Written by Stucco Champions — Southern California’s Authority on Exterior Plastering.

What Is a Weep Screed? The Critical Drainage Component Explained

When planning a stucco project, most homeowners focus on the finish texture and the color. However, the most important component of your exterior wall is one you barely notice: the Weep Screed.

This simple piece of galvanized steel flashing is the primary exit door for moisture in your wall system. It is required by code (IBC and ASTM C1063) for a reason. Without it, trapped water has nowhere to go but into your framing, causing silent, catastrophic dry rot. This guide explains the mechanics of the weep screed and why it is non-negotiable.

1. The Physics: Stucco acts as a Reservoir

To understand the weep screed, you must understand stucco. Stucco is not waterproof; it is water-resistant. It absorbs rain like a sponge.
Gravity pulls this absorbed moisture down through the cement until it hits the waterproof building paper. It then runs down the paper to the bottom of the wall.
The Function: The weep screed catches this water and directs it out through small holes in the bottom flange, allowing it to drip harmlessly onto the foundation.

2. Code Requirements: The 4-Inch Rule

Installing a weep screed isn't enough; it must be placed correctly. California code dictates strict clearances to prevent "wicking" (moisture traveling up from the ground).

Why? If the screed touches the ground, the holes get clogged. Worse, the stucco acts like a wick, pulling ground moisture up into the wall, bypassing the drainage system entirely.

3. Identifying Your Weep Screed

Go outside and look at the bottom edge of your stucco, where it meets the concrete foundation.

• If you see a metal strip: Look for small holes or slots in the bottom edge. This is a proper weep screed (usually a #7 Foundation Screed).
• If the stucco goes into the dirt: Your home likely lacks a weep screed (common in pre-1970s builds). This is a high-risk condition for termite entry and rot.

4. The "Buried" Screed Problem

The most common failure we see is not a missing screed, but a buried one.
Over years of landscaping, mulch and soil build up against the house, covering the weep holes.
The Consequence: Water trapped behind the wall cannot exit. It pools at the mudsill (bottom plate), rotting the wood structure and creating a perfect environment for mold.

5. Retrofitting: Can You Add One?

If your home lacks a weep screed, or if it is rusted out, it can be retrofitted.
The Process: We cut the bottom 6-8 inches of stucco off the wall to expose the framing. We install a new screed, integrate new waterproofing paper (shingle-lapped under the existing paper), and patch the area. This restores the drainage plane and protects the foundation.

Conclusion: Respect the Drain

The weep screed is the unsung hero of the building envelope. It works silently to keep your framing dry. By maintaining proper ground clearance and ensuring the holes remain open, you ensure your stucco system functions as designed for decades.