Improper Repair Of Floor Joists

Notches at the end of a joist should not exceed 1 4 of the joist depth.

Improper repair of floor joists.

Floor is sinking between the floor joists. Tack a beam under the sagging joists. Jacking them up too fast may cause cracks in the walls and floors overhead. Splicing with plywood can have some advantages over splicing with a solid joist in many situations.

A common but improper repair by other contractors is to install more full length joists. Make sure not to install joists so they run parallel to and directly under walls where you intend to install ductwork. Finally if all else fails drop your pipes and ducts down below the joists and box them in with wood framed soffits. Pictured is joist repair method for end rotted joist using plywood and some suggestions for best practice.

Total costs will depend on the extent of the damage and the ease of access to the joists through a basement or crawlspace but in general sistering averages 100 300 or more per joist and could run 1 000 3 000 or more to repair a tilted wavy or bouncy floor under an average room. In situations when sistering damaged floor joists with lumber of similar dimensions it can be easy to notch and slide the sister board into place. However doing this does not fix the slant that the floor has taken since the old joists got damaged. Generally there should never be any cuts or penetrations in the middle third of any joist or anywhere along the bottom of the joist.

Nailing two 2x4s together will work to span about three joists unless the sag is under a weight bearing wall. Repairing flooring vinyl wood or tile costs 347 on average or between 188 and 512 because pros need to go through this layer to get to the structural elements of subfloors and joists expect to pay far more for structural repairs. Use common sense when deciding how many fasteners to use. Click the image to enlarge.

Corbeling is an old school overlapping arrangement of bricks with each course extending farther out from the vertical of the wall than the course below. This will not work as the joist was not designed for this load originally. A day until they re level. Improper holes and notches from alterations and running service lines are a major source of weakened joists.

Set a hydraulic jack and post under the beam and jack up the joists about 1 8 in. Position bathroom vent fans so the ducts can run parallel to the joists right up to where they exit the house.