Fitting a new INTERNAL inspection chamber cover

I am fitting a new internal cover to replace an existing cover which is not sealed.

My question is how do I achieve uniform depth to allow cover to be fitted snug and level with concrete floor? Thanks

SparrowHawk99 said:

I am fitting a new internal cover to replace an existing cover which is not sealed.

My question is how do I achieve uniform depth to allow cover to be fitted snug and level with concrete floor? Thanks

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Not quite sure what you mean by "uniform depth" but the substrate does not need to be that uniform, since the bedding mix will take up the space.
You need a recess a bit deeper and wider than the frame that takes the cover. Just bed it down onto a dryish strong screed mix (including sharp sand). Try to make the edges of the recess rough or irregular so the bedding mix locks in. Just wiggle / push the frame down with a straight edge level with the surrounding concrete and smooth off with a trowel.
If its a square cover over a round hole, the corners take most of the weight so make sure they are nice and firm.
And put something in the hole to catch mortar droppings.
If it is a recess tray to take tiles on top, fit it after the surrounding tiles.

In addition to catching the droppings inside the manhole, it is worth wrapping the lid (not frame) in a bin bag before bedding. This keeps the lid clean of any mortar.

Job done.

I filled the hole with bags to catch mortar and rubble because I had to break out 65mm depth (for the cover) + 40mm for a new concrete bed, so around 100mm. I removed the cover completely when fitting the frame to avoid getting dirty.

Sadly I didn't take on board what simonjay said about the tiles, and have fitted the new cover before fitting new tiles, I just hope it won't be to much of a problem ..