When a girder fails, everything above it takes a vote.

A joist that weakens takes a strip of floor with it. A girder that weakens takes rooms. Because a girder gathers the load of many joists and delivers it to the posts below, its failure is never local: floors sag along the girder's whole line, doors stick in several rooms at once, and drywall cracks open near doorways and ceiling corners far from the actual damage. That wide, coordinated pattern is the clue that separates a girder problem from the single low spot of a failed post.

The causes are familiar ones under homes in our region. Moisture rot eats girders from the underside, where damp crawl space air condenses and lingers. Insects hollow members quietly from within. Overloading cracks girders that were sized for a lighter house than renovations left behind, and some girders were simply asked to span too far between supports from the day they were built. The symptom side of this story is one of the framing repair warning signs we look for; it lives on our sagging floor repair page, while this page is about what happens when the evaluation traces it to the girder itself.

Wood keeps honest records if you check them. The assessment probes the girder along its full length, especially the underside and the bearing points where it meets each post, because rot concentrates where moisture lingers and stress concentrates where loads transfer. Splits, crushing, and past repairs get logged, spans between supports get measured against what the member can actually carry, and floor elevations upstairs tie each finding to the sag you feel.

The point of the mapping is proportion. A girder with a weak stretch and sound remainder is a different project than one failing along its length, and the written findings say which yours is before any scope is proposed.

Full replacement is the right call less often than you might fear. A girder that is structurally sound but tired can usually be reinforced by sistering, attaching new lumber alongside the existing member so the two share the load, which restores strength without the cost and disruption of removal. A sound girder sagging only because its supports sit too far apart needs neither repair nor replacement; it needs more support, which is what crawl space jack installation provides mid span.

Which of the framing repair solutions applies is a measurement rather than a preference. Replacement earns its place when the wood itself is finished: deep rot, insect damage that has hollowed the member, or splits that no reinforcement can bridge. When the measurements say replace, we say replace, and when they say the smaller repair holds, we say that instead. The measurements make the call for every framing repair decision, and you see them either way.

The structure never goes without support. Temporary supports are set on both sides of the failing girder and take over its load before a single cut is made, with hydraulic jacks doing the controlled lifting. The old member then comes out, and the new girder, wood sized for the actual loads or steel where the span and weight call for it, is set into place and secured to the posts below and joists above.

Where the old support spacing contributed to the failure, permanent supports are added at corrected intervals, often as foundation jacks on engineered footings at the heaviest load points. Lifting toward level happens in small, checked increments so the rooms above adjust without cracking, and the final elevations are verified against the survey that began the project.

Girder problems in our markets are mostly water stories with wooden endings. Coastal and inland Southern California crawl spaces hold marine layer dampness and winter rain moisture long after the ground surface dries, and that persistent humidity works on the underside of girders year round. In the desert cities, the water arrives differently, through irrigation, plumbing leaks, and cloudbursts that flood poorly drained crawl spaces, but the rot chemistry is the same once wood stays wet.

The soil adds its own load path problem. Clay, dominant in a large share of the cities we track and carrying moderate to high expansion risk across much of the footprint, moves the posts and pads seasonally, and a girder bearing on wandering supports concentrates stress where it was never designed to. That is why a girder evaluation here always looks down as well as along: fixing the wood while ignoring wet soil and moving supports schedules the next failure.