Home generalBasement ceiling insulation - costs and instructions for insulation

Basement ceiling insulation - costs and instructions for insulation

  • Important questions in advance
  • Various insulation materials
    • polystyrene plates
    • Fibreboard
    • sheep wool
    • cellulose
    • calcium silicate
  • Damm cellar ceiling
  • Further measures
  • Tips for quick readers

The insulation of the basement ceiling is one of the fastest and cheapest measures that can be taken to reduce heating costs. The selection of insulating materials and the optical design are completely free. With the Kellerdämmung the host can start with numerous, small and inexpensive measures to make his house energetically more efficient.

Starting shot of an energy-saving campaign

The insulation of the basement ceiling is a quick way to close a large thermal bridge in the house. The materials are cheap to free, the design is very fast and the effect is huge: virtually the entire living space of the apartment above it falls away as a cold bridge through this measure. The insulation of the basement ceiling can be supplemented with an attic insulation, a wall insulation on the radiators and a sheathing of the pipes of the heating beyond. Alone, the basement ceiling insulation already reduces heating costs by up to 12%. All measures taken at home reduce the heating costs by as much as 60%. Another name for the basement ceiling insulation is the "perimeter insulation".

The cellar: Expensive, but unused

The basement is the most expensive converted room in the house. At the same time, it has the lowest utility value. Therefore, when planning a home, it should be carefully checked if the basement is really needed. Often a larger sized garage serves the same purpose. The costs of the cellar are not only due to its construction and maintenance: a cellar unfortunately has to be constantly checked for moisture entering from the outside. Even with a perfectly executed and absolutely dense basement fall unnoticed constantly additional costs.

One of the biggest costs traps in the cellar is in a completely unexpected place: the basement ceiling. If this is not equipped with effective thermal insulation, it acts like a gigantic cooling rib: the expensive warmed-up heating air is permanently cooled down again. This provides much more than just cold feet. The uninsulated basement ceiling allows up to 20% of heating energy to escape. However, this can be prevented for the most part by an effective basement ceiling insulation. The biggest advantage here is that you have to take the optics in many basements hardly consideration. The insulation of the basement ceiling must work in the first place. What she looks like is secondary.

Important questions in advance

How high is the cellar ">

Which material to use?

The basement insulation is less critical than the rafter or facade insulation. This is mainly because the basement insulation an interior to the next isolated. The air may be quite cold in the basement, but it is always dry and always dry. That's why virtually all insulating materials are well-suited for basement insulation. In the purchase price, the cheapest insulating material is still the polystyrene foam. Nevertheless, we would like to advise against the use of styrofoam and styrofoam plates at this point. This has two reasons:

Fire hazard: Styrofoam boards may no longer be equipped with flame retardants. At the same time these materials are very easily flammable due to their high air . When Styrofoam burns, it not only develops high temperatures and drops of hot, burning plastic. The main danger comes from the toxic gases that are produced by the burning of polystyrene. The position in the basement is doubly unfavorable. For one, a house with a fire in the basement is guaranteed to be completely flooded with gasses and smoke. Second, a smoldering fire in the basement usually goes unnoticed for a long time. Even the smoke detectors installed in the apartments can be activated too late in a basement fire.

Disposal: Polystyrene foam boards are very expensive to dispose of. The recycling depots often do not accept them at all anymore. The homeowner then has to deliver the plates themselves to the special incinerators, of which there are only a few in Germany.

Ideal for the insulation of the basement ceiling are therefore mineral insulating materials. Glass wool and rock wool are now available in safe, environmentally friendly and visually appealing designs, so that there is no reason for the dangerous polystyrene.

The damp-uncritical location of the basement insulation also makes materials of organic materials possible. Mats made of coconut fiber, wood wool, sheep wool or recycled materials such as cellulose are also possible at this point. In contrast to polystyrene these materials may still be impregnated. Thus, a fire hazard is largely prevented by these materials.

The most important question for an insulating material is the insulation value. This value, also referred to as lambda, K value or heat transfer coefficient, indicates how well a material is suitable as an insulating material. Depending on which insulation material is to be used, a different thickness may be required to follow the same insulation performance.

A rock wool plate developed by a well-known manufacturer for the basement ceiling insulation is 80 mm thick and classified as "non-flammable". This gives it the best value that an insulating material can have in fire protection. It has a thermal conductivity of 0.35 and costs 16.60 euros per square meter. This should serve as a basis for a comparison.

Various insulation materials

polystyrene plates


  • Thickness: 80 mm
  • Cost per square meter: 14 euros
  • Thermal conductivity: 0.35
  • Fire protection: "Normally flammable"
  • + Inexpensive
  • - Fire safety concern
  • - Expensive in the disposal

HDPE-impregnated polystyrene plates may no longer be manufactured, but still sold. With the sale of these plates, the disposal problem is shifted to the customers. Therefore, it is not recommended to buy these plates again.


  • Thickness: 80 mm
  • Cost per square meter: 7 euros
  • Thermal conductivity: 0.40
  • Fire protection: "Normally flammable"
  • + Very cheap
  • - No high fire protection class

sheep wool

  • Thickness: 80 mm
  • Cost per square meter: 13, 20 Euro
  • Thermal conductivity: 44
  • Fire protection: "Normally flammable"
  • + very sound-absorbing from all biological insulation materials
  • + very sustainable
  • - low fire protection despite impregnation
  • - must be impregnated against moth infestation


  • Thickness: 80 mm
  • Cost per square meter: 5 euros + substructure
  • Thermal conductivity: 0.39
  • Fire protection: B2 "Normally flammable"
  • + Good heat output
  • + Inexpensive
  • - Elaborate installation, as a substructure for the blow-in insulation must be built

calcium silicate

  • Thickness: 25 millimeters
  • Cost per square meter: 50 euros
  • Thermal conductivity: 0.06
  • Fire protection class: Non-flammable
  • + Binds moisture
  • + Extremely efficient (lowest thermal conductivity of all insulating materials)
  • + Thin version, suitable for low ceiling heights
  • - Very expensive

Damm cellar ceiling

Kellerdämmplatten are usually glued. The glass and rock wool materials are also available today in sheets that can be glued together. The installation is very simple. You need

  • sturdy ladder, due to the height of an average basement ceiling is sufficient for a normal household ladder
  • Drill with whisk (both about 25 euros in the daily rent)
  • clean bucket (5 euros)
  • broom
  • long knife, ideally an insulation knife (about 5 Euro)
  • Trowel (about 5 Euro)
  • Trowel (about 5 Euro)
  • Binding board or steel angle (about 10 Euro)
  • helper
  • ruler

The basement ceiling is thoroughly cleaned with the broom. The glue is mixed with the whisk in the bucket. Then it is applied with the trowel and the trowel. The panels must always be glued over the entire surface. The helper can then press the plate with the broom against the ceiling until the next plate can be glued. Always apply only the glue for one plate after the other. You start at one side and work your way evenly to the opposite sides. The end pieces are measured and cut with the angle and the insulation knife from the plates. For a complete cellar you can plan about 1 day of work. Always use extreme caution when handling the insulation knife! They are very sharp.

Further measures

If you are already in the basement, you can also equal all lines of the heater with Dämmmänteln provided. Retailers offer ready-made products that are simply slipped over the lines. They can also be cut to the desired size with the knife. If they are slipped over the pipes, they are simply fixed with adhesive tape. In the meantime, there are also environmentally friendly and non-combustible mineral wool solutions for insulating the heating pipes. With four to nine euros per meter, they are a bit more expensive than insulating rubber or polystyrene jackets. But they offer this extra extra security. The average cost of saving up to 100 euros per year. This means that even more expensive insulating materials have quickly paid off again.

The popular insulation of the radiator's niche should always be clarified with an energy consultant. If the house already has an insulated facade, this insulation is usually unnecessary.

If the house has no rafter insulation, the insulation of the floor from the attic is a simple and effective measure. If the attic is used very little anyway, only one layer of insulation material needs to be laid out on the floor. Already, you have saved up to 40% heating costs. This can also be implemented as a temporary measure, if the attic is to be expanded later.

Tips for quick readers

  • Insulate basement ceiling with fireproof material
  • With pipes and attic immediately with dams
  • Clarify insulation for radiator mixes with energy consultant
  • Insulate low ceiling heights with calcium silicate
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