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Exterior Insulation Finishing Systems (EIFS), Commonly Known as Synthetic Stucco Ultimate Guide

Exterior Insulation Finishing Systems (EIFS), sometimes referred to as synthetic stucco, is a type of cladding that provides wall exteriors with an insulated finished surface. They are applied in multiple layers over exterior sheathing, to create an energy-efficient, fire-resistance, low-maintenance, beautiful, and versatile exterior cladding.

Over the years, significant improvements have solidified it as an excellent choice for a durable, energy-efficiency cladding system:

  • In the mid-1990s, the EIFS Industry Members Association (EIMA) and the International Conference of Building Officials (ICBO) mandated moisture resistance and retention improvements in EIFS.

In 2009 the International Building Code (IBC) recognized EIFS as an acceptable cladding product, requiring the application of a water-resistive barrier.

National Study Validates the Use of Drainage EIFS

Between 2005 and 2007, the Oak Ridge National Laboratory (ORNL) conducted a study comparing the energy efficiency, moisture intrusion, and temperature control between EIFS, brick, stucco, and cementitious fiberboard siding. It concluded that drainage EIFS is a far superior moisture and temperature control performance than brick, stucco, and cementitious fiberboard siding.

EIFS vs. Traditional Stucco

EIFS, commonly referred to as synthetic stucco,  and traditional stucco both provide fire resistance and a good sound barrier. However, while similar in looks, several characteristics change how the two stucco systems function. EIFS weighs 80 percent less than traditional stucco. In addition, EIFS offers more energy efficiency with an R-value between 4 and 5.6, compared to stucco, with an R-value of 0.2.

Traditional Stucco

The composition of traditional stucco includes a mixture of Portland cement, limestone powder, sand, and water. Builders install a base mesh to apply stucco to the building, then spread the stucco over it with a trowel, using a three-coat system. The stucco dries to a rock-hard finish for an affordable, long-lasting, attractive siding. 

EIFS

EIFS is applied in multiple layers over exterior sheathing, providing more insulation and moisture protection than traditional stucco. The typical components (layers) of EIFS include:

  • A water-resistive barrier over the substrate prevents moisture from infiltrating the system. 
  • A layer of expanded polystyrene (EPS) , extruded polystyrene (XPS), or mineral wool provides added insulation. 
  • A layer of fiberglass mesh provides reinforcement and adds crack resistance. It will also protect against cracks and crumbling due to shifting foundations, thermal expansion, and freeze/thaw cycles. 
  • A water-resistant base coat, embedded into the glass-fiber reinforcing mesh, applies on top of the insulation, and serves as a weather barrier.
  • A finishing coat furnishes the color, texture, and protective nature of the structures’ exterior surfaces.

StoTherm® ci Wall Systems Drainable EIFS  

StoTherm® ci cladding systems combine continuous insulation (ci), air/moisture barrier, drainage, and many textured finishes to create a sustainable, high-performance wall cladding. The unique and durable system sustains maximum curb appeal and saves money through reduced energy bills. Sto offers several StoTherm ci Systems, including four StoTherm ci Hurricane Impact Systems.

Lightweight StoTherm combines StoTherm® and the StoGuard® waterproof air barrier system, improving energy efficiency and protecting against moisture intrusion.

High-performing and durable StoTherm® ci XPS incorporates high R-value extruded polystyrene insulation into the wall assembly and StoGuard® fluid-applied air and moisture barrier, producing water and airtight walls ensuring thermal efficiency and durability. 

StoTherm ci MVES (masonry veneer engineered system) a StoTherm ci system with masonry veneer, ceramic tile, natural stone, or manufactured stone used as the facade finish.  Meets applicable building code requirements.

The StoTherm® ci Mineral System incorporates non-combustible, mineral wool exterior insulation and continuous moisture and air barrier with Sto’s high-performance finishes to create an advanced high-performance cladding assembly. 

Energy-efficient, high-performing, and hurricane-resistant StoTherm® ci HI-LM CMU 180 offer a CI wall cladding that combines StoGuard® waterproof air barrier and StoTherm® insulated cladding and drainage capabilities over concrete masonry unit substrates. In addition, StoTherm® ci HI-CM 180’s engineering satisfies the testing requirements for large and small missile impacts. 

High-performing StoTherm® ci 1177-SM exterior wall cladding assemblies combine a seamless air and moisture barrier with advanced drainage capabilities over glass mat gypsum sheathing. The engineering of StoTherm® ci 1177-SM fulfills the testing requirements for Small Missile impacts. 

High-performing StoTherm® ci 1177-LM exterior wall cladding assembly provides a seamless air and moisture barrier with CI, advanced drainage capabilities, and Sto Armor Mat XX Mesh for added reinforcement and impact resistance over glass mat gypsum sheathing. The engineering of StoTherm® ci 1177-LM achieves the testing requirements for small and large missile impact performance on 16-gauge steel studs with gypsum sheathing.

High-performing StoTherm® ci HI-PLY exterior wall cladding assembly integrates a seamless air and moisture barrier with CI and advanced drainage capabilities over CDX exterior plywood sheathing. The engineering of StoTherm® ci HI-Ply meets the testing requirements for small and large missile impacts.

Structural and Aesthetic Benefits of EIFS

EIFS’s structural benefits and aesthetic appeal make it an ideal product for new and retrofitted construction. Builders can apply these ‘synthetic stucco’ multilayered systems to wood, steel  or concrete substrates in any climate. Specific structural and design benefits include: 

  1. Energy-efficient drainage EIFS meets the requirements of ASHRAE 90.1.
  2. Fire-resistant EIFS pass the significant tests required by building codes for fire resistance (ASTM E119), ignitability (NFPA 268), intermediate multi-story fire test (NFPA 285), and full-scale multi-story, corner test (ANSI FM 4880). 
  3. EIFS resists the spread of flames within the combustible core/component of panels from one story to the next. In addition, EIFS limits the lateral spreading of flames from the origin of the compartment fire to nearby spaces. 
  4. Low-maintenance EIFS resists unhealthy and structurally damaging mold.
  5. Aesthetically versatile, it can mimic brick, granite, stone, marble.

EIFS FAQs

Is EIFS the Same as Traditional Stucco?

No. While EIFS (synthetic stucco) and traditional stucco look similar, several significant differences change how the stucco systems function:

  • Traditional stucco is installed directly to the substrate with a base lath attachment. EIFS stucco is applied in multiple layers over exterior sheathing, making it more expensive and less suitable for DIY than traditional stucco.
  • EIFS weighs 80 percent less than traditional stucco. 
  • EIFS offers more energy efficiency with an R-value between 4 and 5.6 than traditional stucco, with 0.2.
  • EIFS’s layer of fiberglass mesh provides added resistance to cracking. It also helps protect against hurricane-strength winds, cracks, and crumbling due to shifting foundations, thermal expansion, and freeze/thaw cycles.

How Long Does EIFS Last?

If properly maintained, EIFS will last the life of the building. For example, StoTherm ci EIFS synthetic stucco systems applied in 1979 to U.S. buildings remain intact today. Proper maintenance includes:

  • Periodic cleaning
  • Repair of impact damage or punctures to restore surface integrity
  • Inspection and maintenance of cladding abutting elements such as sealant and flashing

Can EIFS Be Repaired?

Yes. However, EIFS repairs often require a professional with EIFS experience to avoid further damage and potential water infiltration. You can refer to the StoTherm® EIFS Reference Guide for information on repairing EIFS or contact one of our experienced representatives at 1-800-221-2397. 

What Is the Best Paint for Recoating EIFS?

The best paint for EIFS should enhance your building’s character while providing superior protection against fading, mold, mildew, and crack bridging. The paint should also offer self-cleaning properties, vapor permeability, and low VOC. 

Fortunately, Sto’s architectural coatings provide all the features of a high-quality EIFS paint. We offer everything from acrylic-based permeable coatings to superhydrophobic coatings. Superhydrophobic coatings have self-cleaning properties and a biomimetic principle for fast drying after rain or dew. In addition, the coatings come in an assortment of textures and sheen, or we can tint them in an endless array of colors to fit all the needs of your exterior design. Click here to learn more about our high-performing coatings.

How Is EIFS Installed?

EIFS stucco is applied in multiple layers over the exterior sheathing. The typical components (layers) of an EIFS include:

  • A water-resistive barrier covers the substrate to protect moisture from infiltrating the system. 
  • A drainage plane located between the water-resistive barrier and the insulation board provides a drainage space (air gap) and weep openings. The drainage space allows moisture to drain between the drainage plane and the exterior cladding. The weep openings direct the draining moisture to the exterior outside the wall system.
  • A polystyrene foam board or mineral wool provides added insulation.
  • A layer of fiberglass mesh provides reinforcement and adds resistance to cracking. It will also protect against hurricane-strength winds, cracks, and crumbling due to shifting foundations, thermal expansion, and freeze/thaw cycles. 
  • A water-resistant base coat, embedded into the  glass-fiber reinforcing mesh, applied on top of the insulation serves as a weather barrier.
  • A finishing coat furnishes the color, texture, and protective nature of the structures’ exterior surfaces.

An experienced professional typically installs EIFSs due to their complexity. Click here for Sto’s StoTherm® ci Install Guide or contact one of our experienced representatives at 1-800-221-2397.

Is EIFS Fire-Resistant?

All EIFS manufacturers in the Industry Members Association (EIMA) have passed ignitability, fire resistance, intermediate multi-story, and flame spread tests, meeting the standards of each test. EIFS and drainage EIFS generally utilize foam plastic as the insulation, making them combustible assemblies. Therefore, according to Chapter 26 of the 2021 IBC, they must test for all building heights. Furthermore, the IBC also mandates the testing of exterior walls to prove compliance with the acceptance criteria of NFPA 285 (Section 2603.5.5). However, Sto also offers StoTherm ci Mineral EIFS with non-combustible Mineral Wool insulation.

Click here for more on NFPA 285 testing of Sto wall systems, or contact one of our experienced representatives at 1-800-221-2397.

What Is an Exterior Insulation and Finish System?

EIFSs apply in multiple layers over exterior sheathing, to create energy-efficient, fire-resistant, low-maintenance, beautiful, and versatile exterior cladding. Over the years, significant improvements have solidified EIFSs as a superior choice for a durable, energy-efficiency cladding system.

Click here to learn more about Sto’s StoTherm® ci systems, drainable EIFS, or contact one of our experienced representatives at 1-800-221-2397.

Is EIFS in Commercial Building Codes?

Yes. The 2021 IBC (Section 1407) outlines the requirements for EIFS construction. For more information on StoTherm® ci code compliance, click here

Do Insurance Companies Cover EIFS Projects?

Yes. Fortunately, the EIFS Industry Members Association (EIMA) website offers updates, education, and resources to help EIFS applicators obtain affordable EIFS insurance with a list of knowledgeable EIFS insurance brokers.

What EIFS Finishes Do You Offer?

Sto Textured Finishes provide architects, buildings, and homeowners complete design freedom with an extensive selection of finishes in many textures and color options, enhancing your design and harmonizing with the surrounding environment. We manufacture durable Sto finishes to the highest quality standards, to resist water and dirt to protect your building or home while providing outstanding curb appeal.

Click here for more information on Sto’s aesthetics.

What to Look For in a High-Quality EIFS System

The design of a long-lasting EIFS system should allow straightforward application, and limit long-term problems due to improper installation. A high-performing EIFS system should also provide impact and condensation resistance, all features offered by StoTherm ci EIFSSystems.

  • Impact Resistance: Designing EIFSs with a high-impact mesh will substantially improve their impact resistance.
  • Condensation Resistance: EIFS insulation thickness should stop the interior air from reaching the dew point (the temperature that water vapor turns to water), minimizing condensation within the wall system.
  • Quality Sealants: Preventing water intrusion to the wall system must include proper installation of quality sealants. 

Why Choose StoTherm ci EIFS Systems? 

StoTherm ci Systems check all the boxes for a high-quality synthetic stucco cladding product – excellent moisture management, low maintenance, durability, the energy efficiency of StoGuard® air and moisture barrier system, and comprehensive design options.

StoTherm ci Systems advanced integrated wall systems combine protective and aesthetic components into superior wall cladding. The system’s high-performance features include:

  • StoGuard® fluid-applied air and moisture barrier: Ideal for all types of construction, StoGuard® ‘s fully-adhered seamless monolithic exterior wall air and moisture barrier protects against moisture infiltration and unwanted air movement. You can apply StoGuard® with a roller or airless spray, which speeds up the application and simplifies integration with other wall assembly components. 
  • StoTherm® ci cladding systems:  StoTherm® ci combines CI, air/moisture barrier, drainage, and numerous textured finishes to produce a sustainable, high-performance wall cladding. The durable and eye-catching system maintains maximum curb appeal and saves money through lower energy bills. Sto offers eight StoTherm ci Systems, including four StoTherm ci Hurricane Impact Systems.
  • Sto Textured Finishes: Sto Textured Finishes provides architects, builders, and homeowners with complete design freedom with an extensive selection of finishes in many textures and color options, to enhance your design and harmonize with the surrounding environment. We manufacture durable Sto finishes to the highest quality standards to resist water and dirt, and protect your building or home while providing outstanding curb appeal.

Don’t hesitate to reach out to one of our experienced representatives today to learn more about EIFS, or synthetic stucco.

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