Do you like the look of stucco but worry that choosing the wrong exterior material for Seattle’s rainy climate could leave you with hidden water damage? If you already have EIFS on your home, are you concerned that water could be getting behind the foam and rotting your walls?
At RoofSmart, we’ve seen firsthand how damaging water intrusion around exterior walls can become when flashing and other waterproofing details aren’t installed correctly. We’ve encountered homes where water made its way behind EIFS and contributed to extensive hidden rot, including damage to walls, fascia, and structural beams.
In this article, I’ll explain how traditional stucco and EIFS are constructed, cover why EIFS can present a greater hidden water-damage risk in Seattle’s wet climate, and compare the pros and cons of stucco and EIFS to help you make your decision.
Stucco is a plaster that is applied to the exterior of your home, while EIFS is a stucco imitation made from insulation boards with a textured coating.
Stucco is typically made of a mixture of:
It’s typically applied in multiple coats until you achieve the desired thickness.
EIFS is made of two layers: foam insulation (EPS) and a coating that gives the textured effect of stucco.
The boards either have an adhesive backing that sticks them in place or they are nailed to the outer wall of the home. The wall should be wrapped in building paper to protect from moisture intrusion.
|
Category |
Traditional Stucco |
EIFS |
What Seattle Homeowners Should Know |
|
Basic construction |
Cement-based plaster applied in multiple coats |
Foam insulation boards covered with a textured coating |
Both can create a similar stucco appearance, but their construction is very different |
|
Water damage risk |
Lower when properly installed |
Higher, particularly when installation or flashing fails |
Stucco has the advantage for water resistance |
|
What happens when water gets behind it |
Proper installation should manage water and allow drainage |
Water can become trapped behind the foam |
Trapped moisture can lead to concealed rot |
|
Drainage |
Designed to manage water when properly installed |
Water behind tightly installed foam may have difficulty draining |
Drainage is particularly important in Seattle's wet climate |
|
Flashing importance |
Critical |
Critical |
Incorrect or missing flashing can allow water into the wall with either system |
|
Hidden damage risk |
Water intrusion can still cause damage |
Damage can remain concealed behind foam boards |
EIFS can hide significant moisture and rot before it becomes obvious |
|
Insulation |
Does not use the same exterior foam insulation system |
Foam boards provide additional wall insulation |
EIFS has the advantage for insulation |
|
Cracking |
Can be susceptible to cracking over time |
More resistant to cracking |
EIFS has an advantage if cracking is a primary concern |
|
Installation |
More labor-intensive |
Faster and easier to install |
EIFS is generally the simpler installation |
|
Cost |
More expensive |
Less expensive |
EIFS may appeal to homeowners prioritizing upfront cost |
|
Repairs |
Depends on the type and extent of damage |
Patches can be difficult to blend, potentially requiring a larger area to be recoated |
Water damage can make EIFS repairs more extensive |
|
Best fit |
Homeowners prioritizing authentic appearance, durability, and lower water-damage risk |
Homeowners prioritizing cost and additional insulation |
Installation quality should be a major factor with either system |
As long as they’re installed properly, EIFS and stucco are both solid options for your home. However, it’s important to keep in mind that EIFS is more likely to leak, especially if there is an installation issue.
People who want the stucco look often end up getting an EIFS because it’s cheaper and less labor-intensive than traditional stucco.
You put your foam on, and then you put your top coat, which looks like the stucco. You don't have to put up reinforcement, put chicken wire up, or do your base coat of cement. You're just putting a top coat on.
When installed properly, you have a flashing termination at the bottom to hold it up, and paper comes over the top of it. If it's all taped properly, then water that gets behind will hit the paper, and it'll come out, just like regular siding.
In practice, it doesn't seem to work that way. You have seams in your foam, and those are buried and hidden. Maybe you tape your seams or whatever, but there's always some way that water gets behind that sheet of foam.
And when it does, it's so tight to the paper that you have permanent capillary action, and the water never drains. So water does make it in there (because of course it does), and it can't get out.
Now, it can get out when it gets a lot of full sun, it gets really hot, and it turns it back into water vapor. In that case, it can kind of evaporate out.
But that only works if it's an area that gets full sun. A lot of times, there are flashing issues that let water get behind the flashing, causing a leak.
For example, on this house, there was a flashing issue, and the water got behind the flashing and EIFS, rotting the beam and the entire wall:
There was also rot where the kick flashing was missing. This caused the fascia to rot right up against the wall:
Unfortunately, you can't patch into the EIFS to do a repair. It won't blend, so you’ll have to re-coat all of it to get it to blend.
A lot of the time, stucco is on a masonry construction. So instead of plywood, there are bricks. Another thing that can happen is the EIFS gets waterlogged because it rains a lot. So let's say that there are some imperfections in the paint or in the caulking, and water manages to get in there. If you get a freeze event, the brick will start cracking everywhere.
Stucco and EIFS both provide the same textured appearance that gives your house a rustic, timeless effect. Although both are good at handling water when installed properly, they both pose a potential risk of leaking. If this happens, then EIFS is an especially big risk because it traps water behind the foam boards or the flashing and causes your wall to rot.
So, the top factor to consider when deciding between these two options is to make sure that you find a contractor that has a lot of experience and will install it properly.
Beyond that, there are a few differences between stucco and EIFS, so to help you make your decision, here are the pros and cons of each:
Pros:
Cons:
Pros:
Cons:
If you’re willing to pay more for the authentic look or you want an option that has the best water resistance, then real stucco is probably the best option for you.
If you want a more budget-friendly option or want extra insulation for your home, EIFS is a good option.
When choosing between traditional stucco and EIFS, the biggest concern in Seattle’s wet climate is what happens when water gets behind the exterior. Properly installed stucco and EIFS should manage moisture, but EIFS can create a particularly difficult problem when water becomes trapped behind its foam insulation boards and can’t easily drain or dry.
As we’ve seen in the field, a seemingly small flashing mistake can lead to much bigger consequences. Missing kick flashing or improperly terminated flashing can allow water into areas you can’t see, eventually contributing to rotten fascia, wall framing, or even structural beams. By the time the damage becomes obvious, the repair can be far more extensive than fixing the original entry point.
And this problem isn’t limited to EIFS or older homes. We’ve also encountered newer homes with other exterior siding systems where installation and water-management details have contributed to unexpected leaks and hidden damage.
Read “Why Do So Many Newly Built Homes with Panel Siding Leak?” to learn how water gets behind panel siding, which installation details can contribute to leaks, and what Seattle-area homeowners should watch for before hidden moisture causes more extensive damage.