Is this EIFS or hard-coat stucco over foam?

Question

EDIT: Updated with new photos, details

• The light blue stuff is foam.
• The wire is metal.
• The base coat looks and feels like real concrete.
• My home inspector said he suspects EIFS.
• I brought in a stucco expert, who told me from a visual inspection that it's definitely real stucco, but he didn't have an explanation for the foam.
• Home was built in the 1994.
• Other than the damaged corner in the photos, I could not find any evidence of any kind of damage anywhere on any of the exterior walls.
• I tried pushing on the wall in many places and did not notice any flex/give.
• I tried to do a knock test and I thought it sounded a bit hollow, but later tried the knock test on a 1961 home with real stucco and it sounded about the same to me, so maybe that's not a good data point.
• FWIW, whatever data source my insurance company generates preliminary quotes from believes that this home has traditional hard-coat stucco.
• This material is over wood framing, not brick/masonry.

1. Is this EIFS or traditional hard-coat stucco over foam?

2. If the latter, would it be susceptible to the same moisture issues as EIFS?

Answer 1

It's important to recognize that not all EIFS is bad, and other cladding systems (beside EIFS) also can have moisture problems. The recipe for disaster is a system where the exterior surface is supposed to be the perfect seal to keep out rain. Somewhere, somehow, rain gets behind that barrier and can't get out. That's where moisture problems begin.

IMHO the foam insulation isn't a problem nor is acrylic stucco. What you really want to know is that there's some provision for drainage inside the wall system.

Traditional hard-coat stucco often used two layers of building paper behind the stucco. The paper got wet during application, then crinkled and shrunk as the stucco dried. This caused it to de-bond from the stucco and to create air spaces, allowing liquid water to drain down the wall and find its way out.

EIFS, whether coated with cementitious or acrylic stucco, needs a drainage plane behind it. Maybe you can view the layers of the wall through some existing penetration. Look for an electrical outlet, a louver for admitting fresh air into the house, a penetration for air conditioning tubing, etc. Remove a cover and look to see if the layers of the system are visible.

Answer 2

My best guess is that this is the traditional stucco because of the wire. The stucco material on both sides of the metal lath. EFIS would have used a fiber mesh with an insulation board behind the mesh.

This is from "www.thespruce.com" article on EIFS.

How to Recognize Synthetic Stucco

Synthetic stucco is soft and sounds hollow when it's tapped, while traditional stucco is hard and brittle. It sounds solid when it's tapped.

Press against the structure with your thumb. It's EIFS if you can feel the finish deflect.

Look for cracks. Traditional stucco is more prone to cracking and the cracks are usually much longer than the smaller cracks typically found in EIFS, typically around window openings.

You most likely have EIFS stucco on your home if you can spot foam board around light fixtures or door frames.

To answer your last question - is the concrete subject to the same moisture issue as EIFS? The earlier EIFS were so watertight in the material that moisture could not escape. Later usage of EIFS added the drainage design during the construction to allow the water/moisture to escape.

Traditional stucco is permeable allowing vapor or moisture to "dry out" and the construction technique allow water to drain.

Answer 3

Finally got a (mostly) conclusive answer.

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My research, along with comments/answers here, was leading me to believe this was probably one-coat stucco, which is somewhat similar to EIFS but uses real stucco materials rather than synthetic.

From what I've read, older EIFS is typically layered like this (I think I've forgotten a layer of paper in here somewhere):

• A backing substrate such as gypsum board or plywood
• A layer of foam insulation attached to the substrate
• A thin layer of synthetic base coat over fiberglass mesh
• An acrylic finish coat

I believe (the slightly misleadingly named) "one-coat" stucco is layered like this (again probably forgetting a layer of paper):

• A backing substrate such as gypsum board or plywood
• A layer of foam insulation attached to the substrate
• A layer of portland cement base-coat over metal mesh/lath, typically with fiberglass fibers added for enhanced durability. This combines the separate scratch coat and brown coat layers of traditional three-coat stucco into a single coat.
• A finish coat

The major difference compared to EIFS is that one-coat stucco uses a thicker layer of real cement over metal mesh, instead of a thin coat of synthetic material over fiberglass mesh. It sounds like it's less durable (in terms of impact resistance) than three-coat but more durable than EIFS. Additionally, the cement base-coat doesn't trap moisture like an EIFS synthetic base-coat, so the wall should be less likely to suffer from mold/rot.

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My girlfriend went door to door asking neighbors what they knew about the stucco. One family she spoke with turned out to be original owners and were familiar with the construction technique used.

They told her the construction uses two layers of real stucco with foam insulation. She hasn't been researching stucco as much as I have and was caught off guard by their level of technical knowledge and got somewhat lost in the details. When she summarized the conversation to me later she wasn't certain if they were saying the construction uses two coats of stucco (perhaps referring to the base coat plus finish coat used in "one-coat" stucco), or if there are two layers of stucco with a layer of foam in between (if that even makes sense). She did recall that they specifically mentioned brown coat.

While she didn't completely follow their technical explanation of the exact construction method, they were aware of the foam and quite certain that the outer material is real stucco, not EIFS.