Stucco Flashing

Providing a watertight flashing system at the joint between roof and stucco walls requires careful consideration. It is necessary to understand the location of the plane at which the stucco wall system in intended to shed water. Similarly, other items that should be considered are the amount of the water that is expected to get to the wall, the size of the roof overhang protecting the wall, openings in the wall for windows and other things and the condition of the stucco itself.

Today the generally acceptable position is that stucco is not waterproof and the construction of a stucco wall system should include a drainage plane behind the stucco. This drainage plane is constructed of a continuous water shedding underlayment that will allow water that gets through the stucco to run down and out at the bottom of the wall. The underlayment is sealed around all openings in the wall and all necessary flashings installed as part of the total system.

In most cases, existing stucco walls were not constructed with an adequate drainage plane behind the stucco. Provision was not made for water to weep out from behind the stucco at the base of the wall, the sealing around the openings was not adequately accomplished and the underlayment often does not form a continuous water shedding layer. The face of the stucco is then acting as a drainage plane.

These two situations can require different methods of flashing treatment. The different methods can have significant impact on the cost, aesthetics and ongoing maintenance.

When flashing against a stucco wall that has a properly installed drainage plane behind the stucco, the flashing must extend up and behind the underlayment. If the flashing piece was not installed as part of the original construction or if it was not installed in the proper location it may be necessary to break out the stucco to properly install a new flashing piece. This should be part of a two piece flashing system where the lower piece can be removed and reinstalled when re-roofing and the upper piece is a permanent flashing that extends up behind the drainage plane

It should be noted that when the stucco is broken out and patched, the patch would usually remain visible unless the entire wall is re-dashed.

If there is not a properly installed drainage plane and the face of the stucco is acting as a drainage plane there are a couple of options for flashing. First would be to cut a reglet in the stucco wall and insert metal counterflashing into that reglet joint and caulk the joint with a high-grade caulking.

This will seal the flashings at the face of the stucco wall, however if water is able to get through the stucco it will be able to get behind the flashings and produce a leak. There are some variations of this where a reglet is not cut into the stucco and instead a surface type flashing is installed against the face of the stucco.

We do not recommend this. The joint between the stucco and the surface flashing requires high maintenance to keep watertight. The other option is to break the stucco away and insert metal flashing up behind the stucco. However, if there is not an adequate drainage plane, water can still run down and get behind the metal that you put behind the stucco. This can be more costly and not any more effective.

To create a proper drainage plane on an existing stucco wall, all of the stucco would have to be removed, a continuous water shedding underlayment needs to be properly installed, the underlayment must be sealed around all the penetrations and a provision must be made to allow a way for the moisture that gets behind the stucco to exit. This process can be very costly.

We will generally flash against a stucco wall by cutting a reglet into the stucco and installing a metal counterflashing into the reglet and down over the flashing which has been installed against the stucco wall. The metal counterflashing will remain visible at the completion of the job. We cannot be responsible for leakage that occurs if water gets behind the stucco and runs down behind our flashing.

Please check with our representative so you will be clear on the flashing detail at the joint between the roof and stucco. You need to notify us if you want to have the stucco broken out, so our proposal can reflect the added cost of that option. You will also need to hire a stucco contractor to repair the stucco wall at the completion of the roofing work since we do not do that work and that will not be included in our proposal.

There is one other specific flashing detail that needs to be recognized to prevent serious damage to your home. This is the flashing piece that is installed at the point where the lower edge of the roof intersects with a sidewall that extends beyond the lower edge of the roof.

This flashing piece must be installed to direct the water from the joint between the roof and wall out beyond the face of the stucco wall.