I'm looking to put a new door way into my kitchen which would be through a supporting wall. Before I would be to fork out for a structural engineer etc. Does anybody know what the requirements are regarding a minimum brick nib size on the end? I know there should be a 6 inch overlay for any lintel, but what about the width of the column of brick itself? I'd probably just undertake the work myself as I've done this before. I can probably get away with a 400-450mm nib for what my intentions are with the rest of the room, but wandering if this would be too narrow? To make room for a 762mm door, would a knock through of 800mm allow enough room for frames etc? I've attached pictures to show where the door would be. With the pink arrows showing where the nib would be left.
For a 762mm/30" door you would add on about 75mm/3" for the lining plus tolerance for fitting, cut the lintel opening out first via stitch drilling, it would be wise to remove the plaster around where the new lintel is to go first before drilling, then check what the wall is constructed from, if bricks it should be fairly straightforward to remove them quietly and mortar new concrete lintels in. If it's a random rubble stone wall, then that's a different kettle of fish and it would be wise to get a builder in.
Thanks for the info, a 6"x4" lintel should be more than enough? It's just a single skin of brick. Any ideas about the minimum thickness of the brick column to support the far end?
Is there a standard concrete lintel for this application that is widely accepted by building control?
No each load bearing walls is different and any calculations would be needing to be give from a structural engineer based on the load its supporting. The works will also need to be signed of by building control, this is the home owners responsibility not a builders