What Is Weep Screed?

A weep screed goes at the bottom of an exterior wall. This flashing – a lath accessory – handles moisture for stucco or stone veneer. It directs water away from the wall’s frame. This small piece of metal is key for keeping outside walls dry, especially those with cement plaster. It also helps set the right stucco depth and works as a control joint. The weep screed guides moisture caught inside the wall to the outside.

Why Is Weep Screed Essential for Stucco Buildings?

Weep screed protects structural framing from moisture damage in stucco buildings. This flashing, fixed at the bottom of framed walls with cement plaster, finishes the stucco’s lower edge. It lets out moisture that gets into the stucco. This stops wood damage, rot, and mold. Weep screed ensures any incidental moisture – like from a window leak – leaves the wall assembly. This keeps the building sound and prevents water issues.

How Does Weep Screed Prevent Moisture Damage?

A weep screed stops moisture damage. It moves water, absorbed behind the stucco, out of the wall. This part has a V-shaped edge and small holes for moisture to escape. These weep holes drain water away before it can collect at the stucco’s base. The system pushes water below the plate line – where the concrete foundation starts – keeping wooden parts dry and safe. The weep screed is a control joint; it hangs beneath the sill plate, guiding water past any materials sensitive to moisture.

What Are the Key Design Elements and Materials of Weep Screed?

Weep screed has a vertical flange, a v-shaped edge, and often drain holes. The vertical flange is at least 3.5 inches (89 mm) tall. It has holes to nail it to wood panels or studs. The v-shaped edge sticks out from the bottom of that flange.

Galvanized steel, aluminum, zinc, and plastic are common materials for weep screed. Galvanized steel lasts a long time and resists rust. Copper is also used. Some designs include flanges that are perforated or solid, or a longer bottom leg to go under sheathing. These choices in design and material help stucco end cleanly and let moisture drain.

What Are the Common Types and Styles of Weep Screed?

Weep screed comes in different types and styles. You will find foundation sill screed, FHA screed, and something called No. 7. The main styles are “V” and “J” – the “J” is also known as casing bead style.

The #7 weep screed is a common V-style. Builders typically use it in most three-coat plaster systems. “J” type weep screed, on the other hand, often appears in one-coat plaster systems. Some specialized types exist, like mid-wall transition weep screeds for lap siding, or positive drain weep screeds. There are even vinyl drip screeds with weep holes and tape for specific transitions and to relieve stress. These screeds are made from materials like vinyl, galvanized metal, and zinc alloy.

What Are the Installation Requirements for Weep Screed?

Weep screed needs careful placement and fastening. Workers install it at a wall’s base – right on the wood panels or studs – where the wall meets the foundation. Nails usually secure the screed along its vertical flange.

Its weep point must sit at least 4 inches (102mm) above bare earth or landscape. Paved areas or hardscapes need a minimum 2-inch (51 mm) clearance. The screed’s bottom edge should stay at least 1 inch below the foundation plate line (the joint between foundation and framing). A water-resistive barrier – waterproofing paper – and exterior lath go over the weep screed’s vertical flange. These specific installation steps are checked during the Exterior Lath Inspection. This ensures proper moisture management in the building.

What Building Codes Mandate Weep Screed?

Building codes now demand weep screed for plaster walls. The plaster (stucco) requirements show up in the 2018 ICC International Residential Code (IRC) Section R703.6.2.1. For cement plaster on framed walls, the International Building Code (IBC) Section 2512 requires weep screed at the foundation plate line.

Standards like ASTM C926 and ASTM C1861 lay out how to use Portland Cement-Based Plaster. They detail weep screed material and application specifications, covering things like corrosion resistance and flange dimensions. When did this requirement start? Weep screeds have been mandatory in building codes since 1970; for timber-framed houses, that date was 1986. Any home built after 1985 needs a weep screed – or at least some other, similar drainage system.

When Is Weep Screed Not Required?

You don’t need weep screed on masonry or concrete walls if you apply plaster straight to them. Materials like concrete and cinder block (CMU) naturally resist moisture. Weep screed is also left off stucco-covered masonry buildings or when stone is glued over masonry. Its main use is for wood-framed walls to keep the framing dry.

When Should Weep Screed Be Inspected or Replaced?

You need to check weep screed and replace it sometimes. Regular building inspections or renovation jobs are good times to look at it. If the weep screed shows rust, becomes brittle, or if its weep holes get clogged – or damaged by something outside – then it’s time for new screed.

Rust creates standing water, which can rot wood and cause mold in the building’s frame. Bad installation, like burying the screed or piling mulch against it, stops drainage. You’ll need to fix this or replace the screed to keep moisture out. This prevents long-term harm to the walls and foundation.