Believe it or not this kind of poor workmanship is not that uncommon.
Floor joist splice detail.
The long view makes the overlap seem longer but i believe the nearest one is less than a foot with very few nails.
Nailing two 2x4s together will work to span about three joists unless the sag is under a weight bearing wall.
Tack a beam under the sagging joists.
Also install diagonal blocking to keep the entire frame from racking.
Use narrower lumber 2x8 blocking on 2x10 joists so the blocking looks less conspicuous from a distance.
A day until they re level.
Floor joists lapping splicing 2013 california building code section 2308 8 table 2304 9 1 the following are general requirements for floor joist lapping and splicing based on the 2013 ca building code.
Drooping and joist sag can be seen in the photo.
No splices in studs joists or other load carrying members may be made without prior engineering review and specific details for any such splice s.
If additional holes are required beyond the scope of the field cut holes table in the floor system contact a licensed professional engineer for guidance before cutting.
Here is a pathetic attempt to splice some floor joists under the bathroom.
To help keep joists flat always attach blocking perpendicular to the joists.
Apa performance rated i joists pris are manufactured in accordance with pri 400 performance standard for apa ews i joists form x720 this performance standard provides an easy to use table of allowable spans for applications in residential floor construction allowing designers and builders to select and use i joists from various member manufacturers using just one set of span.
Set a hydraulic jack and post under the beam and jack up the joists about 1 8 in.
It would have been easy to do it.