I couldn't see anything relevant, but I have an old brick outhouse that I'm currently re-pointing. It's single course and single story and there's a wooden lintel about 3' above the ground that's at least 2m long. It can't possibly be doing anything structural, so would it be possible to replace the lintel with a brick course? I was planning to chisel out a section at a time to make sure that as I replace it the new brick course has a chance to harden - It's very old and I'd be worried about taking it all out at once even with strongboys - they're supposed to be good for 900mm span but is this true, even with ropey brickwork?
Thanks for looking!