Stucco Weep Screed Code Requirements Explained
Written by Stucco Champions — Southern California’s Authority on Exterior Plastering.
Understanding the building codes related to stucco weep screed is not just for inspectors—it is crucial for homeowners who want to avoid rot.
The Weep Screed is the exit strategy for moisture in your walls. Without it, water trapped behind the stucco has nowhere to go but into your framing. Below is a detailed guide to the International Building Code (IBC) and California Residential Code (CRC) requirements that Stucco Champions follows on every project.
Code Requirements for Stucco Weep Screed
Building codes (specifically CRC R703.7.2.1 and ASTM C1063) detail specific mandates for weep screed installation. These rules are non-negotiable for a water-tight system.
1. Dimensions and Materials
The code mandates that the weep screed must have a vertical attachment flange of at least 3.5 inches.
The Flange: This is the back metal piece that nails to the wall studs. It must be tall enough to allow the building paper to overlap it securely.
Materials: Standard screeds are galvanized steel (26 gauge minimum), but in coastal areas like Newport Beach, we often recommend plastic (PVC) or stainless steel to prevent rust corrosion from salt air.
2. Installation Location: The “Plate Line” Rule
Weep screeds must be installed at or below the foundation plate line (the bottom wooden 2×4 or 2×6 plate of the wall).
Why: The screed must cover the joint between the foundation concrete and the wood framing. Typically, the screed hangs about 1 inch below the wood plate, ensuring water drips off the metal and onto the concrete foundation wall, keeping the wood dry.
3. The “Clearance” Rule (The 4-inch/2-inch Law)
This is the most violated code in the industry. To prevent moisture from wicking up from the ground into the stucco, the weep screed must maintain a specific distance from the earth:
Earth/Soil: Minimum 4 inches of clearance.
Paved Surfaces: Minimum 2 inches of clearance (over concrete, asphalt, or pavers).
Note: If you add new pavers or planters later, you must ensure you do not bury the weep screed.
4. The Overlap: Integrating the Water Resistive Barrier
The code requires “shingle fashion” installation.
The Weep Flange goes on first (directly against the sheathing).
The Water Resistive Barrier (Grade D Paper) goes on second, overlapping the screed’s back flange completely.
The Lath (Wire Mesh) goes on last.
The Goal: Any water running down the paper must flow over the screed flange and out the holes. If the paper is behind the flange, water is trapped against the wood.
Weep Holes vs. Plaster Stops
It is critical to distinguish between a Weep Screed and a Plaster Stop (or J-Metal).
Weep Screed: Has holes punched in the bottom edge. Required at the foundation.
Plaster Stop: A solid “J” shape with no holes. This is used for terminations at doors, windows, or ceilings. Never use Plaster Stop at the bottom of a wall—it will act as a swimming pool liner, trapping water and rotting the wall.
The Consequences of Violations
Improper installation of weep screed—or omitting it entirely—is the leading cause of “stucco failure.”
Water Intrusion: Trapped water rots the mudsill and wall studs.
Mold Growth: Constant moisture creates a breeding ground for black mold inside the wall cavity.
Structural Damage: Over time, the structural integrity of the home is compromised, leading to expensive retrofitting.
Final Thoughts
Complying with building codes requires precision, but it saves thousands in future repairs. Homeowners should always verify that their contractor understands the “4-inch/2-inch” clearance rule before work begins.
At Stucco Champions, we view the weep screed as the most critical piece of metal on your house. By adhering to ASTM C1063 and local California codes, we ensure your investment stands the test of time.
