Sealant Joints: Don’t Ignore This Small Component and Its Big Mission

By Christopher Matthews

Here is an all-too-common scenario at our firm:  A client requests an initial inspection of a home or building with complaints of water infiltration problems.  The property owner reports that water stains are appearing on interior finishes around window and door openings.  We arrive at the site, meet with the owner, inspect the interior, and confirm that the interior materials around several window and door openings are indeed stained and wet.  Then, the first thing we observe during our exterior review is wide-open perimeter joints between the window and door frames and the surrounding wall cladding.  In many cases, it is obvious that no perimeter sealant was ever installed, and in many others, there are widespread failures of the sealant joints which have in turn created the open joints.  Either way, the result is the same  – a direct path for water to enter the wall system around the windows and doors. 

It should not take a rocket scientist or even an envelope consultant to determine that open exterior joints can allow large amounts of water into the wall system at these locations, but for many owners, a consultant is required.  Time and time again we find that improperly installed, poorly maintained or completely absent sealant joints are a major contributor to water infiltration problems in the structures we assess.  A properly designed envelope system should include secondary protection to control incidental water within the wall system, so there are also other factors involved.  However, exterior sealant joints are the first line of defense against the elements and should not be overlooked. 

In every type of building, clad with any combination of exterior wall and fenestration systems, there are multiple joints at transitions, penetrations and expansion-control locations which must be properly sealed.  There are four major components to achieving proper performance of these sealant joints: 

1.      Selecting appropriate materials.

2.      Developing good joint details and performing laboratory testing.

3.      Professional installation and field testing.

4.      Regular maintenance. 

And each of these is discussed further below.

Often, it seems that price and lack of knowledge regarding the properties of various sealant materials are the driving factors in product selection.  The attitude seems to be that “a tube of caulk is a tube of caulk,” whether it is bathroom sealant purchased from the local hardware store or a high-quality construction grade sealant.  Thus, “whatever is the cheapest” and readily available is often selected.  This approach leads to adhesive and cohesive sealant joint failures due to several factors including chemical compositions that are not suited for the atmospheric conditions, sealants applied to substrates to which they are not intended to adhere and sealant movement capabilities which are not sufficient for the joint and substrate conditions. 

The products selected should be high-quality construction grade sealants specifically designed for the joint location and type, and these should be tested and certified according to ASTM C920 – Standard Specification for Elastomeric Joint Sealants.  This standard includes requirements for testing and classification of sealants by type, grade, movement capability, use, approved substrates and various other material characteristics.  Generic adhesive sealants, painter’s sealants and bathroom sealants are typically not tested or certified to these rigorous standards.  With the largest share of the cost of a sealing job tied to the installation labor and equipment, the savings of a few dollars per tube of sealant up front are miniscule when compared to the potential expense of a re-sealing job necessitated by an improper sealant which has failed.

Once the appropriate sealant material is selected, proper joint sizes and shapes must be designed in accordance with industry standards and the manufacturer’s requirements.  No matter how good the sealant material, failures can occur if the joints are not properly formed.  ASTM C1193 – Standard Guide for Use of Joint Sealants provides extensive and detailed standards for proper joint dimensions, application, backing materials and many other factors.  The manufacturers of all high-quality sealants further supplement this standard with their own published requirements for application.  These manufacturers will also perform pre-construction, laboratory adhesion and compatibility testing of the sealant contact materials.  There is typically no cost for this testing, and it should be performed as part of the design process.

An experienced, professional sealant installer is then required to take the selected material and properly apply it in accordance with the designed details.  The installer must be familiar with all manufacturer and industry installation requirements, must assure that all substrates are properly cleaned and primed, must verify that all joint dimensions are within product and project specifications and must properly install the sealant and backing material to provide proper joint formation.  Field adhesion testing should be conducted as installation begins, and then periodically throughout the installation process, to assure proper performance.  The Appendix to ASTM C1193 includes standardized procedures for this field adhesion test.

In the real world, joint dimensions are often not as consistent as those shown in drawing details, and a common type of failure occurs when sealant is applied to overly narrow joints with no backing material.  Products and methods are available to properly address almost any field condition, but the installer must bring these conditions to light to allow for revised details and products as required. 

The responsibility for the final leg supporting a successfully sealed envelope lies with the owner.  Although some high-grade silicone sealants carry up to a twenty-year warranty, every product has a finite life span and must be regularly inspected and repaired as required.  Even a relatively small sealant void can allow a large amount of water into the wall system during a wind-driven rain, and regular maintenance can prevent much greater problems in the future.

When compared with the square footage of the entire building envelope, the sealant joints are a very small percentage of the total.  This leads many in the industry to ignore or neglect these joints, but their importance should not be underestimated.  The performance of the intricately designed and tested systems on each side of a joint can be compromised if the sealant is not doing its part.  By properly selecting, installing and maintaining the exterior sealant, you provide that crucial first line of defense.  Take good care of these small sealant joints, and it will lead to large, long-term returns in building performance. 

If you have questions or comments, please contact us at info@glazingconsultants.com. Find out more about GCI at http://www.glazingconsultants.com  or on Twitter @glazingconsult, and join our Building Envelope Matters LinkedIn group to discuss building envelope issues.

Christopher Matthews is Vice President and a Senior Consultant, employed with Glazing Consultants International, LLC, since 2002. He has over 20 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 on Twitter @glazingconsult. Find out more about GCI at http://www.glazingconsultants.com, and join our Building Envelope Matters LinkedIn group to discuss building envelope issues.

Interior Air Seals: The Added Benefit

By William D. Smith 

In a prior column we discussed the importance of using flashing at openings and how the failure to do so can result in significant building damage.  This month we’ll look at another commonly overlooked weathering component for many different types of glazing systems, the interior air seal.

As the name implies, the interior air seal simply describes a seal or barrier installed around the interior perimeter of a fenestration product.  Traditionally, installation instructions published by many residential window manufacturers have required that insulation be placed between the window frame and the rough opening, but now, many manufacturers of both residential and commercial glazing products also recommend the use of expansion foam or an elastomeric sealant with backer rod. 

One benefit of an interior air seal is obvious; while insulation will obviously provide insulating value, an air seal around the inside of a window or door frame will help control air leakage.  But there’s a potential side benefit offered by the air seal that is often overlooked; water leakage prevention.  On the surface, it doesn’t seem like an interior “air seal” would have anything to do with controlling water leakage, so to understand how this works, we need to go back to basics. 

For water leakage to occur, three things are needed; 1) water, 2) a hole or breach for the water to penetrate and 3), a force to move the water through the hole.  Of these three, the volume of water is not a very significant factor.  To illustrate, imagine you’re holding a garden hose in a U shape and the hose is nearly filled with water as shown at right.  If you force air into one end of the hose as illustrated by the arrow, we all understand that the water will rise upward on the other end of the hose.  In fact, the laws of physics tell us that if we apply a pressure of approximately 5 pounds per square foot, the water will rise up the other end of the hose about 1 inch.  And it’s easy to understand that the greater the pressure, the higher the water will rise.  Now, if instead of a garden hose you were to use an equal length of fire hose, which clearly has a significantly greater volume of water, the physics remains the same: a pressure of approximately 5 pounds per square foot at one end will still force the water to rise about 1 inch at the other end of the hose.  So it can be seen that the volume of water is not as significant as the applied force. 

Now let’s imagine that a fully enclosed, air tight box is attached to one end of the hose as shown at left.  Your objective is to put pressure on the open end of the hose and force the water to rise up into the enclosed box.  This time, however, physics tells us that there’s going to be little or no effect on the water level because the box at the other end of the hose is sealed shut.  This prevents displacement of the air in the box which prevents water from entering.  So even though there is an opening where the hose is connected, which is immediately adjacent to the water level, water entry into the box can be minimized or eliminated if the box is airtight.  This is the theory for installing an interior air seal to control water leakage around windows and doors. 

As noted previously, the installation instructions of many residential and commercial glazing system manufacturers now require that expansion foam or an elastomeric sealant with backer rod be provided on the interior around the perimeter of the window frame. In the section drawing at right, it can be seen that using a perimeter seal on both the interior and exterior of a typical storefront window results in an air space between the two seals.  Whether or not this air space is air tight depends on a number of factors including the integrity of the window frame as well as the substrate materials.  Nonetheless, while this space might not be absolutely air tight, the ability for air to enter into the sealed space can be significantly reduced.  As a result, if there were to be a failure of the exterior perimeter sealant the interior air seal minimizes air flow into the space around the perimeter of the frame.  And as we saw in our earlier experiment, if air can’t flow into this space, then water doesn’t flow into it either.  Several window manufacturers have conducted a battery of laboratory tests that confirm success of this installation.  And in addition to installation instructions, we’ve found that the Notice of Approval issued for many windows, doors, and glazing systems illustrate that an interior air seal is to be installed. 

When expanding foam is used as in the photo at left, only low expansion foams should be used in order to prevent excessive bowing of the window frame while the foam expands and cures.  Annex A.1 to ASTM E 2112-07 “Standard Practice for Installation of Exterior Windows, Doors and Skylights” is a very good guideline for using expansion foam around window frames.

In addition to being specified by many manufacturers’ installation instructions, the use of an interior air seal is also becoming noted in reference standards.  Paragraph 16.9.2 and 16.9.3 of AAMA IPCB-08, AAMA Standard Practice for the Installation of Windows and Doors in Commercial Buildings, require that after insulation is placed around the window, “backer rod should be placed over cavity insulation on the interior side of the window” and then, “place sealant over the backer rod in a continuous manner.”  Also, paragraph 3.5.3 of AAMA 502-08, Voluntary Specification for Field Testing of Newly Installed Fenestration Products requires that if field testing is conducted on windows and doors, “Care shall be taken not to disturb the interior side air seal, if present.” 

Unfortunately, many installers omit the interior air seal, which we suspect may simply result from a misunderstanding of its benefits.  We encourage installers and builders to take a second look at the potential advantages offered by installing an interior air seal in both new construction and renovation work.

William D. Smith is the President of Glazing Consultants International, LLC (GCI), a building envelope consulting firm in business since 1988. He has nearly 40 years of experience in the design and construction of glazing systems and building envelopes and is recognized as an expert in the field of windows, doors, glass, and exterior wall systems, including all aspects of weatherproofing and water intrusion. He is an authority on Exterior Insulation Finish Systems (EIFS), sealants, and waterproofing systems, and has an extensive history of forensic building investigation. Mr. Smith has demonstrated his expertise in the field of hurricane damage and development of hurricane protection systems. He has performed many post-hurricane damage investigations. Mr. Smith has designed a variety of glazing applications for new construction projects including windows, doors and glazed curtain walls as well as specialty glazing system for exhibits and blast resistance. Will can be reached at wsmith@glazingconsultants.com or on Twitter @glazingconsult. Find out more about GCI on the web at http://www.glazingconsultants.com, and join its Building Envelope Matters LinkedIn group to discuss building envelope issues.

Henry Gifford’s lawsuit against against LEED, USGBC evolves

A federal lawsuit filed in October 2010 against the U.S. Green Building Council (USGBC) and other defendants, focusing on allegedly fraudulent claims of the LEED rating system, has been amended. Filed February 7th, 2011, the amended complaint has been boiled down to a claim of false advertising, and is no longer a class-action suit.

Read the rest of the article on BuildingGreen.com

Related Reading:

• Gifford’s LEED Lawsuit Takes New Shape
• Class action lawsuit against LEED and USGBC evolves
• PDF: Henry Gifford’s amended complaint

Glazing Consultants International, LLC, committed to fair labor practices

Glazing Consultants International, LLC, (GCI) is providing building envelope consulting services, including quality assurance, site inspections and product submittal reviews, for all phases of the Orlando VA Medical Center project.

Although GCI was mentioned in an Orlando Sentinel article about the investigation into employment practices of some contractors and subcontractors on the new Veteran’s Affairs Medical Center near Lake Nona, the company is not a part of any investigation and has not been asked to provide employment records by state or federal agencies.

“GCI has a small staff of specialized experts in everything from windows, doors and wall systems to roofing and waterproofing. All members of our team have worked for us for a number of years and are U. S. Citizens or fully documented,” said Paul Beers, Managing Member of Glazing Consultants International, LLC. “We are committed to following all employment and immigration laws that are in place.”

GCI is proud to be working on this project with a joint venture team of architecture firms RLF and Ellerbe Becket, who designed the Orlando Veterans Affairs Medical Center to achieve LEED Silver Certification. The 1.2 million square foot facility at Lake Nona, FL, will be a full-service VA medical center providing acute care, complex specialty care and advanced diagnostic services through a 134-bed hospital, an outpatient clinic, a 118-bed nursing home and a 60-bed domiciliary. The site will also contain a veteran’s benefits office that will help veterans to obtain compensation, pensions or other financial benefits earned by military service.

If you have questions or comments, please contact us at info@glazingconsultants.com. Find out more about GCI at http://www.glazingconsultants.com  or on Twitter @glazingconsult, and join our Building Envelope Matters LinkedIn group to discuss building envelope issues.

President Obama’s Better Buildings Initiative Aims to Make Commercial Buildings More Energy Efficient

In his State of the Union Address, President Obama laid out his vision for investing in innovative clean energy technologies and doubling the share of electricity from clean energy sources by 2035. Now the President is proposing new efforts to improve energy efficiency in commercial buildings across the country. The President’s Better Buildings Initiative aims to make commercial buildings 20 percent more energy efficient over the next decade by catalyzing private sector investment through a series of incentives to upgrade offices, stores, schools and other municipal buildings, universities, hospitals and other commercial buildings.

Read the rest of the Press Release from The White House’s Office of Media Affairs 

Discuss what you think of the plan below or on our “Building Envelope Matters” Group.

Related Reading: 
• Will Obama’s Ambitious Energy Efficiency Plan Really Save Businesses $40 Billion a Year?
• AGC Praises New Commercial Building Efficiency Effort
• Obama Pushes Better Buildings and HomeStar
• White House Proposes New Green Buildings Program
• Industry Responds to President Obama’s State of the Union Address

If you have questions or comments, please contact us at info@glazingconsultants.com. Find out more about GCI at http://www.glazingconsultants.com  or on Twitter @glazingconsult, and join our Building Envelope Matters LinkedIn group to discuss building envelope issues.

Overcladding an existing painted Stucco facade with a new EIFS & min. 2″ EPS board

Mike B., a member of the “Building Envelope Matters” group on LinkedIn recently asked, “Over-cladding an existing painted Stucco facade with a new EIFS & min. 2″ EPS board….. Should I specify a barrier system design or a system with secondary drainage, adhesive or mechanical attached?”

Here is the response by Paul Beers of Glazing Consultants International, LLC:

“A lot of the answers to these questions would depend on the specific project conditions. We like drainable systems and mechanical attachments, although if it is not a high wind area, adhesive attachment would work. We would likely apply a liquid applied membrane to the existing stucco facade and then apply a drainable system over it. With a drainable system, it is important to provides means for any incidental water that gets through to drain back to the exterior with weeps and or flashing.

If you use a barrier system, great attention to detail and workmanship is required because if any water penetrates the exterior skin, it is trapped inside the wall.”

To see what other members of the group had to say and to join the discussion, click here.

If you have questions or comments, please contact us at info@glazingconsultants.com. Find out more about GCI at http://www.glazingconsultants.com  or on Twitter @glazingconsult, and join our Building Envelope Matters LinkedIn group to discuss building envelope issues.

Paul 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.