Services: GCI provided water spray testing and infrared scans of the new exterior insulation and finish system (EIFS) on the hospital, MOB and connector; field water infiltration testing of windows and fixed glass assemblies at the MOB; and a non-destructive roof top moisture survey of new roofing at the hospital including visual inspections, infrared scans and localized electrical impedence checks.

The Challenge: The client wanted quality assurance testing of the entire building envelope, where GCI was not originally involved in the quality control process. We developed protocols and provided testing to ensure that the exterior wall cladding, windows, and roofing were installed and performing as specified.

Results: Water infiltration testing, spray testing, thermography scans and visual observations indicated that the overall installation was in general conformance with manufacturer requirements, industry standards, and specification requirements.

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Founded in 1988, GCI is a consulting firm that specializes in the exterior building envelope. The GCI team includes experts in windows and doors, wall systems, roofing and waterproofing. All consultants are highly-trained specialists who work closely with clients to protect their interests and help provide cost-effective results. Our services include design assistance, investigation of building envelope problems, development of repair solutions, field water infiltration testing, quality control services, codes and standards consulting and expert witness and litigation assistance.

With the popularity of lightweight wall construction using studs and sheathing, water intrusion due to poor design or construction errors is inevitable. One of the most critical decisions with wall system design is what type of wall sheathing to use.  I have investigated hundreds of water intrusion failures with stucco, EIFS or brick veneer cladding and the degree of damage can vary widely depending upon the wall sheathing used.

This article will consider three wall sheathing types – wood (plywood or OSB), paper faced gypsum sheathing and fiberglass faced gypsum sheathing.  Wood sheathing is primarily found in residential construction and gypsum sheathing is used predominately in commercial structures.

Oriented strand board (OSB) sheathing and exterior grade paper faced gypsum sheathing are typically treated to resist some wetting during construction.  Fiberglass faced sheathing by design also resists some wetting during construction.  All three sheathing types are recommended to be protected with a moisture barrier or water resistant air barrier as part of wall system design.  The theory is that any water that infiltrates exterior cladding, joints, wall penetration or windows and doors is shed away from the sheathing and drained back to the outs ide.  In effect, the intent is that the sheathing never gets wet.

The reality is that the moisture barrier must be perfectly designed and constructed to prevent any water from contacting the sheathing.  Another reality is that this often does not happen.  Any design concept that relies on perfection, particularly in construction, is likely to result in eventual failure.

When OSB sheathing, plywood and paper faced gypsum sheathing are subjected to water leakage inside a wall cavity, they become saturated and deteriorate.  This causes them to lose their ability to support the cladding and can also lead to mold and other environmental problems.  Most failures of these systems during severe wind storms reveal degradation of the sheathing due to water intrusion.  Figures 1 – 4  below illustrate water damaged sheathing at a small commercial building type with similar wall construction design except for the sheathing:

Figure 1. – Water damaged OSB Sheathing

Figure 2. – OSG Sheathing rotted away

Figure 3. – Water Damaged Plywood Sheathing

Figure 4. – Water Damaged Gypsum Sheathing

In contrast, fiberglass faced gypsum sheathing is better able to withstand prolonged water intrusion within a wall cavity.  Fiberglass faced gypsum sheathing manufacturers recommend that all board joints and fastener penetrations be sealed prior to the application of cladding.  However, even if this is not done, the performance of this sheathing material when subjected to prolonged water leakage is far superior to the others.  Figure 5 below is from the same group of projects as Figures 1 – 4 above but used fiberglass faced gypsum sheathing.  Note how much less damage there is to the sheathing.

Figure 5 – Fiberglass Faced Gypsum Sheathing

I have investigated many projects with water intrusion into the wall cavity that used fiberglass faced gypsum sheathing and the damage is much less that with other types of sheathing.  Fiberglass faced gypsum sheathing is more expensive that paper faced sheathing, although it is not enough to discourage its use.  Based upon our field experience, GCI always recommends fiberglass faced gypsum sheathing for use as an exterior sheathing.  It still needs an air and water moisture barrier over it inside the wall cavity, but if leakage does occur, the damage and subsequent repairs are greatly reduced.

Paul Beers is the Managing Member of Glazing Consultants International, LLC (GCI), a building envelope consulting firm in business since 1988. He has over 25 years experience in the window and glazing trade and with building envelopes. He is a leading expert with glazing systems and hurricane damage and protection and was instrumental in the development and implementation of missile impact tests after Hurricane Andrew hit Dade County, FL. His expertise includes windows, doors, glass and wall claddings with an emphasis on water leakage and damage. He has served as an expert witness in federal and circuit courts for windows, doors, glass and wall systems and water leakage. Paul can be reached at pbeers@glazingconsultants.com.

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The #1 project-type for susceptibility to water infiltration problems:  In my experience, this is the typical, wood-frame apartment complex.  With tight construction time frames and strained budgets, there is typically less emphasis on detailing and field quality-control than is included in most large commercial projects.  Add this to the inherent vulnerability of the wood framing and sheathing, along with the large number of crucial details at window openings, door openings, balconies, decks, landings, floor lines, cladding transitions, etc., and it is no surprise that we see more of these projects with water infiltration and damage than any other type of project.

Many developers believe their budgets cannot support the inclusion of an exterior envelope consultant during construction of these projects,

but I would argue that nowhere is the return on investment greater.  

The photos speak for themselves.

The mysteries of brick veneer installation on single-family homes:  On a smaller scale, but no less disastrous for the owners, there are countless single-family homes with water-damaged walls as well.  When inspecting masonry-clad homes with water infiltration problems, we consistently find a complete absence of attention to long-established details which are commonplace on commercial projects.  The Brick Industry Association provides free, comprehensive details of proper brick installation for most applications.  For some reason, in single-family home construction, basic concepts such as through-wall flashing, weeps, and a proper drainage cavity never make it into the structure.  We commonly see two and three-story walls without a single piece of through-wall flashing or weep hole.  If you’ve ever observed how quickly water penetrates through brick and mortar, you can easily predict the results.  All of that water has to go somewhere, and with the brick typically installed with no drainage cavity, the wall damage begins very quickly.

More about exterior wall sheathing:  As an addendum to Paul Beers’ article in this same newsletter, another type of sheathing we are seeing more frequently is an oriented strand board (OSB) product with a factory-applied, liquid-based weather resistive barrier material on the exterior face.  This seems to be gaining popularity in single-family construction, and it is also being used on some multi-family projects.  There can be potential benefits from selecting this type of material, but it should not be viewed as a guarantee against future water infiltration problems.  Along with the positives offered by a bonded weather barrier applied in a factory setting, there are detailing concerns at joints and cut-outs, and some new challenges in properly shingle-lapping self-adhered membrane flashings with the pre-applied barrier material. Our greatest apprehension relates to the perception by some that if this material is used, it eliminates all concerns about water infiltration and damage.  Remember that this material is not waterproofing, it is a weather resistive barrier, and proper detailing and supervision are still essential components to constructing a successful and enduring project.

Cautious Optimism:  We travel often to projects all over the USA and beyond, and we talk to many people working in every phase of the construction industry.  This includes owners, developers, architects, builders, subcontractors, product manufacturers, and field installers.  We all know this industry has been hit as hard as any by brutal economic conditions, but in the last few months, there seems to be a general consensus that conditions are slowly improving.  For the last couple of years, almost every new project we saw was either a healthcare or institutional facility.  Recently, we have seen more starts in those areas, but also some nice projects in hospitality, commercial, and multi-family residential.  Even some of the single-family homebuilders we know have seen some improvement.  This is no scientific poll, and we at GCI are certainly not economists, but it does appear that the industry has passed through the valley and is on a gradual upslope.  We are as optimistic as we have been in quite some time.

“Green” Contribution:  Energy requirements, sustainability, LEED credits, and air-tightness are terms we hear now on every new project.  At GCI, we believe that these are vital factors in building construction, and that it is equally important that we contribute to these efforts in our part of the design and construction process.  We have been ahead of the curve in our use of digital versions of project plans and specifications, and we have performed electronic “mark-up” reviews of these documents for several years.  We also deliver all of our reports electronically, and we are working on an exclusive access portal for our clients. Some of our project meetings are conducted “virtually”, and some types of inspections are documented digitally on tablet computers.  We remain committed to researching and implementing new methods of providing our services more efficiently – it is our responsibility to our clients, their projects, and our planet.

Christopher Matthews is Vice President and a Senior Consultant, employed with Glazing Consultants International, LLC, since 2002. He has over 27 years of experience working with exterior glazing and wall systems, and specializes in the installation and water resistance of these systems. He has consulted with owners, architects, engineers and builders on hundreds of projects throughout North America and the Caribbean, and also serves as an expert witness in related matters.

 Chris can be reached at cmatthews@glazingconsultants.com or at (561)689-0055.