{"id":3403,"date":"2026-03-17T12:12:28","date_gmt":"2026-03-17T12:12:28","guid":{"rendered":"https:\/\/sa-baustoffe.de\/?page_id=3403"},"modified":"2026-03-17T19:51:48","modified_gmt":"2026-03-17T19:51:48","slug":"flachdach-abdichten-mit-fluessigkunststoff","status":"publish","type":"page","link":"https:\/\/sa-baustoffe.de\/en\/flachdach-abdichten-mit-fluessigkunststoff\/","title":{"rendered":"Flat roof waterproofing with liquid plastic"},"content":{"rendered":"
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Flat roof waterproofing with liquid sealant and polyester fleece \u2013 step-by-step construction<\/h1>\t\t\t\t<\/div>\n\t\t\t\t
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Modern flat roof waterproofing systems are implemented using different materials \u2013 for example polyurethane, PMMA or bitumen.<\/p>

Regardless of the sealing system used, one component remains almost always the same: the reinforcing fleece made of polyester<\/strong>.<\/p>

In the following example, we show the typical construction of a flat roof waterproofing system using liquid waterproofing and polyester fleece \u2013 step by step.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t

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System structure of a liquid waterproofing system<\/h2>\t\t\t\t<\/div>\n\t\t\t\t
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The construction of a flat roof waterproofing system using liquid waterproofing typically consists of several steps:<\/p>

  1. Preparing the substrate<\/strong><\/p><\/li>

  2. Priming of the roof surface<\/strong><\/p><\/li>

  3. Reinforcement of connections and details<\/strong><\/p><\/li>

  4. First sealing layer<\/strong><\/p><\/li>

  5. Full-surface reinforcement with polyester fleece<\/strong><\/p><\/li>

  6. Second sealing layer<\/strong><\/p><\/li><\/ol>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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    Step-by-step implementation<\/h2>\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t
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    Step 1 \u2013 Preparing the substrate<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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    In the first step, the existing tile surface is carefully prepared and coated with the first layer of liquid waterproofing.<\/p>

    This layer ensures a uniform base seal and forms the basis for further construction.
    Transitions, edges and connections are particularly critical and must be completely covered.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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    Step 2 \u2013 Primer<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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    After cleaning, a suitable Primer<\/strong> applied.<\/p>

    The primer improves the adhesion between the substrate and the sealant and ensures a uniform surface.<\/p>

    Different primers are used depending on the system.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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    Step 3 \u2013 Reinforcing the connections<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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    Particularly critical areas of a roof seal are:<\/p>

    \u2022 Wall connections
    \u2022 Inside and outside corners
    \u2022 Penetrations
    \u2022 Transitions between components<\/p>

    These areas will be addressed first.<\/p>

    First, a sealing layer is applied.
    Then Polyester reinforcing fleece<\/strong> embedded in the fresh coating.<\/p>

    This creates a flexible and crack-bridging detail seal.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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    Step 4 \u2013 First sealing layer<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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    Once the details have been prepared, the sealant is applied to the entire roof surface.<\/p>

    In this example, a Polyurethane liquid sealant<\/strong> used.<\/p>

    The first layer serves as a base for reinforcement with fleece.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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    Step 5 \u2013 Full-surface reinforcement with polyester fleece<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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    As long as the sealant is still fresh, the Polyester reinforcing fleece<\/strong> embedded in the coating.<\/p>

    The fleece sheets are laid across the entire roof surface.<\/p>

    The following is important:<\/p>

    \u2022 complete saturation of the fleece
    \u2022 Bubble-free application
    \u2022 Overlap of the lanes<\/p>

    The overlap is at least 5 cm<\/strong>.<\/p>

    The fleece absorbs part of the sealant and forms a stable, flexible reinforcement layer.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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    Step 6 \u2013 Second sealing layer<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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    After the reinforcing fleece is laid, another sealing layer is applied.<\/p>

    This top layer completely covers the fleece and forms a closed, waterproof surface.<\/p>

    Depending on the system, an additional third layer may be required.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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    Finished layer structure<\/h2>\t\t\t\t<\/div>\n\t\t\t\t
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    The finished roof waterproofing consists of several functional layers:<\/p>

    concrete substrate<\/p>