There’s hardly an EIFS job these days that doesn’t use foam shapes in some way. In fact, a lot of other non-EIFS claddings incorporate foam shapes as accents, such as shapes over stucco, block and concrete. Most foam shapes are made of EIFS, while others use non-EIFS materials to create hybrid EIFS-like shapes. Hybrid foam shapes are sometimes substituted for specified real EIFS foam shapes and sometimes this doesn’t work, as they do not perform the same or are incompatible in some way with adjacent materials. At times, the use of foam shapes is extensive on a given building, yet there are no standard guidelines as to what they are made of nor how they should be used. That’s about to change.
WHAT IS A FOAM SHAPE?
This is a good question. There are many types, all of which tend to look the same from the outside. It’s sometimes difficult to tell what is the main wall on real EIFS, and what is a decorative add-on. In a sense, foam shapes are a separate industry from EIFS, yet they come together in the area of architectural decorative trim. The foam shape industry extends into non-architectural uses, such as decorations at theme parks and sculptures.
For purposes of this article, here is an unofficial list of various foam shape-like materials, with comments:
“Real” EIFS: Made of the same materials as an EIFS wall cladding system, installed in layers at the job site.
Pre-basecoated foam: Made of contoured foam blocks that are covered with basecoat off site, and attached to the wall and finished at the site, using real EIFS materials.
Extruded-thick coating: Contoured foam shapes that have a thick basecoat (and perhaps the finish too), applied off-site using an extrusion process, and attached to the wall at the job site. Basecoat is two to three times thicker than a normal basecoat.
Cast-very thick coating: Very thick cast stone shapes that are made off site that have a small foam core. Basecoat is 1/2 inch or more in thickness up to several inches. Essentially, cast stone in terms of weight. High strength and impact resistance.
Sprayed plastic basecoat: Contoured foam shapes that have a basecoat sprayed-on off site, and are attached to the wall and finished at the job site.
Generally foam shapes are used as accents and account for a small percentage of the opaque façade. Occasionally, they are used for large wall areas and thus need to stand up to the wind forces of the main wall. This affects the way they are attached to the supporting wall. Some are attached with adhesives only, some with mechanical clips, and some with both.
Foam shapes are often used at the perimeter of wall areas and are subjected to forces often not present in the field of the wall. This includes leaning and standing on the shapes by maintenance people (such as window washers), as well as being leaned-against or bashed by ladders, swing stages or vehicles. Or sometimes foam shapes have items, such as banners, hung from them.
MAXIMUM SIZE AND WEIGHT
When the desired contoured foam shape is large, there’s a temptation to make the entire shape out of a gigantic block of foam. This eliminates the need to build up a complex matrix for framing and sheathing behind the outer foam layer, thus using a thin foam backing. Sometimes, these foam shapes are a foot or more in cross section. The code limits the maximum thickness to 4 inches for EIFS, yet sometimes these huge shapes do get installed. In the case of parapets, they hang off the top of the wall, and who is to know they are not safe to stand on?
Interest in the fire performance of foam shapes was peaked last year when a major fire occurred on the top floor of the Monte Carlo casino in Las Vegas. The fire spread to lower floors and caused tens of millions of dollars in losses. An investigation was conducted and it appears that the affected areas, which caught fire due to nearby maintenance welding, behaved uncharacteristically for EIFS, perhaps as a result of the foam shape not being real EIFS. The rest of the building is real EIFS but the affected area had a hybrid EIFS-like foam shape system.
This event has the potential for setting a precedent for further regulating the use of foam shapes, especially on large commercial buildings.
When combining multiple cladding systems on the same wall, the question arises for warranty purposes: “Whose wall system is it?” This applies even if the same contractor did all the work. With foam shapes, the shapes are virtually indistinguishable from the main wall, and at some point the two materials come in contact. In fact, this is where defects commonly occur, such as leaks and cracks. This is a matter that should be dealt with in the specifying and contracting stage.
EIFS with drainage presents a special challenge for foam shapes. Drainage is mandated by many codes for EIFS installed over moisture sensitive substrates, like wood. When leaks occur in EIFS-clad wall assemblies, it usually occurs at the edge of the EIFS, such as at an opening, not in the field of the wall. Foam shapes tend to be used at the edge of an EIFS. Yet, how is drainage incorporated behind the foam shape? The attachment method used with some foam shapes does not often allow the creation of the necessary drainage cavity. Guidance is needed for designers and contractors regarding how to integrate the drainage system behind the foam shapes with the real EIFS used on the rest of the wall. In other words, how to marry the two systems together.
Sometimes, foam shapes use surface coatings that are not the same material as the adjacent EIFS. Even though they look the same when installed, they age differently, creating color mismatches. This situation points to using the same EIFS finish coating on the foam shapes as is on the main EIFS wall. This, in turn, suggests applying the EIFS finish to the foam shapes in the field (rather than off site) along with the rest of the EIFS to ensure a continuous color match.
The issue of “whose scope of work is it?” sometimes comes up with foam shapes. When traditional foam shapes are used, the work almost always falls under the scope of the EIFS contractor. For hybrid foam shapes that are like cast stone, sometimes the work falls under the mason’s scope, rather than plasterers.
Some foam shapes are fabricated almost entirely off site in a factory. Thus, they are a form of a prefabricated product. When large amounts of foam shapes are used, the building official might question if the shapes need to be “labeled and listed,” as are other forms of prefab construction. The process of establishing a formal labeling and listing program is a major project, but luckily this can usually be worked around via occasional visits to the foams shape production facility by the inspectors.
WHAT’S HAPPENING NOW
As a result of the above issues, activity is taking place to establish specifications for foam shapes. In particular, ASTM has an active work item to develop a generic spec for foam shapes. The spec, in its current state, simply says that foam shapes need to perform like EIFS. In other words, to meet the same performance requirements as EIFS. Since EIFS is regulated already by the code, and some types of foam shapes are very much like EIFS, this would seem to be a straightforward, uncomplicated approach.
Contractors, foam shape suppliers, distributors, EIFS suppliers and architects will be affected by this specification for foam shapes. You can participate in the development of this specification by contributing your knowledge and experience with this popular add-on decorative part of EIFS. W&C