only what I would do. If it's only a foot down,I would only keep an eye on it.Being under the beam that holds the house up is definately something to be concerned about. Take an exact measurement of how long the crack is. If there is any changes in this in the future,have it inspected. If you are really worried about it,have it looked at now. You could have a 1/4" steel plate fabricated to span the opening. Have 1/2" holes put in the ends of the plate and drive 1/2" anchors in the wall to mount the plate. Hope this helps, Ron J.