Interior sealing

Especially if the damp walls are not accessible from the outside, as in the case of a superstructure, our professionally executed interior waterproofing is a technically sensible alternative to waterproofing from the outside. Moisture ingress into the interior is reliably prevented, just as with exterior waterproofing.

Waterproofing from the inside - ISOTEC interior sealing

The problem: moisture penetrating from the side

Sealing from the outside is not possible

If water enters the basement from the side, waterproofing is necessary. If subsequent external waterproofing of the basement walls is not possible or too costly due to the structural situation, the only sensible technical alternative is waterproofing on the inside of the building. The penetration of moisture into the interior of the basement can be reliably prevented with professionally executed interior waterproofing from ISOTEC.

Interior sealing against penetrating moisture

If you have wet walls due to water pressing in from the outside and a waterproofing measure from the outside is not possible, we offer you one of our tried and tested system solutions. The procedure for us is as follows:

Interior sealing against moisture penetrating from the side

The problem: Lateral moisture penetration

If the exterior sealing is damaged or even lacking, moisture penetrates laterally into the masonry through the area in direct contact with the ground. Our interior sealing is the perfect solution if exterior sanitation is impossible or too laborious.

The solution: ISOTEC interior sealing

Our approach in overview

Prepare masonry and apply ISOTEC sealing plaster

01 Preparing/plastering

We expose and thoroughly clean the masonry that needs to be sealed, and create a groove and a concave moulding in the junction between wall and floor. We then apply our ISOTEC Sealing Plaster. The plaster ensures ideal adhesion and an even spreading of the following sealing layer.

Sealing slurry forms the actual sealing layer

02 Sealing

We apply our ISOTEC Sealing Mud in two steps. This flexible material presents the actual sealing layer. It is waterproof, seals cracks and permanently protects the surface of walls against moisture.

Eine Innendämmung sorgt für angenehmes Raumklima und Energieersparnis

03 Insulate/protect

Depending on the object and the client´s necessity, we either apply a vapour-permeable plaster or an interior insulation system for the protection of the sealing. The interior insulation ensure a pleasant indoor climate as well as energy savings.

The quality of our interior sealing

Our ISOTEC Interior Sealing has been examined according to the regulations of the WTA (German scientific-technical consortium for the preservation of buildings and monuments). The Material Testing Office of North Rhine-Westphalia certified its impermeability under a water pressure of 0.75 bar (7.5 m water column).

Scientific and Technical Working Group for Building Conservation and Monument Preservation e.V.


Your advantages of our interior sealing

  • Solutions for details (penetrations of pipes, cross walls, junctions
  • Energy savings, if the interior insulation has been applied for protection purposes
  • Permanent moisture protection from the inside
  • Pleasant indoor climate after sanitation
  • Conservation of property value
  • Sealing interiors and basements by professionals

Our satisfied customers

Interior sealing of a home with holiday flat

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Structure of the interior sealing

Benefit from our high quality

Basement interior sealing

At first we check whether the affected cellar walls are suitable for our sealing measures. If this is the case, thorough preparation of the substrate and the use of materials particularly developed and tested for this purpose will guarantee a successful and permanent sealing.

Supplementary measures for interior sealing

Apart from our interior sealing, further measures might be necessary in order to reliably prevent the expansion of moisture within the building. In those cases, we offer approved solutions that can be specifically adapted to your requirements. Our ISOTEC Paraffin Injection, for example, prevents the capillary expansion of moisture to adjacent floors and walls.

The special features of retrofitted interior waterproofing from ISOTEC

Illustration of interior waterproofing and wall-sole connection
Illustration Innenabdichtung | Innenabdichtung des Wand-Sohlen-Anschlusses

Damp walls, a wet cellar, flaking plaster, these are all characteristics of damp masonry. In order to repair the typical moisture damage from the inside, the corresponding waterproofing measure must be planned and executed with the utmost care for the specific building. In doing so, the ISOTEC expert takes into account that sealing from the inside leads to a dry wall surface on the inside, but not to drying out of the sealed wall.

Since the wall cross-section remains soaked through by penetrating water after sealing from the inside, the original thermal insulation properties of a dry wall cannot be achieved. In order to avoid the formation of condensation and to save energy, additional thermal insulation is therefore often applied to the walls sealed from the inside as a protective layer. At the same time, the interior waterproofing is also protected against mechanical damage. If you have your cellar renovated and sealed from the inside because sealing from the outside is not possible, the outside walls do not need to be exposed. Moisture can still not penetrate into the interior and wet walls are no longer a problem thanks to basement waterproofing from the inside.

A special form of interior waterproofing is the partial application of an interior basement waterproofing in the area of the wall-sole connection. This is done on the condition that an intact horizontal barrier membrane is present on the first or second row of bricks of the masonry.

The interior waterproofing system is carried out in such a way that a cove is previously formed in the wall-sole connection area and the masonry substrate is prepared in a levelling manner. This form of wall-sole connection sealing is also used for transitions from concrete walls to concrete floor slabs.

What to look out for in interior sealing:


for interior sealing

Download information about our solutions. In addition to overviews, you will also find further subsections or use cases here. We also provide GAEB service specifications for our business customers.

ISOTEC interior sealing


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Service specifications-GAEB-ISOTEC-IAD


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ISOTEC wall-sole waterproofing


655 KB