Expert: Bruce E. Johnson - 9/16/2008

Question
I would like to replace what I think is a load bearing wall which is approx. 12' long w/ a few columns. Its a single story home w/ a flat roof. How many columns would I need? How far apart? Do I need to modify exsisting roof structures? Thanks.

Answer
Hi jim, a bearing wall carries the weight continuously over its length.  This means that if you remove it you need to replace it with something that is just as long to bear that weight.  In other words you need to add a beam and then support that beam with columns.  Mere column placement alone will not work unles you put a column under each roof joist or rafter which would make your column placement 2 feet apart and that would be silly.  For a beam to support a roof load of 12' you would need a 4x12 and then you could put a 4x4 column on each end.  You would need to support the existing roof structure on both sides of the wall to allow the removal of the wall without the roof falling in on you.  Then once the wall is removed and the new supported beam is in place you can remove the temporary shoring. Before removing structural elements in a structure I recommend that an engineer be consulted. I hope this information helps feel free to write again regarding this or other matters, sincerely bruce e johnson..bejohnsonconsulting.com