Hi, I am extending and renovating a 1930's cavity brick semi detached. I am replacing 4 windows on upper level - 2 of these openings are 1200mm and the other 2 are 1800mm. The original windows had no lintel on facing bricks and a wooden lintel on inner leaf.
My builder recommends I get mild steel flat bars (primed to prevent rust) for the outer leaf to hold up the single layer of facing bricks that will sit on top of opening and concrete lintels for load bearing inner leaf. The builder doesn't want catnic lintels because their height combined with the position of the eaves will prevent him from laying the facing bricks from the inside of the house.
Is this approach sound? Can I get away with 6mm mild steel flat bars (80 x 6 x 1500mm for 1200mm openings and 80 x 6 x 2100mm for 1800mm openings) or is more strength required (ie. should I get 8mm or angle bars).
For information, my wife insists on the single layer of facing bricks on outer leaf.
Thanks.