Window & Door Weather Sealing on San Juan Island

This page is narrow on purpose. It is about keeping wind-driven rain out of the wall at the openings — windows, exterior doors, and skylight perimeters. It is not about sticking doors, latches, screens, or interior trim, which is door, window and trim repair, and it is not glass work, which is window glass and sash repair. What I do here is the sealing layer around the opening, which is where the great majority of leaks at openings actually originate.

Why this matters more here than inland: the rain arrives on a wind. A November or December southerly drives water horizontally against a wall, and horizontal water finds joints that vertical water never touches. A caulk joint at the top of a window casing that has opened a sixteenth of an inch is irrelevant in a calm drizzle and is a funnel in a forty-knot southeasterly. That is why the leak you get is almost always on one or two specific elevations, only in a storm, and only sometimes — which makes it maddening to diagnose from inside.

The failures follow a pattern. Sealant fails first at the head and the upper corners of a window, where the sun hits it and where the movement is greatest. Old oil-based or cheap acrylic caulk gets hard, shrinks, and cracks; on an island house it usually has salt and dirt on it as well, which is why recaulking without cleaning back to sound material buys you two years. Sills and the underside of drip caps lose their slope or their sealant and start wicking water back into the wall. Skylight perimeters are the worst of the lot, because they combine a horizontal surface, a curb, and flashing, and they get walked on twice a decade by someone clearing moss.

The most common thing I find, and the most important, is caulk used where flashing should be. A window installed without proper head flashing will not be saved by any sealant, ever, because the water gets behind the joint instead of stopping at it. Where I find that, the fix is a drip cap and self-adhered flashing tape integrated with the water-resistive barrier so water is shed outward, with sealant as a secondary line and not the whole defense. That distinction is most of the skill in this work.

There is a matching rule about where not to seal, and it gets violated constantly. The bottom edge of a window, the weep holes in a vinyl or aluminum frame, and the bottom of a piece of siding are drainage. Caulking them turns a wall that dries into a wall that holds water, and I have opened rot cutouts that were caused entirely by someone running a diligent bead of sealant along the wrong edge. If a previous owner or contractor sealed the weeps on your windows, that is worth undoing.

On the door side the work is thresholds, sweeps, and compression seals. An exterior door on a weather elevation loses its sweep long before anything else, and an adjustable threshold that has been wound all the way down or all the way up is doing nothing. Kerf-in compression weatherstrip gets crushed flat over ten years and stops sealing while still looking present. Salt air is hard on the metal parts here, so on exposed doors I use materials that will survive it rather than the cheapest bulb seal. The result is measurable the first time it blows: less draft, less water at the base, and a noticeably less noisy room.

For second homes this is one of the highest-value few hours available. A house sitting empty from October to May with a failed head joint on the weather side will take water for six months before anyone sees it, and by then it is a siding and framing problem instead of a tube of sealant. I go around the whole envelope, photograph every joint I renew, and give you a written note on anything I think needs flashing work rather than sealing. That report is the actual deliverable.

Where a leak turns out to be coming from the roof, a valley, or a chimney, that goes to a roofer. I do not do roofing or re-roofing. I will show you where the water is entering and what needs addressing, and handle the sealing and any siding repair after.