Weep Screed and Three-Coat Stucco: How a Stucco Wall Is Built
Short answer: A weep screed is the metal strip at the bottom of a stucco wall that lets water drain out from behind the plaster. California code requires it to sit at least 4 inches above soil and 2 inches above paved surfaces. Above it, a standard stucco wall is three coats of cement plaster totaling about 7/8 inch over metal lath and a weather-resistive barrier.
What the weep screed does
Stucco is not waterproof. Some moisture gets behind it and runs down the weather-resistive barrier. The weep screed gives that water a way out at the base of the wall and gives the plaster a clean, straight edge to stop on.
The clearance rule
The California Building Code (Section 2512.1.2) and the California Residential Code call for a corrosion-resistant weep screed at or below the foundation plate line, placed a minimum of 4 inches above the earth or 2 inches above paved areas.
The most common problem we see is a buried weep screed: soil, mulch, planters or a new patio raised up against the wall after the house was built. Water then has nowhere to go, and the bottom of the wall stains, rusts or crumbles.
The layers of a three-coat wall
- Framing and sheathing.
- Weather-resistive barrier — over wood sheathing, typically two layers of Grade D building paper or an approved equivalent.
- Metal lath, fastened to the framing and lapped over the weep screed flange.
- Scratch coat, about 3/8 inch, scored so the next coat grips.
- Brown coat, about 3/8 inch, leveled to a flat plane.
- Finish coat, about 1/8 inch, with the color and texture.
Total plaster thickness is about 7/8 inch. Each coat needs time to cure before the next goes on; rushing that is a common cause of cracking. On a new construction stucco wall, every layer is built from scratch in this order.
What homeowners can check
- •Look along the base of your walls; you should see a metal edge with open space under it.
- •Keep soil and mulch pulled back at least 4 inches below it.
- •If a patio or walkway was poured against the stucco, have it looked at.
- •Rust stains or crumbling at the bottom edge mean water is trapped. See common stucco problems for more on what to watch for.
Get a free estimate
A buried weep screed or cracked base can usually be fixed. Have a C-35 stucco contractor look at it — we give free estimates across San Diego County.
Request a Free Estimate