Synthetic Stucco (EIFS)

By Frank G. Ross

Homeowners are no doubt aware of the high costs associated with heating and cooling their homes. The home’s exterior walls can be key components in energy savings. The type of exterior surface material known as Exterior Insulation and Finish Systems ("EIFS") is often used on exterior walls because of its attractive appearance and good value. However, the true benefit derived from EIFS is its unparalleled energy efficiency which translates into reduced heating and cooling costs.

According to the EIFS Industry Members Association, a number of factors contribute to the outstanding energy performance of EIFS, including:

The exterior location of the insulation
The efficiency of a continuous, unbroken layer of insulation
The high R-value of EIFS insulation materials
The ability to create walls with very high R-values
The lack of thermal bridges through the insulation layer
Low air infiltration rates

Despite a somewhat rocky beginning, EIFS is currently an immensely popular cladding material. 

A Brief History

In 1969, Dryvit Systems Inc. introduced Exterior Insulation Finishing System, a synthetic stucco siding, to North America from Europe where it was introduced after World War II.  By the mid-1980s, the product was being used in residential frame construction.  This synthetic stucco is also known as EIFS, thincoat, softcoat or PB (polymer based) stucco.  It is flexible and spongy to the touch and has a hollow sound.  Traditional stucco is known as hardcoat, thickcoat, cement stucco or PM (polymer modified) stucco and is brittle and sounds solid.

The system consists of:

1.     A substrate (sheathing) such as plywood, OSB or gypsum board

2.     Rigid foam insulation boards (Expanded Polystyrene or EPS) adhered or fastened to the substrate

3.     Glass fiber reinforcing mesh

4.     Up to ¼” thick base coat (cement mixed with acrylic polymer)

5.     A finish coat either sprayed, troweled or rolled on which provides color and texture

In Europe the system was applied to masonry or concrete-based sheathing such as concrete block, brick or stone.  When introduced to the North American market, very few modifications were made in its application in wood frame homes.  With plastic sheeting as a vapor barrier (required by most building codes) and the minimal-breathable quality of EIFS, any water getting inside the walls remained trapped, leading to rotting of wood sheathing and structures. The problem was aggravated in areas of high humidity.

In the 1990s, homes in the southeastern US began to experience moisture damage behind the walls of their synthetic stucco.  The problem showed up in areas prone to heavy rains accompanied by wind.  About 260,000 homeowners in the US are now facing potentially serious water damage to their homes.  Although the system is waterproof, windows, doors and their trim are not waterproof.  In some homes, water has leaked behind the stucco and been trapped, causing damage – particularly around windows, door and deck connections.

There are some lawsuits pending, but the product itself was not found to be defective; rather far too many shortcuts had been taken during its application relative to sealing and flashing.  Since 1997, manufacturers have been offering a “water-managed” (drainable) system to the residential construction market in response to new local building code requirements and growing consumer demand for these products.   Innovations in moisture drainage features are the biggest news in EIFS these days.

A visual inspection cannot determine the amount of water penetration nor damage to the substrate behind stucco cladding.  However, some telltale signs may be observed.  These include cracks in the EIFS dressing bands around windows; swelling, cracking and/or rotting of window or door frames; delamination of the EIFS from the sheathing; staining, mold and/or algae on the exterior and interior; cracking, peeling and blistering of paint; increased level of humidity in the home; or infestation of pests (ants and/or termites) that nest in the moist sheathing of the home.  When these signs are evident, a more in-depth inspection by a trained professional should take place. 

The EIFS Industry Members Association (www.eima.com), Robert G. Thomas Jr. aka “Mr. EIFS” (www.eifs.com), and EIFS manufacturers (such as Dryvit, Senergy, and Texas EIFS or Teifs) offer a wealth of good information at their websites.

Frank Ross is a Certified Utah Home Inspector for Pillar to Post Professional Home Inspection and a full member of the National Association of Certified Home Inspectors and a member in good standing with the Utah Better Business Bureau.  Readers may contact Mr. Ross at (435) 867-6400 or frank.ross@pillartopost.com or www.pillarposthomeinspection.com