Adequate ventilation helps prevent moisture problems, especially in spaces that are typically located below ground level, such as crawl spaces, basements and storage areas. When ventilation openings are located below ground level, for example due to height differences around the building or in glass, timber or metal facades, ventilation must be provided through the garden or paved surface. For this purpose, basement wells (koekoeken) can be used.
A basement well is a ventilation solution for applications below ground level. A basement well makes it possible to supply or extract air at locations where ventilation openings are below ground level, without compromising accessibility or functionality.
This type of ventilation solution is used for applications such as:
The basement well is designed as a plastic front box with a fully open rear side. This open rear side provides maximum flexibility when creating the required ventilation opening in the facade, allowing the position and size of the wall opening to be adapted to the specific situation. Basement wells are suitable for installation in paving and are used when ventilation openings are located below ground level.
Tilmar offers several basement well models:
The T174-A basement well is designed for situations where ventilation must be provided from ground level. The T174-A is stackable, making it possible to extend the depth beyond a single window well and to install ventilation in a simple and flexible way. Each extension provides approximately 280 to 410 mm of additional depth. Thanks to the folded edges, the window well is easy to fix in place, simplifying installation.
The T174-B basement well is a more compact version than the T174-A. Unlike the T174-A, this model is less deep and not stackable. The T174-B is particularly suitable for situations with limited excavation possibilities or restricted available depth, for example due to service pipes or projecting foundations. The T174-B is installed with the top edge at ground level and is suitable for applications where ventilation below ground level is required but space is limited. For applications where greater depth or stackability is required, the T174-A basement well is the more suitable solution.
The T175 basement well differs from the T174-A and T174-B models through its higher airflow capacity and is intended for situations where greater ventilation capacity is required. This model is suitable for applications requiring higher air supply or extraction capacity than the T174 series can provide. The T175 basement well is stackable and features an open rear side, allowing connection to larger pipe diameters up to Ø160 mm. This makes the T175 suitable for applications with higher airflow requirements, such as:
The fixing and installation method for the T174-A, T174-B and T175 basement wells is functionally identical. All basement wells are equipped with four fixing holes for mounting to the wall. The grilles are installed using the supplied stainless steel screws. It is recommended to install a gravel bed at the bottom of the basement well so that any water entering the unit can drain into the soil. When installed in paving, it is important that the paving does not slope towards the basement well in order to prevent water from flowing towards the ventilation opening. The rear side of all basement wells is open, allowing the wall penetration to be freely positioned and aligned with the chosen connection.
Differences Between Models
The T175 is larger and has a higher airflow capacity than the T174-A and T174-B, but this does not affect the fixing method. Installation remains functionally identical; the difference lies solely in airflow capacity and pipe diameter compatibility.
Tilmar basement wells are available with different grille types or as a separate basement well box. For both the T174-A and T174-B basement wells, a choice can be made between a plastic grille and a stainless steel grille (also available in black). These versions are the most commonly used as standard. The airflow capacity of the plastic grille is 60 cm² (maximum pipe diameter Ø80 mm).
In addition, these basement wells are also available with black stainless steel or CorTen steel grilles. When these options are selected, the basement well is supplied as a separate box and combined with a grille. The stainless steel and CorTen steel grilles are also pest-resistant. The airflow capacity of the stainless steel and CorTen grilles is 48 cm².
CorTen steel grilles are mainly chosen for aesthetic reasons. Under the influence of weather conditions they develop a natural reddish-brown patina. Note: This natural discolouration may stain adjacent surfaces, and the material is not suitable for prolonged contact with wet leaves or vegetation.
The T175 basement well is supplied with heavier-duty grilles matching the higher airflow capacity of this model. Available options include:
Separate grilles are also available for the T175, allowing a suitable basement well configuration to be assembled for each application, including installations requiring greater depth due to the stackable design. The T175 is supplied as standard in plastic and can be produced in custom colours on request.
For situations requiring a connection through the facade, the T174-A and T174-B basement wells can be combined with the T080 wall tube. This wall tube is a separate PVC duct with a stainless steel spring and makes it possible to install a wall penetration independently of floor level or ground level and at any angle. The T080 wall tube is part of the renovation duct range. More information about renovation ducts can be found on the renovation ducts page.
Specifically for the T175 basement well, a PVC telescopic wall penetration pipe Ø160 mm is available. This wall penetration pipe is suitable for bridging different wall thicknesses and matches the higher airflow capacity of the T175.
In situations where the ventilation opening is required above ground level, a ventilation shaft may be a suitable solution. Further information can be found on the page about ventilation shafts for crawl space ventilation.
T174-A basement well
Suitable when ventilation is required deep below ground level and when stackability and flexibility are desired.
T174-B basement well
Suitable for renovation projects and situations with limited depth or restricted excavation possibilities, for example due to service pipes or projecting foundations.
T175 basement well
Suitable when higher airflow capacity and greater ventilation performance are required.
If you have questions about the correct application or combination with other ventilation products, please feel free to contact us for advice.
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