Need to install a door in a concrete block wall. The wall is not load bearing but is about 12′ in height. will be cutting an opening for a 3/0 x 6/8 steel door. I have been told that I will need to install a lintel in the wall, and the the lintel should extend 6″ on either side of the opening. Was also told that the opening would temporarly support its self as the only blocks needing support are the first few courses above the opening as the rest of the load is carried by the blocks to the side of the opening, kind of an arch effect?

What I plan to do is to saw out the mortar around the blocks to be removed for the lintel, remove the existing block, install the angle iron lintel and replace the blocks taken our with 4x8x16 blocks laid up on either side of the lintel, let the mortar set, then saw out the balance of the opening. Am I over looking anything? is the advice I have been given sound, and any additional suggestions would be appreciated.

“Am I over looking anything?” Yes
“is the advice I have been given sound,” No
“and any additional suggestions would be appreciated.”

The building wall you are intending to alter, was designed with a particular re-bar schedule and you will probably cut at least two horizontal and possibly the same number of vertical.

And by the way, the wall is bearing.

You didn’t mention the door jamb and although a hollow metal door can be hung in different jambs, the finished wall opening preparation varies in width.

Cut the opening 12″ wider than the rough opening for the selected jamb style, and 6″ higher. Dowel two 1/2″ re-bar on each side of the new opening, min. 6″ embedment into the slab.
“J” bend the existing horiz. bars and tie to the new vertical bars.
At the header you can either weld a lintel to the re-bar, or create a bond beam with two horiz. “J” bent and attached to the new vertical bars.
Fabricate a “U” form to fit the opening required for the jamb, with opening at the top of the legs which will allow the forms to be filled with 5000lb grout.

Sounds like a plan. A couple of things to consider: be sure there are no electric or plumbing lines in the area to be removed. The joints are probably staggered, so you’re going to have some rough edges to clean up. There is likely to be some re-enforcing wire laid horizontally in the mortar joints and rebar in filled cores. You can cut the block with a circular saw or angle grinder with a masonry or diamond blade. Wear gloves, eye protection and a good dust mask.