Note the coupling principle when insulating

Subsequent insulating the exterior walls may be an economic minus business for homeowners. Because just the facade insulation is quite time-consuming and expensive, the investment costs can quickly exceed the savings in energy costs. Thus, the retrofit insulation profitable economically, homeowners should consider a simple principle and choose the right time for the insulation measures. Via the quality of the individual insulation materials give these three metrics information .

Note the coupling principle when insulating

“In an exemplary family house can be described by the insulation of the exterior walls to save each year 8,000 to 9,000 kilowatt hours of energy,” says Christian Stolte, head of energy-efficient buildings of the German Energy Agency (dena). Depending on the energetic state of the building before rehabilitation were the approximately 25 percent of total energy consumption.

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Coupling principle makes Insulation economically viable
From an economic perspective, it is usually wise to the building then energetically upgrade if anyway maintenance or repair work on the façade pending. For Wolfgang Setzler, managing director of the trade association thermal insulation composite systems, is “an ideal time for the subsequent dams when facades and exterior walls repainted anyway and must be repaired.” The insulation layer then causing only minor additional costs which can be recoup quickly by the savings in energy costs.


So cost according Setzler a new plaster and paint 50 to 60 euros per square meter, an insulation with a thermal insulation composite system (ETICS) based on polystyrene additional 20 euros per square meter. Also dena expert Stolte advises to observe the so-called coupling principle, ie to combine the insulation with the other anyway resulting work: “If, for example, next to the roof and the windows also equal to the outer wall with modernized, the framework needs to be installed only once. ”

Dams may be a minus-business
In the spring of 2013 unsettled reports of a KfW study on the costs and benefits of energy renovations , many homeowners, according to the failed investment costs for insulation measures usually higher than the energy savings potential. Accordingly, the subsequent insulation of the building would be economically a loss for homeowners. However, the KfW study did not differ in estimated costs between the energy-related costs of rehabilitation and maintenance costs incurred anyway, so she let the coupling principle in mind.

The Darmstadt Institute for Housing and Environment (IWU) refers, in response to a separate study commissioned by the Federal Ministry of Transport, Building and Urban Development from June 2012. Therein, energy-related costs of the resulting maintenance costs are deferred anyway. Result: “The future energy cost savings exceed not only the energy-related costs, but funding for many components also a part of the repair costs.”

If the coupling principle considered to subsequent dams is worthwhile for homeowners accordingly. Was paid to the calculations based on a 25-year period, to determine the energy cost savings. “When is thermal insulation measures but with a useful life of several decades ago, probably 40 years or more to be expected,” said IWU. Then the savings would therefore be even higher.


Facade insulation with thermal insulation composite systems
Renovators can choose for the insulation of the exterior walls between different systems: for facade insulation from the outside come thermal insulation composite systems, a curtain wall with lying behind thermal insulation or cavity wall insulation into consideration.

“A cost-effective solution to improve the thermal insulation of building elevations are thermal insulation composite systems,” recommends Werner Eike Hennig from IWU. Here, the insulating material is placed on the outside walls or on an intact layer of plaster and then plastered over. “About 80 percent of builders opt for external thermal insulation composite systems based on polystyrene,” says Setzler. Alternatives to cheap polystyrene insulation are about as rock or glass wool, foam, wood fiber and cellulose plates. All insulation materials have their own pros and cons .

Insulation with curtain wall
“Even curtain walls with thermal insulation to reduce the heating requirements of old buildings,” says Eike-Henning. Here, a sub-structure made of wood or aluminum profiles is placed on the façade, on which an outer cladding slate, wood, natural stone or fiber cement board is installed later. In the space then comes the insulation – usually cellulose or mineral wool.

Costs are usually somewhat higher than that of thermal insulation composite systems. Including the insulation, which is about 25 to 40 euros per square meter, the homeowner should depend on the selected material of the outer cladding with a total cost of 100 to 300 euros per square meter count.

Facade insulation with core insulation
For houses with two shells, so-called hollow masonry layer, the core insulation offers. There is a layer of air from 6 to 7.5 centimeters between the inner and outer masonry shell. In this space, the insulation material is blown explains IWU expert Eike-Henning. The insulating materials such as rock wool flakes, perlite granules, glass bead, beads or polyurethane foam silicate are blown through holes in the cavity.


In a family home, the entire work is often done in one day, mostly because the building does not need to be upgraded. This is then reflected in a relatively low cost. For a cavity wall insulation must expect about 20 to 30 euros per square meter. “The insulation of the air core is particularly recommended for built after 1960 building,” says Eike Hennig. From this point on, the shells were laid so that there is a continuous layer of air and only thin wire made of stainless steel anchor connecting the two walls. The disadvantage of a cavity wall insulation: The thickness of the insulation layer is limited to the size of the cavity between the wall shells.

When the internal insulation is preferable
Not always is a facade insulation from the outside is the best solution. “Builders should look in the modernization case, not only to an optimum heat protection, but also to the preservation of the facade image” warns architect Ulrich zinc by the Federal Altbauerneuerung. “A house that the energetic state of the art equivalent, but has lost its original character, lose value.” Therefore, the expert advises with houses more than with an elaborate half-timbered or brick facade of an external insulation. For listed buildings, the facade picture may not be changed often, so then only the inside insulation remains.

Here comes inside the house is a shell on the walls. According IWU is an interior insulation usually consists of several components: the support structure, the insulation, a vapor barrier and the inner lining. Again, renovators have the choice between different systems: There are on deck plates bonded insulating material, optionally with integrated vapor barrier, or structures made of insulating materials between the wood slats. In so-called interior plaster systems of wet plaster comes directly on the insulating plates.

One advantage of interior insulation is that they are relatively easy to install. “And recovery is not tied to specific investment timing,” explains architect zinc. It offers itself, such measures to be connected also with the renovation and rehabilitation: If the living room is already re-plastered or wallpapered or new windows are used. Modernizers should therefore also be considered in the interior insulation, the coupling principle, so that the restoration is possible profitable.


Interior insulation has to deserve its bad reputation
A persistent the misconception interior insulation favor mold growth and other moisture damage in the living room. This is contradicted by the IWU. Overall, the number of such damages after Innendämm measures was due quite low and always on technical design flaws. For example, all installed components must be coordinated and processed correctly. As a layman, so you should rather stay away from them and entrust a specialized company with the work.