It’s a common struggle we come across, people love the concept of removing an old metal manhole cover from their lawn and replacing it with a recessed GrassTop cover but measuring the size needed can be tricky.
Firstly you ideally need to take the lid off your existing cover and measure the chamber size below your current lid. Similar to this handy graphic:
The measurement that matters is the actual hole in the ground as this is what you may one day need to access so you can service your drains. The overall size is to a great extent academic.
If for any reason you cant or don’t want to measure the actual opening then just choose a cover with the overall measurement closest to your current overall size. This will also work nearly every time! You might just get away with a smaller cover if you take option #1.
Manhole/drainage access comes in varying styles – don’t worry about what type you have. Be it a square, rectangle or circular riser just choose a cover that will allow you access to the chamber.
You can for example use a 600mm square cover on a 600mm circular riser no problems. Virtually no manhole covers ever match up to the drain, any sealing to prevent smells is done by the backfill soil and cement base you bed the cover onto.
Coming soon is a blog on how to fit the cover! Also daunting but a very simple process – the basics are detailed on our grass top manhole product listings