Surface-Applied Sealant Strips
Anyone who has repaired sealant joints on EIFS walls knows that it can be a real project. Unlike robust materials such as stone and metal, EIFS does not lend itself well to Rambo-type techniques for removing the old sealant. This makes installing the new sealant difficult, since it must have a clean surface to adhere to. The process of removing old sealant and preparing the edge of the EIFS for the new sealant, approaches getting your teeth cleaned in terms of being a fastidious process, and thus the whole process can take quite a while, and can therefore be expensive.
If you’ve ever replaced EIFS sealant joints, you must have thought, like I have, “There just has to be a better way.” Or, to be exact, “There must at least be another way.” There is, and, for lack of a better term, what is called surface-applied sealant strips, or “SASS,” for short.
SASS is a preformed ribbon of cured sealant that is bonded to the surface of the EIFS. It comes in rolls. SASS spans over top of the old sealant joint, like a Band-Aid. I’ve been involved with a number of projects on which SASS has been used and this month’s column will give some insights into using this unique sealing system.
The pitchThe first time I saw a resealing technique like SASS was on a hotel that had flat, prefabricated EIFS panels. The original caulking was in dismal shape. Upon trying to repair the old joints by picking and cleaning out the old sealant, the repair contractors lost their patience, and the costs went through the roof: It was simply too difficult and labor-intensive.
At that time, there was no such thing as SASS but the concept of applying a Band-Aid of sealant across the existing joints was attractive, for many reasons. For one, the old sealant could stay where it was, and thus it need neither be removed, nor the existing EIFS rebuilt, in order to install the new Band-Aid seal. A daring sealant contractor said he could apply an even strip of liquid sealant across the old joint. He said he could tool it to make it “look great.” He even showed us a sample, but we were skeptical: It was a sample. We doubted he could do it and be able to make it look good on this huge building. He made a template to produce the uniform sealant bead, and proceeded to do a trial job on the actual building. It looked great. We were amazed. In the end, the whole building was done this way. However, we all agreed that this was not something that most times would turn out so well. Something better was needed.
Nowadays, strips of sealant are made in the factory, in various widths, colors and textures, and are coiled up like ribbon. The strips are glued onto the surface using a structural adhesive. Both the strip and the adhesive are silicones. Thus, they are highly flexible under a wide range of temperatures, and have excellent longevity. SASS are, however, not without their idiosyncrasies. Here are a few.
Appearance can be a problem. When installed, SASS look like battens. This makes the joints conspicuous, and some people simply do not like the way they look. As an example, a typical EIFS sealant joint may be 3/4-inch wide. Add to that at least 1/2 inch of “grab” on either side of the joint for the SASS to stick to the EIFS, and you have a batten almost 2 inches wide. The strips are at least 1/8-inch thick, so, appearance wise, it’s equivalent to laying two yardsticks across the joint. On tall buildings, where the prominence of the SASS fades from view on the upper stories, it’s not so much of an issue. When it’s right next to you, it can be another story.
One way around this is to do a trial application at some inconspicuous location, and have the powers-to-be approve it. It’s surprising, sometimes, what people think looks OK vs. what they think looks horrible. There’s no accounting for people’s taste. Actually, their taste is often influenced by their wallet. The cost of installing SASS, even though the SASS themselves and the adhesive are not cheap, using them is a lot less complex than removing, rebuilding and replacing old sealant joints. This reduced labor cost can be a factor in the total cost of the fix. As a ballpark idea, SASS materials, on a lineal-foot-of-joint basis, (and this is just the sealant strip, and not the adhesive used to glue it to the EIFS) are about twice that of wet-applied sealant. Think about it: The amount of material in the strip is quite a bit more than the equivalent sealant bead; hence the cost. However, the labor to install the whole SASS “system” is less. So, in the end, the pricing tends to even out.
The flow must go onApplying SASS to corners and offsets can be a problem. Not being a liquid, SASS cannot flow into odd-shaped cavities. The strips must be bent, or cut and fitted. Sometimes, this just is not possible. Keep in mind that there’s nothing stopping one from using SASS in conjunction with regular, wet-applied sealants in these difficult areas. The sealant used in conjunction with the SASS should be the same product as the SASS. In other words, sealant manufacturers who make the SASS also make traditional sealants and the chemistries are compatible, and can be used in conjunction.
Most SASS are quite limp and flexible, and thus can be bent around normal corners, and can follow the shape of a gentle curve. If there are small offsets in the surface, the adhesive use to bond the strip to the EIFS can also help make up for the gap, without looking bad. This might occur, for instance, when the surface of the EIFS on one side of a joint is, say, 1/8 inch further in or out than the other side of the joint.
SASS can be cut and trimmed with shears or a razor knife. This is handy for mitering corners at windows and doors. It’s possible to create surprisingly neat looking sealant joints in this manner. Stock, molded SASS “shapes” are also available, including angles, miters and arched pieces, as well as custom, gasket-like shapes. SASS come in colors that, not surprisingly, are the same as the equivalent wet-applied sealants made by the same company.
Color matching can be an issue. Being made of silicone, most SASS do not readily accept paint; paint flakes off. Thus, if the adjacent EIFS is being painted, the paint should not be applied to the SASS, as it won’t adhere. There may be an obvious color difference between the SASS and the adjacent EIFS. There are, however, proprietary coatings that will adhere to SASS, but that means using the same coating on the whole wall: the EIFS and the SASS. Since these special coatings have the same paint repellant characteristics as the SASS, you become wedded to using those special coatings from there on.
If SASS is used to seal from a window frame or flashing to EIFS, care must be taken to make sure it bonds well to the adjacent non-EIFS material. Some windows and sheet metal have adhesion resistant types of finishes on them, and thus special primers may be needed to get the SASS adhesive to stick to them.
SASS are normally adhered directly to the EIFS finish; grinding off the EIFS finish to expose a raw basecoat is a daunting, and expensive, task. This means that the finish must be cleaned first. Thus, attaching the SASS is different from adhering wet-applied sealants, which normally should be bonded to the EIFS basecoat. Luckily, the granular nature of the EIFS finish gives a decent surface for the SASS adhesive to dig into and attach to. Also, the fact that the “motion” of the joint, as it expands and contracts, is in the plane of the wall, works well with the essential nature of adhesives: they work best when being “sheared,” rather than “pulled.” There’s a caveat to all this though: If there’s any doubt about the ability of the SASS adhesive to get a grip on the existing EIFS finish, adhesives test should be conducted to determine the quality of the bond, prior to using SASS.
Surface-applied sealant strips strike me as an underutilized product. Most of the time, they are used for repairs but nothing prevents them from being used on new construction. With the high cost of rebuilding failed sealant joints, and the demands of building owners for long lasting, watertight walls, SASS has a bright future—especially if someone can find a way to reduce the aesthetic problems and the cost of the raw materials.