Stucco Moisture Protection

Moisture intrusion can be an issue for any exterior building material, including vinyl siding and both stone and brick veneer. However, stucco is the material that is most at risk because of its porous nature that allows water to more easily infiltrate the wall’s surface. For this reason, moisture protection is needed beneath stucco and all other exterior veneers. This moisture protection takes three main forms. First is the waterproof sheathing that protects the interior wall surface. Second is the flashing around windows, doors, and other openings. And third is the weep screed that drains moisture out of the system.

Waterproof Sheathing Protects Surfaces

Waterproof sheathing is attached directly to underlying wall surfaces to protect them from water damage. These interior walls are often plywood or other manufactured materials that can absorb water. The sheathing protects these materials from soaking in water and rotting, which can damage the internal structure of the building. Wood is the primary internal construction material for most walls, which leaves them vulnerable to rot if not properly protected.

Sheathing is used on all modern buildings regardless of their external material. It is the (often green, yellow, or brown) colored, paper-like material that you see plastered all over buildings that are under construction. Unfortunately, despite the fact that it is now used in all construction projects, some contractors still do not overlap the layers correctly. If the layers are not sufficiently overlapped, then moisture can get in between.

Stucco remediation

Stucco Damage Discovered During a Home Inspection

Damage from improperly waterproofed stucco can show up at the worst times.

Flashing Redirects Water Away from Openings

Old sheathing and flashing

Window and door flashing is used to prevent water from infiltrating deeper into the walls and interior of the building. Sheathing can only protect so much on its own. And while it is certainly good at protecting surfaces, it falls short when it comes to cracks such as those found around various building entry points. Windows and doors are the most common of these entry points, but there are also many smaller openings, including holes in walls where utilities enter the building from outside.

The installation process for flashing is simple, yet important to have done properly. If installed incorrectly, flashing can actually direct water into the cracks rather than away from them. This improper direction of water will also wear away the adhesive that holds the flashing in place, causing it to come loose. Unless a moisture analysis is completed, it may be impossible to tell if your flashing has been installed incorrectly until the water damage becomes visible. If you suspect that moisture intrusion is occurring within your walls, our team of stucco, siding, and veneer experts can perform an analysis to find out.

Weep Screeds Expel Moisture

Weep screeds allow for the moisture that builds up within the layers of a wall to be drained out of the system via slots at the bottom of the wall. Air can also enter the wall through these slots, which helps to dry the internal structure. Preventing the buildup of moisture inside the walls is an important part of keeping the building structurally sound. Without a weep screed, moisture buildup can lead to mold, mildew, and rot that can compromise the internal structure of the wall.

The Drain Screed is a special weep screed that was invented by Denis Friel. Unlike a normal weep screed, the Drain Screed has openings at both the top and bottom of the wall system. At the bottom, moisture can drip out of the slots just as it would with a normal weep screed. However, the difference with the Drain Screed is that evaporated water can also escape out of the top.


Sheathing, flashing, and weep screeds are the three primary components that protect the interior of your walls from moisture damage. Any building with a veneer exterior (stucco, vinyl siding, stone veneer, or brick veneer) will make use of these components. The sheathing is the underlying waterproof layer that is adhered to the internal structure of the wall to prevent it from getting wet and rotting. Flashing is the waterproof tape that is used to seal off cracks around entry points such as windows and doors. It also redirects water away from these vulnerable areas. And weep screeds allow for moisture to escape out of the system while also allowing air into the system to dry everything out.

Friel Plastering

If you have a stucco home or commercial property that is showing signs of water damage, do not wait for the damage to get any worse. Contact the stucco remediation specialists of Friel Plastering today. Our team of experienced professionals can perform an inspection of your walls and perform full remediation if necessary. With decades of experience on our side, you can trust that the job will be done right.