Jacking and Sistering joists

Our first major project was to jack up and sister some 2nd floor joists so we could work on the bathroom above them. The joists were only 2X6. 2 of them made about a 17 foot span with no real support. That long a span should have 2X12 joists by today's standards!

Others had terrible notching. We discovered some awkward attempts at repairing some of the problem.

Since the kitchen ceiling is less than 8 feet hight to begin with, the easy fix of sistering with 2X10s or 2X12s was not an option. We decided to use 2X8s double sistered. (Sistering means adding another joist on the side of an existing one) We also used LVL lumber one one side of each of the long spans. LVL is an engineered lumber thats part wood, part resin. It's basically 50% stronger than regular lumber of the same size. It's also thicker (1.75" thick)

First the kitchen ceiling was removed with some help. Dusty, messy work.

Then, we put down a couple 2X8s on the floor to spread the weight out as much as possible. (These crossed the whole room, spanning as many floor joists as we could.) A 4X6 beam was put on top of those.

Then we made up spacers for the beam that would do the jacking so the new taller joists could be slid right in.

The upper 4X6 and two heavy duty Jack Posts were put in place as close as we could get to the middle/worst part of the span. We raised the beam up with the posts until the house started complaining by making nice cracking sounds.

Over the course of a couple weeks, we slowly raised it up. We raised the joists until the 4X6 beam was bending and compressing with increased load instead of the joists moving up more. The house said that's as far as we were going.

http://hammerzone.com/archives/framecarp/supplement/floor/joist1/sister.htm

http://hammerzone.com/archives/framecarp/supplement/floor/joist1/raising.htm

Great reference above for doing this kind of work.

We ended up using 3 jackposts and a couple 4X6s. Over the course of the raising, we raised the worst part over an inch or so.

Later went on to find out that there was more load on one of those joists than we thought, which was impeding our progress.