The Owner-Builder Network

An easy guide to replacing manhole covers

Manhole covers aren’t exactly sexy, right? I mean, you don’t wake up in the morning saying, “Hey… today is manhole cover day”! So we, the good guys at Drainage Sales UK, are going to make a topic that may be perceived as a little boring, a lot more creative, engaging and interesting.

No, we can’t change the name to ‘person hole cover’! But we have decided to be different and create an infographic to better inform and educate both DIYers and professionals in the drainage industry, as to what to use and why.

Not exactly sexy, but we love 'em anyway!
Not exactly sexy, but we love ’em anyway!

Why replace a manhole cover?

In all likelihood, you will have to replace a manhole cover at some stage. This could be a result of a vehicle load damaging the manhole cover due to its weight, eroded road or pavement surface around it or even rust/age has taken its toll.

All in all, it is imperative that damaged manhole covers are replaced as soon as possible as they can be a serious safety hazard for pedestrians, cyclists and motorists.

Plastic, Iron or Steel?
As detailed in the infographic, you have a choice of three main materials, which each have its own advantages. Traditionally speaking, cast and ductile iron have been the material of choice due to their range of sizes and loading capacities, in some cases up to 90 tonnes; therefore, they are ideal for roads and loading docks that are frequently used by vehicles.

Galvanised steel covers are light, easy to install and have a loading capacity of up to 17 tonnes. Once again, Galvanised steel covers are ideal for roads that are used frequently by lighter vehicles.

Plastic manholes are a modern and popular choice for nearly all new building applications. Not only will they look better in a tarmac driveway but are also good for the environment as they can be recycled at the end of their lifespan.

Inspection chambers
Inspection chambers often referred to as manholes, enable drains to be inspected and cleaned regularly in order to avoid blockage. When replacing manhole covers it’s important to utilise a tape measure to find out the diameter of the chamber, this is especially important for plastic chambers. Once you’ve done that you can purchase a frame and cover to match the size of the chamber (Usually 450mm).

If the plastic inspection chamber is deeper than 1.2m, it’s imperative for safety purposes that a reducer is incorporated to reduce the opening to 350mm. You should always double-check that the frame and manhole cover you plan to purchase fit with the relevant manufacturers’ inspection chamber.

Manhole Cover options
There are two main types of covers to choose from. Standard manhole covers and recessed/ internal manhole covers.

Recessed manhole covers and frames are metal trays that allow you to lay a variety of slabs or block paving. They are easily attainable and eliminate the need for galvanised steel covers, therefore,  they are ideal for patios and block paving; why ruin beautiful patterns and that chic look you love!? Internal manhole covers can also be utilised for use in an extension, garage or conservatory. This incorporates a double seal to ensure no odour escapes.

When installing a manhole cover and frame you need to remove the material around the old frame to ensure your level and bed the new frame in, backfilling around it and eventually installing the cover. View the infographic to guide you.

(If you are viewing this on a mobile device, clicking on the infographic will open it in a new, larger window.)


OK, so we haven’t exactly dressed our manhole covers in lingerie, but we do hope that we’ve been able to ‘lift the lid’ on your options. If you have any questions or need more personalised advice please visit us Drainage Sales!


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