Manhole/drain access cover terms – what you need to know before you buy.

What do I need to know before I purchase a manhole/access cover?

To complement our previous weeks blog on how to measure for a new/ replace an old access cover we have compiled a list of terms associated with man hole covers that might need a bit more explanation.

Obviously we are always on hand to help with any measurement issues or queries about our ranges feel free to call our friendly team on (0151) 515 1415 avaliable 9am-5pm Mon-Fri.


Manhole cover – A removable plate that covers an opening enough for person to pass though.

Flush – A flush or solid top cover fits into the ground at the same level as the other flooring surface and is fully visible when installed

Recessed – A recessed cover has an inset tray used to hold infill e.g. paving to blend with flooring choices. This leaves only the edge of the frame visible when installed.

Overall size – The measurement of the manhole cover and frame.

Aperture – Hole or opening.

Clear opening size – The aperture size once the cover has been removed from the frame. This is the standard way manhole covers are sized on purchasing.

Double sealed – Manhole cover has 1x neoprene seal and a T neoprene seal.

Triple sealed and locked – Manhole cover has 2x neoprene seals and a neoprene T seal. This cover also can be screwed down and locked into place. Not just help in place by infill as with double sealed examples.

Infill – The material e.g. blocks used to fill the recess part of the cover.

Grass recessed manhole cover – Recessed cover with specially added membranes and drainage to allow grass to be grown. Allowing a stylish way to cover any flush and visible manhole covers in grassed or decorative areas of the garden.

Class A – 2.5 tonnes loading

Class B – 5 Tonne loading or slow-moving wheel load of 1.25 tonnes

Class C – 10 tonne loading

Inspection Chamber – An area where a branch pipe meets a main drain. Usually circular cover. You will need to measure the diameter of the chamber before selecting a new cover and frame for this type of access.

Loading class – The max weight that a manhole can take varies with the type of cover be sure you have the correct amount of loading for your needs.

Cast Iron – Black cast Iron covers take a heavy load and work best in high loading areas e.g roads

Aluminium – Interior and exterior within the home has aesthetic look. Polished silver appearance.

Stainless steel – Up to 10 tonnes loading/ heavy pedestrian access.


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