Locating the Source of Water Intrusion Can Be Tricky

The building in question features one whole face that is an aluminum-framed glass curtainwall. The curtainwall extends up above the roof lines, slopes up (from the vertical) forming a peaked skylight, which then slopes back toward the roofs that were holding water.

The building in question features one whole face that is an aluminum-framed glass curtainwall. The curtainwall extends up above the roof lines, slopes up (from the vertical) forming a peaked skylight, which then slopes back toward the roofs that were holding water.

As architects/roof consultants, there is nothing we hate more than to get a call from a client who says, “My new roof is leaking.” Yet, that is exactly what happened to us not long ago. My firm had put a new thermoplastic PVC roof system on a high-profile government building in central New Jersey. The owner was my long-time client, and I ran the project, so I was intimately familiar with it and utterly shocked to get this call about six months after the project was completed. We had just experienced a three-day nor’easter that began on Thursday night and ran straight through to Monday morning when the client arrived at the building to find numerous leaking areas.

I responded by immediately going to the building. I was accompanied by the roofing system manufacturer. As the client led us around the building, water was dripping through suspended ceilings all over, which gave us the sinking (almost apocalyptic) feeling you hope to never know. However, when we went up to examine the roof, much to our surprise, there was no blow off; no seams torn; in fact, no apparent defects at all. Our thermoplastic cap sheet looked perfect on the surface.

On the upper roof, aluminum-framed sawtoothed skylights were dripping water when the team first arrived. This gave the only clue to where the “smoking gun” may lie.

On the upper roof, aluminum-framed sawtoothed skylights were dripping water when the team first arrived. This gave the only clue to where the “smoking gun” may lie.

What we did find, however, was large amounts of water trapped between this cap sheet and the 90-mil bituminous base sheet underneath. This was creating large water-filled blisters on the roof that looked like an old waterbed as you walked up to and around them. No matter how hard we looked we just couldn’t find defects in the membrane surface or at any of the flashing connections or terminations that could be causing this. There was, however, a likely suspect looming adjacent to and above our roofs. The building experiencing the roof leaks has one whole face that is an aluminum-framed glass curtainwall. It extends up above the roof lines, slopes up (from the vertical) forming a peaked skylight, which then slopes back toward these roofs that were holding water. On the upper roof, sawtoothed skylights of the same construction were dripping water when we first arrived. This gave the only clue to where the “smoking gun” may lie.

METHODOLOGY

Water was dripping from the saw- toothed skylights into a planter in the 4-story atrium. The client said that was typical with all hard rains. Armed with this clue, and no other apparent explanation for such a large amount of water intrusion, the owner engaged us to find out what indeed was the root cause of this problem.

On the upper roof, aluminum-framed sawtoothed skylights were dripping water when the team first arrived. This gave the only clue to where the “smoking gun” may lie.

On the upper roof, aluminum-framed sawtoothed skylights were dripping water when the team first arrived. This gave the only clue to where the “smoking gun” may lie.

In a couple days, the dripping subsided and most of the water blisters had dissipated or at least were reduced and stabilized. In the interim, I assembled a team consisting of a roofing restoration contractor (this is not a rip and tear production contractor but one especially geared to finding problems and making associated repairs), skylight restoration contractor and testing agency capable of building spray racks onsite to deliver water wherever it’s needed. With this team, I embarked on a systematic investigation that would make any “detective” proud.

First, we plugged the roof drains and let water pool on the roof until the en- tire surface was wet. Meanwhile, “spot-ters” inside the building were looking for any sign of water intrusion using lights above the dropped ceilings. When this showed nothing, we began constructing spray racks and running water for set intervals on every adjacent surface rising above and surrounding the lowest roof in question. We first sprayed the exposed base flashings, then rose up to the counterflashing, then further up the wall, then to the sill of the windows above, etc. Then we would move laterally to a new position and start again.

The team first sprayed the exposed base flashings with water, then rose up to the counterflashing, then further up the wall, then to the sill of the windows above, etc. Testing moved laterally to a new position before starting again.

The team first sprayed the exposed base flashings with water, then rose up to the counterflashing, then further up the wall, then to the sill of the windows above, etc. Testing moved laterally to a new position before starting again.

This proved painstakingly tedious, but we knew that making the building leak was not enough; we had to move slowly and systematically to be able to isolate the location to determine what exactly was leaking and why. It is important when applying water this way to start low and only after a set period move upward, so when water does evidence itself as a leak, you know from what elevation it came.

After an entire day of spraying the rising walls surrounding the first (low) roof area, we could not replicate a leak. Somewhat frustrated—and rapidly burning the testing budget—we began the second day focusing on the adjacent peaked skylight, which is more than 75- feet long.

The team first sprayed the exposed base flashings with water, then rose up to the counterflashing, then further up the wall, then to the sill of the windows above, etc. Testing moved laterally to a new position before starting again.

The team first sprayed the exposed base flashings with water, then rose up to the counterflashing, then further up the wall, then to the sill of the windows above, etc. Testing moved laterally to a new position before starting again.

Again, we started low, where our base flashing tied into the knee-wall at the base of the skylight, below the aluminum-framed sill. Still no leaks. Late in the day, when we were finally up to the glass level, we sprayed water from the ridge and let it run right down the glass onto our roof below. Finally, we found some leaking occurring at a skylight flashing to wall connection. OK, that was reasonable to anticipate and easy to correct.

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The Roof Cover: The Cap on the Roof System

For nearly two years in this magazine, I have been discussing the various components that make up a roof system: roof deck, substrate boards, vapor/air retarder, insulation and cover boards (see “More from Hutch”, page 3). Although each component delivers its own unique benefit to the system, they are intended to work together. When designing a roofing system, components cannot be evaluated solely on their own and consideration must be taken for a holistic view of the system; all components must work together synergistically for sustainable performance. Unfortunately, I often have seen that when components are not designed to work within the system unintended consequences occur, such as a premature roof system failure. A roof system’s strength is only as good as its weakest link. The roof cover is the last component in the design of a durable, sustainable roof system—defined previously as being of long-term performance, which is the essence of sustainability.

This ballasted 90-mil EPDM roof was designed for 50 years of service life. All the roof-system components were designed to complement each other. The author has designed numerous ballasted EPDM roofs that are still in place providing service.

PHOTO 1: This ballasted 90-mil EPDM roof was designed for 50 years of service life. All the roof-system components
were designed to complement each other. The author has designed numerous ballasted EPDM roofs that are still in place providing service.

The roof cover for this article is defined as the waterproofing membrane outboard of the roof deck and all other roof-system components. It protects the system components from the effects of climate, rooftop use, foot traffic, bird and insect infestation, and animal husbandry. Without it, there is no roof, no protection and no safety. When mankind moved from cave dwellings to the open, the first thing early humans learned to construct was basic roof-cover protection. Thus, roof covers have been in existence since man’s earliest built environment.

WHAT CONSTITUTES AN APPROPRIATE ROOF COVER?

There is no one roof cover that is appropriate for all conditions and climates. It cannot be codified or prescribed, as many are trying to do, and cannot be randomly selected. I, and numerous other consultants, earn a good living investigating roof failures that result from inappropriate roof-cover and system component selection.

There are several criteria for roof-cover selection, such as:

  • Compatibility with selected adhesives and the substrate below.
  • Climate and geographic factors: seacoast, open plains, hills, mountains, snow, ice, hail, rainfall intensity, as well as micro-climates.
  • Compatibility with the effluent coming out of rooftop exhausts.
  • Local building-code requirements, such as R-value, fire and wind requirements.
  • Local contractors knowledgeable and experienced in its installation.
  • Roof use: Will it be just a roof or have some other use, such as supporting daily foot traffic to examine ammonia lines or have fork lifts driven over it?
  • Building geometry: Can the selected roof cover be installed with success or does the building’s configuration work against you?
  • Building occupancy, relative humidity, interior temperature management, building envelope system, interior building pressure management.
  • Building structural systems that support the enclosure.
  • Interfaces with the adjacent building systems.
  • Environmental, energy conservation and related local code/jurisdictional factors.
  • Delivering on the expectations of the building owner: Is it a LEED building? Does he/she want to go above and beyond roof insulation thermal-value requirements to achieve even better energy savings? Is he/she going to sell the building in the near future?

ROOF-COVER TYPES

There are many types of roof-cover options for the designer. Wood, stone, asphalt, tile, metal, reed, thatch, skins, mud and concrete are all roof covers used around the world in steep-slope applications. This article will examine the low-slope materials.

The dominant roof covers in the low-slope roof market are:

    Thermoset: EPDM

  • Roof sheets joined via tape and adhesive
  • Installed: mechanically fastened, fully adhered or ballasted
  • Thermoplastic: TPO or PVC

  • Roof sheets joined via heat welding
  • Installed: mechanically fastened, fully adhered or plate-bonded (often referred to as the “RhinoBond System”)
  • Asphaltic: modified bitumen

  • Installed in hot asphalt, cold adhesive or torch application
  • EPDM (ETHYLENE PROPYLENE DIENE MONOMER)

    Fully adhered EPDM on this high school in the Chicago suburbs is placed over a cover board, which provides a high degree of protection from hail and foot traffic.

    PHOTO 2: Fully adhered EPDM on this high school in the Chicago suburbs is placed over a cover board, which provides a high degree of protection from hail and foot traffic.


    EPDM is produced in three thicknesses— 45, 60 and 90 mil—with and without reinforcing. It can be procured with a fleece backing in traditional black or with a white laminate on top. The lap seams are typically bonded with seam tape and primer.

    EPDM has a 40-year history of performance; I have 30-year-old EPDM roof systems that I have designed that are still in place and still performing. Available in large sheets—up to 50-feet wide and 200-feet long—with factory-applied seam tape, installation can be very efficient. Fleece-back membrane and 90-mil product have superior hail and puncture resistance. Historical concerns with EPDM lap-seam failure revolved around liquid- applied splice adhesive; with seam tape technology this concern is virtually moot. Non-reinforced ballasted and mechanically fastened EPDM roof membrane can be recycled.

    EPDM can be installed as a ballasted, mechanically fastened or fully adhered system (see photos 1, 2 and 3). In my opinion, ballasted systems offer the greatest sustainability and energy-conservation potential. The majority of systems being installed today are fully adhered. Ballast lost its popularity when wind codes raised the concern of ballast coming off the roof in high-wind events. However, Clinton, Ohio-based RICOWI has observed through inspection that ballasted roofs performed well even in hurricane-prone locations when properly designed (see ANSI-SPRI RP4).

    PHOTOS: HUTCHINSON DESIGN GROUP LTD

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Coating Extends the Life of Aging Roofs

The new Silicone Roof Coating System from Mule-Hide Products Co. Inc. can be used to restore and repair asphalt, modified bitumen, metal, concrete, TPO, PVC and EPDM roof systems.

The new Silicone Roof Coating System from Mule-Hide Products Co. Inc. can be used to restore and repair asphalt, modified bitumen, metal, concrete, TPO, PVC and EPDM roof systems.

The new Silicone Roof Coating System from Mule-Hide Products Co. Inc. can be used to restore and repair asphalt, modified bitumen, metal, concrete, TPO, PVC and EPDM roof systems. It includes a cleaner to prepare the substrate for priming; two primers to improve adhesion of the topcoat; a multipurpose sealant for use with reinforcement roofing fabric to complete repair and maintenance tasks; three topcoats—Silicone Roof Coating (available in white and gray), Silicone Masonry Wall Coating (available in white and gray) and Silicone Skylight Coating; and a cleaner to wash tools and equipment. All products are solvent-free and comply with VOC regulations throughout North America.

SFS intec Receives FM Approvals Certificate for Induction Welding System

SFS intec received an FM Approvals Class 4470 Certificate of Compliance from FM Approvals for isoweld.

SFS intec received an FM Approvals Class 4470 Certificate of Compliance from FM Approvals for its induction welding system, isoweld.

SFS intec, Wyomissing, Pa., has recently received an FM Approvals Class 4470 Certificate of Compliance from FM Approvals, part of FM Global, for isoweld. isoweld is SFS intec’s induction welding system. This certificate approves use of isoweld for attachment of thermoplastic single-ply membranes (PVC and TPO) within roofing systems offered by several single-ply membrane original equipment manufacturers (OEMS).

PVC Sleeve Fits over Existing Copper, Cast Iron and Irregular or Damaged Pipe Surfaces

When used with the Ultimate Pipe Flashing, the EasySleeve from Lifetime Tool & Building Products provides a lifetime solution.

When used with the Ultimate Pipe Flashing, the EasySleeve from Lifetime Tool & Building Products provides a lifetime solution.

The EasySleeve from Lifetime Tool & Building Products is a black PVC sleeve that makes it possible to have pipe flashing components available on site to deal with almost any and all pipe penetrations, including those that are damaged, worn or irregular-sized. When used with the Ultimate Pipe Flashing, the EasySleeve provides a lifetime solution.

From failed flashing to unsightly pipes, the EasySleeve provides a solution in three easy steps:

  • 1. Cut off hub.
  • 2. Cut to length.
  • 3. Install Ultimate Pipe Flashing.

GAF Plans to Open PVC Manufacturing Line in Cedar City, Utah

GAF announced plans to open a PVC manufacturing line at its commercial roofing plant in Cedar City, Utah. The line, which GAF expects to become operational as early as mid-2016, will transform the Cedar City operation into a full-service manufacturer and supplier of polyvinyl chloride (PVC) and thermoplastic polyolefin (TPO) single-ply membranes, as well as polyisocyanurate (ISO) insulation.

GAF also announced that it is actively considering locations for an additional plant in the eastern U.S. that will manufacture PVC, TPO and ISO. Known for its flexibility, ease of application and chemical resistance, PVC remains a single-ply solution among commercial roofing contractors.

“The Cedar City PVC line will strengthen GAF’s position as a full-service supplier of PVC, TPO and ISO. By manufacturing all three products at Cedar City and soon on the east coast, we will deliver economies of scale to our operations and quality service to our customers. This investment demonstrates our continued commitment to growth and leadership in the low-slope roofing market,” says Bob Tafaro, president and CEO of GAF.

“GAF is poised to leverage our track record of innovation and operational excellence. We’re ready to bring to the PVC market the same ingenuity and manufacturing expertise that have helped us to manufacture best-in-class TPO products.”

PVC Liner Panels Are Easy to Clean and Install

AG-TUF and AG-TUF UV corrugated PVC liner panels from H&F Manufacturing Corp.

AG-TUF and AG-TUF UV corrugated PVC liner panels from H&F Manufacturing Corp.

AG-TUF and AG-TUF UV corrugated PVC liner panels from H&F Manufacturing Corp. are fire-retardant and provide efficient cladding of structures, offering many benefits for all types of agricultural and industrial applications.

AG-TUF and AG-TUF UV can be used in applications ranging from hog barns to dairy sheds, from poultry houses to wineries.

AG-TUF and AG-TUF UV panels are also ideal for interior applications such as car/truck wash liners, and commercial/residential garages. The panels withstand harsh treatment from chemicals, impacts from livestock and farm equipment, and are easy to clean and install.

AG-TUF UV panels are ideal for exterior applications where a heavier panel with all the same characteristics as the standard AG-TUF panel are required, but with added UV protection.

PVC Resembles Metal Roofing

SOPREMA Inc. has developed SENTINEL PVC, a high-performance roof membrane.

SOPREMA Inc. has developed SENTINEL PVC, a high-performance roof membrane.


SOPREMA Inc. has developed SENTINEL PVC, a high-performance roof membrane that is manufactured using processes that provide rooftop performance, including SOPREMA’s Acrylic Shield surfacing. SENTINEL integrates silver and copper metallic powder in its Silver Art and Copper Art products, providing enhanced aesthetic appearance and weathering capabilities that are identical to metal roofs. The PVC is chemical-resistant, making it well suited for buildings that are prone to grease and oil exposure or factories with exhausts on the roof. SENTINEL PVC is also fire- and wind-rated by Underwriters Laboratories and FM Approvals.

Palram Americas Opens New Logistics Center in Pennsylvania

Palram Americas, a manufacturer of polycarbonate and PVC sheets, has announced the completion of an 80,000-square-foot logistics center positioned directly next door to its Americas headquarters in Weisenberg Township, Kutztown, Pa.

“We did run into some issues due to the harsh winter of 2013, resulting in a delayed opening,” states John Seiffert, vice president of Business Development for Palram Americas. “However, now that the building is operational, we are confident this dedicated logistics center will greatly increase our delivery capabilities and result in greater customer satisfaction.”

The building is a $5 million dollar construction project with two phases. Phase one consisted of this logistics center and includes an additional 80,000 square feet of outside storage space. An additional 80,000-square-foot building will be constructed during phase two and will be built in the near future. The general contractor for the project was Serfass Construction of Allentown, Pa.

This new logistics center is just the latest building block of growth for the company. Palram opened its polycarbonate plant in Kutztown in 2000 and, over the ensuing years, built two large additions to this original plant. In 2007, Palram constructed an entire PVC manufacturing facility at the site. The logistics center, completed in November 2014, is now fully operational.

Adhesive Delivers Long-lasting Bond

HydroBond Water-Based PVC Bonding Adhesive from Mule-Hide Products

HydroBond Water-Based PVC Bonding Adhesive from Mule-Hide Products

HydroBond Water-Based PVC Bonding Adhesive from Mule-Hide Products delivers a high-strength, long-lasting bond while giving contractors the convenience and time savings of a one-sided, wet lay-in application. The adhesive is formulated to bond PVC membranes to a variety of porous and non-porous substrates. It can be used on clean, dry horizontal surfaces with slopes of up to 2:12 and as a contact adhesive in applications with steeper slopes or in vertical applications. The adhesive can be applied using a medium-nap roller or 3,000-psi sprayer.