Expert: Bruce E. Johnson - 2/23/2010

Question
garage ceiling is attic trusts made of 2x4's, 16" on center with a span of 16' and they were engineered specifically for our application.  We were told that we could never fill this area with enough boxes or furniture to cause a problem - told the company we were to use it as an office with desks and file cabinets.  The floor shakes when you walk across it and we are concerned about this.

Answer
Hi Donald, I'm sorry but there is a big difference between storing some junk in the attic and actually using the space as living area.  I don't know who you talked to at the truss plant but I have never seen trusses with 2x4 bottom chords used as anything but storage.  Your joists should be at least 2x8, preferably 2x10.  I hate to say it but you need to rip up your flooring and insert the properly sized joists between the truss bottom chords.  Or have your truss company come out and repair the trusses so that they are compatible with your usage.  I hope this information helps please feel free to write again regarding this or other matters, sincerely bruce e johnson..bejohnsonconsulting.com