Building Homes or Extensions/Removing a load bearing wall
I would like to remove a wall that currently separates our family room from our kitchen/dining area. This wall is currently supporting the ceiling joist where they are spliced together in our attic. The attic is not used for storage.
Our roof is a gable roof built with 2x6 lumber on a 3/12 pitch. Each rafter has a collar support attached. There are no other vertical supports going from the top of the wall to the ridge beam.
I would like to know if 3 - 2x12's or 4 - 2x10's would make a sufficient beam to span a 15.5 opening. I would also be open to any suggestions you would have.
Josh, the big decision is whether to install the header above the joists or below. It may be more simple and straightforward to install the header under the joists.
I think I would strongly consider using LVL or another man made beam as the header. I'm confident that you can find one that will make the span easier than the built up beam you are considering. You will need to check the load path at the ends of the beam so that they are adequately supported all the way to and through the foundation. I don't know how to send you a .pdf link, but go here and and choose one that you trust:
They are all similar.
The collar ties you mention have no structural value in this situation.
The same header beam can be installed on top of the joists in the attic. This will require more drywall work on the ceiling get a nice tie and may well require new texture in both rooms to avoid "the visible remodel" syndrome. You will have some of this on the walls no matter which method you use. Check problems that may be caused by electrical wiring, etc. YOu would need to transfer the load of the joists to the header which can be done with lumber or light weight angle iron. Take out a fairly wide piece of drywall to blend the ceiling together rather than trying to patch a 5" stripe where the existing wall is.
If you are removing that much wall, you might also check the loss of wind bracing. This is normally handled by the exterior walls, but the new code book has changed some of the wind load calculations.