base and thoroughly mixed before bitumen mastic is applied. A uniform fluid solution is necessary to ensure that the bitumen coating lasts as long as possible.

Cold and hot bitumen mastic

Since the mastic does not require heating prior to use, it is referred to as cold mastic after being brought into a liquid state using solvents. Naturally, that is, provided the mercury does not drop below +5 °C.

Using a cold-type mastic has the following benefits:

  1. Safety. There is no heating, which means that there is no risk of burns or the occurrence of a fire in case of violation.
  2. Plastic. Cold bitumen mastics are used to fill in deformation seams, because even after solidification they remain elastic and do not crack when squeezing.
  3. Convenience. Before applying a cold -type bitumen mastic, it just needs to be mixed well. Maximum – add the thickener if it is two -component. In addition, it is easier to apply it than a warm -up and quickly cool bitumen.
  4. Durability. As an non -valid material, cold mastic serves for a long time. Especially if polymer additives are added to it. But more on that later.

While cold mastic is actually the norm in contemporary construction, hot compositions are occasionally employed. Naturally, over time, a lot of fillers and additives are added to bitumen to create a waterproofing coating that is resistant to temperature fluctuations and mechanical damage. However, since none of these fillers contain solvents, hot-type bitumen mastic needs to be heated to between 150 and 180 degrees Celsius before using.

Because they can cause severe burns and quickly thicken after being removed from the fire, hot mastics are extremely uncomfortable and dangerous to use. However, they do have some benefits:

  1. There is no shrinkage. With the evaporation of solvents, the volume of cold mastic is greatly reduced. There are no solvents in hot bitumen mastic, so after solidification the volume remains the same.
  2. Dense structure without pores. Again, there are no solvents-there are no pores that appear during the evaporation of volatile substances.
  3. Fast hardening. After laying, a layer of hot mastic completely freezes very quickly. Therefore, the use of hot bitumen mastic is optimal in cases where there are only a few hours to structuring the waterproofing layer, and not the due day. For example, when repairing a roof in rainy periods.

Hot bitumen mastic is not used for large-scale waterproofing of roofs because of its quick hardening.

What is bitumen mastic for

Let’s talk about the application of bitumen mastic. This all-purpose waterproofing substance is utilized throughout the building process, from erecting a temporary fence to roofing materials. Bitumen mastic can serve four purposes in roofing:

  1. Waterproofing layer When installing a flat roof. The use of bitumen mastic for waterproofing is a classic construction. If the bitumen coating is the final layer of the roof pie, it is sprinkled with mineral crumbs to protect against ultraviolet rays.
  2. Glue When laying bituminous roofing materials: roller roof, flexible tiles.
  3. Filler for deformation seams when pouring cement screed on the operated flat roof.
  4. Sealant For repair work on a roof of bitumen materials.

The task determines which kind of mastic is used.

Types of cold bitumen mastic for roofs

Four different kinds of cold mastics are used to waterproof the roof:

  1. Unmodified mastic. The simplest and cheapest type of bitumen mastic, which is usually used to repair old roofs or as an additional latch for a melted roof.
  2. Bitumen-polymer mastic. For the roof, most often, just such a mastic is used. Due to polymer additives, the mastic is elastic, durable, very resistant to cracking and temperature changes. And she also has excellent adhesion to a concrete base.
  3. Bitumen-teddy or rubber-knitted mastic. The addition of synthetic rubber makes the mastic even more plastic and durable, even compared to the compositions with polymer additives. The best bitumen-fan mastic is suitable for filling the deformation seams and for the installation of a mastic roof.
  4. Bitumen-Latex mastic. Flexible and elastic two -component mastic with exceptional waterproofing properties – withstands water pressure more than 1 MPa.

Certain manufacturers incorporate materials into their mastic to increase its resistance to ultraviolet light. However, this does not preclude the use of sand or mineral sprinkling to protect the mastic roof. The parts of the mastic roof that were, for whatever reason, exposed to direct sunlight are only marginally longer lasting thanks to the UV stabilizer. For instance, because the wind had blown them away from them.

How to distinguish high -quality bitumen mastic from non -infected material

Poor -quality bitumen mastic is much more common in the market than I would like. This is due to a specific appearance and origin – many oil products are visually similar to each other. Therefore, unscrupulous manufacturers can give out a composition similar to it for the bitumen mastic, which, as a rule, is made from "dirty bitumen". There are often fuel oil, bundron and even very toxic creosot in the composition of such a “mastic”. The waterproofing properties of such a mixture leave much to be desired, not to mention direct harm to health at least for a person who will work with the material. And possibly – and for all residents of the house.

Bitumen mastic of questionable caliber Three indicators will let you know:

  1. Very low price. The price of high -quality waterproofing mastic – from 2000 rubles per bucket of 20 kg. Sometimes at a discount you can find offers for 1,500 rubles. Low-quality bitumen mastics is multiplying cheaper: 500-800 rubles, sometimes even 300-400 rubles per bucket of 18-20 kg.
  2. Heterogeneity. High -quality bitumen mastic is a viscous liquid with a silk shine. If the mixture is made of "dirty bitumen", then it will be a lumpy, divided into fractions and, as a rule, with dark gray shades in color.
  3. A sharp specific smell. The most difficult criterion that can use those who know how ordinary bitumen mastic smells. Gudronova, especially with creosote, the smell is much smaller.

These indications should all raise an alarm. But even if you purchased pricey, branded mastic, beware of fakes. Thus, make sure to print a bucket and inspect its contents prior to using a bitumen mastic. It is best to purchase mastic from a different manufacturer and seller if the mixture smells or looks suspicious. Avoid using the mixture for waterproofing.

How to work with mastic of bitumen

Now that you have premium bitumen mastic, how should you apply it to waterproof your roof? It depends on the assignment. However, there are a few key problems that need to be resolved before we can begin describing the work in phases.

Heat or not?

Everything is obvious when it comes to hot bitumen mastic—it needs to be heated before use. How about the cold?

It is thought that bitumen mastic can be used right away if it was kept at a temperature higher than 5 °C. Manufacturers advise bringing a bucket of bitumen mastic into a warm room the day before using it in colder climates. ideal when the interior temperature is around 20 °C.

In actuality, it is preferable to move mastic to a space with such a temperature of air regardless of the weather. Because heat is just as harmful as cold. For instance, bitumen mastic can peacefully warm up to 40 ° C or higher in the afternoon if it is kept in a warehouse during a hot summer. Although the material itself is unaffected, working with it becomes more challenging because of the mastic’s increased surface dispersion and quicker structure due to the solvents’ accelerated evaporation.

What is the mastic

The application of the composition uses various tools depending on the type of bitumen mastic and tasks:

  1. Valik, a macquito brush or soft natural brush Apply liquid mastic. Such compositions are well suited for covering walls, chimneys, anti -aircraft lamps and other roof objects for their sealing. Even from liquid bitumen mastic, an excellent basic coating for other roofing materials is obtained.
  2. Pouring Using a hard brush on a handle, trowel. This application method is also used for liquid mastic. After pouring, the mixture is thoroughly leveled. But before applying a bitumen mastic, you need to remove strong irregularities on the roof, otherwise the coating will turn out to be very uneven thickness.
  3. Spatula or Kelma Apply pasty compositions. In particular, for attaching ramps and lining carpets of soft tiles. In this case, the mixture must be smeared with a very thin layer – no more than 1 mm. A good spatula for repair work, sealing with bitumen mastic of the passage of pipes through the roofing.
  4. A free spray, which gives pressure at least 150 bar. The fastest way to apply for liquid mastics, but it needs professional equipment and appropriate skills.

A separate discussion is warranted regarding the application of bitumen mastic for sealing deformation seams. If you use hot mastic, you just pour it into the opening. Pour cold material multiple times into a deformed seam to account for shrinkage. Additionally, a few hours is sufficient to allow the mastic to shrink slightly but not entirely dry out. Consequently, every layer that comes after sticks to the one before it nicely.

An even simpler method involves releasing pre-made plastic tape from bitumen mastic to style a deformation seam. It just needs to be pushed firmly into the opening; it will then spread out and eventually fill the entire area.

Is it possible to dilute bitumen mastic, and that for this it is better to use

Undesirable, but you can if need be. The truth is that the manufacturer meticulously chooses the bitumen mastic’s density and consistency for particular applications. It will be more difficult to complete these tasks if you reduce its density. However, it can also be used for other purposes; typically, the mixture is diluted for this use.

In other words, if the bitumen mastic thickened from excessive storage, you should dilute it before using it. Otherwise, this step is not necessary.

First off, mastic’s properties can be altered by any dilution. The coating may crack as a result of it being overly fluid and drying either too quickly or too slowly.

Second, mastic is not a metal tile or brick, which do not actually have an expiration date. This is a multi-component mixture with interactions between dozens of active ingredients. The period of time this mixture is guaranteed to retain its properties is called the expiration date. Not even the manufacturer will know what will happen to the mastic after. Although it can form an equally strong, long-lasting, and moisture-resistant coating, it can break down in a matter of months. Is such unpredictability necessary when building a house’s roof? This is a rhetorical question.

It’s acceptable to use the mastic left over from previous projects, for example, as a primer. In actuality, the primer is essentially the same bitumen mastic—it’sjustapplied thinly and is extremely liquid. Mastic can be diluted with kerosene, gasoline, solvent, or white spirit. Diesel fuel is not allowed to be used because it will damage the material.

Remember to put on your respirator, glasses, and gloves before handling bitumen mastic. You must heat the bucket—ideally in a water bath—in order to dilute it with mastic. Heating mastic over an open flame is prohibited since it poses a risk to life. Keep in mind that the solvents you will be adding to the mastic mixture are extremely flammable and volatile materials.

The proper amount of solvent must be added gradually to the heated mass while being stirred continuously. Using a drill with a mixer nozzle is preferable. Before using, diluted mastic has to be allowed to come to room temperature.

How to use bitumen mastic to waterproofing roof

There are seven steps involved in creating the finished roofing from the bitumen mastic:

  1. The roof is thoroughly aligned: cracks, pits and other irregularities are closed, especially those with sharp edges – in these places a mastic coating can simply burst. Are waiting for the complete drying of the solution.
  2. Clean the surface of the roof and drain it. The garbage is removed with a conventional broom, to completely use a special industrial vacuum cleaner for diluting. Alternative – rinsing the roof with a stream of pure water under pressure.
  3. Dried clean roof is covered with a primer in two layers. The second layer is applied only after the first. This is necessary to increase adhesion (clutch) of bitumen mastic to the base.
  4. Before using bituminous mastic, it is mixed well to make a homogeneous mass without inclusions and stratification of the composition.
  5. Ready bitumen mastic is applied in layers. The coating should be continuous, without unlucky areas. Apply mastic in parallel stripes so that there are no drones and influxes.
  6. The first layer is given to dry-usually it takes 6-8 hours. Readiness can be verified simply: the mastic dried to the desired state will not stick to the hands.
  7. The second is applied on top of the first layer. He is also allowed to dry. The process is repeated until the overall thickness of the mastic roof will not be the desired thickness – usually 4 mm. Some manufacturers may have their own standards, so be sure to study the information on the packaging.
  8. The finished roof is sprinkled with gravel, sand and other mineral bulk substances. The main thing is that they do not have sharp edges that can damage the coating.

Bitumen mastic can only be used when it’s dry outside and at least five degrees Celsius. Neither the base nor the intermediate layers should be exposed to moisture. After applying the finish layer, mastic roof can be wetted approximately one day later. You can use fiberglass or another reinforcing material between the mastic layers to strengthen them.

How to use bitumen mastic when installing roofing materials

Apple carpets, flexible tiles, roll roofs, and lining are all adhered to with bitumen mastic. Methods for using mastic may vary depending on the manufacturer and kind of material. However, there are a few broad guidelines:

  1. Mastic is applied with a thin layer, usually about 1 mm.
  2. For a soft roof device, a special pasty bitumen mastic is used, to glue the rolls of roofing material and similar materials – liquid.
  3. When applying mastic, special attention is paid to the edges of roller materials and joints.
  4. When the junction is arranged, bitumen mastic is applied to both the roof and the wall or pipe. In this case, you need to close 30 cm of the vertical surface for reliable sealing.
  5. If the junctions of the adjacency or passing elements are not used for the arrangement of junctions, then the mastic is applied to several layers, strengthening it with fiberglass or non -woven canvas. This is necessary so that the mastic coating keeps the shape and does not "float".

The bitumen mastic that is used as an adhesive composition typically has no reinforcing fillers in it.

Roof repair with bitumen mastic

Bitumen mastic can be used not only to create new roofing coatings but also to repair old ones. Nevertheless, this is frequently a short-term fix for a season or two.

The area with leaks or damage is cleaned and completely dried before the roof is repaired. This is crucial because, frequently, water that has seeped beneath roller bitumen materials stays there for a long time and damages the coating. Additionally, the areas of the roof where the bitumen mastic will be applied need to be cleaned with a protective mineral sprinkling before the patch is adhered to.

Now let’s talk about bitumen mastic application for roof repair:

  1. A rectangle is cut out of fiberglass or roofing material, the edges of which should protrude outside the damage site by at least 15 cm. This is an internal patch.
  2. The second rectangle is cut out of the same material, which is more than the first by 10-15 cm on each side. This is an external patch.
  3. Bitumen mastic is applied to the place of damage in one layer and let it dry. The mastic layer should be of the same size as the outer patch.
  4. The inner patch is laid on top of the first layer of mastic and pressed it with a roller.
  5. The second layer is applied to the inner patch and on the first layer of mastic.
  6. An external patch is glued to the bitumen mastic and covered with another mastic layer.
  7. The finish layer of mastic is protected from UV rays with quartz or shale sand. Other mineral powders can be used, but they should not have sharp edges.

Bitumen mastic can be applied to minor roof cracks without the need for fiberglass reinforcement.

Because of its waterproofing qualities, bitumen mastic is a versatile material that is frequently used in roofing. Bitumen, a sticky black material obtained from crude oil, is used in its production. To improve its functionality, different fillers and additives are combined with it. This mixture produces a thick, surface-adhesive compound that works wonders.

Roof sealing and repair are two of bitumen mastic’s main applications. Because of its sticky nature, it can effectively fill in gaps and cracks to stop water from leaking through. It is frequently applied by roofers around vents, chimneys, and other protrusions where leaks are known to happen.

The key to using bitumen mastic is preparation. To guarantee excellent adhesion, surfaces must be dry and clean before application. Using a trowel or brush to apply it evenly will help to create a uniform layer that optimizes its protective properties.

Moreover, bitumen mastic can be strengthened by reinforcing it with polyester or fiberglass mesh. This reinforcement aids in stabilizing the mastic, particularly in regions that are prone to expansion or movement as a result of temperature fluctuations.

To sum up, bitumen mastic is a dependable roof repair and waterproofing material. Roofing professionals prefer it because of its durability, ease of application, and sealing effectiveness. Bitumen mastic is essential for maintaining the longevity and integrity of roofing systems, whether it is used for new installations or maintenance.

Bitumen mastic is a multipurpose material that is used in roofing to efficiently waterproof and seal surfaces. For durability and stability, bitumen, a viscous black material made from crude oil, is combined with fillers like sand or limestone. Bitumen mastic is a flexible barrier that can be applied hot or cold to a variety of surfaces, including concrete, metal, and wood, to protect against moisture and weather-related damage. It offers durable protection for both new construction and repairs, and roofers frequently use it to seal joints, patch leaks, or coat entire roofs. In roofing construction and maintenance, bitumen mastic is an essential tool because proper application ensures that roofs stay weatherproof and durable for a long time.

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Gleb Zuev

Exterior designer, author of books about roofing materials. I will help you make your roof not only reliable, but also beautiful.

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