Waterproofing

Moisture protection for decks & walls

In a wet climate, waterproofing is essential — especially on decks, balconies, and wall assemblies exposed to constant rain. We install and repair waterproof systems designed to protect structure, prevent leaks, and reduce long-term moisture issues.

Typical waterproofing work

• Deck and balcony waterproofing systems
• Wall moisture protection details and targeted repairs
• Flashing and transition corrections to address leak points
• Surface prep and finish coordination for a clean final appearance

Why details matter

Most water issues start at edges, penetrations, and transitions. We focus on the details that prevent recurring problems: correct prep, compatible materials, and careful execution.

How much does deck waterproofing cost?

In the Puget Sound area, a professionally installed waterproof deck membrane system typically runs $10–$25 per square foot, depending on the system, the condition of the substrate, and details like drains, posts, and door thresholds. A typical 200-square-foot deck usually lands between $2,500 and $6,000. Recoating an existing sound membrane costs considerably less than a full tear-off — one more reason not to postpone maintenance until the plywood underneath is rotten. If the deck has already leaked into living space below, budget for substrate repair as well; we'll tell you exactly what we find before work begins.

How long do waterproof deck systems last?

A correctly installed membrane system lasts 10–20 years in Western Washington, with a maintenance recoat roughly every 5–7 years extending its life. What kills deck systems early isn't rain — it's installation shortcuts: missing or wrong flashing, no slope to drain, and coatings applied over damp or damaged plywood. That's why the prep and the details matter more than the brand on the bucket.

Signs your deck or walls have a moisture problem

• Water stains or dripping on the ceiling or walls below a deck or balcony.
• Soft or spongy spots underfoot on the deck surface.
• Cracked, bubbling, or peeling coating — the membrane has lost its seal.
• Staining below windows and at wall penetrations — often failed flashing rather than failed siding.
• Musty smell in rooms adjacent to exterior walls — moisture may be trapped in the assembly.

How to choose a waterproofing contractor

Waterproofing fails at the details, so choose on details. Verify the contractor is licensed, bonded, and insured in Washington (our license is #JPBUIBI854NM — checkable through the state L&I lookup). Ask what membrane system they install and why, how they handle flashing at doors and posts, and whether slope-to-drain is part of the scope. Ask to see photos of their own completed decks, not manufacturer brochures. And get the scope in writing — including what happens if damaged substrate is discovered during tear-off. A contractor who answers those questions clearly will also handle your deck correctly.