Stucco is one of the oldest exterior wall finishes in the construction industry. And because of its many properties, it’s still a popular option.
Stucco is versatile, therefore it bonds to a wide range of substrates such as concrete, plywood, and OSB. Today, we’re going to find out if stucco can be used on ICF (insulated concrete form) walls.
So, if you’re planning such a project, this article will educate you on all that you need to know.
Can You Stucco on ICF?
Of course, stucco can be used over ICF. Stucco is amongst the best finishes for insulated concrete forms.
As long as it’s installed correctly, stucco creates a durable and highly aesthetically appealing finish on top of ICF.
However, you can’t apply stucco directly to insulated concrete forms. You must use a metal lath to improve adhesion between the two materials.
How to Apply Stucco on ICF?
Step 1: Gather essential materials
To pull off this project, you’ll need enough stucco, a metal lath, and a trowel or a sprayer. Also, look for some sandpaper.
Step 2: Prepare the ICF surface
I’m going to assume that you have already poured concrete inside the ICF and it has dried. You’re going to start with cleaning the surface. Contaminants and dirt are known to affect the adhesion of stucco to ICF. So, a thorough cleanup is vital.
After cleaning, it’s also advisable to sand the surface of the ICF. Doing so creates a texture for the stucco to bite onto.
Even though sanding the ICF is not mandatory. It does contribute to improving the bond between these two materials.
Step 3: Lay the base coat of stucco
Using a trowel, start applying the first coat of stucco. This is often referred to as the scratch coat. The purpose of a scratch coat is to create a more conducive surface for the finish coat.
Step 4: Attach the metal lath
Before you get to the final coat, you need to install a metal lath. Please note that this step is very crucial because it promotes a strong bond between stucco and insulated concrete forms.
What you will do with the metal lath is to screw it into the furring strips on the ICF. Ensure that it’s firmly attached.
Step 5: Apply the finish coat
It’s now time to apply the finish coat. But this should only be applied after the first coat fully dries. The finish coat is usually thinner.
And its also during this step where you can create texture or your preferred pattern. Once that’s done, give it enough time to dry and you’ll have successfully laid stucco on ICF.
What Types of Stucco Can You Use on ICF?
As you may already know, there are different types of stucco and each has varying features. Here is a list of the types of stucco that can be used on ICF;
• Portland cement stucco – Also known as traditional stucco, this is the most common type that’s used on insulated concrete forms. What I like most about traditional stucco is its durability.
• Acrylic stucco – This is the synthetic version of stucco which contains acrylic polymers. Most people these days prefer this type of stucco because it’s more resistant to cracking.
• One-coat stucco – As the name suggests, this is a type of stucco that only requires a single coat. It’s the best option if you’re in a hurry to finish your ICF walls.
Before settling for a particular type of stucco to use on ICF walls, make sure that you consider factors such as aesthetics, durability, and local climate. This is the only way you can be guaranteed a long-lasting finish over your ICF walls.
How Thick Should Stucco Be on ICF?
The thickness of stucco on ICF depends on three main things; the base coat, metal lath, and finish coat. The base coat is usually 3/8 inch, and the thickness of the metal lath is about 1/8 inch.
As for the final coat, it can range from 1/8 inch to 1/4 inch. So, when you add all these three, you can expect a stucco thickness of about 5/8 inch on insulated concrete forms.
While evaluating the thickness of stucco on ICF, pay attention to local building codes. Also, factor in the local climate. Areas that experience terrible weather often require the stucco to be laid on much thicker.
Can You Apply Stucco on Curved ICF Walls?
You can apply stucco on curved ICF walls. But in this case, you’ll need an extra set of skills. To kick things off, you must use flexible stucco which is elastomeric, that it is it can bend to the curved shape of ICF walls.
A metal lath is compulsory. Also, in such a project, you need to work with thin layers of stucco because they are more resistant to cracking.
As for joints along the curved ICF walls, ensure that you install control joints to facilitate expansion and contraction.
Do You Have to Worry about Moisture When Applying Stucco on ICF?
Whenever stucco is involved moisture management is very crucial. Because stucco is a porous material, as you install it over insulated concrete forms, you must ensure that the water that passes through doesn’t get to the ICF and there are a few things you can do to ensure that.
The first line of defense is a weather-resistant barrier which should be applied to the exterior of the ICF. House wraps such as Tyvek often do a great job of keeping moisture away.
Also, around windows and doors, install flashing and weep screeds. These will direct moisture away from the ICF wall and stucco system.
The control joints that I was talking about earlier, besides accommodating expansion and contraction, also act as drainage points.
Do not hesitate to take extra moisture management measures if you live in an area that experiences heavy rain.
Can You Stucco on Interior ICF Walls?
There is a new trend where homeowners are using stucco as an interior wall finish. And the good news is that if you also want to embrace such a design it is possible if you have ICF walls.
Stucco on interior ICF walls can improve aesthetics by incorporating a Mediterranean appearance. The installation process is the same as above, only that you have to be mindful of the thickness.
I would also advise you to seal the stucco to prevent it from staining.
Should I Hire a Professional Contractor to Install Stucco on ICF?
Well, that depends on how experienced you are. If you are not an expert in such matters, it’s best to hire a professional contractor to install stucco on your insulated concrete forms.
On paper, applying stucco on ICF may seem easy but it’s more complex than one may think. Improper installation can lead to very serious problems later on.
And if you lack skill, you may find yourself not complying with local building codes. Working with an experienced contractor guarantees quality workmanship and you can also get a warranty.
Therefore, if you have such a project in mind, I’d encourage you to list the pros and cons of both approaches. I understand that hiring a contractor increases the project’s costs. But are you up for such a task?