Sistering joists - going larger

[seamlyne]

The living room floor in our 100 year old house is starting to bounce noticeably, even under the small weight of my two children (60 and 20 pounds). The joists are too small anyway, 2x6's on 16-20" centers spanning just over 9'. I would like to sister 2x8's, but I'm curious what to do with the ends.

In order to fit onto the sill plate and central support beam, I would have to trim the ends of the sister joists to fit, right? Or do I cut short and trust the existing joist to hold on the ends? How is this handled in the world where people know what they're doing?

Bill in KC

[HayZee518]

I would think that to support weight you'd have to do what you said. Notch the ends to fit over the plate. since you don't have the room to put the joists in at an angle (between existing joist spaces) you might have to trim some off the ends so you can hammer them into place and the end supports may be 1 or 1 1/4 inches. Then bolt and glue the new joist to the old ones.