<
Back to Knowledge Hub29.05.2026
Anyone planning a decentralised ventilation system in a new building today is often faced with a fundamental question: Should the ventilation opening be created later using core drilling, or is it worth preparing it during the shell construction phase with a wall mounting block?
On many construction sites, this decision is still made too late. The result is additional coordination, subsequent drilling work, unnecessary costs, and problems relating to airtightness or façade construction.
Especially with decentralised ventilation systems, however, it is becoming increasingly clear: those who prepare the ventilation opening during the shell construction phase save time later and significantly reduce typical construction site problems.
Craft businesses in particular benefit from:
In this context, the so-called wall mounting block or wall installation block is becoming increasingly important.
In the following article, we show the differences between core drilling and wall installation blocks, which solution is suitable in which situation, and why many new buildings today are already prepared for decentralised ventilation during the shell construction phase.
For many years, decentralised ventilation systems were usually installed only during a later construction phase. The wall opening was subsequently created using core drilling through the exterior wall.
This approach was particularly common because the exact position of the ventilation system was often only determined after the shell construction phase, or because different trades worked separately over time.
Especially in renovations and retrofit projects, core drilling often remains the only practical solution to this day.
The traditional process usually looks like this:
In practice, however, this often creates additional coordination between shell construction, façade work, electrical installation, and ventilation installers.
Especially under time pressure, delayed core drilling frequently leads to unnecessary construction delays.
Despite modern alternatives, core drilling still makes sense in certain situations.
For example:
Core drilling may also remain the most economical solution for special wall structures or individual projects.
In conventional new construction, however, it is becoming increasingly apparent that early preparation during shell construction offers many advantages.
At first glance, core drilling appears straightforward. In practice, however, additional costs often arise that were not considered during early planning.
These include:
Especially in projects with multiple residential units, these factors quickly become a significant cost issue.
Core drilling is often carried out only after shell construction, electrical work, or façade work has already progressed considerably.
This leads to typical construction site issues:
Especially under tight schedules, such situations quickly lead to delays in the construction process.
Core drilling becomes particularly critical once the building envelope has already been partially completed.
Subsequent drilling may cause problems with:
In addition, the risk of untidy transitions or visual inconsistencies on the façade increases.
Core drilling always creates additional effort on site.
Typical consequences include:
Especially in apartment buildings or tightly scheduled construction projects, this additional effort is often underestimated.
Another critical issue is the airtightness of the building envelope.
If the wall opening is only created afterwards, sealing often has to be completed under time pressure. Errors frequently only become apparent during the blower door test.
Typical problems include:
Particularly in energy-efficient new buildings, this significantly increases the requirements for clean and carefully planned execution.
A wall mounting block or wall installation block is a prepared wall duct for decentralised ventilation systems that is integrated into the exterior wall during the shell construction phase.
Instead of creating a core drill opening later through the finished wall, the opening is planned from the outset. The actual ventilation unit is only installed at a later stage.
Especially in new construction, this solution is becoming increasingly common because it simplifies many work processes and fits better into modern construction workflows.
During shell construction, the future ventilation opening can be integrated far more easily than after completion of the exterior wall.
The wall installation block is inserted directly during masonry work and initially remains as a prepared duct inside the wall. This means the position of the future ventilation unit is already precisely defined.
This offers several advantages:
This approach is becoming increasingly attractive, especially for modern new buildings with ETICS or high airtightness requirements.
Depending on the system, a wall installation block consists of a prepared duct including insulation, fixing options, and suitable connections for the future ventilation unit.
This creates a technically clean foundation for later installation already during shell construction.
Particularly important are:
The actual ventilation system is only installed later, once interior finishing and façade work have been completed.
The biggest difference lies in the timing of preparation.
With traditional core drilling, the wall opening is only created later in the finished exterior wall. With a wall installation block, however, the duct is already integrated during shell construction.
As a result, many construction workflows change. Instead of intervening in the exterior wall again later, the building envelope largely remains untouched during final installation.
Especially in larger construction projects, this often ensures a smoother and more predictable workflow.
Wall installation blocks are particularly suitable for new buildings where decentralised ventilation is planned at an early stage.
The solution is especially beneficial for:
The earlier ventilation is integrated into shell construction planning, the greater the practical benefits on site.
Whether core drilling or a wall installation block is the better solution mainly depends on the timing of the planning process. Technically, both variants work. In new construction, however, they differ significantly in terms of on-site effort.
While traditional core drilling is usually carried out at a later stage, the wall mounting block is integrated during shell construction. This is exactly where the biggest differences in the later construction workflow arise.
With core drilling, the exterior wall must be opened afterwards. This creates additional effort on a construction site that is often already well advanced.
Typical issues include:
A wall installation block shifts this effort into the shell construction phase. The wall opening is already prepared, making the later ventilation installation significantly easier.
At first glance, the direct costs of core drilling appear manageable. In new buildings, however, additional indirect costs often arise through coordination, waiting times, or rework.
These include:
Especially when multiple ventilation units are involved, early preparation during shell construction can become significantly more economical.
In modern new buildings, airtightness of the building envelope is becoming increasingly important.
Subsequent core drilling always means additional penetrations that must be carefully sealed. Errors often only become apparent shortly before project acceptance.
If the duct is prepared during shell construction instead, connections can be completed in a much more controlled way. This simplifies preparation for the blower door test and reduces the risk of later corrective work.
Early planning also offers advantages in terms of sound insulation and façade appearance.
The duct can already be integrated to match the wall structure. This often results in cleaner transitions and technically more controlled integration into the exterior wall.
This aspect is becoming increasingly important, especially for high-quality façades or larger residential projects.
Despite the advantages of wall installation blocks, core drilling remains useful in certain situations.
For example:
In conventional new construction, however, it is becoming increasingly clear that early preparation during shell construction is the simpler and more economical solution.
Not every construction project follows the same process. Nevertheless, practical experience clearly shows that wall installation blocks offer the greatest benefits wherever clean planning and efficient construction are priorities.
The earlier decentralised ventilation is considered in new construction, the greater the impact of the prepared solution later on installation effort, construction time, and coordination.
In typical single-family homes, the future position of ventilation units can usually be defined early. This is exactly where the wall installation block demonstrates its strengths.
The duct is integrated directly during masonry work, while the actual ventilation installation takes place later after interior finishing and façade work.
This results in:
Especially for private homeowners, this also avoids the need for later drilling or corrective work.
As the number of residential units increases, so does the effort required for subsequent core drilling.
In larger projects, the following quickly add up:
If ventilation is already prepared during shell construction instead, the workflow becomes significantly more structured. Especially in serial construction projects or repeated floor plans, this noticeably saves time.
Modern new buildings place increasingly high demands on airtightness, energy efficiency, and façade quality.
Subsequent core drilling through finished ETICS façades creates additional effort and increases the risk of later corrective work.
A prepared wall installation block ensures that the duct is already cleanly integrated into the wall structure. This simplifies later sealing and reduces additional interventions in the building envelope.
Prepared solutions also offer advantages on projects with tight schedules.
If the ventilation opening already exists, later drilling appointments and many typical delays on site are eliminated. Final installation of the ventilation system can therefore be carried out much more flexibly.
Especially for contractors, this means:
This is why wall installation blocks are increasingly viewed today as practical preparation solutions on many new-build construction sites — not only technically, but above all organisationally.
In practice, it is not only important whether a ventilation opening is prepared, but also how cleanly this solution can be integrated into shell construction.
This is exactly where the Ventomaxx wall installation block comes in. The system was specifically developed to prepare the later installation of decentralised ventilation systems at an early stage — without additional improvisation on the construction site.
While with subsequent solutions it is often only determined later how the duct can be implemented cleanly, the future ventilation opening is already precisely defined with the Ventomaxx wall installation block.
This particularly simplifies:
Especially with modern wall structures, this provides significantly greater planning reliability.
A major advantage on site is that important technical requirements are already prepared within the wall installation block.
This includes the necessary outward slope of the duct. In decentralised ventilation systems, this is crucial so that condensation can drain away in a controlled manner and no moisture enters the interior.
Additional important aspects are also already considered, including:
This significantly reduces on-site effort and minimises typical sources of error.
The actual ventilation unit is only installed later, but the decisive preparation work has already been completed.
This significantly reduces effort during the final project phase. Especially in projects with multiple units or larger developments, this saves time and simplifies workflows for installers and site management.
Today, many contractors deliberately rely on prepared systems to avoid later additional work. This is exactly what the wall installation block is designed for: a practical preparation solution for decentralised ventilation systems in new buildings — cleanly integrated, planned at an early stage, and easier during later installation.
Traditional core drilling remains a sensible solution for renovations or retrofit installations. In new construction, however, it is becoming increasingly clear that preparing the ventilation opening at an early stage offers many advantages.
Those who already consider decentralised ventilation during shell construction reduce later coordination effort, avoid additional interventions in the finished building envelope, and significantly simplify later installation. Especially in modern new buildings with high requirements for airtightness, energy efficiency, and clean façade integration, more and more contractors are therefore choosing prepared solutions instead of subsequent core drilling. The Ventomaxx wall installation block supports exactly this approach. Through early integration into the wall structure, important installation details can already be considered during shell construction — including the prepared slope for the later decentralised ventilation duct.
This creates a practical solution for new buildings where clean workflows, easy installation, and controlled preparation of the building envelope are the main priorities.
Anyone looking to prepare decentralised ventilation systems cleanly during shell construction will find the Ventomaxx wall mounting blocks to be a practical solution for modern new buildings.
You may also be interested in other English articles from the Ventomaxx Knowledge Hub. Learn more about decentralised ventilation systems for modern buildings, discover practical tips for mechanical ventilation planning, or explore how decentralised ventilation can be seamlessly integrated into modern façades. These articles provide additional insights into energy efficiency, airtight construction, façade integration, and modern ventilation concepts for residential and commercial buildings.
Contact
We provide architects and technical planners tailored solutions to address every ventilation challenge with precision. Whether it is sound insulation, energy efficiency, or optimising facade aesthetics, our expert technical teams are equipped to provide you with the ideal solutions.
With Ventomaxx, you gain access to comprehensive hybrid ventilation concepts that seamlessly combine passive and active systems from a single, trusted source. Our mission is to improve indoor air quality in the most efficient way.
We provide architects and technical planners tailored solutions to address every ventilation challenge with precision. Whether it is sound insulation,
energy efficiency, or optimising facade aesthetics, our expert technical teams are equipped to provide you with the ideal solutions.
With Ventomaxx, you gain access to comprehensive hybrid ventilation concepts that seamlessly combine passive and active systems from a single, trusted source. Our mission is to improve indoor air quality in the most efficient way.
