Floor Joist Repair That Restores Structural Integrity to Your Home
Damaged floor joists are the most common cause of soft, bouncy, or sagging floors in Middle Tennessee. Ground Up repairs and reinforces the framing that supports everything above.
On cost: Floor joist repair pricing depends on the number of joists affected, the method of repair, and crawl space accessibility. Sistering a small number of joists can start around $800 to $2,000. Larger scopes involving multiple joists and subfloor work can range from $3,000 to $8,000 or more.
Overview
Floor Joist Repair
Floor joists are the horizontal structural members that span from beam to beam beneath your subfloor, carrying the weight of everything in your home. When they are damaged by moisture, rot, or pests, they lose load-bearing capacity and the floors above begin to flex, bounce, or sag. Floor joist repair restores the structural capacity of compromised framing through sistering, partial replacement, or full joist replacement, depending on the extent and nature of the damage. Ground Up Foundation Repair specializes in crawl space framing repair across Middle Tennessee, where humid conditions make joist damage an especially common problem.
Floor joist repair begins with a thorough crawl space inspection to identify every damaged member and assess the severity of the compromise. Damaged joists are then addressed through the most appropriate method: sistering a full-length new joist alongside the damaged one using structural fasteners and construction adhesive, replacing a section of a joist where damage is localized, or fully replacing a joist that has been compromised along its entire length. Moisture control measures are integrated into the repair to prevent future damage.
Wondering if this is the right fix for what you are seeing? Learn more about the warning signs: Broken or Cracked Floor Joists in the Crawl Space and Mold on Crawl Space Framing . Or browse the full Problem Signs library for framing repair.
Installation Process
How we install floor joist repair
Crawl Space Inspection and Damage Assessment
A Ground Up technician performs a full inspection of the crawl space, probing each joist with an awl to identify areas of decay, assessing for pest activity, and documenting the full scope of damaged framing. This assessment determines whether sistering, partial replacement, or full replacement is appropriate for each member.
Preparation and Temporary Support
Before any framing work begins, the affected floor area is temporarily supported from below to relieve the live load on damaged joists and prevent further movement during the repair. This ensures that the floor above remains stable throughout the repair process.
Removal of Compromised Material
Damaged sections of joists, including any wood that has progressed beyond early-stage decay, are cut out and removed. Debris is cleared from the crawl space and disposed of properly. This step also includes treating adjacent framing with borate-based preservative to slow further biological activity.
Installation of New or Sistered Framing
New dimensional lumber sized to match or exceed the original framing is installed. For sistering, a full-length new joist is positioned tight against the damaged member, fastened with structural nails or screws at close spacing, and bonded with construction adhesive where contact permits. For full replacement, new joists are end-nailed to the beam pockets and rim joists per current structural standards.
Subfloor Reconnection
Where subfloor panels have separated from the damaged framing, they are re-secured to the new or sistered joists using appropriate fasteners. This eliminates squeaking, floor movement, and soft spots that resulted from the lost connection between the subfloor and the framing below.
Moisture Control Integration
New framing is treated with borate-based wood preservative to resist future biological activity. Moisture control recommendations, including vapor barrier installation, encapsulation, or active dehumidification, are reviewed with the homeowner to ensure the conditions that caused the damage are permanently corrected.
The sooner we get to a damaged joist, the more options we have. A joist that is caught early can usually be sistered quickly and at reasonable cost. A joist that has been ignored for a few years often has to be fully replaced, and by then the adjacent members may be compromised too. Floor joist repair is one of those situations where calling early pays off in a real and measurable way. Derek Veselich, Owner, Ground Up Foundation Repair
Why Ground Up
The difference is in the diagnosis
Get several quotes and you'll see a wide range of prices. The gap isn't luck. It's whether the contractor finds the actual cause and stands behind the work.
- In-house certified crews: we never subcontract your repair
- Optional independent third-party engineer review on larger jobs
- Honest three-tier triage: we tell you what can wait, in writing
- Family owned from the same Shelbyville Highway address since 2009
FAQ
Floor Joist Repair questions
The determination is made based on the percentage of the joist cross-section that has been compromised. Joists that retain most of their structural mass and can be reinforced with a sister joist do not require full replacement. Joists that have been hollowed by pests, heavily decayed through most of their depth, or damaged along their full length typically require full replacement. Ground Up makes this assessment during the crawl space inspection.
In most cases where squeaking is caused by framing damage, sistering or replacing the damaged joists and re-securing the subfloor resolves the squeak. If squeaking persists, it may indicate a subfloor-to-finish-floor issue that is separate from the structural framing.
The timeline depends on the scope of damage. A straightforward sistering job on a limited number of joists in an accessible crawl space can often be completed in one to two days. Extensive repairs involving multiple joists, beam work, or difficult crawl space access conditions may take three to five days or more.
In most cases, yes. Ground Up uses temporary shoring to stabilize the floor during repairs, and work is confined to the crawl space below. Homeowners are advised to minimize foot traffic directly above the repair area during the project. In cases of severe structural compromise, we will advise on any necessary precautions.
Joist repair restores structural integrity and stops further deflection. In cases where significant sagging has already occurred, some leveling may be possible as new framing is installed, but a floor that has sagged substantially over years cannot always be returned to perfectly level without additional floor leveling work. We discuss realistic expectations with every homeowner before starting.
More Solutions
Other solutions we offer
Beam Repair
Structural beams throughout a crawl space home serve distinct load-carrying roles, the sill plate transfers floor loads to the foundation wall, rim joists close off the floor system at the perimeter, and secondary beams support floor joists between the main carrier and the foundation. When any of these members is damaged by rot, insect activity, or physical stress, the floor system above loses support. Ground Up Foundation Repair identifies the affected beam, determines the appropriate repair method, and restores full structural capacity without disrupting the living space above.
Structural Beam Replacement
The main girder beams and support beams in a crawl space are the primary load-bearing members of the floor system. They span between foundation walls and piers, carrying the floor joists that in turn support the subfloor and everything above. When these beams are compromised by moisture-driven rot, pest infestation, or overloading, the consequences extend throughout the floor system above. Structural beam replacement is the appropriate solution when beams have degraded beyond the point where repair or reinforcement is sufficient. Ground Up Foundation Repair provides beam replacement in crawl spaces throughout Middle Tennessee, using properly sized dimensional lumber or engineered lumber products to restore full structural capacity.
Carrier Beam Repair
The carrier beam, also called the main girder, is the primary horizontal member that supports your floor joists and transfers their load to posts and the foundation. When a carrier beam cracks, sags, or rots, every joist it carries becomes compromised, causing widespread floor movement across an entire section of your home. Ground Up Foundation Repair assesses carrier beam damage, determines whether repair or replacement is appropriate, and restores full load capacity with minimal disruption to the living space above.
Crawl Space Jack Installation
Crawl space support jacks are adjustable steel columns installed on concrete footings beneath the floor framing of a crawl space home. They provide permanent supplemental support for floor joists and carrier beams that have deflected beyond what sistering alone can address, for spans that are too long for the existing framing depth, or for homes where the original post spacing was inadequate. Because they are adjustable after installation, crawl space jacks also allow incremental floor leveling without additional structural work. Ground Up Foundation Repair sizes, spaces, and installs support jacks to match the load conditions of each specific home.
Floor Joist Repair Plates
Floor joist repair plates, also called mending plates, joist plates, or structural connector plates, are heavy-gauge galvanized steel plates fastened across a crack, split, or notched section of a floor joist to restore local bending and shear capacity. They are most effective when damage is localized to a specific point along an otherwise sound joist, rather than distributed along its length. Repair plates are a faster and lower-cost solution than sistering in specific circumstances, and they are frequently used in combination with sistering when a joist has both a discrete crack point and overall reduced stiffness. Ground Up evaluates each joist individually and recommends the repair method, plates, sistering, or full replacement, that matches the actual damage pattern.
Floor Leveling Services
Uneven floors are more than a cosmetic problem, they signal that the framing or foundation beneath them has shifted, weakened, or settled unevenly. Ground Up Foundation Repair diagnoses the root cause of sloping, bouncy, or sagging floors and develops a targeted leveling plan. Depending on the cause, floor leveling may involve jacking sagging joists, sistering damaged members, installing or adjusting steel support posts, or addressing the foundation settlement that started the movement. We restore floors to level without disturbing finished flooring wherever possible.
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