End Door-Frame Rot by Choosing a Jamb That Can't Wick Water

The Problem

The bottom of a wood door jamb sits at the wettest spot on the wall, and end grain drinks. Water wicks up the jamb from below — slowly, invisibly — until the paint peels, the jamb goes punky, and the door stops closing right. Paint delays it; it doesn't stop it, because the wicking happens from the cut end the paint never fully seals.

The Main Thing to Know

Door manufacturers sell frames built for exactly this failure: the lower portion of the jamb is fiberglass or composite instead of wood, spliced to the wood jamb above the splash zone. "FrameSaver" is the common searchable name for the type. The composite section can't absorb water at all, so there's nothing for winter to rot.

When you're replacing an exterior door — or repairing a rotted jamb and deciding what goes back in — ask for a frame with a composite bottom. The upgrade is modest money on the price of a door unit, and it removes the most common exterior door failure permanently.