How to seal a balcony or terrace? A comprehensive guide

Leaks from balconies or terraces are one of the most common problems in apartment buildings and single-family homes. Leaks typically occur due to:

• microcracks in the joints and cladding
• degradation of waterproofing under tiles,
• construction errors (lack of expansion joints, inadequate waterproofing)
• aging of materials under the influence of UV rays, frost and moisture. 

Water seeping through leaks can cause water stains, concrete degradation, mold growth, and even structural damage. Therefore, properly sealing balconies and terraces is crucial to their durability.

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How to seal a balcony? What to use?

Balcony waterproofing is primarily achieved using polyurethane or epoxy coating systems, which create a flexible, seamless layer that protects against moisture penetration. The choice of material depends on the type of substrate, its technical condition, and the desired visual effect.  

How to prepare a balcony for sealing?

Preparation is key. You should:

1. Remove any loose components and clean the surface of dust, grease, and lichen. If there are any leaking tiles, they must be removed. 
2. If necessary, fungicides can be used if efflorescence has appeared on the balcony surface.
3. The next step is to level out any unevenness in the substrate. Various self-leveling compounds, PCC compounds such as Troken FCM1 or Troken FCM2 , epoxy repair compounds such as Epoxol® Putty or Epoxol® Liquid , or solvent-free epoxy primers mixed with quartz sand, such as Epoxol® Primer SF-P or Neopox® Primer WS , can be used for this purpose. It's important to remember that epoxy resins must be primed beforehand.

How to seal a balcony - step by step

Concrete waterproofing requires several steps to be effective. Each step is equally important, and omitting any one can compromise the quality of the entire waterproofing system. Below are the recommended steps:

1. Priming – For exterior concrete substrates, Neopox® Primer WS , which can be applied to damp concrete. Additionally, with the appropriate thickness, it can provide a vapor barrier. This allows for the safe application of resin systems on exterior concrete.
2. The waterproofing layer is most often a liquid polyurea membrane, Neoproof® Polyurea R. Its flexible structure allows for the closure of expansion joints and the creation of a completely joint-free system.
3. , the Neotextile® NP reinforcing fabric is additionally used , which strengthens the waterproofing layer in the areas of greatest stress.
4. Protective/Decorative Layer – There are a number of modern, aesthetic decorative solutions. These include single-color finishes, such as Neodur® FT Elastic , decorative flake backfill, liquid granite – Troken Stone , or colored aggregate backfill. It's worth remembering that flakes, imitation granite, and colored sand should be protected with varnish against both weathering and chipping caused by wear and tear.

How to seal balcony tiles? What to use?

Unfortunately, there's no foolproof solution for leaking tiles. If tiles are leaking, it means moisture has already accumulated underneath. Sealing this moisture from above can result in bubbles or loosening of the coating, so sealing leaking tiles is not recommended. 

How to seal a balcony without removing tiles?

As mentioned above, there is no effective, long-term protection for leaking tiles. The best solution is to remove the tiles, level the substrate, and apply a new system, e.g., a resin-based one. 

How long does it take to seal a terrace? How long will it be unavailable?

Completion time depends on weather conditions and the system. For full waterproofing systems based on Neoproof® Polyurea R, it can take up to 5 to 7 days. This time may vary depending on the selected finishing option.

How to seal a leaky patio? Which products are best for this?

A leaky terrace requires coatings with increased flexibility and weather resistance. Polyurea membranes, resistant to UV and standing water, are the most effective. It's crucial that the product adheres well to various substrates, including concrete and metal. 

How to prepare a terrace for sealing?

As with a balcony, the surface must be cleaned, dried and repaired, and then a suitable resin primer must be applied.

How to seal a terrace - step by step

1. Priming the substrate – for concrete substrates, the recommended primer, as with balconies, is Neopox® Primer WS , a primer for damp concrete. It's worth remembering that this is a two-component product, so after mixing component A (base) and component B (hardener), the mixture has a specific use-by time .
2. Applying the sealing membrane - Neoproof® Polyurea R. Liquid polyurea waterproofing is applied in at least two layers, at approximately 24-hour intervals, depending on the prevailing weather conditions (temperature, humidity).
3. Protection of places particularly exposed to leaks - connections of vertical and horizontal lines, as well as details made of other materials, e.g. planking, should be secured with Neotextile® NP , which is applied using the "wet on wet" method.
4. Finishing and protecting the coating – the waterproofing coating is covered to protect it and give the terrace floor an aesthetically pleasing appearance. For this purpose, a single-color, fast-setting polyurea resin, such as Neodur® FT Elastic , colored quartz sand, liquid granite imitation, or decorative flake filling are used. The last three variants require a varnish, such as Kryptanate 100 Flex .

How to seal a terrace above a room?

Neoproof® Polyurea R work best . This membrane is also resistant to root penetration, so it can be used for so-called green roofs.

How to seal a terrace above a garage?

It's recommended to use coatings that are resistant to standing water and future wear and tear. A suitable system is Neoproof® Polyurea R-2L FTE , a system based on the Neoproof® Polyurea R protected by the abrasion-resistant Neodur® FT Elastic . This not only ensures complete watertightness but also provides excellent resistance to mechanical stress and abrasion.

How to seal a concrete terrace?

On clean, matt concrete, it's recommended to apply an epoxy primer, such as Neopox® Primer WS, which can be applied to substrates with a moisture content of less than 90%. If the substrate is very damp, it may be necessary to apply two layers of primer to create a vapor barrier. Then, apply at least two layers of Neoproof® Polyurea R polyurea membrane to provide complete moisture protection.  

How long does it take to seal a terrace?

Under standard weather conditions - from 2 to 5 days depending on the system.

Also read: Polyurea resin for the terrace. Overview of solutions.

sealing coatings for balconies and terraces aesthetically pleasing?

Modern sealing coatings combine protective and decorative functions. Available in a variety of colors and finishes, they can enhance the character of a terrace or balcony. Depending on the system chosen, the surface can be smooth, textured, or enriched with decorative aggregate.

What coating patterns are available for sealing terraces and balconies?

Smooth, structural, and decorative coatings with quartz aggregate are available.

What colors are the sealing coatings available in?

Shades of grey and white are most commonly used, but you can also use decorative flakes in a specific colour or liquid granite imitation, which will always create a unique, one-of-a-kind effect.

Mistakes When Sealing Balconies and Terraces: Avoid These

• Applying coatings to damp surfaces. Only Neopox® Primer WS - primer for damp concrete can be applied to damp surfaces.
• Lack of priming or use of incorrect primer. 
• Too thin a layer of membrane or other intermediate layers. 
• Incorrect securing of expansion joints and critical areas.

How to maintain a sealed terrace or balcony ? What to remember?

• Regular cleaning of surfaces with mild agents. 
• Inspection of areas exposed to mechanical damage. 
• Avoiding strong detergents that may damage the coating.
  Using soft-bristled mops.

How to seal a balcony and terrace - frequently asked questions

In this section, you'll find answers to common questions from investors and contractors regarding product selection, project time, costs, and other tips for balcony and terrace renovations. This practical summary will help you make decisions and plan your work. 

What's the best way to seal balconies and terraces? What products should I use?

The best results are achieved with liquid polyurea membranes (e.g. Neoproof® Polyurea R ) sealed with flexible finishing coatings, e.g. Neodur® FT Elastic or Kryptanate 100 Flex .