Manhole Cover Buyer’s Guide & FAQs

Manhole covers explained 

Manhole covers are designed as barriers over openings to underground networks, such as sewers and drainage systems. Manhole covers date back to ancient Roman times and were made from stone. Modern manhole covers are made from materials including cast iron, steel and plastic, each designed to withstand specific loads. They can be made in different shapes, but their purpose remains the same – to provide secure, durable access to underground utilities while protecting the public and infrastructure from hazards. 

Manhole cover benefits

Manhole covers are required because they provide a safe cover for underground utilities, helping to protect the public from harm. Along with enhancing public safety, the other main benefits of manhole covers include secure access to underground utilities and environmental protection. 

Because a manhole cover fits directly into the opening and requires specialist tools to open, trip hazards and collisions with vehicles are eliminated. The cover also prevents people and animals from falling into the opening, and they can be designed to manage extensive load rates from vehicles, meaning they won't collapse under stress.  

The shield-like design also protects the underground system from contamination, such as surface water or large debris that can cause blockages.  

Manhole cover use cases 

The UK’s infrastructure includes sewer systems, storm drains, electrical conduits and telecommunications networks. Manhole covers are used to provide safe and secure access to these underground facilities, allowing maintenance workers to inspect, repair and upgrade infrastructure while keeping pedestrians and vehicles protected from open access points.  

Covers also support traffic loads, making them essential in roads, pavements, industrial sites and public spaces. Manhole covers are used to prevent debris, animals and unauthorised access from entering utility systems, ensuring both operational efficiency and public safety. They are a highly versatile barrier that is critical across urban, commercial and industrial environments. 

Manhole cover shapes 

Most manhole covers will feature either a circular, square or rectangular shape, designed to fit the different manhole openings found across the UK.  

Circular and round manhole covers have a slight advantage over square and rectangular alternatives, as they can be rotated without the risk of them falling into the opening, potentially causing serious injury. In contrast, workers must be careful not to diagonally rotate square and rectangular manhole covers, as these shapes can drop into the manhole itself. While most of the manholes in the United Kingdom are square or rectangular, circular shapes are still found in certain locations. Triangle manhole covers are also used but are less common and typically used for smaller openings. 

Manhole cover sizes

Manhole cover sizes range from 300mm x 300mm to 1200mm x 1200mm for square and rectangular covers, while circular types will measure between 450mm and 650mm in diameter. However, these ranges can differ for specific uses. For example, roadways and pavements will likely have manhole covers measuring 600mm x 450mm, whereas industrial sites will feature larger covers measuring 900mm or more.  

Manhole cover materials 

Cast iron, galvanised steel, stainless steel and plastic are the most common materials used for manhole covers.  

Cast iron manhole covers are the strongest of these and are capable of withstanding loads of up to 90 tonnes. For this reason, cast iron manhole covers are widely used on public roads and highways, car parks and commercial or industrial areas where heavy vehicles and loads are to be expected.  

Galvanised and stainless steel covers are a sturdy, lightweight alternative to cast iron, but as they are only able to withstand weights of up to 17 tonnes, they aren’t suitable for locations where high-volume traffic or heavy loads are expected.  

Steel manhole covers can feature a recessed top, which can be flush-filled with brick or concrete paviours, asphalt, resin-bound aggregate or even grass. This makes them an ideal choice for domestic drives and gardens.  

Plastic manhole covers are made from PVC or polypropylene, which makes them highly resistant to corrosion and chemicals. They don’t have a high load rating, however, so their use should be limited to gardens and paths. 

Recessed manhole covers – how do they differ?

While conventional manhole covers are designed to fit flush with the surrounding surface, recessed manhole covers allow for infilling, so the cover blends into its surroundings.  

A screed cover is only deep enough to be filled with a layer of concrete screed, whereas a block paviour cover will need a deeper recess to accommodate the additional height of block paving or setts.  

A recessed cover may also be used if a manhole is located in a resin-bound drive or a grassed area. Resin-bound aggregates require little depth, but grass will need sufficient room for root growth and to prevent grass from drying out too quickly.  

What is a sealed manhole cover and when is it used?       

A single sealed manhole cover is characterised by a single tongue-and-groove joint that creates an airtight seal between the cover and frame. A single sealed manhole cover helps to prevent foul odours from escaping and water from entering the manhole. 

Double sealed manhole covers feature an additional neoprene rubber seal which, providing there isn’t an accumulation of pressure in the manhole, is better at preventing gases and odours from escaping the manhole. For this reason, a double sealed cover is often used for foul drainage manholes situated within buildings or enclosed spaces. 

How do FACTA loadings differ from cover loadings? 

FACTA (Fabricated Access Covers Trade Association) load test ratings are based on structural engineering calculations for covers which are normally restricted in use in 20mph speed limit zones, as well as more commonly used for recessed covers. Therefore, these cover types are not subject to the same dynamic loads as cast iron manhole covers. 

Cover loadings are based on European Standard BS EN 124, which was the original method of rating the strength of a grating, manhole or access cover. This was revised in 2015 to include annexes that include the various materials used for covers. BS EN 124 calculates the dynamic vehicle loading for fast-moving traffic to ensure that it rates all material types against the highest possible installation requirements. So, on the lower end of the scale, you’ll have manhole covers rated A15 for light traffic, all the way up to D400, which are specially designed to work under loads of up to 40 tonnes. 

How do I select the correct manhole cover size?

Manhole covers are usually sized according to the clear size of the opening. This is so the cover will sit securely across the manhole. It is always considered best practice to select a cover that is a good size match for the manhole and one that covers the location’s load-rating requirements. 

• A cover that is too small may need additional work to the brickwork at the top of the manhole to ensure the cover is held securely in position and unlikely to become dislodged and fall into the manhole. 
• While an oversized cover won’t need this extra work, it could potentially look too large for the location and be unnecessarily cumbersome if access to the manhole is required. 

Is an access cover the same as a manhole cover?

While access covers and manhole covers may look similar and serve a similar purpose, an access cover is used to provide access to smaller utility equipment such as water meters, stopcocks and hydrants. An access cover is generally small and made of aluminium, steel or composite material. 

In contrast, a manhole cover will always be large enough to accommodate an adult body (a manhole’s full name is a ‘man-sized hole’) and is mostly used to access inspection and maintenance chambers for drainage systems and utilities. 

How can I disguise or conceal a manhole cover?

Manhole covers aren’t always placed in an ideal spot on a property and can look a bit of an eyesore in the middle of an otherwise unspoilt driveway or path, lawn or flower bed. 

If you want to disguise a manhole cover in a driveway or path, you can choose one with a recessed top that can be filled with the same blocks or aggregate used for the drive or path. The narrow lip around the recess and the edge of the manhole frame will still be visible, but far less obtrusive than a full manhole cover. 

A recessed lid can also be used to partly conceal a manhole cover in a lawn, although care should be taken to ensure the rim of the recess and the frame edge sit below the level of the turf, helping to prevent damage to mower blades, for example. Another way of hiding a lawn manhole cover is to turf over it entirely. This will only work if the cover is low enough to allow a reasonable depth of soil above it for grass to grow, and you will need to be prepared for your lawn to be disrupted when access to the manhole is required. Whichever of the two options you choose, bear in mind that root depth will be significantly less than that of the surrounding turf, and the grass is more likely to suffer in warmer, drier seasons.  

If you have a manhole cover in a flower bed or border, you may find a black plastic cover is sufficient to let it blend in with the surrounding soil or mulch, particularly if you can conceal it under the branches of a shrub or bush. We have a full guide on how to disguise manhole covers if you need more inspiration.  

Can I build over a manhole cover?

If you are considering extending your property, there may be a manhole somewhere within the space you have allocated for the extension. Building directly over a public sewer manhole is not only prohibited but undesirable, as odours from the sewer will be detectable inside the property. If you are building within three metres of a public sewer, you will also need to obtain a build-over agreement from your local water authority. To protect all sewers from damage, foundations for an extension will need to be kept at a safe distance from the pipes and excavated to a lower level than the pipes.  

If your sewer is privately owned (i.e. serves only your property) and it isn’t possible to redesign the extension to avoid it, local authorities may allow you to install a sealed chamber that will prevent odours from escaping. Bear in mind, however, that should the manhole need to be opened, you will be in for an unpleasant experience until it has been resealed! 

Who is responsible for maintaining and repairing manhole covers?

The responsibility of maintaining and repairing damaged manhole covers depends on where the manhole is located. If it is on your property and forms part of the system used exclusively by your property, then you or the property owner will be responsible.  

If the manhole cover is situated on your property but is on a part of the system that you share with neighbours, it will be the responsibility of your local water authority. Manhole covers situated in public spaces, such as on the pavement or road, will also fall under the responsibility of the local water authority. 

Manhole covers with Drainfast 

We hope you’ve found our full guide on manhole covers helpful and interesting, and that your burning questions have been answered. If you have any other questions to help find the ideal manhole covers to buy, you can call the friendly team of experts at Drainfast on 01420 555600 or email [email protected].