Structural Repair
Floor Joist Sistering and Repair
Joists that are cracked, rotted, notched or overloaded make floors bounce and sag. Sistering fastens a new, full-length board alongside the weak one, with adhesive and bolts, so the floor is strong again without tearing anything out.
- Best forBouncy, sagging or cracked joists
- Typical rhythmOften one to two days
- TeamCarpenters who work in tight spaces
- Pairs well withMoisture control and jack post support
What you get
What floor joist sistering and repair includes
- 1Full-length boardsNew lumber runs past the weak area so load transfers cleanly.
- 2Glued and boltedAdhesive and fasteners join the new board to the old one.
- 3Cause addressedWe fix the moisture or load that damaged the joist.
- 4Floors checkedWe recheck the floor for bounce and level afterward.
How it goes
From the first call to a dry, finished space
- 1Find the weak joistsWe probe, measure and mark the problem boards.
- 2Prepare the areaDebris and old fasteners are cleared and supports are set.
- 3Install the new boardsSister boards are fitted, glued and bolted.
- 4Check the floorWe check level and stiffness and explain the repair.
Good fit when
Is floor joist sistering and repair right for you?
- The floor bounces or feels soft
- Joists are cracked, notched or stained
- Wood is rotted at the ends
- A plumber or contractor cut a joist
Questions
About floor joist sistering and repair
How do you know a joist needs repair?
We measure its condition with a probe and a moisture meter, and look for cracks, rot and sag. Solid wood does not need replacing.
Will sistering fix a sagging floor?
It restores strength. Leveling sagging floors may also need jack posts or a beam, which we assess at the same visit.
Related services
Often paired with this
Sagging Floor and Jack Post SupportAdjustable posts on solid footings to lift and hold a sagging floor.See the service 
Subfloor Repair and ReplacementCut out the soft or rotted section and replace it with new, solid panels.See the service 
Termite and Wood Rot Damage RepairRepair of wood weakened by termites or long-term rot.See the service Where we work
Find floor joist sistering and repair near you
Pick your city to see local conditions and the services people ask for most.
Thinking about floor joist sistering and repair?
Call or text, or send the form. Tell us what you have noticed and we will tell you how we would handle it.