Features of polyurethane external joint sealants

Seams and other details outside the house, located on the outer walls, need to be sealed. Special compounds based on polyurethane cope with this task better than many other sealants and even cement mortar or polyurethane foam. But this does not mean that such mixtures do not need to be chosen. On the contrary, a lot depends on making a competent decision..


Polyurethane external joint sealant effectively eliminates all kinds of cracks, splits and unnecessary gaps that often occur during construction. Even professional builders, let alone amateur builders, find it difficult to avoid defects. Polyurethane sealants are manufactured using polyester resins. The emerging material successfully challenges rubber and plastics in a number of applications. It is allowed to use polyurethane in quite different climatic conditions, even sudden temperature changes will not become a negative factor for it..

As for the disadvantages, polyurethane mixtures are more expensive than most other options and are unstable to UV rays.. However, their attractive characteristics outweigh these problems by 100%. For example, butyl reagents will be inferior over the temperature range of work. It is relatively easy to cover the surface from ultraviolet radiation, but to protect it from the cold in the conditions of the Russian Federation is almost impossible. And when compared with bituminous options, the advantages of polyurethane mixtures turn out to be a much greater variety of colors and the ability to withstand significant temperatures..

Polyurethane group of sealants:

  • perfect for closing seams and joints in concrete floors and screeds;
  • performs similar functions in floors made of other materials;
  • works well only on a perfectly dry and grease-free surface;
  • works best at temperatures from 10 to 30 degrees Celsius;
  • effectively adheres to concrete and plastic, metal and ceramics, bricks, as well as to itself.

Technological parameters

In foreign countries, compositions based on polyurethane are even more in demand than silicone mixtures. They are considered the most frost-resistant, easily tolerate cooling up to 60 degrees. But the maximum allowable temperature is limited to 120 degrees. The overwhelming majority of such mixtures are intended strictly for outdoor use, since toxic emissions are formed at the time of application and during polymerization. For your information: if there are no tenants in the house yet or they may temporarily move somewhere, processing is possible inside, since the hardened seams are absolutely harmless.

Polyurethane-based sealants at sub-zero temperatures not only serve stably – it will not become an obstacle to their use. Regardless of how warm or cold it is outside, you will have to moisturize the seams to be treated. In cold weather, this is even more relevant, since the polymerization rate depends on the presence of water, which is strongly limited by the cold. During the hardening process, the mass hardly shrinks. Processing of vertical planes is allowed, since the sealant is quite sticky and does not drip from there arbitrarily.


No matter how much manufacturers care about the waterproof and frost-resistant parameters of their product, almost everything is in the hands of users. It is extremely important to follow the technology to the smallest detail, otherwise the result is not guaranteed. First of all, you should take care of cleaning all seams from dust particles, old paint and just dirt. It is not allowed to treat a non-uniform surface with a sealant. If the material delaminates, it is at least naive to hope for a strong bond with it..

Observe, of course, the manufacturer’s instructions, especially regarding the exact application temperature.. Important: these are just the maximum permissible limits, whenever possible, even a polyurethane sealant should be used in a warm environment. With regard to the curing time of the sealing agent, it is worth distinguishing between the curing period of the top layer and the duration of full curing. The first stage is sometimes completed within 30 minutes after the release of the reagent to the surface. The second one lasts several days.

Fast solidification can be not only a plus, but also a minus. The mistake in choosing the place of processing sometimes turns into fatal consequences..

The two-component polyurethane sealant is almost 100% elastic. Storage of material should be organized in places known to be inaccessible to children and pets. Also, excessive heating during storage is unacceptable. When the proper handling conditions for the sealant are maintained, it will retain its properties for up to 10 months even in an open container..

Selection Tips

To close a seam with a depth of 1 cm and a length of 1 m, only 0.1 liters of the finished mixture will be required. The key property of the sealing compound in everyday life is strength. It is she who primarily determines how great the resistance to deformation or shrinkage.

Sealants with a hardness of 15 units are suitable for repairing gaps in roofing materials and joints, in wall corners. The mixes, designed for 25 units, are designed to close gaps in structures that are in continuous contact with moisture. The next group – with 40 units – is optimal when working with glass and expansion joints in reinforced concrete. 50 units are typical for mixtures designed to work with metal. And polyurethane sealants for 60 points are ordered by shipbuilding and automotive corporations in different countries..

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