Manhole / Inspection Cover

Hi there. New here so hope some of you can help.

My garden is currently in two levels and I want to raise the bottom half so it is all one level. However in the middle of the lower half we have a rectangular man hole cover, so I need to raise this up. It only needs to be raised about three inches.
Do I need to get the local authority to do this or can I do it myslef. If so, are there things out there you can buy, like a collar to fit over the exisiting hole? I have not seen anything around.

Its so tempting to just cover it over with soil!!!

 

Don't cover it!

One question is who does it belong to? It may well belong to you. I have three and have been told they belong to me and don't belong to the water board until the drain reaches the road.

Its not a difficult job - if you are relative handy. I have done it, but I wouldn't try it if you don't feel capable. In my case, the top layer of bricks were loose so it badly needed doing. The question of an extension piece didn't arise. Note the relative position of the bricks, the metal frame and the sloping cement around the top, because you will need to redo it the same way.

Mine was loose so the metal frame could be lifted off quite easily. The whole operation was extremely simple, but the key part was to not drop anything down into the drain. So do it slowly and very carefully, holding one hand under to catch the bits as you work with the other hand. Small bits of old loose material might be washed away by the flow of water. But any cement dropped could stick to the side and will solidify even underwater. A lump of cement will interfere with the smooth sides of the drain and could impede solid material and cause a blockage.

I removed all the loose bricks, using a hammer and chisel, until I had a sound foundation. I then replaced the bricks using mortar in the same way that you would if you were building a wall. To make it higher I just laid an extra layer of bricks. I used ordinary house bricks ( you can get them from a builders yard) as they will be well away from the water level. I then put a layer of mortar on the top and laid the metal frame on that. Then added mortar around the side to give it a smooth professional looking finish similar to how it was before.

 

Have to agree with Peter.

I have done the same job a few times myself and it is relatively simple. Just remember to make sure you have everything you need to do the job before you start. You can even buy ready mix mortar from places like B&Q or Focus. You won't need very much to do it.

Just one other thing. Use a hose pipe to flush out both directions of the pipe. Then scrunch up a few plastic bags and block both ends of the pipe while you do the job. If you do drop anything you won't have to worry where it has gone and it will be much easier to recover it.

DON'T FORGET TO UNBLOCK BOTH ENDS OF THE PIPE WHEN YOU HAVE FINISHED!

Chopper.

 

lift the cover and see what is made of, either brick, concrete sections or plastic risers. All are easy enough to raise the height on. The concrete sections are usually available from large builders merchants as are plastic riser extensions.

If its brick then use an engineering brick and lay them on 3-1 mortar, put some plastic or a board inside the manhole to prevent any mortar falling in. Bed bed the frame on a thinnish bed of mortar and make sure its level.

With some of the more modern light weigh frames that are made of plastic with a thin galvanized cover it pays to screw and plug the plastic frame down as well as bedding it on mortar as the plastic doesn't bond very well to the mortar

Do not cover it, you'll rue the day you did if you get a blockage.