A girder/beam at about mid span should take care of the problem. Another solution is to sister new joists to the existing ones (possibly using lumber sized larger than the existing) if the bounce is excessive. In many cases sistering a new larger joist next to every other existing joist will solve the problem. If it still has more bounce than you want you can always go back and add to the ones you skipped.

Glenn

The span is about 16 feet, where the rest of the house is 14 feet. The 14' spans dont bounce. The reason I ask is there is a pocket in the corner of the foundation where a beam would go about 2' from the end wall and the other side is a cement block fireplace. The font of the house has a similiar bumpout, but they have a beam in place and there is no noticeable bounce.

Putting a beam midspan is out of the question due to the fact its over 60' from the foundation wall to the other foundation wall, and we plan to make a family room down there in the future and all those posts would just ruin the area.

Speaking of posts and beams, the construction of this house has 4 2x12's sistered together in a staggered fashion being supported by the type of posts that use pins and holes. Im not too concerned over the 2x12's but the posts on the other hand I dont like. Should I be concerned?

The post you are talking about will support a good deal of weight if they are installed properly. There should be a concrete footing or thickened slab under the base of the post, the post should rest on a square steel base plate, there should be at least 2 pins through each post, and the top of the post should also be caped with a square steel plate that is nailed to the girder above. I do not know how much weight is resting on the posts but if you are concerned you might consider having some 3 or 4 inch diameter pipe columns made to replace them. They would be made of a solid piece of pipe with a 4-6 inch square plate welded flat on both ends with holes in each corner for fastening to the footing and the girder.

Placing a girder 2’ out from the foundation wall will help some. There is no way to tell exactly how much it will help without seeing the conditions myself. Another factor you must consider is the distance the 2x10 girder is going to span between supports.

What size are the floor joists that are now spanning 16’?

Glenn www.consultationdirect.com