Waterproof Decking in Everett, WA

Waterproof decking is a sealed surface that sheds rain the way a roof does. It is for homeowners with a deck above a living space, garage or storage area, where a leak shows up as a stained ceiling. Everett Deck Repair installs and repairs these systems across Everett and the surrounding cities.

What a waterproof deck membrane does over a living space

Ordinary deck boards leave gaps on purpose so water falls straight through. That works over open ground. It fails over a room, because every gap becomes a drip in the ceiling below. A waterproof system closes the surface and sends the water to an edge or a drain instead.

This page is about the membrane itself. If you are planning the whole structure, our Deck Building page covers that side. The usual case here is a second-story deck over a garage or finished room, though the same methods apply to balconies and covered platforms.

Vinyl sheet membrane or liquid-applied membrane

Both systems do the same job. They differ in how they are laid and where they work best.

Vinyl sheet membrane

Sheet vinyl comes in rolls. The seams are heat-welded, and the sheet is turned up the wall and over the edges. The thickness is uniform because it is made in a factory, not applied on site. It needs a smooth, firm, correctly sloped plywood surface, and the corners and edges need careful cutting and welding.

Liquid-applied membrane

A liquid membrane, usually a polyurethane coating, is rolled or troweled on in coats. Reinforcing fabric is bedded into the joints and corners. It has no seams, so it suits odd shapes, curved edges and decks with many posts or pipes coming through. It needs dry weather and enough cure time between coats.

Which one suits your deck

A simple rectangle with few obstacles often suits sheet vinyl. A deck with an irregular outline or lots of penetrations often suits liquid. The finish matters too. A membrane can be topped with a gritted coating for traction, or covered with pedestal pavers or raised wood sleepers and boards. We look at the deck and tell you which fits.

Signs a deck over a living space is leaking

Water travels along framing before it shows itself, so the stain is often not under the spot where the leak starts. Look for these signs:

• Brown stains or bubbling paint on the ceiling or soffit below
• Drips along the beams or at the wall after heavy rain
• Bubbling, cracking or peeling in the coating or vinyl
• Soft or spongy plywood near door thresholds and edges
• A musty smell in the room or garage under the deck

How a waterproof deck membrane installation goes, step by step

The membrane is only as good as the surface under it. Most of the work happens before any waterproofing goes down.

Strip and inspect the structure

We remove the old surface and check the plywood, joists and the ledger where the deck meets the house. Wet or rotted material is cut out and replaced. A membrane laid over soft wood will fail along with it.

Set the slope and substrate

Water needs somewhere to go. The surface should fall away from the house, commonly about a quarter inch per foot, toward an edge, scupper or drain. We add tapered material where the framing is flat, then lay exterior-grade plywood with sealed joints.

Flash the edges and openings

Metal drip edges go on the perimeter. Door thresholds, wall junctions, posts and drains get their own flashing and a membrane turn-up. This is the detail work that decides whether the deck stays dry.

Lay the membrane and test it

The vinyl is welded or the liquid is applied in coats, then the finish surface goes on. Where it is practical, the surface is checked for pooling and the seams are inspected before it is covered.

Door thresholds, drains and railing posts: where leaks start

Most failures are at the details, not in the middle of the field. The door threshold is the biggest risk, because water meets the wall at the lowest point of the building. A good threshold detail lifts the membrane up behind the siding and the door sill, with the flashing lapped in the right order.

Drains and scuppers clog with needles and leaves and then back up. Posts that pass through the membrane need a sealed boot or a flashed base. Surface-mounted deck railing posts, fixed to blocking beneath the finish, avoid cutting through the waterproofing in the first place.

Waterproof decking and Everett's rain

Everett gets 35.71 inches of rain a year, and most of it falls from October to March, peaking in December. The city sits at the north end of the Puget Sound Convergence Zone, which brings heavier rain and stronger winds than much of the region. Wind-driven rain is what pushes water sideways into door thresholds and wall junctions, so those details matter more here.

Winters are mild and snow is rare, so freeze damage is less of a worry than constant wetness. Dry summers are the right window for membrane work, especially liquid systems that need dry days to cure. Where you want less rain on the surface, a deck cover over part of the deck reduces how much water the membrane has to handle.

Repairing a worn membrane or replacing it

A localized crack, a failed seam or a bad flashing can often be repaired or recoated. That works when the plywood underneath is still firm and dry. If the coating has failed across the deck, or the substrate is soft, patching only hides the problem for a season. In that case the surface comes up, the damaged wood is replaced, and a new membrane goes down.

Upkeep is simple. Keep drains and scuppers clear, sweep debris off the surface, and look over seams and thresholds after the first heavy autumn rain. Small problems found early stay small.