The 20-minute underside check from our corrosion map, as a working document. Grade each location at the car, read the verdict, then print the sheet (or save as PDF) for your negotiation file.
On a lift. Probe the box sections around all four mounts — sound steel knocks, rot thuds.
Bonnet open. Tower tops and inner-wing seams — bubbling seams or cracks around the damper mount.
All four corners. Thumb-press the tubes and surrounding sill — fresh underseal only here is a tell.
Trim edges, A-pillar bases, scuttle corners. Check parcel-shelf corners inside for water stains.
Thumb under each lip; push up at the quarter seam. Lip rot is cosmetic, seam rot is structural.
Carpet and spare out. Surface rust is normal; holes at the drain plug or seams are not.
From below, never through the carpet. Probe seams and previous welding.
Drain holes clear? Bubbling along the lower skin edge?
Acid-spill corrosion — localised and repairable, but check it has not spread to the tower seam.
Slow-moving cosmetic spots. Note for negotiation, not alarm.
// Nothing is uploaded — the sheet lives in your browser and your printout. Want the checklist refreshed when we update the corrosion map? Join the registry.