Outdoor Chambers & Covers

Choose the right outdoor chambers and covers for your property

A well-designed system of outdoor chambers and covers diverts surface water and groundwater quickly and safely, while ensuring easy access for future flushing and inspection. When selecting the right components for your groundworks project, it is important to consider soil conditions, load requirements, and pipe dimensions.

Common types of outdoor drainage chambers and their applications

Different ground zones place varying demands on water collection and filtration:

• Stormwater and gully chambers: Placed in open areas, on driveways, or at downspouts to manage rainwater and surface runoff. They are often equipped with sediment traps (silt traps) that capture grit and sludge before the water is directed into the stormwater network.
• Drainage chambers: Installed in conjunction with the building foundation's drainage pipes to collect groundwater and divert it away from basement walls and floor slabs.
• Inspection and flushing chambers: Vertical shafts providing direct access to underground drainage and sewer lines for regular cleaning, clearing, and camera inspections in the event of blockages.

Load classes and cover selection

The cover assembly—comprising the frame and the lid—forms the surface layer at ground level and must withstand the loads to which the surface is subjected:

• Pedestrian and garden areas (A15): Lightweight covers made of plastic or ductile iron, suitable for green spaces, walkways, and patios where there is no vehicular traffic.
• Driveways and passenger car traffic (B125): More durable covers designed to withstand passenger cars on residential driveways and private parking areas.
• Heavier vehicle traffic (D400): Robust cast-iron covers for areas with frequent or heavy vehicular traffic.

Key factors to consider before purchasing

• Trafficability: Ensure the cover is rated for traffic if the manhole is located near a garage driveway or turning area.
• Telescopic function: Telescopic covers and sealing sleeves facilitate height adjustment to the final ground surface—such as when paving with asphalt or stone—and reduce the risk of damage caused by ground settlement.
• Dimensions: Carefully match the inner and outer diameters of the cover and lid to the dimensions of the manhole riser pipe (typically 315 mm, 400 mm, or 600 mm).
• Strainers and grates: For areas where leaves and debris accumulate, dome strainers or grate lids are recommended; these allow large volumes of water to pass through without becoming clogged.