Expert: Bruce E. Johnson - 9/7/2008

Question
Hi Bruce -
We want to expand our first floor family room with a bump- out 6' deep by approx 15'long. It is a stucco exterior wall that supports the second floor bedrooms. It will be covered by a concrete tile shed roof. The existing ceiling is 8', and we do not want a soffit or support posts, in order to maintain the open feel in the room. What kind of beam is required to support the 2nd story load? The beam's width is a non-issue, as it will be covered by the "attic space" under the shed roof. We will pull permits and draw plans, but we are experienced DIYers and will do the majority of work ourselves. We are open to using either wood or steel. Additionally, can you provide a rough cost estimate for installing such a beam (in northern California)? Any help you can offer is appreciated.
Thank you,
Larry and Dina Campoy

Answer
Hi Larry, a beam to span 15 feet should probably be at least a 6x12 doug fir or southern yellow pine beam.  I would have to see the way your home is constructed to figure out the work entailed installing such a beam.  The house in that area would have to be shored up and the existing structure opened up and exposed.  The materials in the way would have to be removed and the new beam lifted into place.  Then any floor or ceiling joists would have to be secured to the beam and support posts installed.  I imagine this work could take up to several days for three good carpenters if the building's structural make up is not evident and the area in question needs to be exposed first before a plan can be made.  If it is basic and easy to get at and the planning done in advance it could probably be done in a day if all the materials are present.   I hope this information helps feel free to write again regarding this or other matters, sincerely bruce e johnson..bejohnsonconsulting.com