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Limitations on V-Grooves

Q:We’re starting an EIFS job where there’s a large open area that, for a variety of reasons, requires us to move the scaffolding around as we go. So, in order to avoid having cold joints, where the finish color or texture makes an abrupt visible change due to stopping and resuming work in the middle of a large uninterrupted area, we must install “V-grooves” as places to start and stop the finish work. What, if any, are the limitations for the length and frequency of V-grooves?




A: As is my practice, I first scoured the pertinent ASTM standard, C1397, Application of Class PB Exterior Insulation and Finish Systems (EIFS), in an attempt to discover the limitations on V-grooves, but found no reference to such a feature there. However, having attended several AWCI training sessions on all things EIFS over the years, I did remember discussions about V-grooves being cut into the EPS foam board using a hot knife, so my next step to locate verbiage on the elusive V-groove was in AWCI’s EIFS—Doing It Right® handbook. Again, I found nothing written specifically about V-grooves, but I did find an image (shown) in the section discussing aesthetic reveals depicting a V-shaped feature (bottom of the three). So, having confirmed that a V-groove must be one of the countless ways to fashion an aesthetic reveal—as you can see, there are two other shapes depicted in the same image—I continued to look for length and spacing and other constraints for installing aesthetic reveals in EIFS.




AWCI’s EIFS—Doing It Right® handbook offers the follow on the topic: “Aesthetic reveals are cut into insulation board before the application of the reinforcing mesh and base coat. Insulation board thickness shall not be less than 3/4 inch in the bottom of the reveal. No aesthetic reveals should be cut into insulation board that is less than one inch in thickness. The preferred minimum depth for reveals is 3/4-inch, which requires insulation board to be 1 1/2 inches thick.




“Ensure the following:




• Reveals are cut true and straight, as per the specifications.




• Horizontal reveals require positive outward drainage. In other words, the lower edge of the reveal should slope downward.




• Reveals must be cut into the insulation prior to applying the base coat and reinforcing mesh.




“Reveals provide architectural effects that appeal to many designers because they can create interesting architectural features. The reveals also provide mechanics with a start/stop point for the finish coat application, allowing portions of the wall areas to be applied in stages.




“Caution: Although some may think that reveals can serve the function of a control joint, if any movement in the assembly or substrate is expected, then an expansion joint is required.”




So, the italicized passage above confirms that an aesthetic reveal, in this case a V-shaped one, will serve the purpose of avoiding cold joint by providing places to terminate the EIFS finish. However, there is no mention either way about length or frequency of placement. So, back to ASTM C1397, which offers the following on aesthetic reveals:




“18.1 Aesthetic reveals shall be cut into the insulation board prior to applying the reinforcing mesh.




18.2 The insulation board thickness in the bottom of a reveal shall be not less than 3⁄4 in. (19.1 mm).




18.3 Aesthetic reveals shall be cut true and straight.




18.4 Horizontal aesthetic reveal configuration shall provide for outward positive drainage.




18.5 Aesthetic reveals shall not occur at the abutment of two pieces of insulation board.




18.6 The reveal shall be reinforced with base coat and reinforcing mesh prior to application of the full base coat and reinforcing mesh.”




This is essentially the same information imparted by the AWCI literature, with the addition of the prohibition against cutting grooves where the joints between the boards fall, which otherwise probably would result in cracking. So, in a nutshell, no limitation is mentioned on length or frequency. Cut the reveals before applying lamina and finish. Use a minimum 1 1/2-inch thick foam board to ensure that there’s still 3/4-inch foam board left in the bottom of the groove.




Lee G. Jones is AWCI’s director of technical services. Send your questions to jones@awci.org, or call him directly at (703) 538.1611.

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