Hi All

I have a small 1944 cottage, in which the floor in my second floor bathroom has sagged over the years, the joist (2X9 and 16"oc) span 12 feet and the sag is approx 1 inch in the middle, I've read through many of the discussions and forums, I was initially going to jack up (slowly over a few weeks) and then Sister joist., but its complicated as there is plumbing and electrical. Then I came upon a discussion suggesting adding a 2X4 along the bottom of the joist, sort of like a reverse T, this seemed like an easier option. The problem is I don't know how to approach it, they say it important to get the joist level (I would use 3 jacks and a perpendicular beam), then apply the adhesive on the 2X4 and glue to bottom of the joists, then screw to joist, wait till dry, then remove jacks.

If I need to jack up the floor over several weeks, how would I go about adding the 2x4s on the bottom of the joists if my Jacks and perpendicular beam are in the way? I could put the 2x4s in place (without gluing) then jacking with the 2x4 squeezed between my temporary perpendicular beam and the joist, then once joists are leveled, I can bend the 2x4s and try to squeeze in the glue as much as I can! but it seems kinda ridiculous to do it this way, and I wouldn't get a continuous bead of adhesive!

My other thought was jacking up the floor till level, then un-jacking, adding/glues 2x4s and quickly re-jacking, could this work?

Anyone have Ideas on how I can approach this? and secondly do you think this method (if done properly) would actually succeed in removing the sag?

Thanks