It's quite common for outdoor signs to be used in conjunction with EIFS. Often, signs are in direct contact with an EIFS wall or are somehow connected to it or through it. In fact, you can make signs themselves out of EIFS but that's another story.
Size and weightSigns obviously come in all sizes, shapes, weights and materials. The range is huge, from tiny lightweight placards and individual numerals, to huge metal illuminated structures that can weigh more than a ton. Lightweight numerals of metal or plastic can be glued to the outside face of the EIFS using a structural adhesive. Silicones and urethanes are usually good candidates. Using adhesives has the advantage of not putting holes in the EIFS (and hence, precluding leaks) but causes a problem when removing them: Often, a mark is left that must be repaired.
One of the key issues regarding to installing signs on EIFS is simple: How big and heavy can it be before it cannot be attached to the EIFS? In other words, when must a sign be attached through an EIFS? The answer is also simple: Except for the lightweight materials described above, all "signs" should be attached through the EIFS. "Through the EIFS" means all the way through to a structural member behind the EIFS. This does not mean attaching to gypsum-based sheathing, which is not a structural material from a sign attachment standpoint. Rather, attachments should be made to structural materials like wood studs, metal studs, concrete, block or a structural type of sheathing like plywood.
I've seen people try to attach 100-pound signs to the EIFS lamina using molly bolts. I've even seen it tried using pop rivets. The attachment needs to go all the way through the entire EIFS to a structural material. Finding the structural material behind the EIFS can be difficult from the outside: Where are the studs? This is complicated by the fact that the indoor side of the sign attachment area is often an inaccessible area above a ceiling. Thus, the sign mounting process must be done completely from outdoors.
Some signs have electrical equipment in them like lights and motors. Electrical equipment obviously requires a power source and the wiring almost always goes through the EIFS. Such penetrations need to be sealed. Also, keep in mind that high-temperature heat-producing devices can affect EIFS insulation materials that have low melting points. EPS has a lower melting point than polyisocyanurate. A hot light bulb or transformer can literally melt the EIFS insulation behind the EIFS lamina.
Many attachment methods use bolts or screws that go through the whole EIFS and are cinched down to make a tight connection. Tightening the attachment fasteners can squash the EIFS. To avoid this, a spacer such as a wood block can be embedded within the EIFS. The block is attached to a structural material in the substrate and the sign is attached to the block through the EIFS lamina.
The EIFS re-animatorAnother approach is to drill a hole through the EIFS after the EIFS is installed and then to install a hollow spacer. A piece of tubing or pipe is often used. A bolt is then passed through the tube and into a structural member in the substrate. The tube allows cinching down the bolt without crushing the EIFS. The tube also allows locating the attachment point after the EIFS is installed, rather than creating a fastening point within the EIFS, which is not visible from the outside. The use of embedded spacer blocks requires layout work to be sure they are located where they are needed.
Sometimes, signs are replaced time and again. This is especially true on retail buildings such as fascias on strip shopping areas, where the tenants change frequently. Often, the new sign is not the same size as the old one, leaving a "shadow" of the previous on the EIFS finish, as well as abandoned penetrations from wiring or fasteners. The shadows can usually be painted out and the holes can be patched.
A better but more expensive solution is to install a permanent structural bracket through the EIFS. The bracket protrudes past the outside face of the EIFS finish and is sealed to the EIFS. The sign is then attached to the bracket. Future signs can also be attached to the same bracket, making it less unnecessary to drill another hole through the EIFS. Although a great idea in theory (and sometimes in practice), the use of permanent brackets assumes that all the signs are mounted the same way. This is not often true, so sometimes a light framing system is attached to the bracket and the sign is then attached to the framing. The use of the framing as an intermediate fastening point allows for flexibility in accommodating different signs with different mounting points.
It often helps if the sign is "stood off" from the surface of the EIFS by a few inches. This helps keep dirt from accumulating behind the EIFS, which can stain the wall below. The stand-off space allows access to mounting hardware and wiring on the back side of the sign. In addition, standing off the sign from the wall helps prevent rust stains from occurring on the EIFS finish below. Many signs have cases made of light-gauge galvanized steel. After a few seasons, they rust a bit and the rust can drip onto the EIFS, causing a stain. Luckily, rust stains can be removed using cleaners compatible with EIFS.
Occasionally, you'll see signs that are recessed into the EIFS and area attached directly to the substrate. Keep in mind, however, that signs attached like this are effectively penetrations through the EIFS in the same sense as a window. Thus the sign itself, as well as the sign's seal to the EIFS, needs to be watertight, lest water get at the substrate. A lot of signs I've seen are not watertight, as they can be opened for access to light bulbs, and are not well sealed.
Often, the installation of signs is done as part of the initial construction of a new EIFS building. In this case, there's at least a chance that someone will be able to talk to "the sign man" about how to attach signs on EIFS walls.