Go get your tape measure, we are doing this now!
All manhole covers have a tray and a frame with a certain amount of thickness, which means their inner and outer sizes will be different. Instead of measuring from edge to edge with products like tiles or paving stones, you need to know measurements from different parts of a manhole cover to ensure they will fit your need.
Measuring a Manhole Cover
When it comes to manhole covers, Alusthetic describes the size by their clear opening size (See the image on the right). For example, our Aluminium Double-Sealed Recessed Manhole Cover has 9 sizes available. They are specified as 300mm x 300mm or 600mm x 450mm, which always refers to the clear opening.
However, they also have depth options available. When the manhole cover is specified as 60mm or 80mm overall depth, it refers to the depth of the manhole cover measuring from the outside.
Decide the Manhole Cover Size You Need
We would recommend having the clear opening size the same as the hole on the ground so that the manhole cover can fit nicely and cover the hole completely.
Having said that, we do understand customers might not be able to find the exact manhole cover size that fits the hole. There are a few solutions to this. The first option is to order a bespoke cover, that way the manhole cover can have the exact size you need. The second option is to amend the hole to fit the manhole cover you are going to buy. And the third option is to find a manhole cover that has the closest size to the hole but make sure the clear opening size is bigger than the hole itself.
If you want to choose option three, ensure the surface is flat for the manhole cover to be placed on. You might have to recess the ground a little to fit the manhole cover, so it won’t stick up over the surface.