Last Updated: Nov 26, 2021
For most homeowners, the exterior cladding options we choose to protect our home from the elements and the insulation we use to improve our homes' energy efficiency and thermal performance are entirely different building aspects. Since the 1960s, however, construction teams have had at their disposal a unique exterior cladding option that combines to work as both an exterior siding and home insulation. Exterior insulation finish systems (EIFS) were initially developed in West Germany in the 1960s and were introduced in the US in 1969 by Dryvit. This innovative exterior finish system remained relatively obscure for several years. However, the increased focus on boosting home insulation as part of a broader strategy to lower household energy use has brought this product back into the spotlight. Below, we take a look at the advantages and drawbacks that come with using EIFS for your home.
Simply put, exterior insulation finish systems are both insulation and siding. This definition might bring to mind a home exterior coated in bright pink fiberglass insulation made to look like a cotton candy house you might find at the local fair. On the contrary, however, homes with EIFS can benefit from a virtually unlimited spectrum of colors, textures, and designs.
Exterior insulation finish systems generally consist of some rigid insulation boards placed on the wall sheathing's exterior. EIFS are designed to work with several different substrates, including wood, cement, and masonry. The original Dryvit system, introduced into the United States almost 50 years ago, was made from expanded polystyrene (also known as beadboard). The product was attached adhesively to the exterior sheathing of the house structure. Installers subsequently covered that rigid polystyrene insulation board with a thin coating of a modified cement base coat, glass fiber reinforcement, and a textured colored finish coat chosen by the homeowner.
Today, EIFS is highly preferred by architects and builders looking to offer continuous insulation for homes built in areas with strict energy codes or homes looking to attain specific green building certifications such as LEED. According to ASTM International, EIFS are considered non-load bearing and exterior wall cladding systems made up of an insulation board subsequently fastened either adhesively or mechanically to the substrate. A reinforced base coat is then applied over the insulation board before a textured protective finish coat is finally applied.
In more recent years, the vast majority of exterior insulation finish systems used by home builders are known as "EIFS with Drainage." As we will discuss below, traditional EIFS did have problems with moisture accumulation and leakage. EIFS with drainage, which is the predominant method used by builders and architects today, incorporates specific safeguards to reduce moisture before it has an opportunity to enter the wall cavity.
EIFS are unique because they are the best exterior cladding system for offering thermal control and improved energy efficiency to the home. EIFS are a fundamental aspect of continuous insulation systems. Continuous insulation offers constant protection across all structural members of the house. This insulation alternative aims to eliminate all thermal bridges in the structure, except for fasteners and service openings.
The Oak Ridge National Laboratory, which the Department of Energy supports, finds that the EIFS is the "best performing cladding" to provide thermal and moisture protection. EIFS with drainage allows homeowners to maximize their energy savings, reducing their household carbon footprint and the home's environmental impact. Besides offering continuous insulation around the exterior of the house, these exterior cladding systems can also improve the airtightness of the building envelope - one of the most critical elements of energy-efficient home construction.
On the downside, most of the insulation board used in EIFS is either made from expanded polystyrene (EPS) or polymer-modified (PM) systems. There are some, StoTherm® ci Mineral, that makes versions using mineral wool as the insulator. Both the EPS and the PM products are synthetic and come with several potential environmental drawbacks. According to the Children's Environmental Health Network (CEHN), polystyrene degrades slowly, and when improperly disposed of, the foam can leach chemicals harming water sources. Polystyrene manufacturing is a large creator of hazardous waste. Because expanded polystyrene is a relatively low-value product, many recycling centers will not accept it. So it can be challenging to dispose of at the end of its useful lifespan responsibly.
EIFS offers a pathway to improve your home's energy efficiency and thermal performance with no negative health consequences when properly installed. However, improper installation techniques and older variations of EIFS that did not include specific drainage systems have been shown to lead to serious mold growth. Around 10% of the American population is allergic to mold. About half of those people are at risk of developing illnesses due to mold exposure.
If moisture penetration does occur, the water is essentially "stuck" inside the exterior cladding. As water and moisture accumulate against the sheathing of your home, mold growth is likely, especially for wood sheathing. Besides leaching allergens into your home, this mold growth can also decay your structure leading to expensive repairs.
According to the National Association of Home Builders (NAHB), homes with barrier EIFS are "prone to moisture intrusion problems even when properly constructed according to industry standards. Unlike other cladding types, the design of barrier EIFS does not allow the draining of water that gets behind the system, either through building components (openings in the building envelope for doors, windows, etc.) or when sealants break down or crack. Depending upon the climate and the wall assembly's overall make-up, the wall may not readily dry out. Sustained elevated levels of moisture without adequate drying will cause rot or decay to sheathing and framing."
Another significant benefit of exterior insulation finish systems is that they are widely regarded as one of the most economical exterior cladding systems. The exact cost of EIFS will depend on the thickness and quality of the insulation board and the type of exterior finish coat. For example, an EIF system with a textured brick appearance will most likely cost more than an EIFS with a simple stucco-like coating. According to some estimates, EIFS have an average cost of $0.86 per square foot for material and an additional installation cost of $5 to $6. For comparison's sake, homeowners can expect to pay up to $15 per square foot for premium brick siding. Considering that EIFS should help you shave off some of the cost of your monthly energy bills, this exterior cladding option has a quantifiable payback period.
Another great benefit of EIFS is that they come in various textures, colors, and other design options. A skilled contractor or installer should have the ability to fashion the final coat of the system into virtually any shape or design. Thicker finals coats on EIFS allow for relief sculptures and other architectural detailing such as arches, keystones, cornices, columns, and unique decorative accents.
Unless you live in an exceptionally mild climate, you will still want and need interior insulation for your home as well. However, EIFS can undoubtedly add to the R-Value of your home. Most commercially available EIFS contain an insulation board with an R-value of between R-4 to R-6 per inch. Suppose this exterior insulation finish system is combined with traditional wall cavity insulation. In that case, the extra exterior layer can boost your wall insulation to R-11 to R-16, or even more for colder climates.
Some experts estimate that EIFS can reduce air infiltration by as much as 55 percent compared to standard brick or wood construction, which only further increases your home's energy efficiency and thermal performance.
The maintenance task with EIFS is related to regular cleaning, surface crack repair, and reapplication of sealants. If you see any visible dirt, mildew, algae, or other contaminants building up on the exterior layer of your EIFS, simple washing with a hose can get rid of the accumulated debris. Because the main problem with EIFS is related to moisture infiltration, any surface cracks need to be immediately repaired. Fortunately, newer EIFS are designed to be flexible and highly crack resistant.
Suppose a particular part of your home suffers from extended exposure to driving rains. In that case, you will most likely want to reapply a sealant every couple of years. Most silicone-based weatherproofing sealants are compatible with EIFS. With proper maintenance, an exterior insulation finish system can last for 60 years or more.
With a renewed focus on energy-efficient construction techniques, EIFS are becoming much more popular with homeowners and home builders. Among the top brands producing high-performance and durable EIFS, you can find
Because proper installation is essential to avoiding water infiltration, homeowners should generally hire a professional installer. If you have advanced DIY skills, EIFS are attached to the outside face of exterior walls, and you will need to decide whether you want to use adhesive or mechanical fasteners. Check out these YouTube videos for a complete tutorial on how to install your own EIFS.
For homeowners wanting to tighten up their building envelope and increase the R-value of their home's insulation, EIFS are great options. Besides increasing the home's energy efficiency and thermal performance, EIFS are also one of the cheaper exterior cladding options. They come in a wide variety of finishes allowing you to customize the exterior aesthetic of your home. EIFS that do not incorporate drainage systems are prone to moisture accumulation and mold growth on the downside. There are also environmental concerns related to proper disposal and recycling of the polystyrene insulation boards, if that type is chosen, at the end of their lifetime.
Tobias runs an agroecology farm and a natural building collective in the mountains of El Salvador. He specializes in earthen construction methods and uses permaculture design methods to integrate structures into the sustainability of the landscape.