Nederlands 
Deutsch 
Français 
If you have questions or would like advice about crawl space ventilation, please contact us. More information about these products can be found on the crawl space ventilation category page.
The crawl space is a structural space beneath a building that plays an important role in moisture management and in preventing long-term problems. Adequate crawl space ventilation contributes to improved moisture control and helps prevent moisture-related issues.
Under the Dutch regulations the crawl space is considered a structural space for which no specific ventilation requirements apply, meaning it falls outside the conditioned building envelope. In new construction, the focus is on making the ground floor airtight and watertight in order to prevent moisture and harmful substances from entering occupied spaces. The same principle applies during renovation and when insulating occupied areas.
However, good crawl space ventilation is strongly recommended to prevent problems related to moisture management, mould growth, and unwanted gases. Proper crawl space ventilation creates a drier and better-ventilated space, preventing moisture accumulation, mould growth, and unwanted gases and odours. This benefits the building structure and contributes to safer maintenance conditions.
To achieve air renewal and proper airflow, ventilation openings should be provided in at least two different facade elevations. Ideally, these openings should be located in two opposite facades.
Based on this principle, general guidelines apply for the minimum ventilation opening area, depending on the floor construction:
Calculation example
A dwelling measuring 5 metres wide and 10 metres long has a ground area of 50 m² (5 × 10 m). In this case, the crawl space has the same area of 50 m².
For a dwelling with a timber floor construction, this means: 50 m² × 4 cm² = 200 cm² required ventilation opening area. This ventilation opening area should be distributed across at least two facade elevations. Ideally, it is evenly divided, resulting in 100 cm² in two opposite facades.
For a dwelling with a masonry or concrete floor construction, the requirement is: 50 m² × 2 cm² = 100 cm² required ventilation opening area. Ideally, this is also evenly distributed across two opposite facades, resulting in 50 cm² per facade.
If all ventilation openings are provided in a single facade, no effective airflow will occur. It is therefore recommended to distribute the ventilation openings evenly. When one facade has less ventilation capacity than the other, the facade with the smallest ventilation opening area determines the total ventilation capacity.
Various crawl space ventilation solutions are available, ranging from new construction applications to renovation projects, and from facade-based ventilation to ventilation through the garden or ground surface.
For new construction projects where crawl space ventilation is integrated during the building process, Tilmar offers the following solutions:
These products can be combined with the T172 stainless steel built-in tray, creating a durable and neat facade detail.
For existing buildings and renovation projects, Tilmar offers crawl space ventilation solutions that allow existing openings to be repaired or improved. These products are suitable for restoring or replacing existing ventilation openings without extensive demolition work:
When ventilation openings are located below ground level, for example in deep crawl spaces or where there are height differences around the building, ventilation is often provided via the garden or paved surface. In these cases, basement wells are used. Products in this category include:
In situations where the ventilation opening is required above ground level, for example to improve airflow or provide additional protection against rainwater, a ventilation shaft can be installed. This solution is suitable for both new construction and renovation:
If you have questions or would like advice about crawl space ventilation, please contact us. More information about these products can be found on the crawl space ventilation category page.