Jul 282011

There is work underway to develop a standardized protocol for inspecting Exterior Insulation Finishing Systems as it is being installed. This work is being done by the ASTM technical society. The protocol, as it currently exists in draft form, requires being at the job site at specific times to view the various layers of the Exterior Insulation Finishing Systems as they are being installed. This month’s column will give you a heads-up about what this protocol is likely to be like, and perhaps inspire you to get involved with writing it in a way that is simple, not expensive and not overly burdensome.

Specifications and Building Codes

The widely used International Building Code and the International Residential Code require inspections when the Exterior Insulation Finishing System is being installed in certain circumstances. In particular, inspection is required on wood framed buildings. However, these codes do not say how to do the inspections, but merely that they be done. It’s thus reasonable to ask: “What exactly constitutes a proper inspection?” For example, “Is it a visual-only process?”, or “Do samples need to be taken, and tested or measured?” And also, “How often does the inspection need to occur, and what are the inspector’s qualifications?”

The same is true in project specifications, where the building designer may want assurances that the Exterior Insulation Finishing System is being installed properly and wants to include inspection requirements in the contract documents. Unfortunately, the specifier has little to refer to as an agreed inspection protocol, lest he take the time to write one himself, or makes use of a protocol offered by a third party, such as from an Exterior Insulation Finishing System producer or a trade association.

What is Inspection?

The term “inspection” can mean a number of things, depending on whom you talk to. This column deals with Exterior Insulation Finishing System inspection as it is being installed. There is also what is sometimes called a “condition assessment,” which involves looking at an Exterior Insulation Finishing System after it has been installed. This can occur, for instance, when an existing Exterior Insulation Finishing System-clad house is being sold or when problems are suspected and an investigation is in order.

It is difficult to meaningfully assess the condition of Exterior Insulation Finishing Systems after it has been installed, without some form of digging into the wall. This leaves marks on the wall, and the inspected areas need to be repaired. If moisture in the wall is an issue, moisture meters that use nondestructive radio waves, and probe-style moisture meters, can be used without marring the wall too much.

When doing Exterior Insulation Finishing System inspections, it’s smart to discuss the scope of the work, including whether it is just the Exterior Insulation Finishing System or also is to include windows, flashings, caulking and other wall elements. The question can also come up as to whether the inspector’s work includes telling how to fix defects, and helping with design changes and contracting. This needs to be agreed upon before the inspection starts. Generally, inspectors inspect, and don’t become architects or project managers.

Types and Frequency of Testing

In most cases, using visual-only, nondestructive testing will get the job done. Sometimes, the specifier wants actual physical tests, such as:

  • Basecoat thickness
  • Proper adhesive/cement ratios
  • Impact damage resistance (presence of heavy reinforcing mesh where mandated)

These kinds of tests require removing pieces of Exterior Insulation Finishing Systems, such as by cutting out sections of the Exterior Insulation Finishing System or taking core samples using a hole saw. Some of these tests can be done onsite, but many need to be taken to a laboratory. This can take time—slowing up the installation process—and can get expensive. They also require patching the removed area, which will likely be unsightly and also takes time.

An extreme example of Quality Assurance testing is proof-testing of large wall areas for the strength of the bond of the Exterior Insulation Finishing System to the substrate. This is done occasionally if the bond is suspect, and involves using a winch-like apparatus to pull off a 4-feet-by-4-feet section of the EIFS.

The number of visits to the site depends on the project size and how certain the specifier wants to be of the quality of the installation. Full time, continuous inspection rarely makes sense, as it is really expensive, but occasionally is viable, such as in large developments with multiple buildings scattered around a large site.

Basecoat Thickness

One of the more difficult but important inspections is for basecoat thickness. The thickness greatly affects the longevity, impact resistance and waterproofness of the wall. Basically, thicker is better. Once installed, the only way I’ve seen that works well is to take small samples and measure them with a micrometer.

EIFS producers and industry specs vary as to what constitutes a proper thickness. Sometimes, a hard number is used, such as 1/8 inch. Other times, thickness is expressed in relationship to the thickness of the mesh, such as a minimum of one-and-a-half times the mesh thickness. The latter seems smarter to me, as mesh thicknesses vary. But wait, there’s more …

You have to be careful to take a lot of measurements; multiple samples and multiple points within the sample. You also need to watch that you’re not measuring at mesh overlaps, which give a higher reading.

If you’re trying to measure basecoat thickness after the finish has been applied, the problem is worse, as the finish’s thickness varies, too.

Another way to assess thickness is to look at the basecoat. The faux axiom that the mesh pattern should not be visible—i.e., the mesh is fully embedded in the basecoat adhesive—is not a good test. The adhesive dries at different rates on the mesh strands and between the strands, and sometimes the mesh pattern is very obvious, yet the mesh is well-embedded. A better approach is to lightly rub your fingertips across the cured basecoat. It should not have a “waffle” feel but should be smooth. If there’s not enough adhesive on top of the mesh, then a skim coat can be applied. This is an extra step but many Exterior Insulation Finishing System producers require it anyway.

Yet another way to measure basecoat thickness is by seeing how much adhesive is used to do a given amount of wall area. EIFS producers publish “coverage rates” for their materials, and if too much wall is being covered for a given amount of adhesive, then it’s possibly too thin, has been watered down or extra cement has been added.

Aesthetic Inspections

Sometimes, the person wanting an inspection wants to know more than just that it will be functional (not fall off or crack). This can even get into making sure the wall looks good. This type of inspection, for aesthetics, can open a real can of worms, since it’s sort of like telling someone that red wine is better than white. There are no standards for how to do such inspections, and sometimes picky architects and owners can get really wired about this issue. But there are ways around this.

First, establish beforehand what constitutes acceptable appearance. The best way is a large wall mock-up that is kept at the job site and used as a reference.

Another way is to establish how flat the wall needs to be—in other words, how much waviness is OK. This can be measured using a straight edge and setting a limit of, say 1/8 inch in 4 feet. It’s important to also establish the condition under which the wall will be viewed. For example, “down lights” that shine a beam of light at a shallow angle can accentuate a lack of flatness. The time of day also matters, particularly when the sun is low in the sky.

Color and texture variations are easier to deal with than flatness. The mock-up mentioned earlier will help do that and color samples can be eyeballed against a calibrated sample of the Exterior Insulation Finishing System producer’s colors, or standard color cards, such as those used to mix paints, to see if they match the wall.


Oftentimes, the person requesting the inspection wants some type of written report. But there are cases where they specifically do not want anything in writing. In other words, the “report” can be verbal, often while the inspector is still on the job site and can talk with the person requesting the inspection about what they have found.

If writing a report, keep in mind that unless the inspection is done continuously for the whole project, it’s possible that something can be missed. In other words, inspectors can only really report on what they have witnessed; but it’s usually the case that if the work is being done right, it’ll be right for the whole job. However, on large projects, there may be multiple Exterior Insulation Finishing System crews, and the workmanship may vary depending on where and when you look.


EIFS inspections should be done by inspectors who have undergone training about EIFS. Exterior Insulation Finishing System inspections are a specialized form of inspection, and normal building inspectors usually don’t have this specific type of training. Several industry groups offer courses in Exterior Insulation Finishing Systems inspection.

In Conclusion

The ASTM activity to develop this inspection protocol is underway in the ASTM Subcommittee on EIFS that I chair. David Johnston, the executive director of EIMA, is heading up the task group that is drafting this document. If you’d like to provide input, you can do so through Johnston (at EIMA’s office in Virginia via djohnston@awci.org), or me, via rgt@rgthomas.com. Or, better yet, you can join ASTM at www.astm.org (the dues are minimal) and join-in on the discussions and vote on what this inspection document should be like.

Robert Thomas is a nationally recognized EIFS consultant, based in Jacksonville, Fla. He was the manager of technical services for a major EIFS producer, is the author of several books about EIFS and chairs the ASTM committee on EIFS.

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