12/04/2025
roof-to-wall drainage and the correct method for remediation. It uses a cross-section diagram of a wall and roof edge to show Before (a failure point) and After (the correct repair).
🌧️ BEFORE: THE DRAINAGE FAILURE
The top diagram shows a construction detail where poor installation has led to water damage:
• Drip Edge Failure: The drip edge (a metal fl**ge designed to direct water away) is applied "too tight to fascia trim" and has "no overhang" relative to the 1x fascia.
• Water Trapping: Water flowing off the roof shingles clings to the drip edge and runs down the coll-stock fascia.
• Gutter Bypass: The water runs *behind* the gutter and the housewrap (red).
• Housewrap Failure: The housewrap (the red layer, which provides water resistance) "run short of fascia" and is not properly lapped.
• Damage: This combination of failures allows water to repeatedly bypass the intended drainage path, causing a "Gap allowed repeated wetting of sheathing and wall cavity", leading to potential rot, mold, and damage to the wall assembly.
✅ AFTER: THE CORRECT REPAIR
The bottom diagram shows the steps taken to fix the drainage problem and protect the wall cavity:
• Drip Edge Correction: The drip edge is "pulled away from fascia, directs water to gutter". This creates the necessary gap for surface tension to break, guiding the water into the gutter.
• Improved Flashing: A piece of "Metal flashing (blue)" is slid under the fascia (where the leak occurred) and laps the housewrap. This directs any water that gets behind the fascia outward, over the housewrap.
• New Sheathing and Insulation: The damaged wall components are replaced, indicated by "New sheathing and batt insulation".
• New Housewrap: "New housewrap (red) taped along top edge" is installed. Taping the seams is essential to creating a continuous water-resistant barrier.
The repaired system ensures a redundant drainage path, with the drip edge guiding most water into the gutter and the new metal flashing directing any residual water outside the wall assembly, protecting the sheathing and insulation.
