Diagnose Before You Repair Any Structural Joist

Repair keeps the existing joist in place and adds material (sister, repair plate, end splice) or adds support below (jack post) to restore load capacity. Replacement removes the existing joist and installs a new one in the same bay. Repair is appropriate when sound wood remains across at least 70% of joist length and bearing ends are intact. Replacement is appropriate when more than 30% of length is compromised or bearing ends are crushed. Pricing: repair $300 to $800 per joist; replacement $400 to $1,000 per joist.

Most 1950 to 1970s NE and IA construction used 2x8 joists at 16-inch on-center spanning 14 feet. That was at the code edge when built. After 50 years of creep deflection the floor bounces noticeably when walked. The joists aren't failed. They're undersized for current comfort expectations. Sistering with a 2x10 or installing a permanent mid-span jack post stiffens the floor. The fix is $300 to $600 per joist for sistering or $300 to $600 for a single jack post.

End-rot repair $400 to $800 per joist. Sistering $300 to $600 per joist. Repair plate (steel scab) $250 to $450 per joist. Full replacement $400 to $1,000 per joist. Permanent jack post $300 to $600 per post. Helical pier below a settled support post $1,500 to $2,500 per pier. Beam reinforcement $80 to $200 per linear foot. Full multi-joist sagging-floor scope $2,500 to $15,000. Written estimate after on-site inspection reflects your scope.

When the joist isn't the failed part. Roughly 30% of joist calls in our diagnostic data turn out to involve a settled support post, an undersized or sagging beam, or perimeter foundation movement. Not the joist itself. Fixing the joist on top of a still-failing support puts new wood on the same failure path. Don't repair joists in a wet crawl space without addressing the moisture source. The new wood follows the old failure within five to ten years.

Almost always, if the crawl space or basement is accessible from below. End-rot repair, sistering, repair plate install, and full replacement are all done in the joist bay without disturbing the subfloor above. The exception is full replacement where access from below is blocked by HVAC ducts or finished basement ceiling drywall; those access points are coordinated with the homeowner and the relevant trade before scheduling.

Four checks on every on-site assessment: visual inspection for cracking, checking, notching, or rot; awl probe at sill contact and discolored areas to confirm wood density; moisture-meter reading on the joist body to distinguish active rot from healed historical damage; and a laser-level survey of the floor above to map the sag pattern and determine whether the failure is in the joist or in the support below.

Yes. Carpenter ant or termite damage requires a licensed pest-control applicator to treat the infestation and confirm dormant before Epp executes structural repair. Repairing structural damage from pests without first eliminating the active colony puts new wood into the same infestation. Epp sequences the work and coordinates with the homeowner's pest contractor. Pest treatment first, structural repair after treatment is confirmed dormant.

Let's take the first step toward a healthy home.

A local specialist will inspect your foundation, walk you through the findings, and send a clear estimate. no cost, no pressure.