I would like to add a seven foot header to an exterior wall. My major concern is that my joists run perpendicular with the rafters. Becasue of this I am having a hard time thinking of how to temporarily brace the wall while I add the header. My idea would be to build a knee wall above the closest joist to the load bearing wall and then building a temporary wall below the knee wall. This would create a continous load from the rafter to the slab. What are your thoughts or ideas. Thanks.