FAQ

Within the framework of the building permit application procedure, it is not within the municipalities’ field of competence to monitor compliance with private property boundaries. The right of ownership is a fundamental right enshrined in the Constitution, therefore any encroachment of the façade insulation (considered as a fixed element of the building) on a neighbouring private property must be covered by the transfer of a real right over the plot of land in question, otherwise there is a risk of legal recourse within 30 years of the work being carried out (acquisitive prescription in real estate matters).

In the context of the building permit application procedure, it is necessary to respect the municipal planning regulations relating to setbacks from neighbouring private properties. The same provisions apply to constructions along the municipal public domain.

As is the case for buildings along the municipal public domain, buildings along the State road (national road and State-managed road) must, within the framework of the building permit application procedure, comply with the municipal urban planning regulations on setbacks.

For constructions located in the vicinity of the State public domain at a distance of 25 metres from a national road (N) or at a distance of 10 metres from a State-managed road (CR), established from the property line, a road permit is required from the Minister of Sustainable Development and Infrastructure. As part of a road permit, provisions regarding the setbacks of buildings in relation to the road will be applied. These may differ from the setbacks set by the municipalities.

With regard to building permits, the municipalities systematically check that buildings are set back from the municipal public domain or plot boundaries.

As a rule, the planning regulations for setbacks are regulated by the municipalities in their General Development Plan (Plan d’Aménagement Général, PAG) or in the Special Development Plans (Plans d’Aménagement Particulier, PAP).

For municipalities whose PAG has not yet been adapted to include current legislation, the planning regulations relating to setbacks are still included in the written part of the PAG or in the building regulations. For these municipalities, the measurement of setbacks in the event of energy retrofitting is set out individually, by municipality, in those documents.

On the other hand, for those municipalities whose PAGs have been completely revised since 2011, the Grand Ducal Regulation that is the basis for the applicable definitions provides that the building setbacks are to be measured without the additional insulating layer in the case of an energy retrofit.

In both cases, the municipalities can include derogation mechanisms in their regulations in order to promote energy retrofitting, for example through a reduction in the minimum setback to be observed.

Houses are used for decades; in terms of their maintenance and modernisation, one must therefore take a long-term view. Every owner who adopts a sustainable approach will invest in the building to maintain or increase its value. Some measures pay for themselves very quickly, others only after 10 or 20 years. In all cases, a properly executed energy retrofit contributes to reducing dependence on rising energy prices by reducing energy consumption for heating. And even if, in rented buildings, the savings in heating energy do not immediately compensate for any increase in rent, one must always take into consideration the fact that heating energy prices are constantly rising. In most cases, therefore, the measures pay off in the long term.

When calculating the cost of an energy modernisation, don't forget that many measures will have to be implemented sooner or later and that financial aid can be requested today.

If you rely on non-airtight windows to ensure good ventilation, you are sure to make a mistake and it will be an expensive error: the exchange of air takes place in a purely random way, depending on the weather conditions and air pressure. On the other hand, on the coldest days you can be sure that you will suffer from heat loss. In addition, there is a risk that moisture in the air will condense on single-glazed windows, leading to the formation of mould. Windows that are not airtight will lead to an unpleasant indoor climate and unnecessarily high heating costs.

In the case of retrofitting, new windows must be installed by a specialist who not only works with the latest materials but also ensures that existing thermal bridges are eliminated.

Mould growth is caused by poor construction standards or poor/insufficient ventilation, not by levels of insulation.

In fact, if you insulate your house properly, you will prevent mould growth. This can be seen in many passive houses and in buildings undergoing energy retrofitting. These buildings are well insulated, airtight and completely free of mould. If the external walls are not satisfactorily insulated or not insulated at all, air moisture condenses in the cold areas, thus giving rise to the development of mould. Thermal insulation of the façade tends to raise the surface temperature of the external wall and prevent moisture from accumulating.

In this context, it is important to identify and eliminate all thermal bridges in the building. These include, for example, window apertures, i.e. the wall surfaces facing into the window or door openings, against which the respective frames are placed. In addition, external walls should not be encumbered with furniture, as this prevents the indoor air from circulating, meaning that the surfaces behind any furniture cool down.

Therefore, in summary, proper insulation of the façade and adequate ventilation are key measures that prevent mould growth.