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Manhole Covers FAQ

A Guide to Manhole Covers


Manhole (or inspection) covers can be found everywhere you go every day, from roads to warehouses, swimming pools to local parks, patios to restaurant kitchens, gardens and driveways. They come in a variety of shapes, sizes, weights and applications. This guide will provide a quick, simple explanation of manhole covers and how you can determine which one is required for the job.

Types of Manhole Cover

Manhole covers are generally split into three main categories:

  • Recessed
  • Solid Top (Flush)
  • Cast & Ductile Iron

Recessed covers have an inset tray which is used where tiling, block paving or any type of infill is required, leaving only a few millimetres of the frame visible.

Flush (or solid top) covers have fitted flush with the ground and the entire product is visible when installed.

Cast and ductile iron covers are the same as flush covers, but there is also a sub-category of gully gratings. An example of these would be your typical kerbside grating.

Choosing the Correct Manhole Cover

  1. Measuring the Correct Size

The most common mistakes made with manhole covers come with the measurements. Within the entire industry, manhole covers are measured based on their clear opening size. This is the aperture size that is left when the cover is removed from the frame, as shown in the diagram below:

Base copy







The clear opening size is equivalent to the size of your chamber. It is not uncommon for people to measure the overall size of an existing manhole cover, but we strongly advise against this as manhole covers can have the same clear opening and different overall sizes.

It is also important to know the total cover or internal tray depth, depending upon the type of manhole cover you require.

Q. Can I fit a square manhole cover into a round chamber?

A. Yes, there are a select few manhole covers which are square-to-round, meaning they will fit square or round chambers. These covers are the T1G3, CLKS 450SR/46SL, CLKS 450SR and 300SR.

Q. I have a heavy traffic manhole cover but it has been broken by a forklift, why?

A. Forklifts have solid wheels which apply pressure differently to standard pneumatics and therefore covers must be specially adapted to suit this.

Q. I installed a recessed manhole cover in my garden, filled it with grass but it’s just dying; what can I do?

A. We produce bespoke GrassTops which feature drainage holes and geotextile membranes, allowing the water to drain through and your grass to grow. These are also suitable for other infill materials such as chippings, gravel and suchlike.

Q. I’ve measured my clear opening size but none of your covers match it, can you offer anything?

A. It’s likely that your cover is quite old and in imperial measurements which are no longer manufactured. However, we can offer bespoke solutions with manhole covers made to the specification you require.

Q. The project I’m working on requires a manhole cover with a quality finish, what’s available?

A. Naturally, galvanised steel of black polypropylene aren’t always ideal, and so we offer brass or stainless steel edging, as well as complete stainless steel covers.

Q. Odours are coming through where I have installed my manhole cover, why?

A. Your cover must be sealed and locked, or neoprene sealed, so you would require a T-Range Cover, or if you require a solid top, a selection of the PC range (e.g. PC2BG3, PC6CG3, not PC2BG) are suitable.

Q. I need access through my manhole cover on a regular basis, is this possible?

A. Yes, the majority of covers have built-in lifting keys, and for those that don’t we also supply lifting keys. However, the best way to obtain easy access is to have a bespoke, hinged manhole cover. We also offer spring and gas assisted lifting.

Our highest priority is the innovation and development of new and existing products with a continued dedication to the highest standards of quality and customer service. With an ever increasing focus on environmental issues, our Research & Development Team support the launch of a growing number of new products to the industry with many products independently certified to British, European and International standards.

Alongside our standard product portfolio we have the capability and capacity to create bespoke, individual products as well as component parts. If you are interested in this service please contact one of our sales team to discuss your requirements. We also have the facilities to carry out product development and testing on your behalf. Costs for this may be applicable, but could be waived if manufactured by us and the item is purchased.

Delivery lead times for stock items are 3 to 5 working days and we offer a 1 to 2 working days express option.

Follow us on Twitter via @EcoGridLtd. For any enquiries contact or call 0151 639 4281.