Expert: Bruce E. Johnson - 11/4/2008

Question
I framed houses for about a year back in the 90's.  I'm looking at buying a split level with gable trusses.  My understanding is that all interior upstairs walls should be non load bearing..correct?  The down stairs has a single beam that runs down the middle of the house (probably posted) that carries the upstairs joists.  Is it safe to assume I can move all the interior walls so long as I don't compromise the beam / post carrying the the joists? My plan is to add a great room onto one end with a vaulted ceiling that uses both levels and put the entry on the lower floor.  This should work shouldn't it?

Answer
Hi David, most truss type roof systems are two point bearing, meaning that they bear on the outside walls and free span the interior walls.  It is a good bet that your house's trusses are this way unless you have a real cut up roof with dormers and/or other protruding roof lines.  The floor system is similar.  If your joists are adequate they usually are supported mid span by a bearing beam and the other downstairs walls are superfluous to the structure.  Your plan should work fine especially if you use vaulted scissor trusses to make up your roof system on the new addition. I hope this information helps feel free to write again regarding this or other matters, sincerely bruce e johnson..bejohnsonconsulting.com