John,
Expert in Metallurgy and Precision Cutting
The John Tip: choosing the right inspection cover
A poorly sized inspection cover is a headache waiting to happen: it jams, it rattles, or worse, it fails under the load it was meant to carry. At John Steel, we manufacture every cover to order from your exact opening measurements. Non-slip steel is ideal for pedestrian and vehicle areas, treaded stainless steel resists wet and chemical environments, and non-slip aluminium offers the perfect balance between lightness and strength. Square and round formats cover the vast majority of drain, manhole, and ventilation openings.
Load classification is a criterion many people underestimate. A garden cover handles up to 150 kg, while a road cover must support several tonnes. Failing to specify the load class means risking a cover that deforms under weight. We offer covers suited to every use: from pedestrian gardens to industrial areas, including driveway access.
💡 Pro tip: always measure the inner dimensions of your opening — that means the clear void of the drain, not the rim. Allow a 5–10 mm margin over the opening for the frame housing. Send us your measurements in millimetres and the desired load class, and we'll take care of the rest.
To order, use our online configurator or contact us directly with a drawing of your opening. Every piece is laser-cut and fabricated in France in our workshop.
Selecting a cover or plate depends on three technical criteria: the material, the load capacity, and the exact dimensions of the manhole, whether for drainage, rainwater, or utility networks. John Steel provides custom-cut steel, stainless steel, or aluminium covers and plates for applications where standard commercial cast iron or concrete covers are unsuitable.
Which material to choose for a custom manhole cover?
Cast iron, concrete, or glass-fibre reinforced composite covers are standard for public roads with regulated loads. For private, residential, or semi-professional use, custom metal offers a lighter, more adaptable alternative for non-standard dimensions.
Steel tread plate: strength for heavy traffic
Steel tread plate is the most load-resistant material for repeated traffic. Its raised pattern provides slip resistance, making it ideal for manholes located in vehicle access areas or garage entrances.
Stainless steel tread plate: corrosion resistance for semi-heavy traffic
Stainless steel tread plate combines mechanical strength with corrosion resistance, perfect for manholes exposed to moisture or runoff. It is suitable for semi-heavy traffic, ranging from intensive pedestrian use to light vehicles.
Non-slip aluminium: lightweight for light traffic
Non-slip aluminium is the lightest of the three materials, making it easy to remove and replace for frequent maintenance. It is intended primarily for pedestrian or light use, both indoors and outdoors.
What dimensions and load capacity for a drainage cover?
Standard covers fit fixed sizes in 10 cm increments. When a manhole has non-standard dimensions (round, square, or rectangular), custom cutting is the only reliable way to ensure a flush fit.
Pedestrian and light use
For garden, patio, or domestic pedestrian areas, a thin aluminium or stainless steel plate is sufficient to support the expected load.
Vehicle traffic and semi-heavy use
Access areas for light vehicles require greater thickness and materials like steel or stainless steel tread plate.
Non-standard cases: the advantage of custom cutting
For manholes in pavements, car parks, or pedestrian zones with atypical shapes or off-catalogue sizes, custom cutting allows for exact dimensions to achieve a precise fit, such as a square steel tread plate cover manufactured to specific measurements.
Installation, sealing, and maintenance of a custom cover
Installation and sealing
Installation follows the same principle as a standard cover: position it on the existing frame, leaving a few millimetres of clearance for metal expansion. The tread or non-slip finish protects the opening and enhances safety around the manhole.
Maintenance by material
Stainless steel and aluminium require little maintenance beyond regular cleaning. Steel tread plate, which is more prone to oxidation if deeply scratched, should be inspected after intensive use or prolonged exposure to moisture.
