Is there a wood ledger on the brick wall? If there isn't, I see why you're installing the header and hanging the tail joist off of it. Be sure to use joist hangers. I'd also make an effort to keep the header as close as reasonably possible to the brick wall since the plywood floor sheathing will be overspanned the way it is currently drawn. 24" is the maximum span for 23/32" rated floor sheathing.