EIFS stucco is a pretty confusing stucco system for some people and understanding what it is will give you a better idea of what goes into it, what the advantages and disadvantages of it are and much more.
To get a better overall idea of how EIFS stucco claddings work and what they are, I wanted to make a more in-depth article and share a few different pictures with you to give you a much better understanding of what goes into it and what you can expect from it. Here goes...
What Is EIFS Stucco, Anyways?
EIFS stands for Exterior Insulation Finishing System and is a wall cladding system that focuses on insulating exterior walls and using multiple layers of materials over that insulating layer to achieve things like crack resistance, moisture control and an appealing, colored finish.
EIFS uses multiple layers of different products that make a complete wall system that can have special properties to it like improved water protection or increased air barriers.
Some of the typical layers include a water/air barrier, an adhesive basecoat, foam, a base coat that is embedded into a fiberglass mesh, a primer coat (sometimes optional) and a finish coat.
Parts Of EIFS Stucco Explained...
Let's take a look at some of the parts of an EIFS cladding to get a better breakdown of what's involved and this will really help you understand what they are, what they consist of and how they differ from a hard coat stucco system.
1. Water Resistive Barrier (WRB):
These are not always a mandatory part of an EIFS cladding but are typically installed as a "premium system" which gives the wall more water resistance. Walls that would not need this first layer would be materials where water would not damage it, like concrete.
Fluid Applied WRBs: These can be a fluid applied product (is applied like paint is) that is usually rolled/brushed on or can be sprayed on and is usually around 20 mil in thickness.
This coat can not have any pin holes, as this is the main waterproofing coat and any holes would allow water to come in and likely be trapped.
Other WRBs: Another type of water resistive barrier that is found with an EIFS cladding is the same paper that you would find on a hard coat system and is usually a form of asphalt infused paper, like roofing felt but much thinner and oftentimes two plies are applied and stapled to the wall.
The wall will usually have mechanical fasteners (nails, screws, etc.) that attach the foam insulation to the substrate and is why this type of WRB is used (self healing properties).
2. The Adhesive Coat:
The foam is attached using an adhesive that is usually troweled on using a notched trowel and the notches will usually run vertically (up and down).
Not all EIFS cladding calls for an adhesive to be applied, sometimes the foam is mechanically fastened to the wall and an adhesive is not needed.
3) Foam Insulating Board:
The foam usually acts as a major insulator for the wall and can come in different thicknesses (ranging from 1" - 6") and the thicker the foam, the more R Value you can get out of your walls.
A good rule of thumb regarding R Value is that for every 1" of foam (thickness) it equates to roughly an R-4 rating.
The foam board is usually made from an EPS type of foam but can vary based on manufacturer and can have grooves on the back side that run vertically (up and down) to allow water to drain if it is ever present in the system.
Not all foam will have grooves on the backside though, just something worth noting.
The foam board can be attached mechanically, using staples, nails or screws or it can be attached using an adhesive, which is specifically designed to attach foam to other surfaces and acts as a very strong glue.
The adhesive is usually applied vertically, using a notched trowel.
4) Mesh And Base Coat:
These are usually two different steps in an EIFS cladding but are usually applied together and are essentially one single step because the base coat MUST be embedded into the mesh.
The picture on the right shows the mesh in the process of being embedded into the base coat.
The mesh is usually a fiberglass type of mesh that comes on a roll, like what you would typically use for drywall, but is much larger and can be found 3' wide by 100' long or longer. There are also different weights of mesh that provide different impact resistance ratings, the thicker the mesh, the more impact resistant it will be.
5) The Primer Coat:
The primer coat is exactly what it sounds like it is... just a primer coat of paint that goes on prior to the finish being applied.
The primer coat is optional (in most cases) but I always recommend a primer coat because it will seal the base coat which nearly eliminates any possibilities of the base coat flaking off and getting into the finish coat.
It actually helps to provide an even suction on the wall too, making for a much better and consistent end result.
Having a primer coat will also allow the finish material to go much further because it eliminates a lot of the suction, which tends to eat up more finish material during the application process.
Manufacturers will sometimes state that their warranty is void if a primer is not applied prior to the finish being applied, so you will want to check to see if that is true or not in your situation.
6) The Finish Coat:
The finish coat is the last coat that goes on and is what you will see on the outside of the building, so it has to look very nice!
EIFS cladding is typically designed to keep out moisture from the outermost layer, which happens to be the finish coat, so the material will have to be water-resistant to be effective.
The finish can be made up of an acrylic material, but it is important to note that an EIFS wall cladding may require a different type of finish material than a hard coat stucco system will require. Most manufacturers have specific finishes for their EIFS cladding system and it is important to follow their recommendations, if using their specific system.
Let's Look At Some Pictures To Get A Better Idea...
I always loved what pictures can do to help solidify an explanation and to help understand some of the "variables" that words just can't solve. Let's take a look at some example EIFS claddings to get a better idea of how they work.
A Basic EIFS Cladding: A basic EIFS cladding is going to have the "basics" that nearly all EIFS stucco walls will have and is a good example of a basic overview.
The system pictured on the right is from Omega Stucco and is applied right over the substrate (light yellow material). This system does not have a water barrier and is a more economical choice.
An EIFS Cladding With Added Water Barrier: Some Systems have an added moisture barrier integrated into them for a little "extra insurance" and is usually applied right over the substrate, as shown in this picture (to the right).
These can be fluid applied water barriers or a paper type of moisture barrier and are also referred to as "drainage planes".
Remember that all EIFS cladding is designed to keep moisture out on the surface level (finish coat) but these systems that use an additional water management system are just an added barrier that provides even more resistance.
Different Manufacturers Have Their Own EIFS Systems...
EIFS is essentially the same from manufacturer to manufacturer but each company will have a little bit different twist on their system and they will call their products different names.
For example, most EIFS systems will use an adhesive coat that will go on in the beginning of the installation process and is usually applied in a vertical fashion to aid in water drainage.
They can be a pure material (like an acrylic based product) and some can be added to portland cement to achieve more of a basecoat and adhesive in one.
Here are two examples of different EIFS claddings from two different manufacturers, Omega and LaHabra. Notice the similarities between the Omega and LaHabra systems, which are both pretty basic EIFS claddings.