Floor Bounce How do I Get Rid of It?

I bought a house last year and I’ve noticed recently a lot of floor bounce in our kitchen and family room. In the kitchen this makes the island shake and you can feel it when a 80lbs dog walks through the rooms. I did notice itwhen we first moved in and I asked about it, but never got a response from the builder.

This occurs mainly on my first floor, but a slight amount does occur on the second, but it’s not that annoying or bad. Both floors use Engineered I-beams that are at least 12” tall, spaced 16” on center. With OSB standard subflooring glued and screwed down. (I have to double check if they were actually glued)

The area it occurs includes the following areas:

Kitchen (18’x12’) - 18’ long I beams with concret foundation at both ends – Unfinished below Family Room (16’x18’) – 18’ long I beams with concrete foundation on one end and steel beam on the other – Unfinished below Dining Room (13’x13’) with concrete foundation on one end with steel beam on the other – Finished below w/1/2” gypsum.

The other areas of the house seem unaffected and have hardwood floors or are areas with less than 12’ lengths of I-joists.

I have read about several solutions and was wondering what would you recommend.

Sistering Joists – Family Room and Kitchen it is possible, but the Kitchen has furnace ductwork and other items in the way.

Running 1”x3” boards perpendicular to the I-joist - Possible in kitchen and family room

Adding another beam - Possible in both kitchen and family room, but would detract from usable space.

Gluing and Screwing in Subflooring perpendicular to I-Joists

Stiffening the underside – Glue and Screw 2×4s along the bottom of the I-beams after raising them up slightly with a jack.

Blocking- Adding blocking to the mid-span area, but this is the least effective method and I’m not sure it will work.

With the Dining Room Finished and the basement finished below it, the only thing that I think will help is adding hardwood flooring since it seams to help in the foyer which has the same span length.