floor reinforcement

[cherrie]

I have a really old house and the floor in my living room and den are bouncy. I want to stop the shaking in the floors and am wondering how to fix it. The joists span 17 feet and my cellar ceiling is not very high so I cannot use a steel beam, at least not a big one. Thank you.

[HayZee518]

this is a two person project. have one person upstairs and another downstairs. have the person on the upstairs jump a little on the floor while you watch underneath for any bouncing - loose joists where they meet the bottom plate. if you see any motion, insert shim stock and hammer it into place where the joists meet the plate. if the midspan area is also bouncy you'll need two lally columns and a long wide 2X12 board crossways across the joists and jacked up with the lally columns.