What is an EIFS system? Are there geographic limitations to its use?
Exterior Insulation and Finish Systems (EIFS) are a type of building cladding commonly used on both commercial and residential structures. Originally developed in Europe after World War II as a means of repairing bomb damaged masonry buildings, today’s EIFS is substantially different. It is recognized more as a North American development, where it was first applied to framed and sheathed walls, instead of masonry or concrete.
EIFS provides both weather resistance and architectural appeal. Basic EIFS is a thin “lamina” of cementitious material applied directly over a fiberglass “screed”. This is applied over rigid foam insulation which is attached to sheathing such as exterior rated gypsum board. Preferably, a waterproofing barrier is applied to the exterior sheathing prior to application of the EIFS. Occasionally you will hear EIFS referred to as synthetic stucco; however, EIFS and traditional stucco are very different so it is important the two are not confused.
There are no significant limitations to where EIFS can be used. It works in most climate types and conditions, provided the appropriate type is selected and is properly installed.
What is the advantage of using an EIFS system?
Economics play a major role in selecting an EIFS system over another type of exterior cladding. In addition to being typically less expensive, it is also readily available. The cementitious lamina is mixed on site and field applied, so there are less transportation costs involved. In comparison, other types of cladding systems need to be ordered with a significant amount of advance notice and cannot be built on-site. Most of the foam insulation used in EIFS assembly can be locally sourced, again providing economic benefit. EIFS also gives designers and installers increased flexibility and creativity without breaking the bank; it is architecturally easy to work with. Lastly, EIFS improves energy efficiency as compared to some other systems. The increase in energy efficiency continues to be one of the driving forces behind EIFS popularity.
How do you determine which type of EIFS system will work best for a particular project?
The answer here truly is “it depends”. Decision-making factors are the owner’s goals and budget, there is no single solution for all situations. Specific systems vary from manufacturer to manufacturer but EIFS can generally be condensed into four basic categories:
- Direct Applied EIFS (DEFS) – Direct applied EIFS systems are not really EIFS at all using the North American stan-dard. The foam insulation is removed from the assembly and the 1/8” cementitious lamina is applied directly to the sheathing. In a sense, this is exactly how EIFS was envisioned to be used in Europe after World War II; however, it was never applied over framed walls like we use it today in the U.S. This is a very fragile and simplistic system. Today, DEFS is used only in regions with small thermal swings like Hawaii – it is almost never used on the U.S. mainland. Although owners like it because it is the least expensive of all EIFS assemblies, we would not recom-mend it as a primary cladding system.
- Barrier EIFS (‘Classic’ EIFS) – Barrier EIFS systems are the most basic of EIFS assemblies and do not incorporate any back-up systems or redundancy. Essentially, the 1/8” of cementitious lamina is the only means of keeping water out of the building; it is a barrier without a back-up. This system has evolved and improved over the years, but it is still essentially the same system that has been used in the U.S. since the 1970’s and 1980’s.
- Water-Managed EIFS (‘Drainable’ EIFS) – Water managed EIFS systems combine a barrier EIFS assembly with a back-up waterproofing system and are far superior to barrier EIFS. The design of these systems concedes that no building is perfect, and that eventually, a crack or a leak will almost always develop. Therefore, a weather resistive barrier (WRB) is incorporated into the assembly as a back-up, which directs any water which does make it past the primary barrier, out of the assembly instead of into the walls. In a sense, this is the closest EIFS gets to emulating traditional stucco.
- Rainscreen EIFS (EIFS with Cavity Wall) – Rainscreen EIFS or “cavity wall” systems are rarely installed due to their high installation cost, but they are unquestionably the most robust EIFS assemblies. This system incorporates a water managed EIFS assembly with an open cavity wall behind it. An entire secondary waterproofing system is then applied to the cavity wall. It is almost like having two exterior walls. Very effective, but very expensive.
What are the cons or caveats to using an EIFS system? What types of projects are best suited for EIFS? Under what circumstances would an EIFS system not necessarily be the most effective choice for a building?
EIFS can be a very effective system for almost any low or mid rise building and is cost effective. However, anytime you rely on 1/8” of cement over foam to keep water out of a building things can go wrong. Barrier EIFS and DEFS systems have no backup, so if there are any problems, water is going directly into the wall cavity. This causes corrosion, premature failure of components, and worse yet, mold.
EIFS systems are theoretically trying to emulate traditional stucco at less expense. But if you think about it, stucco systems always have a weather resistive barrier as a back-up.
In fact, it is a building code requirement for stucco systems. With this in mind, our firm never recommends using DEFS or a standard barrier EIFS because they have no WRB backup. Instead, we always recommend owners use a water-managed EIFS assembly thereby making it an effective choice to protect their investment.
Many reports describe problems with moisture buildup in an EIFS system. What causes these problems in an EIFS system and how can they be prevented?
To be fair, water intrusion into buildings is a problem with many types of cladding systems, not just EIFS. Moisture buildup in wall systems is especially prevalent in regions with hot and humid climates regardless of the type of cladding. Moisture problems can be associated with material defects and design errors; however, the overwhelming majority of these problems are caused by construction defects and poor craftsmanship.
This is particularly true of DEFS and classic EIFS since there is no WRB as a back-up. Even the smallest of construction errors can allow water directly into the wall cavity. The good news is prevention can easily be obtained. If expired material arrives at the job site, reject it. Consult with knowledgeable designers and building envelope specialists. Insist on quality and be sure to include a quality assurance program in your project.
From a contractor’s standpoint, what must be done to ensure that an EIFS system performs successfully?
Construction is a tough business and translating design intent from “mouse clicks” to “bricks” is often a dilemma for contractors. It is not an enviable position and we respect the challenges they face. Nonetheless, installing EIFS (or anything else) correctly and in compliance with the construction documents is ultimately the contractor’s responsibility. If we could offer one piece of advice to contractors, it would be to invest in better training for your crews, and then as a follow up, hold your craftsmen accountable to installing a quality product. It has been our observation over the years that this is single-handedly the biggest thing contractors could do to improve the performance and reduce risk.
Any reassuring words for owners/developers who are considering an EIFS system?
First, don’t be afraid of EIFS. It is a perfectly acceptable cladding system. That said, do your homework. As you can see from our comments above it is more complicated than it may appear. Always use a water-managed EIFS system that incorporates a weather resistive barrier as a back-up. Second, get your designer or a third party to provide observations in the field to verify the installation is in compliance with the construction documents and manufacturer requirements.
Since most construction defect litigation is attributable to poor craftsmanship, this is the single best thing owners can do to protect their investments.
Last, plan for and resolve your warranty and insurance concerns at the front end of the project. Comprehensive labor and material warranties are available from the EIFS manufacturers, but you have to ask for them in advance!
Category: EIFS, Exterior Wall System