Repair Rotted Window Sills: How To

Shape the repair to shed water. The sill must slope away from the house, about 5 degrees. Any backward tilt is a suicide pact. Chapter Five: The Armor Hendricks sanded the whole sill smooth—old wood and new epoxy together—with 120-grit, then 220. Dust flew. The patch became indistinguishable from the original under a coat of primer.

He brushed on an exterior oil-based primer, then two topcoats of satin latex. But the real secret came last: he did not caulk the bottom edge of the sill where it met the brick. Many people make that mistake. Caulk there traps water. Instead, he left a ⅛-inch gap—a “weep path”—so any future moisture could escape. how to repair rotted window sills

Crucially, he checked beneath. Rot that goes all the way through the sill’s thickness and into the wall framing is a different beast. This was surface rot—deep, but not structural. Repairable. Shape the repair to shed water

He brushed the hardener into every pore of the cavity. It soaked in, sizzling faintly as it bonded with the remaining cellulose. After an hour, the soft edges turned rock-hard. Chapter Five: The Armor Hendricks sanded the whole