From a fabricator erector standpoint, we typically use E309 as the filler metal of choice, but the filler metal does not appear the primary source of your situation.
From what you have said, it sounds as though the problem was in the procedure (or lack thereof). You did not mention the...
The joist company(s) you select will perform the calculations for you (most work with decking as well) and will ask all the right questions to get your design locked in. You are on the right track as far as an economical approach.
The following companies are the major players covering the East...
