Waterproofing an Upper Deck: Protecting the Space Below

Deck Builders Madison · Apr 23, 2026 · 2m

In this episode of Deck Builders Madison, we explain how to properly waterproof an upper deck so the space below stays dry, usable, and protected. Many homes in Madison, Monona, and surrounding areas have second-story decks over patios, walkout basements, or lower-level doors. Without the right waterproofing approach, water can leak through the deck surface, drip onto everything below, and slowly damage framing and finishes. We walk through the basics of planning, materials, and detailing so your elevated deck can safely cover another outdoor or indoor area.

You will learn the difference…