A balcony is a structural element that can decorate, as well as add a remarkable functionality to many buildings. When it is properly designed and protected against water, its owners can be sure that they will enjoy such a space for a long time. Nevertheless, said space is typical for the southern hemisphere, where the climate is stable and there are no such extreme temperature differences as in the case of Poland. Said adverse conditions may negatively impact the durability of a balcony. The most problematic issue when it comes to the sturdiness and condition of a balcony are the so-called zero temperature transitions, which – while combined with high humidity – may lead to a rapid degradation of its durability. Therefore, it is extremely important to ensure that the waterproofing system opted for is professionally designed and carefully made.


Balconies are typically made out of concrete. Without a proper protection, said material is not waterproof and may be exposed to excessive humidity and ice thawing. As a result of being exposed to constant moisture, the reinforcement inside the slab may corrode, which may in turn lead to the weakening of the structure’s load capacity over a long period of time. Said phenomenon is called carbonization of concrete or corrosion. It intensifies in winter, when the water-soaked concrete undergoes constant freezing and thawing cycles. As it may be easily guessed, they may cause structural chipping and cracking. To prevent such a destruction of the balcony, effective waterproofing systems should be taken advantage of.

We highly recommend opting for modern materials that are properly adapted to the task they are to serve. In order to protect one’s balcony against water and moisture, it is worth ensuring the correct order of work performance. It will ensure that the utilized insulation of balconies and terraces will effectively protect structural elements against water. We think that it is worth explaining what balcony insulation looks like step by step. It should be started with a proper waterproofing of the balcony slab. Beforehand, it should be insulated on all sides. A poorly insulated concrete element will generate a thermal bridge, significantly cooling down the entire building. A slope layer of concrete mortar should then be poured on the upper layer of the insulation. The bottom of the balcony may be finished by using proper materials as well. To ensure a reliable waterproofing of both new and already constructed buildings, it is vital to opt for materials that are characterized by their high quality and flexibility. They guarantee tightness, as well as are resistant to frost, aging, and adverse weather conditions.

Professional balcony insulation

Before applying the waterproofing system, it is vital to protect the surface with the WB PRIMER. Priming is important for two reasons. Firstly, by using it, it is possible to improve water-repelling properties of the concrete layer. Secondly, it allows to create a proper foundation for the waterproofing system (after priming, it will be much sturdier and more durable).

What is also exceptionally important when securing a balcony is to pay attention to sensitive places, such as all corners and connections of finishing elements, including drip caps. It is worth mentioning that newly constructed buildings take a long time to settle in place and their structure has to then withstand remarkable forces. Therefore, numerous cracks may appear in places where joints have been applied. Said situation may also lead to cracks occurring in the waterproofing layer. The issue also affects old buildings, as they are influenced by various external factors and harmful weather conditions. When temperature changes, concrete tends to expand and then contract, which may lead to cracks occurring.

To prevent such a situation from happening, it is sensible to opt for the WB TAPE PRO that is reinforcing and sealing in character. The WB TAPE PRO is not only characterized by its reinforcing properties, but – unlike many other tapes available on the market – is also waterproof. If a crack occurs and the waterproofing system fails, the tape will protect the building against excessive water penetration. The tape should be applied to all corners and joints equipped with drip caps. If the balcony is large and there are expansion joints within its scope, they should be sealed with the discussed tape as well.

It should also be remembered that it is worth using solutions that are parts of a single system. Such an approach will guarantee the full compatibility of individual components and eliminate the possibility of adverse chemical reactions occurring between the products.

When the surface is primed and WB TAPE PRO has been applied, it is possible to start waterproofing the balcony. To do this, one has to utilize two waterproofing solutions: WB DUO FLEX as an adhesive for WB MEMBRANE, which will also serve as a waterproofing layer, and WB 2K to serve as the final layer, which will be applied after covering the surface with the WB MEMBRANE. Both insulations are characterized by a remarkable ease of application and notable adhesion to the surface. They help the user create flexible coatings that are resistant to freezing and thawing cycles. They remain flexible even at very low temperatures. WB MEMBRANE strengthens a given surface and improves its tightness in places where it is affected by a notable water pressure. It is characterized by hydrostatic pressure load capacity of 0.5 MPa, temperature resistance from -30 °C to + 90°C and high tensile strength of up to 13 MPa. Said product is also capable of withstanding the pressure of 50 meters per square cm. The utilization of the WB MEMBRANE as a part of terrace and balcony-oriented systems guarantees prolonged tightness, even in extreme weather conditions. The aforementioned insulation can be covered with traditional finishing cladding (including adhesive tiles), as well as with ventilated systems, such as slabs on brackets and terrace boards.


The proper sequence of balcony waterproofing-related undertakings:

  • Preparation of a concrete slab with a slope. WB FAST FLOOR material can be used for said purpose

  • Priming the surface with WB PRIMER

  • Application of the WB TAPE PRO in the corners and on the joints equipped with drip caps,

  • Application of a waterproofing system ( WB DUO FLEX WB MEMBRANE – WB 2K)

  • Application of the preferred finishing layer (glued tiles, boards on adjustable brackets, or a composite board). Proper glue and grout for gluing tile coverings have to be used. WB FLEX GLUE and WB FUGA FLEX will be perfect for such projects.


Cross-section of balcony-specific waterproofing layers:

Required materials:

Materials to be used for balcony finishing:


As a finish, it is possible to opt for ventilated solutions, such as boards on adjustable brackets or composite boards.

Amount of materials required for balcony-specific insulation:


  • WB Duo Flex 20 kg waterproofing – sufficient for 13 to 15 m2

  • WB Duo Flex 10 kg waterproofing – sufficient for 6.5 to 7.5 m2

  • WB 2k waterproofing – sufficient for 10 to 12 m2


Please note!


If you are not sure how much material you may need to insulate your balcony, you can always ask our professional support. Just contact our technical team via phone or e-mail.

Method of WB Membrane application:

Film instruktażowy:

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Water Block are premium class products designed for customers who value solutions for years. Long-term cooperation of technologists from Poland and Switzerland has allowed us to create complete system solutions for such structural elements of the building as balconies, terraces, roofs and foundations. Water Block is successfully used wherever parameters such as high flexibility, resistance to low temperatures or resistance to water pressure are important.

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