Floors do not sag without a reason. When a house feels bouncy underfoot, or you see a gentle trough across a room, something in the load path is no longer carrying its share. Termites are one of the usual suspects. They do their work quietly, often along the hidden faces of floor joists, beams, or sill plates, and the first clue a homeowner notices is not wings by a window, but a dip in the dining room.
I have repaired termite damaged framing in crawlspace bungalows, slab-on-grade additions, and century homes with stacked stone foundations. The jobs differ, but a few truths repeat. You have to stop the insects, stabilize the structure, and restore the strength of the framing with sound, code-compliant materials. Shortcuts, especially cosmetic ones, tend to come back to bite hard.
What sagging floors are telling you
Deflection happens for a handful of reasons. Overspanned joists were common in older homes, and a minor sag that held steady for decades is not unusual. Termite damage is different. It tends to start with subtle bounce, then a gap at the shoe molding, and eventually doors that stick. The sag progresses because termites eat springwood faster than dense latewood, hollowing webs in the joist. At notches and bearing points, that hollowing turns into crushing.
I look for location patterns. If the dip centers over a bearing wall or a main beam, the issue might be a termite damaged beam or a compromised post. If the dip shows up at the perimeter and radiates inward, the culprit might be the sill plate and the first few inches of the joist ends. Subfloor delamination adds a dish shape you can sometimes see by sighting along the baseboard.
How termites reach your floor framing
Subterranean termites find wood through the soil. They push up mud tubes to reach sill plates, rim boards, and joist ends, wherever moisture stays high. They like accessible wood with a moisture content above 16 percent. Crawlspaces with poor ventilation or plumbing leaks are prime. Slab-on-grade homes are not immune. Termites can bridge up inside a framed wall and work into the band joist or the underside of a subfloor, then move into joists.
Drywood termites arrive differently, flying in and colonizing small, enclosed pockets of framing or trim. In most regions east of the Rockies, subterranean species are the challenge at the floor system. On the coasts and in the Southwest, you may see both.
The pathway matters to repair. If activity started at the sill, you may need termite sill plate repair and to address masonry wicking or missing flashing. If the entry point was a porch slab abutting siding, termite wall repair often accompanies the floor work. After treatment, it is common to plan termite drywall repair after termite treatment because techs open chases to verify galleries are inactive.
Diagnosis that saves you money
Termite damage repair goes wrong most often at the diagnostic stage. If you do not chase the problem to its ends, you wind up sistering one joist in a room where five are half gone, or you replace a beam without fixing the crushed sill it bears on. The inspection needs to map all compromised members, from beam to joist to subfloor.
Here is a quick field checklist I use to separate surface scarring from real structural loss.
Probe and sound every third joist for at least 6 feet beyond visible damage, focusing on bearing points and plumbing runs. Measure deflection with a laser or tight stringline, noting low spots and their relation to supports. Check moisture content. Anything above 16 percent in a crawlspace signals an environmental problem to correct. Follow mud tubes to their origin, and look for frass, wings, or live insects to confirm activity level. Inspect the sill plate, rim board, and the top of foundation walls for soft zones or crush at anchor bolts.If the damage is moderate to heavy, a licensed pest control operator should treat first. Termite repair services that do structural work often coordinate with the pest company so the warranty on termite damage restoration stays intact. Many pest firms want a 7 to 14 day window post-treatment before opening up framing again, so plan the calendar.
Stabilize first, then fix
You cannot glue a sagging house back together from the middle. Before any termite wood repair or carpentry begins, provide temporary support. I lay down 2 by 10 cribbing on the soil, then set adjustable steel posts under a parallel temporary beam, such as a triple 2 by 10 or an LVL, positioned a foot or two away from the damaged zone. Jack slowly. The safe rule is no more than 1/8 inch of lift per day, especially on plaster ceilings and brittle tile. If you try to take an inch out of a floor in an afternoon, you will buy yourself cracked finishes throughout the room.
I also establish dust containment and, in finished basements, protect mechanicals and wiring. You will be cutting old nails, pulling damaged subfloor, and running saws in tight quarters. Good lighting and knee protection matter more than most folks expect on a two-day crawlspace repair.
Choosing a repair strategy for termite floor joists
Termite floor joist repair sits on a spectrum. The goal is to restore original or better strength and stiffness, tie members convincingly to their supports, and provide clear pathways for future inspection. I choose between sistering, partial replacement, full replacement, or engineered reinforcement based on how much of the cross section is gone and where.
Sistering solid lumber. If at least half of the joist cross section is sound and the top and bottom fibers are intact across the midspan, I often sister with matching dimensional lumber, such as a pair of new 2 by 10s on a nominal 2 by 10 joist. Full-length sisters that bear on the same supports as the original are ideal. When obstructions prevent full length, I lap at least 6 feet past the damaged region and use a combination of construction adhesive and staggered structural screws or through-bolts. A typical fastening pattern is two 1/2 inch bolts every 16 inches, staggered 1 1/2 inches from edges, or a pattern of 3/8 inch structural screws 12 inches on center. Use manufacturer data for exact values.
Sistering with LVL. For long spans, LVL sisters excel because their stiffness helps remove bounce. One 1 3/4 by 9 1/2 LVL alongside a 2 by 10 often equals or exceeds the original capacity, provided you get proper bearing at supports. Where bearing is not possible, hang the new member from the existing beam with a listed hanger and supplemental blocking to transfer loads.
Partial replacement, also called scabbing. At joist ends where termites chewed bearing zones, I cut back to solid wood and install a new end section with a scarf or butt joint over a supporting ledger or hanger. In crawlspaces, a short joist section hung from a new ledger attached to the rim or a beam repairs many end rot or insect issues. It is not as elegant as a full-length sister, but it is safe and economical when the middle of the joist is healthy.
Full replacement. When the top or bottom third of a joist is hollow over much of its length, replacement is the honest fix. Cut the old joist free, slide in a new member, and secure it with hangers or full bearing. In older houses with irregular spacing, I layout the new joist to match subfloor support and shim carefully with steel shims, not cedar or stacks of composite shims. If utilities block a full replacement, I sometimes pair two shorter members that lap and bolt at midspan, but an engineer’s input is smart if you go beyond straightforward spans.
Flitch plates and steel angles. Where headroom is tight or the load is high, a 1/4 inch steel plate sandwiched between sisters turns a compromised joist back into a stout beam. Steel angles add bearing strength at ends chewed to a slope. This leans into termite structural repair territory and benefits from stamped drawings if you change the section significantly.
Repairing the supports the joists sit on
Termite sill plate repair is one of the most common companions to floor joist work. The sill is the first stop for subterranean termites. If the sill is soft, the joists can look tired even before their own webs are eaten. For partial sill replacement, lift the rim and joists gently on temporary posts, cut out the affected section, and slide in new pressure-treated sill stock. Anchor it with modern epoxy-set anchors or mechanical anchors at code spacing, then re-establish termite shields or flashing against the masonry if local practice uses them. Grout or non-shrink fill under gaps to ensure full bearing.
Main beam or girder repair follows similar logic. Termite beam repair can be as simple as sistering a new LVL alongside an old built-up beam, or as involved as jacking, removing a third of the beam, and stitching in replacement with scabs and bolts. If a post is rotten or eaten at its base, replace it with a steel lally column set on a new concrete footing. Footing sizes vary by load and soil, but a common crawlspace fix is a 24 by 24 by 12 inch footing with rebar for a typical 8 to 10 foot joist span and a light frame floor. Always check local requirements, and when in doubt, ask a structural engineer for sizing.
Subfloor repairs matter too. Termite subfloor repair often means cutting back to the center of adjacent joists, gluing and screwing in new tongue and groove panels, and adding blocking so edges are fully supported. An eaten subfloor can make a floor feel spongy even when joists test solid.
A real-world example with numbers
A few summers ago, a 1950s ranch with a vented crawlspace called about sagging in the kitchen. From the doorway to the refrigerator, the floor dropped 5/8 inch. The pest company had already treated, and activity was cold. Moisture in the crawlspace measured 19 percent at the sill and 15 to 17 percent in the joists, high for July. Mud tubes climbed the interior of the foundation wall where a downspout had dumped water for years.
We found four 2 by 8s with moderate web loss over 6 to 8 feet and two joist ends crushed at the sill. The sill plate itself was spongy for 10 linear feet at a corner, and the rim board had trails but still had meat. The main beam was fine.
The plan combined several approaches. We set a temporary 3 ply 2 by 10 beam with two adjustable posts and lifted a quarter inch over two days. We replaced 10 feet of sill with pressure-treated southern pine, set with new anchors at 4 feet on center. We sistered the four tired joists with full-length 2 by 8s, bolting 16 inches on center and gluing the faces, and we cut back the two crushed joist ends and installed new end segments on galvanized hangers https://s3.us-east-005.backblazeb2.com/Articles101/daily-learnings/uncategorized/plywood-vs-osb-in-termite-subfloor-repair.html off a ledger screwed to the new sill. The subfloor had three small termite paths but no delamination, so we left it intact.
We added a 6 mil vapor barrier across the crawlspace soil, extended the downspout 8 feet, and set a small fan on a humidistat for the muggiest weeks. Material cost landed near 1,400 dollars. Labor took two carpenters about 24 hours, plus two hours for the vapor barrier and fan. The total invoice, including debris haul-off and permits, came to just under 5,000 dollars. The client later had the kitchen floor refinished, and the dip all but vanished.
That job worked because we treated the causes, not only the symptoms. If we had ignored the soggy sill, the new sisters would have ridden a soft landing and the floor would have sagged again.
Codes, permits, and when to bring an engineer
Not every termite framing repair needs an engineer, but many benefit from one. If you are altering beams, changing bearing points, or swapping in steel, get an engineer’s review. Municipalities vary on permits, but as a rule, any structural termite repair near me has triggered at least a simple structural permit and an inspection of the temporary shoring. Plan for it. Inspectors appreciate neat work, proper connectors, and clear load paths. They also like to see that pest treatment was performed.
For connectors, use code-listed joist hangers, post caps, and beam hangers. Keep fastener types and quantities per the manufacturer. A common mistake is using roofing nails in a joist hanger. That haircut savings can cost capacity. Structural screws with ICC listing are widely available and speed work in tight spots.
Materials that last and how to fasten them
The temptation is to grab whatever 2 by stock is on sale. Choose straight, dry lumber for sisters and replacements. Kiln-dried after treatment is the best option for any wood touching masonry or soil. In a crawlspace, stainless steel is overkill for most fasteners, but a hot-dip galvanized finish is not. Construction adhesive between sisters helps load sharing. Spread an even film and clamp or screw tight before bolting.
Where moisture is persistent, borate treatment for framing repairs adds a line of defense. It soaks into the alkaline environment of wood and deters termites and rot fungi. Do not rely on it alone, but combine it with physical measures like vapor barriers, soil grading, and good drainage.
Sequencing the work to minimize disruption
Many houses stay occupied during termite damage restoration. Sequencing helps avoid chaos in the living space. I favor a clean order: treat, stabilize, open, repair, restore finishes. Coordinate with the pest contractor so their monitoring stations are not disturbed. If you will pull baseboard or cut drywall for access, schedule the drywall finisher a couple days after the carpentry to let wood acclimate and any jacking settle. Termite drywall repair after termite treatment often involves patching modest exploratory holes. Larger drywall replacement signals major wall repairs that should be in your scope from the start.
Other common termite repairs connected to sagging floors
Floors do not live alone. If the floor system has termite damage, I look up and around.
- Termite attic wood repair comes up when drywood termites colonize roof framing. You may see pinholes and frass on insulation. While it does not sag a floor, it affects whole-house strategy. Take attic damage seriously if you rely on the ceiling joists for bracing. Termite wall repair, especially at exterior walls with low siding clearance, often ties into rim board and joist ends. If sheathing is soft, rebuild from outside in, and revisit flashing details at decks and stoops. Termite framing repair in basements with finished ceilings can quietly follow plumbing lines. Listen with a stethoscope or use a moisture meter to find suspicious runs.
Each of these adds context. Good termite repair services think about the building as a system, not a pile of disconnected fixes.
A simple roadmap for a typical joist repair project
Stop activity with a professional treatment and verify inactive galleries. Stabilize the structure with temporary shoring and lift slowly to reduce finish damage. Open only what you must, then probe and map all damaged framing and supports. Execute structural repairs with proper bearing, connectors, and material choices, addressing sill plates, beams, subfloors, and joists as needed. Close up, then control moisture and access with vapor barriers, grading fixes, and scheduled inspections.The best termite wood repair is the one you do once. That means integrating pest control, structural carpentry, and moisture management, not treating them as separate chores.
Moisture and access, the two long-term levers
I have been back under the same crawlspace ten years after a repair to find everything tight as a drum because the owner kept the ground dry and the vents working. I have also been back five years later to find new galleries marching up a different wall because a downspout elbow broke. Moisture is the dial you control. Grade the soil so water runs away from the foundation. Keep gutters clean. In humid regions, consider encapsulation with a continuous liner and a dehumidifier set to 50 percent relative humidity. In arid climates, simple ground poly and occasional venting can suffice.
Access matters for two reasons. Inspectors and pest techs need to see the edges of your repairs. Termite shields, clearances from soil to siding, and removable crawlspace doors make that possible. Do not bury critical connections behind foam or finishes unless you provide alternate inspection points.
Cost expectations and how contractors price this work
Homeowners ask for numbers. Repair costs vary with access, extent, region, and finish risks. For termite floor joist repair alone in a crawlspace, I have seen jobs range from 1,800 dollars for two short sisters to 12,000 dollars for multiple replacements, sill plate work, and extensive shoring. Add drywall, flooring, or cabinet removal and costs creep up. Structural termite repair near me tends to cluster in the middle of that range. In high-cost urban markets, labor rates push the upper end.
Contractors usually price by a blend of time and materials, with line items for sisters, replacements, ledgers, hangers, and posts. Termite damage repair near me often shows a separate charge for temporary shoring, and another for moisture mitigation. Ask that the quote clearly list termite beam repair, termite sill plate repair, and any termite subfloor repair if they apply. Transparency helps you compare apples to apples.
If you are searching for a wood repair contractor termite damage near me, look for firms that do both structural work and have relationships with pest companies. The best teams work in lockstep. When you evaluate a termite damage contractor near me, ask about their connector choices, jacking rate, and how they protect finishes. If they shrug at those questions, keep calling.
Safety, health, and small but important details
Old houses hide surprises. Expect occasional asbestos, lead paint on baseboards, or knob and tube wiring hovering in a floor bay. Plan containment and safe handling. Protect your lungs in the crawlspace. Wear goggles. Keep a fire extinguisher close when using cutting tools near dry wood dust. Shut off circuits feeding the area you will open.
Mark utilities with painter’s tape on the subfloor above. A plumber once ran a copper line diagonally across three joist bays I was sistering. We would have put a 3 inch screw into it if we had not probed first. A half hour spent mapping utilities beats a flood and a second bill to the homeowner.
When repairs are not enough
Every so often, you find a floor system so eaten that patchwork makes no sense. If five out of six joists in a 12 by 15 foot room are compromised, the most efficient route is to open the room, replace the run of joists with new members, and drop in new subfloor as a unit. Termite damage restoration sometimes points to bigger life cycle choices. If the kitchen is overdue for new cabinets and flooring, it can be a good moment to coordinate projects and save on duplication of labor.
On historic homes, repairs might need to respect original materials. Sistering lets you preserve old joists while restoring capacity. Keep documentation for future stewards of the home. A sketched plan, photos, and receipts for termite treatment and structural work help with resale and with warranty claims.
Bringing it all together
Termite damage repair is not just a matter of swapping chewed wood for new wood. Proper termite floor joist repair starts with understanding the load path, then fixing the supports, the members, and the environment that allowed the insects in. The best results come from a disciplined process that balances caution with decisiveness. Treat the insects. Shore carefully. Make clean, strong, verifiable repairs. Dry the space and keep it dry. And choose a team that treats your home as a system, not a set of parts.
If you need help, search for local termite damage repair and talk to a few contractors. A good pro explains their plan, names the connectors they prefer, and tells you how they will keep dust and disruption under control. Those small signals often predict the quality of the work that will hold up your floors for the next generation.