Expert: Bruce E. Johnson - 1/31/2011

Question
In my basement I want to tear down about 9 feet of bearing wall and a 3 foot doorway and span 12 ft.  I have a rambler built in 2000 the 12 foot span would be at the end of the house under the master bed and bath.  The floor joists are the "TJI 250 PRO" (engineered) and span from one side of the house 15.3 feet to the outside cement wall and on the other side they span 11 feet to a cement wall (under the garage).  Can you tell me what kind of beam would support this span?  I have spanned another area of the basement with about 8.5 feet (right in the middle of the house bearing wall).  And for that project i had used 2 2x12's nailed and glued with 4x4 posts on either end.  I just need to know what I would need to span this bigger (12 foot) opening.  Or would I need a 4x4 post right in the middle as well?

Thanks for the help.
John

Answer
Hi John, a simple formula is one foot of span per inch of depth on a four inch beam..In other words a 4x12 should be able to span the 12'.  If you have a concentrated load in the area you may need to increase the depth or width by two inches i.e. 6x12 or 4x14...I advise anyone, prior to removing any load bearing walls or partitions that an engineer be consulted.  An engineer can determine the actual loads and design a beam to suit your needs.  I hope this information helps, please feel free to write again regarding this or other matters, sincerely bruce e johnson..bejohnsonconsulting.com