Stucco and EIFS
Most stucco today is made with Portland cement and sand, and, like other cement-based products, the raw materials provide for a high embodied energy compared to non-cement products. At the same time, the surface can be low-maintenance, affordable, and durable; offers versatile design options and a breadth of color choices; and is easily repairable, according to the Stucco Manufacturers Association.
Products such as EcoStucco use limestone instead of Portland cement.
EIFS—exterior insulation finish systems—offer a look similar to stucco but with different components and installation. EIFS consists of rigid insulation board with a base coat (acrylic and cement or all acrylic), imbedded fiberglass mesh, and an acrylic finish coat. With a base coat of about 1/8 to 3/16 inch thick, EIFS are thinner than traditional stucco and therefore have less cement content, more flexibility, and, combined with the imbedded mesh, greater durability.
Though EIFS utilizes virgin foam board, acrylics, and cement, it offers the benefits of continuous insulation, a feature that some expect will be required in future energy codes. The board can add an additional R-value of up to 4 per inch.
EIFS’ primary challenge is overcoming perceptions brought about by envelope failures in the mid-90s. According to Kent Stumpe, marketing communications manager for BASF, the problems occurred when insulation board was still applied directly to wood-based sheathings; if moisture penetrated the envelope through faulty window installations or exterior joints, the moisture became trapped and led to damaged sheathing.
Because the failures were in installation, the industry has focused on improved training and requiring a drainage plane, as well as introducing drainable EIFS. The category also is now recognized by the IRC.
Other Options
Aside from the major types of cladding mentioned above, there are plenty of alternatives available that might fit your needs.
Some architects are designing around steel cladding, which typically contains high recycled content and is recyclable, but also comes with high price and embodied energy levels. Companies like Richlite and KlipTech offer attractive cladding products made from recycled paper.
And of course there’s an increase in re-use of reclaimed and salvaged wood and masonry products that has spawned growth in local suppliers who specialize in these materials.
Installation
No matter which product you choose, how it performs will largely come down to the quality of installation, especially in how windows and other penetrations are prepared and flashed, and how rainscreens and drainage planes are detailed and installed. (For more on rainscreens, see page 17.) Follow manufacturers’ instructions and proper building science practices.
As with most specs, selecting the most appropriate cladding will require weighing a number of factors, from durability to price to environmental aspects, requiring you to prioritize which attributes will help you meet your goals.