I'm opening a wall between two rooms. The neW opening will be 12'
8". I have a header span table and it indicates that the maximum
span for a 4" X 12" header is 12'. The header is only going to
support the 10' long ceiling joists above (no roof or floor above).
If I increase the header to a 6" X 12" will this work for a 12' 8"
span? Or will I need an LVL. IF SO WHAT SHOULD THE DIMENSIONS OF
THE LVL BE? Thanks in advance

Check your header span tables for the maximum span for a 4x12 header.

--
Steve Bell
New Life Home Improvement
Arlington, TX USA