Cutting out part of chimney breast

[Hager]

Hi,

Sorry i know this has probably been discussed many times but....

I have a chimney breast in my bedroom that i want to open up a little so i can put some shelves in it.

The chimney is 1370mm wide and 2470mm high, i would like to cut a 900x900mm square out of it about 800mm from the FFL.

The question is what sort of lintel (if any) do i need? Would prefer to over engineer this just to stay on the safe side.

 

[big-all]

if you have a fireplace below it will run up one side or the other or maybe behind
it is also possible the person that backs onto you will share some off the space