Why does stucco have problems?

What are the problems with stucco systems?

Stucco systems that have been installed over the last 30 years can tend to suffer from specific problems related to installation.  These issues generally center around the waterproofing applied behind the stucco system.  Because stucco is a non-waterproof material, there needs to be components installed behind it to prevent moisture intrusion.  What most people refer to as a problem with stucco is actually a problem with the waterproofing behind the stucco.

So what needs to happen to avoid problems with stucco?

In todays modern installations, there are several protective layers behind the stucco system. This includes:

Window sill pan flashing

Window Sill Pan Flashing

Two layers of 60-minute paper

2 Layers of 60 Minute Paper

  • Moisture resistive barriers (at least 2 layers)
  • Rainscreen Application
  • Flashings including window sill pan flashing, head flashing, kickout flashing  and weepscreed flashing

Flashing details prevent stucco problems because they are able to direct water away from the wooden part of the structure.  Having several ways that deflect moisture from the structure is how modern systems prevent stucco problems.

What items were missed that cause most stucco problems?

What we see in the field are 3 main items that cause the majority of stucco problems. First, single layer of Water Resistive Barrier (WRB) does not allow much room for error. It is also common that the building paper is not tucked behind the window nailing flange on the bottom leaving a reverse construction lap. Second, little protection around the window is applied. See window pan flashing above, this is a very durable system for keeping moisture out. The final item is lack of flashing details, particularly kick out diverter flashings. The lack of these flashings at perpendicular terminations of gutters causes accumulation of moisture. This concentration of water when heavy rains occur commonly penetrate the single layer WRB eventually. If we could check only one location, these missing kick out locations can be a bell weather for how the system has performed overall.

How do I determine if I have Stucco Problems?

That’s easy, give Stucco Safe a call!  Stucco Safe is the premier stucco inspector near you.  WE offer thorough inspections. at very fair prices.  Click here to learn more Learn More

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