Remediating Stucco Siding to Prevent Future Issues

If you are like many stucco homeowners in the Pennsylvania area, you may have discovered that your home is suffering from wall rot. Fortunately, you discovered the problem in time for it to be repaired. However, it is very important that, once repaired, the problem does not occur again. In this blog post, we are going to talk about how stucco siding can be remediated to prevent future issues with mold and wall rot.

Stucco Remediation

Remediation can be a complicated process, but it starts with removing the exterior stucco and determining the source of the problems. This can involve simply removing the sheathing, or it could mean that supporting materials such as 2x4s need to be removed. As the rotted materials are pulled, an experienced remediator will take note of problem areas. Before the new stucco can be installed, the rotten wall materials will need to be replaced, including sheathing, insulation, and waterproof barriers. Openings such as doors and windows will need to be reinstalled, which leads to our next topic: flashing.


Metal flashing (such as kick-out flashing and step flashing) must be installed correctly to create a watertight seal around any openings in the exterior wall. Flashing must be used with all windows and all doors. In addition, multiple layers of tar paper or Tyvek must be installed under the bottom window flanges and sides. This should be further sealed with caulk or an appropriate tape.

When the roof does not extend over the stucco wall or in cases where the roof intersects the stucco wall, kick-out flashing should be used. Tyvek or tar paper should also be installed at the top of the walls as well as at the soffit line. This creates a tight seal to prevent moisture intrusion. Some experts will also recommend the installation of rain gutters to direct the water away from problematic areas.

When flashing and waterproofing is correctly installed, it will aid greatly in preventing the water intrusion that leads to mold and wall rot. If installed incorrectly, then you can be sure that wall rot will begin again.

Six-Layer Method

Once the wall materials and flashing are complete, the walls are ready for the stucco to be applied. Many stucco experts use a multiple-layer method of installing stucco, both for new stucco and remediated stucco. When stucco is installed over a sheath such as plywood or OSB, the typical layers are as follows:

  • Single layer of weather resistant barrier (WRB), such as asphalt paper or Grade D paper, applied over the sheathing
  • 3D plastic drainage matrix (serving as an air gap) applied on top of the WRB
  • Single layer of WRB applied over the drainage matrix
  • Lath, which is a metal or fiberglass mat, on top of the last layer of WRB
  • Multiple layers of stucco (typically 3 layers) applied over the lath

This is a typical stucco installation for a reputable stucco contractor and further prevents the formation of mold and wall rot behind your stucco walls.


You may have noticed the second layer listed above: 3D plastic drainage matrix. The plastic drainage matrix is one of major ways of preventing wall rot and other moisture-related issues. It allows any moisture trapped behind the stucco to evaporate or drain out from between the walls, and it also provides a capillary break to prevent the moisture from spreading to other materials in the wall.

Failure to implement some type of air gap or drainage matrix spells disaster for either a new stucco installation or a stucco remediation. Do not use a stucco installation company that does not include some type of air gap in its installation process. Failure to include an air gap is the most common cause of the wall rot plaguing Pennsylvania’s stucco homes.

Along with the drainage matrix, experts say that weep screeds should be used to allow water to drain out at the bottom of the stucco. Anywhere stucco is installed on the foundation should include weep screeds and tar paper or Tyvek to encourage safe, directed drainage.

After Care

Once your stucco has been remediated, there are some precautions that homeowners can take to prevent future problems. The first is to never use a pressure washer to clean stucco walls, because it will force water into places it does not belong. Be on the lookout for discolorations in the stucco, and immediately attend to any cracks or openings that appear on the stucco walls. If you are not sure how to handle a stucco problem, do not hesitate to call in an expert. Also, do not plant shrubs or trees so close to the wall that the leaves are touching the stucco, because this can cause moisture to be trapped against the stucco.


If you are concerned about the possibility of wall rot or already know you have a problem, contact a reputable stucco installation company that uses a multi-layer stucco installation method like the one outlined here and is careful to use flashing and waterproofing in problematic areas. Look for reputation, quality, and guarantees of their work.

Schedule an inspection of your home’s siding or request a quote today!