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Modern construction focuses on achieving maximum airtightness. While this is desirable in living spaces, a “thermos garage” can become a trap. Water vapour condensation in the garage is a phenomenon that not only affects the appearance of the door, but above all threatens the building structure and the operational reliability of the drive system. Understanding how a sectional door can become part of an effective ventilation system is crucial for ensuring the long-term durability of the investment.
Key Information at a Glance
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The appearance of water on the door leaf is a result of the physics of air and temperature differences and usually indicates insufficient ventilation, not a lack of airtightness in the door itself.
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Excess moisture leads to corrosion of mechanical components, can cause short circuits in the drive electronics, and promotes the growth of mould and fungi.
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Through the use of ventilation grilles and sealing systems with controlled air infiltration, the door takes on an additional role in the building’s air exchange system, beyond its primary protective function.
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In unheated garages, continuous ventilation is essential, whereas in heated garages, the ventilation function integrated into the drive system is the optimal solution.
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The best results are achieved through a combination of door ventilation, an unobstructed gravity ventilation duct in the building, and the regular removal of water and snow brought in by the vehicle.
Condensation in the Garage – Why Does a Sectional Door “Cry”?
Water droplets on the inside of the door leaf worry many owners, who often suspect a lack of product tightness. However, the real cause lies in the physics of air.
As the largest external closure of the garage, the sectional door is particularly exposed to temperature differences.
The Physics of the Dew Point: Where Does the Moisture on the Inside of the Door Leaf Come From?
The key concept is the dew point, the temperature at which air can no longer hold water vapour in its gaseous state, causing it to condense into liquid water.
How the Process Works
When warm, humid air (for example, after parking a wet vehicle) comes into contact with the cold surface of the door panels, the boundary layer cools rapidly and condensation occurs.
Moisture Balance
After rain or snowfall, a vehicle may bring several litres of water into the garage in liquid or solid form. Without adequate air exchange, the relative humidity can quickly rise to 80–90%. If the temperature of the door leaf is only a few degrees below the ambient temperature, the door may immediately begin to “cry”, forming visible condensation.
Consequences of Poor Air Circulation – From Corrosion to Mould Growth
Persistent moisture in a garage is not just an aesthetic issue. The consequences of insufficient ventilation can be costly:
1. Moisture and Condensation
Moisture settles on torsion springs, guide tracks, and hinges. Even galvanised steel can oxidise under continuous condensation. High-quality galvanised steel also has its limits. With constant exposure to moisture, the zinc coating gradually deteriorates, leading to rust formation.
Corroded springs become brittle and are far more prone to sudden failure during operation, increasing the risk of door blockage. In addition, the increased friction caused by corroded rollers places the drive system under a greater load, shortening the service life of the entire operating system.
2. Damage to Electronics
Sectional door operators, typically mounted beneath the ceiling, operate in the area where the highest concentration of moisture accumulates. Moisture entering the housing condenses directly on circuit boards and electrical connectors. This creates unwanted conductive paths, which can lead to short circuits and control system failures.
3. Biological Hazards
Dark, damp corners of the garage, especially around bottom and side seals, provide ideal breeding grounds for moulds and fungi such as Cladosporium and Aspergillus.
This becomes particularly critical when the garage is integrated into the structure of the house. Fungal spores can easily enter living spaces through internal doors, contaminating indoor air and potentially causing allergic reactions and respiratory problems.
Technical Solutions from Krispol: How Can a Door Support Ventilation?
As a leading supplier of door and gate systems, Krispol offers solutions that enable a door to evolve from a passive barrier into an active component of a building’s moisture control system.
Today, a ventilated sectional door is a standard solution in facilities with elevated humidity levels.
Ventilated Profiles and Ventilation Grilles: Precise Airflow Control
The simplest and at the same time most effective way to prevent condensation in a garage is the installation of ventilation grilles directly in the door panels.
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Adjustable ventilation grilles
These allow users to close the airflow during severe frost and open it during transitional periods with high humidity. -
Strategic positioning
The best results are achieved when ventilation grilles are installed in the bottom door panel, while an exhaust ventilation duct is located on the opposite side of the room. This creates a natural chimney effect that improves air circulation.
Profile Geometry and Water Drainage: Engineering Solutions Against Door Leaf Moisture Penetration
Modern door panels are designed so that condensation does not accumulate in the panel joints.
Specially shaped edges direct water droplets outward or channel them in a way that prevents them from penetrating the polyurethane foam core. This is crucial because waterlogged insulation loses its thermal performance, which further intensifies the condensation problem.
How to Choose the Right Ventilation System for Your Door?
There is no universal solution. The appropriate approach to moisture control in a garage depends on the thermal characteristics of the building.
Heated vs. Unheated Garages: Different Strategies for Moisture Control
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Heated garage
In this case, it is essential to keep the temperature above the dew point while ensuring mechanical air circulation.A door with permanently open ventilation grilles may result in energy losses. Therefore, automatic door ventilation (partial opening provided through the drive system’s ventilation function) is the recommended solution.
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Unheated garage
Here, the indoor temperature is usually close to the outdoor temperature. The main objective is to balance humidity levels.Ventilation openings in the sectional door are indispensable in this situation and should operate continuously.
Site Analysis: How Does the Surrounding Environment Affect Garage Humidity?
Garages located in low-lying areas, in regions with a high groundwater table, or on the north-facing side of a building are particularly susceptible to moisture-related problems.
In such locations, passive ventilation may not be sufficient. In these cases, it is worth investing in a door with a lower U-value (better thermal insulation). This helps keep the inner surface of the door warmer, effectively reducing the risk of reaching the dew point and, consequently, condensation formation.
The Role of Professional Advice in Creating a Dry Garage
Choosing the right door configuration should take place already during the planning stage or before ordering the garage door system.
A Krispol technical advisor can calculate the required airflow rate and select the appropriate number of ventilation grilles to ensure compliance with building regulations (for example, 1.5 air changes per hour in garages equipped with a ventilation duct).
It is important to note that the door is only one part of the overall system and must work together with the building’s natural (gravity) or mechanical ventilation.
FAQ – Frequently Asked Questions
1. Why does water appear on a new sectional door?
The appearance of water (condensation) usually indicates excessive airtightness of the garage space and insufficient ventilation, rather than a defect in the door itself.
Modern doors are highly insulated and airtight, which prevents the natural air infiltration that was common with older types of garage doors.
2. Does a door with ventilation grilles make the garage colder?
Ventilation grilles cause a controlled heat loss. Therefore, this solution is primarily recommended for detached and unheated garages, where the main objective is to balance humidity levels with the outdoor environment.
The repair costs associated with mould growth and corrosion damage resulting from excessive moisture in an overly airtight garage are generally significantly higher.
3. What are the most effective measures against moisture in the garage?
The most effective solution is an efficient and properly functioning ventilation system, which in practice is achieved through the combination of three factors:
- Using a door with ventilation openings or a micro-ventilation function.
- Maintaining an unobstructed gravity ventilation duct in the wall.
- Removing snow and water from the garage floor after bringing the vehicle inside.
4. How Much Air Should a Door Allow Through?
The required air permeability depends on the individual requirements of the investor and the design assumptions of the building.
For example, regulations for unheated garages often require ventilation openings with a minimum total net area of 0.04 m² per parking space.
With Krispol sectional doors, this requirement can be easily achieved through the appropriate selection of ventilation grilles.