Upper Deck Leak Repair in Admiral, West Seattle

The water was showing up in the kitchen ceiling, right next to a big window. So the window was the obvious suspect. It was not the leak.

This is the story of a leak hunt at a house on SW Admiral Way in Admiral, West Seattle [CONFIRM: neighborhood label for 5702 SW Admiral Way, Admiral vs. Alki], and why we spent two visits finding the water before we touched anything.

What the homeowner wanted

The homeowner had staining in the kitchen ceiling near a large window and wanted to know where the water was coming from. Old windows are expensive to replace, and replacing one that is not leaking fixes nothing. The ask was simple: find the actual entry point, then fix that.

How we looked: two visits, nothing cut open

Visit 1 (September 1). Stan and Angelo did a full visual inspection inside and out, from a ladder. Roof, gutters, the window, the storm window, and the wall around the stain. Nothing was opened up.

Visit 2 (September 3). We came back in wet weather on purpose, so we could watch the leak behave. We sprayed the window directly with water and used a thermal camera to see moisture behind finished surfaces without cutting a hole in anything. On a thermal image, wet material reads colder than dry material.

Austin turned both visits into a written leak report the same day.

What we found

• The upper deck sits directly over the window. The deck is effectively the roof for the window bay below it. Anything that gets past the deck's waterproofing lands in the wall and ceiling at exactly the spot where the stain was.
• The deck edge waterproofing had failed. The black membrane along the edge was cracked, curled and lifting in a continuous line, and the paint above it was blistering. Instead of shedding water out, the edge was letting it in behind the flashing.
• The railing post bases were open. All four posts sat on the deck with a gap at the base, no sealant, and debris packed underneath. Each one was a second, smaller way in.
• The thermal camera told the rest. A continuous cold band ran the full length of the joint where the deck meets the wall. A line, not a spot. Inside, a cold plume spread across the kitchen ceiling away from the window wall. Water had been traveling sideways inside the ceiling, so the damp area was wider than the stain you could see.

What we ruled out

• The window. We sprayed the window and frame directly. Nothing came through. The staining and corroded hardware at the window head were from water that got in from above, not from the window itself.
• The roof. Roof and gutters were in good shape, with no soft spots in the plywood.
• The cracking above the window. Surface paint, not water damage.

One honest side note. The window jamb read the coldest of anything we measured, as low as 58.7°F. That was cold air moving through an old single-pane assembly, not water. It explains why the room feels drafty and why condensation gets trapped between the storm window and the main window in heavy rain. Worth fixing someday. Not part of this leak.

What we built, and why waterproofing came first

The repair went after the entry points and nothing else:

1. Rebuilt the deck edge. Cut back the failed membrane, primed the substrate, and installed new membrane with metal edge flashing, lapped so water sheds outward.
2. Flashed the deck-to-wall joint. New L-flashing around the perimeter, tucked behind the siding so water cannot get behind it.
3. Sealed the post bases. Cleared the debris from under all four posts and sealed around each one.
4. Cleared the drainage. Cleaned the deck and removed the debris that was holding water on the surface.

The crew worked on a pitched roof surface, tied off to the existing anchor points with our own harnesses, and trimmed back the branch near the power line while they were up there. [CONFIRM: steps 1–4, tie-off and branch trim all done as quoted]

What we left out on purpose: the kitchen ceiling, the window, a deck rebuild and post replacement. You do not paint a ceiling until you know it is dry. The plan included a free thermal re-scan of the kitchen ceiling two to three weeks after the repair to confirm it was drying out. [CONFIRM: was the re-scan done, and did the ceiling read dry?]

How long it took

Diagnosis took two visits in one week. The repair was scoped as a one-day, dry-weather job for two techs. [CONFIRM actual repair duration: first repair visit Sep 7, follow-up visit Sep 15, job closed Sep 18 per Jobber. Say "one day" only if that is what happened.]

Why a bathroom company cares about a deck

Most of what we build is bathrooms, and this job is the same lesson we preach in every shower: water finds the seam. Tile does not stop water and paint does not stop water. The membrane and the flashing at every change of plane do. That is why our waterproofing goes in, and gets tested, before any finish goes on.

If you are in West Seattle and planning a bathroom, see how we handle a bathroom remodel in Seattle, read about our bathroom renovations in West Seattle, or check real Seattle price ranges in our cost explorer, no email needed.

Questions West Seattle homeowners ask us

My ceiling leaks under a deck. Is it the roof or the deck?

If a deck sits over a living space, the deck surface is the roof for that room. The usual entry points are the membrane at the deck edge, the joint where the deck meets the wall, and penetrations like railing post bases. A direct water test and a thermal camera usually narrow it down without opening anything.

Do you have to cut open the ceiling to find a leak?

Not as a first step. Wet material reads colder on a thermal camera, so we can map moisture behind drywall from the room side. We would rather find the entry point outside, fix it, and confirm the ceiling is drying before anyone repairs or repaints it.

Is a leak next to a window always the window?

No. On this Admiral house the window tested dry. The water came in above it and ran down to where it showed up. Test the window directly before you pay to replace it.