Stucco Weep Screeds Explained: Grade Clearance, Corners, and Keeping Them Open

A stucco weep screed sits at the exterior wall terminus of the stucco and marks the drainage plane. It is distinct from other flashing components and serves as the termination point for moisture management. Understanding its role helps protect the wall assembly from moisture damage.

Its drainage function creates a path for moisture to exit and promotes drying behind the stucco. It must terminate at the proper plane above the foundation to allow for effective drainage. Proper installation criteria include clearance above grade, alignment with the drainage plane, and continuity with the weather-resistant barrier to prevent moisture intrusion.

Purpose and basic components

A weep screed’s job is simple but crucial: let water out. It’s the drainage/termination point for your exterior stucco. Here’s what makes it tick:

Metal or PVC screed: This is the backbone, creating a channel for water to flow through.

Perforations/weep openings: These tiny holes let water drip out. They’re usually on the bottom and sides of the screed.

Drip edge/hem: This keeps water from running behind the screed, ensuring it all goes down and out.

How a weep screed works in a wall system

Water gets into stucco, no matter how well you apply it. Here’s how the weep screed handles that:

Incidental water seeps through the stucco and hits the water-resistive barrier (WRB). The WRB redirects it down to the flashing at the base of your wall.

The flashing then guides this water into the weep screed. It flows through the perforations, out the bottom, and drips onto the ground.

This keeps your walls dry, preventing moisture damage. It’s a simple system, but it needs to be installed right to work.

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Grade clearance defines how high the weep screed sits above the finished grade and why that matters for drainage and moisture management. High or low placements can affect how water is vented away from the wall.

Local code and manufacturer instructions guide the required clearance, with references to IBC/IRC when applicable. Always check site-specific requirements with the local building department and review product data sheets for each job. Practical checks include verifying grading, ensuring continuous drainage paths, and documenting compliance for inspections.

Interpreting building code vs. manufacturer guidance

The International Building Code (IBC) and International Residential Code (IRC) set the minimum standards for stucco weep screed clearance. But, local codes might have amendments, and manufacturers may recommend specific clearances in their installation instructions.

Always follow the most stringent requirement. If there’s a conflict, consult your local building inspector. They can clarify which rule takes precedence on your site.

Manufacturers’ guidelines are based on extensive testing and experience. They might suggest higher clearances for optimal performance. While not legally binding, ignoring these recommendations could void warranties or lead to moisture issues down the line.

Site factors that affect required clearance

Before determining grade clearance for your stucco weep screed, consider these site-specific factors:

Grading: The slope of the ground around your foundation influences water flow. A steeper slope may require a higher clearance to ensure proper drainage.

Finish surfaces and potential splash zones: If there are hard surfaces nearby, like driveways or patios, that could direct water onto your walls, you might need extra clearance to prevent water from being forced up behind the stucco.

Adjacent walkways: If people will be walking near your walls, consider a higher clearance to accommodate for any accidental kicks or impacts that could dislodge debris and block weep holes.

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Substrate prep and WRB interaction involve confirming the wall assembly, the grade clearance from the footing, and current moisture conditions. Make sure the weather-resistive barrier is properly installed and continuous to prevent water tracking to the framing.

Flashing and integration at openings require careful planning around windows, doors, and terminations. Seal joints to keep drainage paths open without blocking weep slots. Setting the correct plane means aligning the weep screed height with the lath and ensuring compatibility with insulation or siding edges.

Fastening, alignment, and plane control

Properly securing the weep screed ensures clear drainage paths and maintains a consistent stucco thickness.

Use corrosion-resistant fasteners spaced according to code. Ensure they don’t penetrate through the screed, blocking weep paths.

Align the screed plumb with the wall plane. Maintain this alignment throughout installation to ensure consistent stucco thickness to the screed.

Tip: Use a level or laser level to maintain plumb and check consistency as you go.

Temporary protection and sequencing during construction

Protecting weep screeds during construction prevents mortar and debris from clogging drainage paths. Here’s how:

Cover the screed with a protective material, like plastic sheeting or cardboard, to keep out debris. Remove it once stucco application begins.

Coordinate with other trades to minimize disruption around weep screeds. Keep the area clear of excess mortar and debris during construction.

Note: If you notice any blockages or damage during construction, address them immediately to prevent long-term issues.

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Best practices for outside corners include proper corner bead use, formed returns, and backing support to prevent cracking and water ingress. Inside corners should maintain a clean transition that preserves drainage while allowing movement.

End terminations at parapet edges and transitions to openings require watertight seals and continuous drainage paths. The screed should integrate with flashing and weather barriers without creating gaps.

Outside and Inside Corner Details

Corners are critical areas where water can easily penetrate. Here’s how to handle them:

Outside Corners (Gable, Sill): Use formed returns or corner beads for a clean finish. Support with sheathing/backing to prevent cracking.

Inside Corners (Wall-to-Ceiling): Apply mesh and scratch coat before installing the weep screed. Ensure drainage continuity by maintaining a consistent slope.

Transitioning to Flashings, Window Sills, and Penetrations

Proper transitions ensure water flows freely without leaks. Here’s how:

Flashings: Tie the weep screed into below-window flashings using compatible materials. Ensure a watertight seal.

Window Sills: Integrate the weep screed with window sills, maintaining drainage continuity and preventing cold joints.

Penetrations: Seal around penetrations (e.g., pipes) using appropriate materials to prevent bypass leaks. Ensure they don’t bridge the drainage plane.

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Design strategies focus on profiles that keep openings clear and accessible screens that can be serviced. Choose shapes and features that promote unobstructed air channels and debris shedding.

Maintenance routines should be practical and include inspection points for debris removal without damaging the stucco. Plan serviceable access and testing methods to verify open channels and consider retrofitting cleanouts where feasible.

Routine cleaning and minor repairs

To keep your weep screeds clear, perform routine cleanings. Here’s how to safely remove debris without damaging the system.

Gently brush: Use a soft-bristle brush or compressed air to remove dirt and debris from weep holes. Be careful not to damage screens or the screed itself.

For tougher clogs, use a thin wire or pipe cleaner to gently poke into the weep hole and dislodge any obstructions. Be gentle to avoid damaging the system.

If screens are damaged, replace them with new ones that match your existing system’s size and material. Ensure they’re securely fastened but not too tight, which could restrict airflow.

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Flashing details around heads, sills, and terminations must work with the grade clearance and corner treatments to prevent water intrusion. Proper sequencing helps maintain a continuous drainage path.

WRB continuity across penetrations and joints is essential, with no gaps that allow moisture to bypass the drainage plane. Drainage plane compatibility and material sequencing influence overall performance and durability.

Flashing best practices

The key to effective flashing is ensuring a continuous slope towards the weep screed. This allows water to drain efficiently.

Terminate flashings correctly at the weep screed. They should extend just below the screed’s bottom edge, allowing water to exit without obstruction.

Overlap and seal flashings properly to preserve the drainage path. Overlapping creates a stepped effect that directs water downwards, while sealing prevents water from seeping behind the flashing.

WRB, rainscreens, and material compatibility

Material choices significantly impact the performance of your stucco weep screed. Incompatible materials can lead to cracking, staining, or weak bonds.

• Weather-Resistant Barrier (WRB): Tie the weep screed into the WRB plane for a continuous moisture barrier. Use compatible tapes and sealants at joints and penetrations.
• Rainscreens: Consider vented or rigid backing for rainscreen cavities to promote drainage and drying. Place weeps within these cavities, ensuring they’re not blocked by insulation or other materials.
• Flashing Metals: Choose compatible metals that won’t corrode when in contact with each other. Galvanized steel and aluminum are common choices.
• Coatings: Ensure stucco coatings are compatible with flashings and other materials. Check for proper adhesion, flexibility, and resistance to cracking.
• Fasteners: Use fasteners rated for the specific materials they’re connecting. Incompatible fasteners can cause corrosion or weak connections.

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Frequent mistakes include blocked openings, inconsistent grade clearance, and missing or poorly installed flashings. These issues can compromise drainage and cause moisture intrusion.

Inspection checks should cover clearance measurements, debris signs, fastener corrosion indicators, and flashing integrity around openings. Use corrective steps to reestablish drainage and consider preventive measures for future jobs.

Diagnosing blocked or underperforming weeps

First things first, you need to inspect visually. Look for any signs of blockage or debris in your weep screeds. Check for:

– Paint overspray or drips covering the openings.

– Stucco droppings or other construction debris clogging the weeps.

If you find any, use a wire brush or needle-nose pliers to clean them out. For paint, use a scraper and some solvent if needed.

Material failures and corrosion issues

The materials you choose for your weep screeds matter. Incompatible metals or finishes can lead to corrosion, cracking, and staining. Here’s what to look out for:

• Galvanized steel: Look for rust. Replace if you see it. Use with compatible materials.
• Stainless steel: Check for discoloration. It’s rare, but it can happen. Specify 304 or 316 grades.
• Aluminum: Look for pitting. Avoid if you’re near saltwater. Use with compatible fasteners.
• Plastic: Inspect for cracking. UV exposure can cause it. Use UV-stabilized types.
• Zinc: Check for white corrosion products. It’s normal, but excessive means replace. Use with compatible coatings.

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A DIY-friendly tools list should cover hand tools, measuring devices, safety gear, and specialty items. Include quick-use notes for when each tool is needed during installation or inspection.

The materials list should explain the purpose of each item, from weep screed types to fasteners and flashing. Include guidance on how to read specs, verify tolerances, and check compatibility with stucco and weather barriers.