Through, not to
The most important basic concept is to not attach the sign to the EIFS, but through it. The EIFS lamina is thin and not especially strong. It simply cannot be attached to. The only exceptions are small lightweight objects, such as plastic street address numbers that can be glued to the EIFS using a structural adhesive. Attaching through the EIFS means going all the way through it and into a structural member within the supporting wall.
Some signs produce heat. This can come from transformers, various types of light bulbs and electric motors. The heat can be transmitted through the EIFS lamina and into the EIFS foam insulation. Foams with a low melting point, such as EPS, can be come detached from the lamina by melting, thus creating blisters in the surface of the EIFS. In a very extreme case, a super hot heat source might even set the EIFS on fire. Such heat-producing devices need to be isolated from the EIFS. The most common technique is to place an air gap between the heat producer and the EIFS; in other words, to locate the heat producing device away from the EIFS. Another way to is to place a layer of weather resistance, noncombustible insulation between the heat producing device and the EIFS.
The less holes, the better
Since signs need to be mounted through the EIFS, by definition, a hole is thus produced in the surface of the EIFS. This could be an opportunity for water entry, if not properly sealed. Often, mounting holes are created after the EIFS is fully installed, usually by drilling through the EIFS. An extreme example would be doing welding of a sign bracket immediately adjacent to the EIFS, and setting the EIFS on fire. The holes need to be sealed.
The usual way of sealing the edge of the EIFS is to back wrap it. With small holes, this is impossible, since there's no way to get the basecoat around the edge of the EIFS at the hole. In this case, the most expedient way to seal the hole is to simply caulk around it. Sometimes this is difficult, as the holes are behind the sign, and the sign is mounted directly against the EIFS.
When there are a lot of small, separate sign elements, such as a string of alphanumeric letters, the wall can literally be perforated with dozens of holes. It's a better idea to have a small number of larger, easier-to-seal large holes than a lot of small ones. This points in the direction of attaching the letters to a subframe, and mounting the subframe through the EIFS at a handful of locations.
Cutting through an already-installed EIFS, and making neat, odd-shaped mounting holes can be difficult, especially when the EIFS foam insulation is thick. Round holes are easier to make than odd-shaped ones, and a tungsten carbide hole, works well; plain steel or high-speed steel blades will go dull in an instant. In the case of round holes, round tubing is used to penetrate the EIFS, and caulking is used to seal the opening.
Sometimes, the exact size and location of signage can be predetermined. Such is often the case on fascias on strip shopping centers, where all the signs are the same basic size and shape. One way to avoid the tedium of penetrating and sealing mounting holes in the EIFS is to embed mounting blocks into the EIFS insulation layer, and to screw through the EIFS lamina and into the blocking. The blocking is fastened to a structural member in the supporting wall, such as the studs, and comes into direct contact with the backside of the EIFS basecoat. The EIFS lamina goes over the block, and the block thus is not visible.
Crushing the EIFS
When making mounting holes through the EIFS, a spacer is needed within the EIFS to keep the EIFS from being crushed as the mounting bolts are tightened. Usually, this takes the form of a PVC or metal tube that butts against the substrate on the inside, and is flush with the outside of the EFS finish on the outside. Once the spacer is installed, the mounting bolts can be tightened without crushing the EIFS.
Signs, especially those in sheet metal cases that are mounted directly against the EIFS, are an open invitation for discoloring the finish system. Snow and water tend to pile up on the upper edge, causing streaks as it exits below, and from behind, the sign. Rust can also occur on metal sign cases, which can stain the EIFS. It's better to provide an air gap between the sign and the EIFS so that water can flow freely behind the EIFS. The air gaps can also allow access to the back of the sign for construction and maintenance purposes.
Open back signs
Some sign designs, especially those that are illuminated, have no back to the sign housing; they rely on the EIFS to seal water from getting into the sign from the rear. This is a bad design, as it is very difficult to affect a decent long-term seal. The sign itself needs to provide its own weather protection, and not to rely on the EIFS to keep water away from the inner workings of the sign, especially electrical components.
As tenants change in buildings, so do their signs. This often leaves holes in the EIFS when the old sign was mounted. Obviously, the holes need to be patched. To achieve a decent looking patch and to preclude water intrusion, someone who knows how to work with EIFS should do the patching. This usually means an EIFS contractor, not maintenance people.
Even when skillfully done, mounting hole patches for an old sign can be visually apparent and reduce the attractiveness of the sign. The easiest way to deal with this is usually simply to "paint-out" the area with a color that matches the adjacent wall areas. The painting should go to the nearest joint or corner, so that the painted area does not look quite so obvious.
The attachment of signs to EIFS walls is often an afterthought. When promoting the use of EIFS on a building, it's worth taking a minute to discuss how signage will be handled with the building designer. This is especially true for large heavy signs, which may require major structural members to support them. In theory, the best way to deal with signage is to pre-locate the exact position of the signs and heir mounting points, and have the EIFS contractor deal with the sign mounting hardware as an object that penetrates the EIFS and is worked-around during the EIFS installation process. Such planning rarely occurs but doing so can help achieve a good looking and weather tight seal.
Signs often need maintenance. This includes such basic work as changing light bulbs, and removing and replacing old signs with new ones. Maintenance people need to be aware of what EIFS is. This article can be used to give them a clue about what type of wall material they are dealing with. This includes the issue of how to get to the sign to maintain it, without beating up the EIFS wall. For example, sometime signs are up near the top of tall buildings, and the only way to get at them is via a swing stage.
EIFS as signage
Of course, one of the many aesthetic advantages of EIFS is that the EIFS itself can be the signage. EIFS foam shapes can form 3-D surfaces that make letters and logos and other graphic elements. This can often create a classy, distinctive look at surprisingly low cost. The "rub" to this approach is that if the building tenant changes, the EIFS signage still stays. Thus, the EIFS signage needs to be torn off and the EIFS rebuilt to reflect the new client.
EIFS with drainage
Sometimes, signage is installed on walls that use the newer "EIFS with drainage" type of EIFS. Sealing sign penetrations through these types of walls can be difficult, as the weather resistive barrier is accessible behind the EIFS. The continuity of the weather resistive barrier needs to be maintained in order for the drainage capability of the wall to remain fully effective. To do so, larger than normal penetrations through the EIFS need to be made to get at the barrier and properly seal it. This can create an ugly appearance, and often is ignored; the penetration is made as if the wall is a barrier EIFS.
Small, sign-like penetrations
The above information is directed to signage but is also sometimes applicable to other types of objects mounted on the surface of an EIFS. Examples of such objects are endless, and include light fixtures, flag poles, tie-backs for window washing equipment, railings, and a whole host of similar penetrations through the EIFS.