Adhered Manufactured Stone Veneer (Part 2)

JNX-clusives

Chips Off the Old Block

and other ruminations about masonry 

by

Larry D. Jenks

 

Manufactured Stone Veneer

Perhaps the problems encountered by the EIFS industry are making me extraordinarily apprehensive about the current recommended installation protocols of the Adhered Manufactured Stone Veneer industry. Or, possibly those problems are making me appropriately apprehensive.

I recently read the Adhered Natural Stone Installation Guide, (written by Diane Travis of the Rocky Mountain Masonry Institute, Mike Schuller of Atkinson-Noland and Associates, the Building Stone Institute, and Robinson Brick),  as well as many other installation guides and Manufactured Stone Nightmares by Dennis McCoy. Everything I have read makes direct comparisons to the water intrusion problems discovered in the EIFS industry in the ‘90s. I have also read the MVMA Installation Guide, the MVMA Technical Bulletins on water penetration tests (see the links in my last installment), and I am troubled by a couple of things.

First, I have been unable to find the results any tests that might have been done on EIFS systems before the need for a drainage system was discovered (if you know of any, please let me know). I suspect that this is because there were no tests done at that time.

Second, the testing performed by Architectural Testing, Inc. and reported in the MVMA technical bulletins used the protocols from ASTM E331. ASTM E 331 requires the system to survive testing for a period of 2 hours in order to receive a “no failures” evaluation. I am troubled by this because I suspect that if the old EIFS systems had been subjected to a test that lasted only 2 hours, that it might well have received a “no failures” evaluation as well.  It seems to me that the failures in the EIFS systems occurred over much longer periods of time.

Therefore, I find myself wondering whether there any long-term tests being done on the adhered (manufactured or) natural stone veneer systems to determine the long-term success of this system to prevent water intrusion, especially in the absence of a rainscreen or drainage plane. I know that some Authorities Having Jurisdiction are requiring the drainage plane approach, while many others do not. Further, I can find very little information from manufacturers about the wisdom of using the rainscreen, except from the rainscreen manufacturers. Adhered Natural Stone Installation Guide says only that the rainscreen approach is “optional”.

Adhered Natural Stone Installation Guide

I am concerned that we may be in a sort of limbo period where the system is new enough that internal problems have not yet been discovered, and that, over time, the Adhered Manufactured Stone Veneer system will come to the same conclusions that the EIFS industry has come to.

So, I guess my question is this... What reason is there to believe that the AMSV system where the mortar scratch coat is in contact with the water-resistant barrier can be successful for the long term? And a follow-up question... How effective is the drainage that occurs without a drainage plane (given that the EIFS problems seem to be traceable to the fact that water was held in place against the WRB for long periods of time, eventually causing the WRB to fail)?

This installment is long enough, so I'll provide some installation details in my next installment. However, if you are a homeowner with the Adhered Manufactured Stone Veneer (AMSV) system in place on your house, I would encourage you to check to see if it is a draining type application. You can tell fairly easily --

1. First, check to see if the AMSV stops at least 4" above the grade, or 2" above any pavement.
2. Second, look up at the bottom of the application (you may have to use a mirror) -- you should see a piece of galvanized metal with holes in it, like this...

If you see the bottom of the manufactured stone, or mortar, or both -- your home almost assuredly does not use a drainage system. I would encourage you to check out the underlying materials to determine whether moisture is present. If moisture is present, you can't address it soon enough.



 











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