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The Finish Line: Things Not To Do With EIFS

29.02.2008 14:36

by Robert Thomas
January 29, 2008

In my 30-plus years of working with EIFS, I’ve seen some pretty crazy things done with this product. Part of this zeal to experiment with EIFS’ capabilities is that EIFS is such a versatile and enjoyable product to work with, that it’s fun to try to see what kinds of curious things can be done with it.

But sometimes the limits of what EIFS can do get pushed too far, and problems ensue. Usually these misguided uses of EIFS are well intentioned, and are due to a lack of understanding of the properties of EIFS: It is not stucco, brick, metal or glass. Here are some real doozies:

Embedded Downspouts and Other Items

This occurs mostly on retrofit applications. The downspouts are already there, and the addition of a couple inches of EIFS insulation means the downspouts would need to be moved outboard of the EIFS. This relocation can be a real project, especially when trying to hook up the downspouts at the top end with gutters and scuppers at the eave. So the easy way would seem to be to bury the downspouts in a thick layer of foam. This is fine, until the downspouts rot out and pour the water into the wall, and from there into the building.

This odd situation can also occur when a designer gets the bright idea of trying to hide the downspouts in the foam on new construction. The truth is that internal gutters and downspouts are quite common (one doesn’t see downspouts hanging off the side of the UN building), and work just fine. They simply need to be engineered so they will work, which excludes taking some cheap tin-can downspout and covering it with foam.

This same “embed it and forget it” presents a similar problem when attempted with conduits and ducts, if the embedded item malfunctions. The rule of thumb is this: Put the item either all the way outside, or within the wall structure or indoors, but not within the EIFS itself.

Whole Walls of Tile

EIFS is a flexible, resinous, synthetic material. Ceramic tile definitely is not: It is hard and brittle. Generally speaking, one can attach a flexible material to a rigid one and it can work, like putting a car tire to a car wheel. But if a rigid material is attached to a flexible material, the rigid one can get overstressed and can crack and come off. An example would be gluing seashells with epoxy to a scuba wet suit.

With EIFS, it is possible to glue small areas of ceramic tiles onto the EIFS base coat as a form of decorative trim. It can actually be quite attractive, such as an accent in a Southwestern-style building using pretty patterned tiles. Silicone and urethane structural adhesives/sealants work well - not standard EIFS adhesives. The key is using such tile areas in moderation. Whole EIFS walls should not be covered with tile. The flexibility of the EIFS applied to a springy substrate like metal studs and sheathing can cause cracking at the tile mortar joints, or cracking of the tiles themselves. This may also allow water in, which may cause the tile to pop off when it freezes.

Mixing Different Types of Foam Insulation

Most EIFS use EPS insulation, and some use polyisocyanurate. Sometimes the two types are used together on one wall; not a bright idea. Usually this occurs when using one or the other insulation types as a base layer, and the other as a foam shape. Problems can ensue because these two insulation types have quite different properties. For example, EPS is soft and springy, while polyiso is more brittle. Sometimes, different base coats are used over different foam types: such as a normal EIFS base coat applied over EPS, versus a spray-applied urethane base coat over polyiso. The problems usually occur where the two insulation types meet, such as when a foam shape is applied to a flat base layer. Cracks often occur at this interface. This obviously looks bad but also can let water in.

There’s a major question that arises when products from different EIFS producers are used in the same project. Whose EIFS system is this? The answer, when a warranty claim is presented, would typically be: “No one’s.” To make my point, try to find a code-approved commercial EIFS that uses two types of insulation. The answer is to use one EIFS system only: It should either be all EPS or all polyiso. Don’t mix them.

Foundation Insulation

It’s tempting to bring the EIFS right down to, and into, the ground. It looks good. But it’s not good for the EIFS, especially if the ground is wet. Boat hulls are not made of EIFS because it is water shedding but not waterproof. A worse idea would be when some brainchild who decides that his wood or concrete foundation can be waterproofed and insulated with EIFS. That’s not what EPS is for. I’m unaware of any EIFS producer that advocates that their EIFS can be used as a below-grade waterproofing and insulation system. It’s for above grade use only.

Big Flat Window Sills

This misuse of EIFS is so common it’s almost embarrassing to mention it. EIFS is made of soft foam and thin flexible coatings. EIFS is not a structural material. Sometimes in their zeal for a dramatic architectural effect, designers recess the windows a foot or more, thus creating large, flat, low-slope sills.

The first thing that happens is the window washer crew walks on the sills and crushes them, no matter how much extra mesh is used in the base coat. The second, and worse thing, is that the EIFS coatings deteriorate because water ponds on the surface. The finish also gets stained and ugly due to dirt and mildew and is visible from inside the building, such as by an executive who is drinking his coffee by the window. It can be worse if the sill slopes downward slightly toward the indoors; the water will run toward the window, leading to a higher tendency to leak at the window sill/wall interface area.

The basic rule is that large, low-slope areas are a bad idea for EIFS. If such areas are a must-have, then heavy gauge metal flashings are needed to cover them. The key is heavy gauge, so the weight of workmen will not mangle the flashings. This also applies to parapet caps that are made of EIFS. They should have metal flashings that slope downward toward the inside. Workers will invariably try to stand on the parapet caps, lean ladders against them, dangle ropes over them, and otherwise mutilate them.

Rounded Foam Shapes

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Horizontal, half-round foam shapes are commonly used as accents, especially at floor lines. Here’s the problem: Rain water, laden with dirt, runs down the wall, over the top half of the rounded shape, and then dries out as it moves back toward the base wall on the underside of the foam shape, leaving ugly streaks. There is no easy way around this. It’s not an EIFS problem per se (it occurs with masonry and wood too) but is an architectural design and geometry problem.

The problem stems from the fact that water clings to the surface, yet is unable to break free and fall away. The dirt gets stuck on the surface. In other words, there’s no “drip” mechanism to shed the water, as when flashings are used.

I don’t know of an answer to this problem. People have tried putting “drip grooves” into the foam on the foam shapes, and also putting drip spaces where the foam meets the base wall. The drawing shows these seemingly effective options. Neither one actually works well. So, if you’ve got to have this rounded detail, build some money for scrubbing services into the maintenance budget.

Indoor Usage

EIFS is an outdoor product. Building codes do not permit it to be used indoors for fire safety reasons. Ah, but what about just a little bit of EIFS? This is a good question. Sometimes EIFS is used as decorative material to sculpt features on walls, such as in lobbies as corporate logos or artsy landscapes. If you are contemplating using EIFS in this limited way indoors, check with the building department first to see if its OK with them. Otherwise, if you just want the look of EIFS finish on corridors and lobbies - just apply the finish alone to the drywall.

Handrails Attached to the Lamina

EIFS is a nonstructural material. It can only withstand wind loads and support its own weight, and is not designed to support major forces, such as decks or railings or fire escapes. All major structural connections on an EIFS wall need to go through the EIFS and into the supporting wall structure. This means into a member that can support structural loads; studs, block, concrete or structural sheathing. This “attach-it-through” rule especially includes safety hardware, such as handrails.

“Down” Lights on Large Flat Walls

A dramatic architectural effect can be created at night by placing lights at the top of walls and shining them downward. The problem is that this “down lighting” brings out every single offset in the surface, making a basically so-called “flat wall” look like sand dunes. There is no easy way to deal with this other than to be very sure that the owner and A/E realize that it is impossible to get a fully flat look with jointless, hand-made, trowel-applied materials.

As an architect, I think this “down light” approach works best with rough materials, and really brings out the lovely, rich texture of the surface, such as some handsome old brick or elegant textured trowel finish. With EIFS, down lighting can generate some serious ranting if the wall is not super-flat.

Huge Soffits

Building codes as a general rule do not recognize the use of EIFS in upside-down positions, except for small areas such as at window heads. By “upside down,” I mean “inverted,” as an outdoor ceiling or soffit.

I have seen some people try to use EIFS upside-down in huge soffit areas, such as at the covered entrances to large hotels. This is fine, until a fire ensues, and the whole thing collapses because the foam melts.

Also, sometimes the EIFS is attached to gypsum sheathing that is screwed to channel iron that is hung from wire like a suspended ceiling. Such an assembly relies on gravity to not move around too much. But when the wind gets under the soffit, it can lift it and make it “flutter”, causing cracks. What’s needed is a stiff, rigid substrate, constructed using studs and bracing, and not built like a hung ceiling.

EIFS Is As Impact Resistant As Masonry

Sometimes it seems that designers think that if they put enough mesh in the base coat, it’ll withstand any impact. That’s nonsense. When detailing entrances around buildings, instead of selling a few more square feet of EIFS with heavy mesh, designers should specify inherently robust, hard materials (such as concrete block) at impact areas, such as next to sidewalks where there are shopping carts. Up and above that level, even a normal-weight base coat works fine.

EIFS Breathes

The term “breathes” applies to materials that allow water vapor (water in “gas form”–humidity) to pass through them. Most materials do, to some extent, but some don’t at all. Window glass itself doesn’t, nor does metal. Fiberglass insulation does so very well, but EIFS is one of those materials that “breathes” somewhat. It is not a “vapor barrier,” yet vapor does move slowly through the foam and coatings.

In building design, attention needs to be given to the question: If water gets into the wall, how does it get out? If the water intrusion is small, it’s no big deal; it’ll slowly dry out on its own if the local climate promotes drying. But if there’s a lot of water stuck in the wall, having the vapor escape only through the EIFS takes time. This long drying time frame can cause perpetually damp conditions that can affect moisture-sensitive wall components such as wood-based products. It can also promote mold and mildew.

The solution is to not let water get into the wall in the first place, by using good flashing design and decent caulking, and then, if the water does get in, getting it back out at the leak source. EIFS are not gutter systems or substitutes for poor wall design practices. The newer EIFS with Drainage systems go a step further and have an advantage of not only allowing liquid water to run out, but also for water vapor to seep out via the drainage cavity, as well as protecting the sheathing with a water resistive membrane.

The Dumbest EIFS Thing

To quote the hilarious comic Dave Berry, “I am not making this up!” The dumbest thing I’ve ever seen was some rock’n’roll star who wanted his guitar-shaped swimming pool area to look like a beach. He thought that since some EIFS finishes look like sand, he wanted the pool apron and the pool walls to have an EIFS finish. He did not comprehend, however, that the texture is like sand paper, so those hanging out at the pool would get skinned alive by rubbing against the pool walls. I also explained that the chlorine would dissolve the EIFS coating, leaving a pool full of sand. It took using the “no warranty” trump card to get him to dispense with his idiotic idea.

So, What Can You Do, or Not Do With EIFS?

The thing to do is to read about what the producers of EIFS promote as proper uses of their products, and to be humble about what you think might be a cool new use for their product—such as one that is not specifically listed as an approved use. We can be sure that if the EIFS producers knew of some new ingenious way to use their product, that they would promote it.

The fact that nothing is mentioned about strange uses of their products does not mean that they are OK. In other words, stick with what they say will work, and if you have questions, talk with them first. They’ve seen lots of uses for their product, and have a pretty good idea of what you can get away with.

Robert Thomas
Robert Thomas is a nationally-recognized EIFS consultant, based in Jacksonville, Fla. He was the Manager of Technical Services for a major EIFSproducer, is the author of several books about EIFS, and chairs the ASTMcommittee on EIFS.

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