One of the most common things that isn’t right is the way things are attached to the EIFS. I’m not talking about deck beam penetrations or ducts or hose bibs that go through the EIFS, but rather common things that are attached to the outside of the EIFS, such as light fixtures, downspouts, railings and so on.
This month’s column will give you some ideas about how to attach things to EIFS in ways that work and warnings about things that don’t.
First, please remember that EIFS is a nonstructural material: It does not hold up the building. However, it is attached to a wall system that may hold up the building (sometimes studs do and sometimes not). In any event, the wall structure has much more strength to support things than the EIFS, and, hence, things should be attached through the EIFS and to the wall structure.
Second, just because something is in contact with the EIFS does not mean that it is attached to it. Windows and deck beams are common examples. This may seem a bit simplistic, but bear with me for a few examples.
Wood workObviously, major heavy building components should not be attached directly to the EIFS itself. For example, a large sign should not be attached to the EIFS lamina only. Nor should safety items like handrails or fire escapes. But what about items like downspouts that can freeze full of water and weigh a lot more than when they were attached? The basic answer is simple: Such heavy objects must be attached through the EIFS to something structural behind the EIFS. Sometimes the material connected to (through the EIFS) can be the substrate (the sheathing, if it is capable of affording some holding power), but more often, it should be to the main structural member—the studs or a solid wall.
Attaching an object to an EIFS wall is not just a matter of running a big bolt through the EIFS and into the stud. The reason is simple: If you cinch down on the bolt, it will crush the EIFS. Also, over time, the connection will become loose and ineffective. The solution is to embed something in the EIFS between the outside face of the EIFS lamina and the substrate, which is capable of resisting being compressed as the fastener is tightened.
There are two basic ways to do this. One is to embed a piece of material (wood works well), in the EIFS insulation layer as the EIFS insulation is being installed, and attach the object to it or through it. If the object is attached to the spacer, then obviously the spacer itself must be connected to a structural part of the wall. A wood block simply floating loose within the EIFS insulation layer is not enough.
Another way is to put a spacer in the EIFS after the EIFS is installed. This can take the form of a tube (plastic or corrosion-resistant metal), which is inserted into a hole drilled through the EIFS, after the EIFS is in place. This is done using a carbide-tipped bit and drilling a hole through the EIFS to the substrate, inserting the spacer tube, sealing the hole and tube with sealant, and inserting the fastening bolt through the tube.
The first method is a bit more complicated because of layout work needed beforehand to be sure the spacer is in the right place when the object is attached to it. The former is also stronger, especially if bolted through. This fastening method is the way to go for heavy objects.
The above two methods are useful for a wide variety of small objects being fastened to the EIFS, but for heavy objects, another approach is needed. In such cases, a structural bracket that is attached to the wall structure and around where the EIFS is installed, is necessary.
To emphasize how far off course things sometimes get, let me give you some hard-to-believe examples of fastening foul ups. How about using pop rivets to attach downspout mounting straps to EIFS by going through the EIFS lamina only? Another is using molly bolts through the lamina only to attach handrails (lawyers and OSHA would love this!). Neither is a viable solution. The EIFS lamina is not a structural material nor has it the substance to support much weight, other than its own.
A plastic solutionThe above methods may sound a bit involved, but luckily there is an even simpler solution when dealing with very light objects, such as lightweight plastic address numerals. In this case, the numbers can be bonded to the surface of the EIFS. This has a number of advantages.
The first is ease. All you need is a structural adhesive. Second, there is no penetration through the EIFS lamina. Thus, no sealing is needed. Third, it looks good, no exposed fasteners, etc. A couple of caveats though: Use a water-resistant synthetic structural adhesive to bond the object to the lamina, not grout or EIFS adhesive, but structural-grade silicone or urethane. The reason is that water might get behind the object and freeze or otherwise affect the adhesive, thereby causing the object to fall off. Also, don’t try this method with heavy materials such as tile or metal plaques, unless the matter is locked-into carefully to make sure it will work for the long run.
For example, I’ve seen bands of decorative tile recessed in a shallow aesthetic reveal in the EIFS that were attached using adhesives only. This design was carefully looked into by the building designer prior to doing so, and has been holding up well for years in drizzly Seattle.
Finally, regardless of what attachment method you use, make sure to keep the penetration sealed. With drainage-type EIFS, this can be a finicky proposition but it needs to be done to allow the EIFS to retain its drainage capabilities. As all EIFS are proprietary systems (especially the drainage types), you should also get design input from the manufacturer of the specific EIFS product being used on your project. This will ensure that it meets their requirements for design and warranties. EIFS manufacturers also publish drawings showing various ways to attach objects to EIFS for each of their EIFS products.
In the end, remember that EIFS is not stucco. With real stucco, you can attach some objects to the stucco membrane. This is because of the thick, hard, beefy nature of Portland cement plaster. EIFS is a lightweight, thin, flexible material, and simply does not lend itself to being attached to. Thus, the key to attaching things to EIFS is either to go through the EIFS into a structural material or to embed a structural material in the EIFS insulation, and attach to it.