Expert: Dan Griffin - 9/15/2011

Question
I have a garage door that is 18' wide with expansion joints running the entire way up each side. How big would the angle iron need to be and how would it best be secured to support this wall. It is 18' wide and say 18' tall.chicago brick

Answer
Brady, I apologize but I do not feel qualified to size this.  The height of brickwork is not important as masonry loads bridge quite quickly, BUT NOT YOURS - you said that you have a continuous joint at each end, so you will be carrying the entire load.  It will be functioning as a uniform load.  Your lintel will require horizontal reinforcement to insure arching. I am guessing here, but I don't think there is any angle iron capable of spanning 18' and I suspect you will be in a fairly heavy I beam for this span.  Lumber would be in the doubled 18" deep range which means truss, LVL, TJ joists, etc.  Steel us uaually 1/2" of depth for each foot of span, so something in the 9" deep range, so probably a 10" I beam with a brick bearing plate welded to the bottom.

This might be interesting reading to you:
<http://www.constructioncalc.com/blog/structural-design/brick-lintel-trouble/>
You will notice that one respondent indicated that in his firm they spanned and carried the load on wood LVL and used it to carry the angle iron lintel.  Commercial work usually uses some form of built up steel that would typically involve an I beam with a brick bearing plate welded o the bottom flange.

I'm sorry I couldn't give you an answer.