FloPlast Underground Drainage Square Blank Cover Grid – 150mm x 150mm (D508)

Access Chambers are installed close to a house, usually on a path or patio near to the top of the drain so they ONLY have the option of a light-duty lid for pedestrian areas such as patios and paths (A15 Rating).

Only a 450mm Inspection Chamber should be used on a driveway or high foot traffic area, and the appropriately rated lid must be used to comply with The Building Regulations.

Inspection Chambers are a very important part of an underground drainage system, they provide access for testing and inspecting, as well as clearing blockages.

There are different types of inspection chambers, each with its own intended use and placement, depending on circumstances such as location, depth and foot or vehicle traffic. We’ve created a quick guide below:

Access Chambers

Access Chambers, often referred to as mini or shallow access are used close to a house, and near to the top of the drain, so they’re not fitted deeper than 600mm (0.6m) and have a diameter of 300mm. They provide easy access for inspection and equipment.

*Access Chambers ONLY have the option of a light-duty lid for pedestrian areas such as patios and paths (A15 Rating).

Inspection Chambers

Inspection Chambers are a larger version of an access chamber, usually with a diameter of 450mm to 600mm, enabling them to be installed further away from a house, and to a maximum depth of 1200mm (1.2m). They tend to also have more branches feeding into them.

Inspection Chambers a more versatile so have a choice of compatible lids rated for different applications, for example, driveways etc.

Manholes

Manholes are larger than access and inspection chambers as they’re designed to be big enough for maintenance staff and equipment to enter the drainage system, they’re usually deeper than 1 metre and wider than 600mm x 900mm and lead to the sewer. They’re kept sealed and not accessible to the public.

Mini Access Chambers (300mm Diameter)

Mini Access Chambers can be used effectively to a maximum depth of 600mm (0.6m), this is simply due to their narrow width. However, as they’re supposed to be installed near the house, they’re close to the top of the drain.

Standard Inspection Chambers (450mm Diameter)

Due to them being wide enough for a child to fall down, Standard Inspection Chambers have a maximum permitted depth of 1200mm (1.2m).

*Using an inspection chamber deeper than 1200mm: In the rare instance that a deeper inspection chamber is required, then a 350mm Chamber Reduction Ring must be used, under these circumstances the maximum depth would be 3000mm (3m).