What can you do to fight flooding?

Restoration of water damage

After floods or floods: The remediation of water damage

Once the water has disappeared, the damage in, on and around the building is revealed for the first time. To get a first overview, you should make a thorough inspection of the property and the house. A checklist can help.

Flood damage checklist: damage detected quickly

1. External damage

  • Enclosure walls sagged
  • Washed away sidewalks to the house
  • Washed down terrace
  • Cracks in the terrace
  • Carport shifted in itself (no longer perpendicular)

2. Damage to the house

  • washed-out / washed-out foundations
  • Rinsed external insulation on cellar walls
  • damaged external insulation
  • damaged vertical insulation on cellar walls
  • Vertical insulation folded down from the masonry
  • torn off, leaky, muddy downpipes
  • chipped exterior plaster
  • hollow spots in the external plaster
  • Cracks in the exterior plaster
  • soaked outer walls
  • peeling, cracked paint
  • Damped core insulation (between masonry and facing masonry)
  • Damaged thermal composite systems (torn off lattice plaster supports or rigid foam panels)

3. Damage in the house

  • Screed cracked and pushed up by water pressure
  • destroyed insulation of the basement floor (severe cracking)
  • soaked interior walls, crumbly joints
  • Cracks in the interior plaster (hollow plastered areas)
  • Cracks in the interior masonry
  • Removed wallpaper and paint
  • swollen wall panels (water residue behind panels)
  • swollen / bent suspended cellar ceilings
  • damaged lightweight walls / partitions
  • destroyed, softened plasterboard
  • Fluffy interior insulation of the stud walls
  • loose, outwardly pressed tiles
  • swollen wooden stairs / arched steps
  • swollen parquet / damp carpets
  • damaged door leaves / door panels / doors
  • damaged windows / fittings (risk of corrosion)
  • dirty, damp roller shutter boxes
  • Damp electrical house connection / meter box
  • Damp sockets / switches / junction boxes (risk of corrosion)
  • Moist measurement and control technology in heating systems
  • dirty burners and nozzles on the boiler
  • silted condensate traps on chimneys
  • silted underground pipes / drains
  • silted backflow valves

The remediation of water damage after flooding caused by heavy rain or flooding on buildings is usually very time-consuming. The homeowner is often faced with the key question: "Renovate or have it renovated? What can I renovate myself, what can I renovate myself and what should I leave to experts? ”The list“ Renovate or have it renovated? ”Can be a little help.

"Renovate or have it renovated?"

What every homeowner can do for themselves:

  • Tear off or putty off wallpaper and paint
  • Remove windows and doors
  • Tear out floor tiles
  • Tear out parquet
  • Tear out floorboards and wooden floors
  • Knock off loose and hollow-sounding interior plasters
  • Apply interior paint
  • Wallpapering
  • Laying carpets

What a reasonably accomplished handyman can do:

  • Lay planks and wooden floors
  • Lay the finished parquet
  • Apply thermal insulation to interior walls and basement ceilings
  • Apply interior plaster
  • Lay floor tiles
  • Glue the wall tiles again
  • Demolish non-load-bearing massive walls
  • Tear / install stud or lightweight walls
  • Introduce new insulation in the walls of the stud or dry construction method
  • Attach new fittings to windows and doors
  • Demolish and replace suspended ceilings

What an accomplished do-it-yourselfer can only do with limitations:

  • Re-route cables as instructed by an electrician
  • Carry out minor work on the sanitary installation
  • Remove blockages in drains
  • Reinstall doors and windows
  • Renew the exterior plaster
  • Renew exterior paintwork
  • Renew external insulation
  • Vent the radiator
  • Install fittings and objects (tub, washbasin, etc.)

What a do-it-yourselfer must not do under any circumstances:

  • Repair electrical installations
  • Working on gas pipes or gas appliances
  • Work on heating systems
  • Work on load-bearing walls
  • Work on core insulation
  • Working on the chimney

Water damage after flooding caused by heavy rain or floods can only be compared to a limited extent with conventional moisture damage caused by leaky roofs, water pipe damage or minor flooding in the basement. Here completely different forces act on the building. It can lead to under- and washouts. The degree of pollution from the water, often with a completely unknown composition, must also be taken into account. A point that can have long-term and pleasant consequences if the renovation is too quick and thoughtless. After all, the water hits fields and washes out pesticides, herbicides and fungicides, brings faeces, germs from sewers or chemicals such as heating oil, fuel or other substances from basements or garages.

Even if you, as an affected homeowner, want to repair the damage as quickly as possible, there are unfortunately no off-the-peg renovation concepts! Therefore, a differentiated damage analysis is necessary before the renovation.

Refurbishment in individual steps

It is important that all parts of the building dry off as quickly as possible after the water has receded. To do this, it is necessary to remove residual water and sludge. During this activity you should already check the stability of the walls. For example, softened clay walls no longer support and should therefore be supported. If you notice undermining, these should be filled in at least provisionally. In these cases you should consult a specialist to check the statics of the house.


In any case, you can remove all wet furnishings, carpets or floor coverings yourself. Built-in wooden parts, such as floors or walls, must be dismantled in such a way that they dry well and are ventilated from the rear. This prevents the formation of as little mold as possible and no wood-destroying fungi.

Drywall should be opened. However, it is better to completely remove the wet plasterboard including the mineral wool so that the cavities and the load-bearing wall components can also dry out. The profiles can remain. The mineral wool must be disposed of because it can no longer be used after it has come into contact with water.

IMPORTANT: In many prefabricated houses, chipboard has a stiffening function. It is safest to contact the manufacturer to find out how and which damaged components can be replaced. Hasty activities can influence the complete statics under certain circumstances!

In principle, proper cross ventilation must be ensured. Basement windows or doors can be temporarily removed for this purpose. It is also possible to create an additional wall opening that can easily be closed again later. Support fans can be used. If it is also possible to increase the room temperature, this can accelerate the drying process.

Eliminate moisture damage

Moist gypsum plaster or gypsum lime plaster should be removed. With prolonged moisture penetration, these salts form on the surface (efflorescence). Gypsum building materials bind a lot of moisture and thus also prevent rapid drying. When removing, the underlying masonry can dry out more quickly.

It is very important that soaked wooden components are not covered again immediately. Wood beam ceilings pose a particular problem. All loose ceiling plaster should be removed. Hallings are to be opened. Moist embankments are to be dried or removed. One or two faulty floor boards on both sides of the joists must be removed from the edge area. This creates drafts to dry the floors. In order to avoid mold, fungus or sponge, it is recommended to carry out a technical drying.

A high level of humidity in the building also has a negative effect on components and furnishings that are not directly affected. Therefore, the parts of the building that are still dry should be protected from moisture penetration by keeping the doors to this area closed.

Technical building drying

There are four types of technical building drying: accelerating the drying of components by reducing the room humidity, ventilating cavities as a result of an air flow, generating an air flow around the affected component and heating the soaked area. When repairing flood or flood damage, several drying processes are usually combined in order to achieve rapid drying.

The insulation layer drying is used when horizontal heat and impact sound insulation, leveling fillings of any kind or heat insulation in external wall constructions or partition walls have to be dried. The overpressure or underpressure method is used here. In the overpressure process, heated air is introduced into the insulation layer through special openings. During this process, the dry air is enriched with moisture from the thermal insulation layer, before the moisture-saturated air is then fed into the room via the open edge joints and dehumidified there using drying devices. In the vacuum process, the moist air is drawn out of the insulation layer with vacuum pumps and dry air flows in through the open edge joints. So that the incoming air is really dry, it must be pre-dried using drying devices.

Odor neutralization

Depending on how long the flood or the flood has been in the house and how high the exposure to faeces and germs was, odors develop relatively quickly. It is not uncommon for the odor to be traced back to insufficiently dried areas or undetected standing water in cavities.

IMPORTANT: Basically, true odor neutralization is always based on eliminating the source of the odor and cleaning and disinfecting the damaged areas. Because everything else would only be a masking odor - and this is not a long-term solution!

After the odor source has been removed and cleaned, very different methods of odor neutralization can be used. Dry and wet mist generation, spraying or steaming are often used here. Disinfecting and odor-neutralizing substances are transformed into the finest droplets that float in the air using the appropriate devices. They can penetrate into cavities and reach and neutralize odorous substances that have been drawn in there.

Re-coating of walls and facades

The completion of the renovation after water damage is the recoating of walls and facades. Numerous factors are decisive here: Is it a facade, an exterior or an interior wall? Has the existing subsurface already dried out or does it still have some moisture? Does the facade or wall possibly have a salt load or is it contaminated by oil? And what use is intended for the room? Correspondingly, renovation must be carried out on a case-by-case basis - and the advice of a specialist should be sought here. In general, however, diffusion-open coatings such as lime plasters or silicate paints have proven their worth.

The reaction of individual wall construction materials to moisture

Every building material reacts differently when it comes into contact with water. Building materials and components that are in contact with the ground, such as basements or plinths, are generally designed for permanent exposure to moisture. This does not apply to building materials and components of the facade or the ground floor. As a result, the materials used there react very differently to strong moisture penetration. Some building materials are not even designed for short-term moisture penetration.


Concrete is resistant to water. Without technical aids, a drying time of up to two years can be expected.

Bricks, sand-lime bricks and aerated concrete

Bricks, sand-lime bricks or aerated concrete absorb water. If they are soaked in water, technical drying is necessary.


Plasterboard absorbs water. Therefore, lightweight walls should be completely dismantled, the plasterboard should be replaced and the mineral wool they contain should be disposed of and replaced.

Core insulation

Foam plastic does not absorb water. However, all cavities fill with water and it takes a while for it to escape. Mineral insulation made of glass wool clumps even when it is only slightly wet. A complete replacement is required here. Mineral insulation made of rock wool remains largely dimensionally stable when wet, but changes its insulation properties disadvantageously. The water tends to stick to the spaces between the mineral wool and, if the water does not escape in a natural evaporation process, it will be stubborn. Therefore, an expansion is recommended. After it is completely dry, a decision can be made whether it will be used again.

Biological insulation materials

Biological insulation materials such as wood fibers, wool, flax or paper retain moisture for a very long time and are very quickly attacked by mold or wood-destroying fungi. A complete expansion is required.

Wood-based panels

Flat pressed panels (FP), construction veneer plywood panels (BFU), wood fiber panels or OSB panels swell and warp when wet. This can damage or loosen connections in the wooden structure. Since wood-based panels also have load-bearing functions in prefabricated houses, for example, no general renovation solution can be offered. The replacement of some components or assemblies can, however, make more sense than years of repairing new defects.

Fighting mold and repairing moisture damage by a professional

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Tags:Moisture, flood, cellar