Manhole cover sizes and load classes are all dependent on their application. If you’re installing a new manhole cover or you’re replacing an existing one you’ll need to measure the space to ensure you get a perfect fit. If your manhole cover doesn’t fit perfectly then you can compromise the structural integrity and it could fail, regardless of the load class.
How do you measure manhole cover size?
Manhole covers need to sit comfortably over the hole they’re covering so you need to measure the inside dimensions of the hole, not the manhole cover itself. This measurement must be taken in millimetres for accuracy because that’s the standard unit for manhole cover manufacturers. Once you have this measurement you can browse for manhole covers.
Use our table below to work out which product suits your application or contact our helpline to determine which manhole cover will be the best fit for your project.
Manhole cover sizes
Manhole covers come in sizes from 300mm x 300mm to 1200mm x 1200mm in square and rectangular sizes from manufacturers such as Wrekin, EJ , ACO and Clark Drain.
Circular manhole covers with 450mm and 600mm diameters are also available from EJ.
Cast iron manhole cover weight classes
Cast iron manhole cover weight classes follow the same system as channel drains.
| Class | Max. weight load (tonnes) | Uses |
| A15 | 1.5 | Very light duty for pedestrian areas like gardens, patios and driveways |
| B125 | 12.5 | Domestic driveway thresholds for family cars, vans and 4x4s |
| C250 | 25 | Lightly trafficked roads and small private car parks |
| D400 | 40 | Main roads, highways and high traffic areas like public car parks |
| E600 | 60 | Industrial estates, loading bays and cargo handling yards |
| F900 | 90 | Docks and airports, extreme heavy duty applications |
Steel manhole cover weight classes
Steel manhole cover weight classes are slightly different because steel is not as strong as cast iron. Keep in mind that there is also more than one type of steel manhole cover, including galvanised steel manhole covers, stainless steel manhole covers and BSP steel manhole covers.
The table below should help you work out which is best for your application. If in doubt, go a class higher than you think you may need.
| Max. weight load (tonnes) | Uses |
| 2.5 | Very light duty for pedestrian areas like gardens, patios and driveways |
| 5 | Domestic driveway thresholds for family cars, vans and 4x4s |
| 10 | Lightly trafficked roads and small private car parks |
| 17 | Main roads, highways and high traffic areas like public car parks |
| 25 | Industrial estates, loading bays and cargo handling yards |
| 38 | Docks and airports, extreme heavy duty applications |
Types of manhole cover
Ductile Iron
Ductile iron manhole covers are strong, resilient, heavy-duty covers that are predominantly used over a D400 class. Ductile iron, also known as cast iron, is used because it has great strength. This material then lends itself to a long life span for installation in airports, docks and other heavy-duty industrial areas.
Recessed
Recessed manhole covers are covers that have essentially a cut out in the tray so that brick paving, cement, and screed can be installed. This allows the recessed manhole cover to blend in with its surroundings which is useful in pedestrianised areas where the aesthetics matter. It’s also a good solution for internal manhole covers in hospitals and workshops as well as for domestic gardens where homeowners don’t want an unsightly but mandatory manhole cover sticking out.
Solid top
Solid top manhole covers are designed to be prominent on the floor. These are typically installed in areas where seeing a manhole cover would be more beneficial (to safety and to regular maintenance) than it would to hide them. A solid top is often a visible silver manhole cover with an anti-slip surface. Sometimes they may be raised too, again this will depend on where they are installed. The contrast between the solid floors and the solid top manhole covers makes them easy to identify.
Want to learn more about manhole cover replacement and how to disguise one? We have a dedicated guide for that explaining various ways to keep that manhole cover out of sight, including how you can utilise artificial grass and more.
