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.

Pages: 1 2

Swing Tape and Layout Methods Make Tile Layout Easy

When I see a home with a tile roof, my first thought is, “Nice roof”. A roof goes from “nice” to “Wow, that roof is spectacular!” when the installer pays attention to the details. Some details that make a difference are appropriate flashings, or chimney, skylight and wall metal work that is consistent and does not detract from the aesthetic look of the roof. However, nothing conveys the knowledge and skill of a craftsman more than crisp, clean, straight lines of tile, row after row.

Nothing conveys the knowledge and skill of a craftsman more than crisp, clean, straight lines of tile, row after row.  PHOTO: ROOFWERKS INC., RALEIGH, N.C.

Nothing conveys the knowledge and skill of a craftsman more than crisp, clean, straight lines of tile, row after row. PHOTO: ROOFWERKS INC., RALEIGH, N.C.

Consistent row spacing (exposure) is aesthetically more appealing. It requires dividing the space between the top and bottom of the roof by the number of rows while avoiding a short course at the ridge. Using long division and 1/8- inch increments from a tape measure is one way to achieve this goal. However, that’s a method that challenges my calculator, let alone eager installers who just want to start pounding nails. They may believe it’s easier to deal with the ridge when they get there! It’s no wonder new installers can be intimidated by the layout stage of a tile roof installation. Even experienced installers may miss opportunities to minimize cuts, increase efficiency and achieve that “perfect look” we all admire.

WHAT IS LAYOUT?

Unless precluded by a specific manufacturer’s design, proper clay and concrete tile installation requires a 3-inch minimum overlap. That means a typical 17-inch-long concrete tile has a “maximum exposure” of 14 inches. If the goal is to space the rows evenly, we must first determine the location of the eave course and ridge course. For example, if we find the space between the eave and ridge courses is 140 inches, we can have 10 rows set at the maximum exposure of 14 inches. Perfect!

But what if the distance is only 135 inches? Setting nine rows at 14 inches will require us to cut 5 inches off of our top row. Cutting the tile would remove the fastener holes and tile lugs and make the top course uniquely short, taking away from a precision aesthetic. Most tiles have an “adjustable headlap”, meaning the overlap can be increased. If we set each of the 10 rows at 13 1/2 inches, we would absorb the extra 5 inches evenly over the entire slope with an extra 1/2-inch overlap per row. Row spacing would be consistent; fastener holes and lugs intact; and we would not have to cut tile, drill new holes and throw away the scraps.

The math is not always as easy as an extra 5 inches divided by 10 rows. Eighths and sixteenths don’t work well in long division. The TRI/WSRCA Concrete and Clay Roof Tile Installation Manual, from the Edmonds, Wash.-based Tile Roofing Institute and Morgan Hill, Calif.-based Western States Roofing Contractors Association has a Quick Reference Chart on page 27. It shows proper row spacing for sample eave- to ridge-row measurements. You may find situations where the chart is helpful.

HORIZONTAL LAYOUT USING THE SWING TAPE METHOD

ILLUSTRATION: TRI/WSRCA CONCRETE AND CLAY ROOF TILE INSTALLATION MANUAL

ILLUSTRATION: TRI/WSRCA CONCRETE AND CLAY ROOF TILE INSTALLATION MANUAL


Craftsmen develop “tricks of the trade” that make complicated tasks simple, their work easier or the finished product better. The “Swing Tape Method” does all three.

To avoid the math and use the Swing Tape Method, installers mark their measuring tape at the maximum exposure of tile they are using. Continuing with the example of a 17-inch tile and a 14-inch maximum exposure, the tape will be marked at 14, 28, 42, 56 inches, etc. Using the 135-inch eave- to ridge-course distance in the previous scenario, the installer would place the tip of the tape at the eave-row chalk line and run upslope to find the top-row chalk line at 135 inches. Seeing his tape is marked at 140 inches, the installer would swing his tape in an arc to the left or right until the 140-inch mark aligns with the top-row chalk line. Although the tape is marked in 14-inch increments, the now diagonal lay of the tape has shortened the distance of each horizontal row to 13 1/2 inches. The Swing Tape Method arrived at the same conclusion as the previous arithmetic. The installer marks the underlayment with chalk or a crayon next to each 14-inch increment on the tape measure. He repeats the same process at the other end of the slope and then chalks horizontal lines along the new markings on the underlayment.

Using a tape measure with this method requires marking each row onto the underlayment. This only should be done with chalk or a crayon. Scarring the underlayment with a nail or screwdriver can lead to premature failure of the underlayment.

A modern advancement to the Swing Tape Method uses Layout Tape instead of a marked tape measure. Layout Tape is a paper roll marked with red arrows highlighting the maximum exposure for the tile being used. In this example, the arrows would be at 14-inch intervals. Using the same process as with a marked tape measure, the installer can secure the Layout Tape, placing a red arrow on the top of the eave-row chalk line, then unroll the tape upslope to the top-row chalk line. Using the same 135-inch eave- to ridge-course example, the installer will find a red arrow 5 inches above the top-row chalk line. He will swing the tape to the left or right until the red arrow lines up with the top-row chalk line. The red arrows become the targets for the horizontal chalk lines. Because the Layout Tape is left in place, the installer avoids the step of marking each and every row on the underlayment.

PICTURE PERFECT

Of course not all roof slopes are simple rectangles. Some roof designs are quite complicated and as installers we have to play the hand we are dealt. The Swing Tape Method can help you make the best of challenging situations by allowing you to virtually try out different layout options. If a slope has multiple ridgelines, you can set the tape to the most beneficial location. This may reduce your cutwork or put a short course in the least visible location. On larger sections, you may choose to adjust the row spacing to better accommodate ridgelines, headwalls or dormers. Be aware that midslope adjustment of exposure can result in a change to the diagonal line of the tile sidelaps but does not affect function.

Using the Swing Tape Method with Layout Tape or a marked tape measure appropriate for the tile being used will ensure proper exposure. It will also reduce cutting and increase your efficiency while laying the foundation for a picture- perfect installation.

SWING TAPE METHOD STEPS

1 Determine eave-course placement (consider eave closure, gutter, desired overhang) and snap a line to place head of the tile or top of the battens if battens are to be used.
2 Determine top-row placement (consider ridge riser board, ventilation, etc.) and snap a line to place head of the tile or top of the battens if battens are to be used.
3 Using Layout Tape or a marked tape measure, place an arrow or mark at the eave-course line. Measure straight to the ridgeline. Swing the tape to the left or right until an arrow or mark aligns with the top-row chalk line.
4 If you are using Layout Tape, fasten the tape. If you are using a marked tape measure, you must mark the underlayment at each mark on the tape measure.
5 Repeat this process at the other end of the roof. Snap lines between the arrows or marks on the underlayment.

Copper-clad Stainless Steel Replaces a Tornado-damaged Roof at the St. Louis Airport

Hundreds of people milled about the terminals at Lambert-St. Louis International Airport on the evening of April 22, 2011. Three airplanes with passengers on board sat on the tarmac. It was business as usual at one of the largest municipal airports in the country. But meteorological conditions were anything but usual. A powerful supercell over St. Louis spawned an EF4 tornado (view the Enhanced Fujita Scale, which rates the strength of tornados by the damage caused, on page 2) packing 150-mph winds. The twister barreled directly into the airport 11 miles northwest of downtown, blowing out half the floor-to-ceiling windows in the main terminal and inflicting approximately $30 million in damages. In addition, the tornado seriously damaged part of the copper roof over Terminal 1.

CopperPlus was installed in stages over the domes at Lambert-St. Louis International Airport. Like solid copper, copper-clad stainless steel acquires a patina over time.

CopperPlus was installed in stages over the domes at Lambert-St. Louis International Airport. Like solid copper, copper-clad stainless steel acquires a patina over time.

The 55-year-old roof was iconic and beautiful. Its four copper domes had been the crowning glory of Lambert-St. Louis International Airport, welcoming up to 13 million international passengers each year. But the roof had been showing its age for some time, leaking often and requiring frequent maintenance. Following the tornado strike, airport officials made the difficult decision to permanently retire the roof. “The tornado damaged less than 10 percent of the total roof, but that section needed to be totally replaced,” explains Jerry Beckmann, deputy airport director of Planning & Development. “That damage, plus the fact that the roof was almost 60-years old, influenced our decision.”

Airport officials were challenged to install more than 100,000 square feet of material over four domed vaults as quickly as possible with minimal disruption to the public. Beckmann, who is an engineer, wanted a roof that was watertight and capable of withstanding high winds while airport administrators wanted to maintain the roof’s mid-century architectural integrity. All parties wanted the project completed as economically as possible with results that were aesthetically pleasing, historically appropriate and, most important, built for harsh weather events.

COPPER AND STEEL

They found the solution in copper-clad stainless steel, a material that has been used in roofing applications for roughly 50 years. The selected ASTM B506-09 architectural metal features two outer layers of 100 percent copper strip roll bonded at very high pressures to a core of Type 430 stainless steel, the same metallurgical bonding process used to make U.S. quarters and dimes. The material delivered the natural beauty and patination properties of solid copper with the strength and durability of stainless steel—exactly the attributes desired by officials at Lambert-St. Louis International Airport.

“Copper-clad stainless steel is a great-looking material that can be fabricated for any roofing style. You can’t tell the difference between it and straight-up copper,” says Shane Williams, vice president of Civil Construction for Kozeny-Wagner Inc., the Arnold, Mo.-based general contractor awarded the public bid by the city of St. Louis. “It’s stronger, has a better shelf life and costs less than pure copper. This allowed us to bid competitively for the job and even return a credit to the city of St. Louis.”

Workers install CopperPlus batten-seam panels over a dome at Lambert-St. Louis International Airport. Stepby- step, the installation of CopperPlus is virtually identical to that of copper.

Workers install CopperPlus batten-seam panels over a dome at Lambert-St. Louis International Airport. Step-by-step, the installation of CopperPlus is virtually identical to that of copper.

The owners of Missouri Builders Service Inc., the Jefferson, Mo.-based roofing subcontractor, were attracted to the material’s lighter weight and easy solderability. “We were going to have to maneuver a lot of material on the job site and perform a very large amount of soldering to cover four domes,” notes John Kinkade, Missouri Builders Service’s vice president. “We liked that copper-clad stainless steel had a lower thermal conductivity for easier soldering. That was important to us, given the scope of the project.”

The $6.7 million project to replace the airport roof was announced at a press conference in March 2014 by St. Louis Mayor Francis Slay, St. Louis County Executive Charlie Dooley and Lambert-St. Louis International Airport Director Rhonda Hamm-Niebruegge. “The new skin will shine of raw copper like it did in the mid ’50s when the terminal was built,” Slay stated in a press release issued by the airport. “The roof will slowly transform in color again in time as this airport serves new generations in this region.”

WEATHERING NATURE’S WORST

Copper-clad stainless steel has become more popular in tornado and hurricane-prone regions of the U.S. in recent years, thanks to the strengthening of building codes for wind-lift and hail-resistance standards. Copper-clad stainless steel conforms to Miami-Dade BCCO requirements and exceeds UL2218 Class 4 hail-test requirements; wind-uplift tests have shown its strength to be equivalent to steel at the same gauge. It offers a strength advantage compared to solid copper, providing higher tensile strength and yield strength at a thinner gauge than monolithic copper.

Numerous churches, college buildings, museums, private residences and other buildings nationwide now feature copper-clad stainless steel in their custom roofs, dormers, cupolas, flashings and downspouts. Notable installations include the following:

  • Several 67-foot panels of copper-clad stainless steel were rolled onsite, then lifted and put in place by a crane to replace the ice-damaged roof at the St. Francis of Assisi Catholic Church, Traverse City, Mich.
  • In 2012, more than 30,000 square feet of copper-clad stainless steel were installed in the fascia and coping of the Trinka Davis Veterans Village, Carrollton, Ga., the nation’s first privately funded U.S. Department of Veterans Affairs’ VA facility.
  • In 2014, the material was selected for a 2,100-square-foot perforated sunscreen installation in San Francisco’s Mission Bay neighborhood, one of the most significant urban development projects in the U.S.

PHOTOS: MISSOURI BUILDERS SERVICE INC. AND LAMBERT-ST. LOUIS INTERNATIONAL AIRPORT

Pages: 1 2

The BTI-Greensburg John Deere Dealership Installs Tornado-Resistant Daylighting Systems and Other Sustainable Materials

On the night of May 4, 2007, brothers Kelly and Mike Estes saw their BTI-Greensburg John Deere Dealership obliterated by an EF5 tornado nearly 2-miles wide (according to the Enhanced Fujita Scale, which rates the strength of tornados by the damage caused; view the scale on page 3). Astoundingly, 95 percent of their town—Greensburg, Kan.—was also destroyed that day. The tornado did much more than rip roofs off buildings and toss things around; it turned the entire community into what looked like kindling.

Rarely do communities get hit by an EF5 tornado, which can come about when air masses collide. Sometimes warm, humid air from the Gulf of Mexico rises above drier air from the Southwest deserts in the U.S. This can create unstable conditions resulting in thunderstorms and worse. A strong collision of air masses creates a strong storm. Additionally, wind patterns and the jet stream can magnify the storm, resulting in what people refer to as “the perfect storm”.

After being completely destroyed by an EF5 tornado, the BTI-Greensburg John Deere Dealership has been rebuilt in Greensburg, Kan., in a better, greener way.

After being completely destroyed by an EF5 tornado, the BTI-Greensburg John Deere Dealership has been rebuilt in Greensburg, Kan., in a better, greener way.

Despite the large-scale losses incurred by the entire town, 100 customers and friends of the Estes family showed up the morning of May 5 to help them salvage what remained of their business. Shortly after the tornado disaster, Kansas Gov. Kathleen Sebelius stated her wish that Greensburg become the “the greenest city in the state”.

As part of their commitment to their community, Kelly, Mike and their family decided to rebuild their business in a better, greener way. They wanted the new 28,000-square-foot prefabricated metal building to be the world’s greenest farm-machinery facility; attain a LEED Platinum rating from the Washington, D.C.-based U.S. Green Building Council; and use the least energy possible. One of the most important considerations was using building materials that could withstand future tornados.

DAYLIGHTING

To help achieve LEED Platinum and outlast any future high-velocity winds, they incorporated 12 Daylighting Systems in their retail area’s roof to showcase their merchandise; reduce lighting energy costs; and flood the area with natural light, a benefit for customers and employees.

The Daylighting Systems capture light through a dome on the roof and channel it down through a highly reflective tube. This tubing is more efficient than a traditional drywall skylight shaft, which can lose over half of the potential light. The tubing fits between rafters and installs with no structural modification. At the ceiling level, a diffuser that resembles a recessed light fixture spreads the light evenly throughout the room.

The dome is made from high-quality acrylic resin that is specifically formulated for increased impact strength, chemical- and weather-resistance, and high clarity (a polycarbonate inner dome is used for high-velocity hurricane zones). Domes are engineered to deflect midday heat and maximize low-angle light capture. The tubing is made from puncture-proof aluminum sheet coated with the highly reflective material for maximum light transfer. The units (independently tested by Architectural Testing in Fresno, Calif.) comply with various building codes including the 2009 International Building Code and 2010 Florida Building Code, including high-velocity hurricane zones.

“When our power went out one time for four hours, we were able to keep the shop open and operating due to daylight strategies, which includes the Daylighting Systems,” notes Mike Estes. “We didn’t anticipate this benefit but we’re really happy to have this bonus.”
PHOTO: SOLATUBE INTERNATIONAL INC.

Pages: 1 2 3

Asphalt-based Low-slope Roof Systems Provide Long-term Service Life

Asphalt-based roof systems have a long-standing track record of success in the roofing industry. In fact, asphalt-based roof systems have more than a century of use in the U.S. Building owners, roofing specifiers and contractors should not lose sight of this fact. It is important to understand why asphalt roofing has been successful for so long. Asphalt roofs demonstrate characteristics, such as durability and longevity of materials and components, redundancy of waterproofing, ease and understanding of installation, excellent tensile strength and impact resistance. Each of these characteristics helps ensure long-term performance.

Using a composite built-up/ modified bitumen roof system provides redundancy helping ensure durability and longevity. Surface reflectivity and a multilayer insulation layer provide excellent thermal resistance. Quality details and regular maintenance will provide long-term performance. PHOTO: Advanced Roofing

Using a composite built-up/
modified bitumen roof system provides redundancy helping ensure durability and longevity. Surface reflectivity and a multilayer insulation layer provide excellent thermal resistance. Quality details
and regular maintenance will provide long-term performance. PHOTO: Advanced Roofing

There are two types of asphalt-based low-slope roof systems: modified bitumen (MB) roof systems and builtup roof (BUR) systems. MB sheets are composed primarily of polymer-modified bitumen reinforced with one or more plies of fabric, such as polyester, glass fiber or a combination of both. Assembled in factories using optimal quality-control standards, modified bitumen sheets are manufactured to have uniform thickness and consistent physical properties throughout the sheet. Modified bitumen roof systems are further divided into atactic polypropylene (APP) and styrene butadiene styrene (SBS) modified systems. APP and SBS modifiers create a uniform matrix that enhances the physical properties of the asphalt. APP is a thermoplastic polymer that forms a uniform matrix within the bitumen. This matrix increases the bitumen’s resistance to ultraviolet light, its flexibility at high and low temperatures, and its ability to resist water penetration. SBS membranes resist water penetration while exhibiting excellent elongation and recovery properties over a wide range of temperature extremes. This high-performance benefit makes SBS membranes durable and particularly appropriate where there may be movement or deflection of the underlying deck.

BUR systems consist of multiple layers of bitumen alternated with ply sheets (felts) applied over the roof deck, vapor retarder, and most often insulation or coverboard. BUR systems are particularly advantageous for lowslope applications. The strength of the system comes from the membrane, which includes the layers of hot-applied bitumen and the reinforcing plies of roofing felt.

FACTORS FOR LONG-TERM PERFORMANCE AND SERVICE LIFE

It is important for building owners and roof system designers to recognize the principles of long-lasting, high-performance roof systems. Roof longevity and performance are determined by factors that include building and roof system design, job specifications, materials quality and suitability, application procedures and maintenance. The level of quality in the workmanship during the application process is critical.

Longevity and performance start with proper design of the asphalt-based roof system. Proper roof system design includes several components: the roof deck, a base layer supporting a vapor retarder or air barrier when necessary, multi-layer insulation and a coverboard, the asphaltic membrane, appropriate surfacing material or coating, and the attachment methods for all layers. Roof consultants, architects and roof manufacturers understand proper design. Roof design needs to follow applicable code requirements for wind, fire and impact resistance, as well as site-specific issues, such as enhanced wind resistance design, positive drainage and rooftop traffic protection. Roof designers can provide or assist with the development of written specifications and construction details that are specific to a roofing project for new construction or reroofing.

Low-slope asphalt-based roof systems are redundant; they are multi-layered systems. BUR systems include a base sheet, three or four reinforcing ply sheets and a surfacing, either aggregate (rock) or a cap sheet. MB sheets include one and sometimes two reinforcing layers and are commonly installed over a substantial asphaltic base sheet. Modified bitumen roofs can be granule surfaced, finished with reflective options or coated after installation. Aggregate, granules, films and coatings add UV protection, assist with fire resistance, provide durability to the roof system and can improve roof aesthetics.

An asphaltic cap sheet with a factory-applied reflective roof coating is installed over three glass-fiber ply sheets and a venting base sheet. The reflective coating reduces heat gain, and insulating concrete provides a stable substrate and high R-value. PHOTO: Aerial Photography Inc.

An asphaltic cap sheet with a factory-applied reflective roof coating is installed over three glass-fiber ply sheets and a venting base sheet. The reflective coating reduces heat gain, and insulating concrete provides a stable substrate and high R-value. PHOTO: Aerial Photography Inc.

Coverboards provide a durable layer immediately below the membrane, are resistant to foot traffic and separate the membrane from the thermal insulation layer. Protecting the thermal insulation helps maintain the insulation R-value as specified and installed.

Asphalt is a durable and long-lasting material for roof membranes and flashings. Asphalt is stable under significant temperature swings and can be highly impact resistant. Various reinforcements can be used to increase an asphaltic membrane’s durability. All asphaltic membranes are reinforced, during installation (BUR) or the manufacturing process (MB membranes). Polyester reinforcement has excellent elongation, tensile strength and recovery. It provides good puncture resistance and stands up well to foot traffic. Glass fiber reinforcement resists flame penetration and provides excellent tensile strength and dimensional stability.

Pages: 1 2

An ERA Study Proves EPDM Easily Lasts More than 30 Years

More and more building owners are seeing the light: Roof systems based on historical in situ performance for more than 30 years are the best roof system choice to benefit the environment. EPDM roof membrane has been utilized as a roof cover for more than 40 years, and there are numerous examples of ballasted roofs greater than 30-years old still performing. New seaming technologies, thicker membrane and enhanced design are creating roof systems with projected 50-year service lives. EPDM roof covers’ physical characteristics have changed little in 30 years, and because potential for 50-year-plus service life is possible, they are a solid choice of design professionals, building owners and school district representatives who truly desire a roof system that benefits the environment.

PHOTO 1: This ballasted 45-mil EPDM roof system has been in service for 32 years.

PHOTO 1: This ballasted 45-mil EPDM roof system has been in service for 32
years.

In 2010, the Washington, D.C.-based EPDM Roofing Association (ERA) was determined to answer the question: “How long can an EPDM roof perform?” Consequently, roof membrane samples from five roof systems with a minimum age of 30 years were obtained for testing of their physical properties. The physical and mechanical properties evaluated (using relevant ASTM standards) were overall thickness, tear resistance, tensile set, tensile strength and elongation, and water absorption. The results were positive, showing that even after 30 years of infield exposure nearly all the physical characteristics of EPDM membrane meet or exceed ASTM minimums. But the question of how long EPDM roofs could last remained. Thus, a second phase of testing was undertaken.

These properties were studied for “as received” and “after heat-conditioning” for up to 1,500 hours at 240 F. Results showing how these membranes performed before and after heat-conditioning are presented with the intent of defining characteristics for long-term service life of roof membranes.

TESTING PHASE ONE

Ethylene-propylene-diene terpolymer (EPDM) has been used in waterproofing and roof applications for more than 45 years in North America. Introduced into the roofing market in the 1960s, EPDM grew, especially after the 1970s oil embargo, to be a roofing membrane choice for new construction and roofing replacement projects. EPDM has achieved long-term in situ performance in part because of its chemical structure, mostly carbon black, which resists ozone and material decomposition, as well as degradation caused by UV light, which is the No. 1 degradation element to roofing materials exposed to the sun (see photo 1). The carbon black also provides reinforcement, yielding improved physical and mechanical properties.

Long-term performance of roof-cover material is dependent upon its resistance to the combined effects of ponding water, UV radiation, ozone, heat and thermal cycling. Geographical location can exacerbate or reduce the impact of climatic factors. In ballasted systems, the ballast acts to provide protection from the UV rays and minimizes the effect of climatic influences.

ERA’s study had three specific goals:

    1. Verify the long-term performance characteristics of EPDM membranes over 30 years. (At the time of the study, the only in situ membranes that were around for 30 years were 45-mil EPDM membranes. Currently 60- and 90-mil are the standard choices. It is assumed that results for the 45-mil material can be prorated for the thicker membrane.)

    2. Scientifically validate the empirical sustainability experiences.

    PHOTO 2: This recently installed, ballasted, 90-mil EPDM roof was designed for a 50-year service life.

    PHOTO 2: This recently installed, ballasted, 90-mil EPDM roof was designed for a 50-year service life.

    3. Create a foundation for specifier-to-owner discussions in regard to long-term service life. Five roofs, four ballasted and one fully adhered, with in situ service lives approaching or over 30 years were identified and samples were taken. All roofs were fully performing without moisture intrusion.

The samples were sent for testing per ASTM D4637 for:

  • Elongation
  • Tensile strength
  • Thickness
  • Factory seam strength (psi)

PHOTOS: HUTCHINSON DESIGN GROUP LTD.

Pages: 1 2 3 4

Galvalume-coated Metal Roofs Will Last at Least 60 Years with Minimal Component Repair

The term “infrastructure sustainability” continues to gain importance because of rapidly increasing building infrastructure components around the country needing major repairs and/ or replacements. Consequently, roof maintenance or replacement materials and methods must last at least 60 years; consider LEED v4 from the Washington, D.C.-based U.S. Green Building Council. For more than 30 years, millions of square feet of Galvalume-coated roofs have resisted the atmospheric conditions to which they are exposed with little or no maintenance and are well prepared to continue protecting building interiors for more than 30 additional years. Material science and professional project engineering and installation prove Galvalume-coated metal standing-seam roofs will perform for that period of time.

This is a nine-year-old painted Galvalume roof in Alabama.

This is a nine-year-old painted Galvalume roof in Alabama.

MATERIAL SCIENCE

The first standing-seam metal roof was introduced by Armco Steel Corp., Middletown, Ohio, at the 1932 World’s Fair in Chicago. Armco Steel ceased doing business many years ago, but its standing-seam metal roof design has been adopted by all manufacturers in today’s commercial metal roofing market. The second longest-lasting introduction into this market was in the early 1970s when Bethlehem, Pa.-based Bethlehem Steel introduced a Zinc/Aluminum coating—now known as Galvalume—for carbon-steel metal roofs. This coating, applied to both sides of the steel coil, has been successfully used for the majority of metal standing-seam roofs ever since.

Since Galvalume was introduced, there have been several evaluations, reports and predictions as to how this product would “weather” the test of time. In 2012, the Chicago-based Metal Construction Association (MCA) and Olympia, Wash.-based Zinc Aluminum Coaters Association (ZAC) commissioned a study to perform forensic tests at 14 existing Galvalume standing-seam metal roof sites throughout the country in varying climates and precipitation pH. The average age of these roofs was more than 30 years at the time of testing.

Initially, the sites were selected based on temperature and humidity zones throughout the U.S. As the field results were processed, however, it became apparent the expected lives of these roofs were directly dependent on the precipitation pH levels with very little correlation to temperature and humidity. The building sites chosen were located in the following states:

  • Massachusetts (2 sites)
    This Galvalume roof in Missouri is nine years old.

    This Galvalume roof in Missouri is nine-years old.


    Ohio (3 sites)
    South Carolina (2 sites)
    Georgia (1 site)
    Colorado (1 site)
    New Mexico (1 site)
    Arizona (1 site)
    Oregon (1 site)
    Wyoming (2 sites)

The study was directed by MCA and three independent consultants and their firms, which managed and performed the field work: Rob Haddock of Metal Roof Advisory Group, Colorado Springs, Colo.; Ron Dutton of Ron Dutton Consulting Services LLC, Annapolis, Md.; and me and my firm Metal Roof Consultants Inc., Cary, N.C. This group, plus Scott Kriner, MCA’s technical director, authored the actual report, which was issued by MCA and ZAC in November 2014 and is available online.

The team harvested and analyzed actual field samples of Galvalume-coated metal standing-seam roof panel materials and sealants and examined all the individual roofs’ ancillary components. Finally, it created an experienced assessment of the roofs’ conditions and associated costs to replace.

PHOTOS: METAL ROOF CONSULTANTS INC.

Pages: 1 2 3

Metal Roofing Underlayments Protect Structures in Hawaii

The newly constructed Safeway Shopping Center, Honolulu, happens to be the largest Safeway on the Hawaiian Islands. It contains a parking garage below—in part, because of its location in a densely populated neighborhood.

The underlayment manufacturer worked on and approved a design in which the underlayment could be installed directly on the metal deck.

The underlayment manufacturer worked on and approved a design in which the underlayment could be installed directly on the metal deck.

ITS METAL ROOF WAS INSTALLED by Kapolei, Hawaii-based Beachside Roofing, which has been doing business in Hawaii for more than 25 years. The company, which installs all kinds of roofing and waterproofing systems, specializes in high-rise buildings, resorts and complex projects.

The 20,000-square-foot metal roof on the Safeway store had to meet strict color requirements in keeping with the Safeway brand. The color of the roof is Gargoyle, which is a greenish-brown.

The metal roofing was designed to be installed over corrugated 20-gauge steel decks. The underlayment manufacturer worked on and approved a design in which the underlayment could be installed directly on the metal deck.

The metal deck (HSB-36SS type) was installed with the wider corrugations facing up and parallel to the eaves (horizontally). The self-adhering underlayment also was installed horizontally, and the metal panels were then attached to the horizontal corrugations of the deck using panel clips and self-drilling fasteners penetrating through the underlayment into the flattop of the corrugations of the steel deck.

The self-adhering underlayment also was installed horizontally, and the metal panels were then attached to the horizontal corrugations of the deck using panel clips and self-drilling fasteners penetrating through the underlayment into the flattop of the corrugations of the steel deck.

The self-adhering underlayment also was installed horizontally, and the metal panels were then attached to the horizontal corrugations of the deck using panel clips and self-drilling fasteners penetrating through the underlayment into the flattop of the corrugations of the steel deck.

The walkability of the underlayment was an important factor, considering that the roof slope was 4 inches per 12 feet in some places. Also, the 120-day exposure allowance for the underlayment was reassuring, though not necessary for this project.

The metal roofing system included many architectural elements, such as canopies, penthouses and mansards. It covers not just the Safeway supermarket, but also other shops in the Safeway Shopping Center. The way the metal was used architecturally really dressed up the exterior of the project.

Secondary Water Barrier

A self-adhering metal roofing underlayment, like the one on the Safeway Shopping Center, perfectly complements metal roofing panels. The underlayment provides a watertight secondary membrane while the metal panels serve as the primary roof to protect against wind-blown objects and UV radiation. If the primary roof is damaged, the secondary roof acts as the water barrier.

Pages: 1 2

Built-in Gutters Should Be Carefully Inspected, Restored and Maintained

Sheet-metal gutter linings, whether made of copper, lead or both, are relatively involved and require the services of a highly skilled artisan craftsman.

Sheet-metal gutter linings, whether made of copper, lead or both, are relatively involved and require the services of a highly skilled artisan craftsman.

Built-in gutters may be the most complicated system in the building envelope, yet they are also the most elusive when you start searching for information about them. Sometimes called Yankee gutters, box gutters or even Philadelphia gutters, it’s no wonder they remain a mystery to many. Built-in gutter systems are actually built into the cornice structure and drain through internal or external leaders. They are not readily visible from the ground, further lending to the mystery of their design and function. Because they are integrated into the structure, built-in gutter linings that fail will cause extensive damage to the cornice and sometimes also the interior of the structure.

In “Traditional Rainwater Conductor Systems of the 18th and 19th Centuries,” Karen Dodge of the U.S. National Park Service, Washington, D.C., states built-in gutters were first adopted in North America during the 18th century in high-style Georgian and Federal-style buildings, usually institutional or commercial, where refined architectural qualities were desired. Although built-in gutters are highly functional, they also serve an aesthetic purpose. As structures were erected in the classical order with elaborate cornices and entablature, it became necessary to collect and channel rainwater without detracting from the architectural character of the building. Built-in gutters served this function well, hidden from sight and shedding water to the exterior.

Built-in gutters, today, are typically constructed in the same manner as they have been since the 18th century. They are wooden boxes with bottoms sloped toward the outlets where water is drained to leaders, or conductor pipes, that channel the water away from the building. The first gutters in this style were actually troughs or box gutters, carved out of wood and rubbed with linseed oil or painted to protect the wood. Corners and seams were bonded with lead wedges. Needless to say, maintenance was critical to their success or failure. Later, the advent of sheet lead allowed for broader gutters, as linings covered the wooden troughs. By the end of the century, copper became available in the U.S. and a popular choice for gutter linings because of its durability and the functional nature of the material in a sheet-metal application.

INSPECTION AND MAINTENANCE

The most common sign of water penetration is peeling paint and decay in the wood soffit under the gutter. Other signs are dark stains and mildew or deterioration of masonry. Water infiltration may be visible in attic spaces or areas beneath the gutters where plaster and other interior finishes evidence water damage. The sooner a leak or area vulnerable to failure is addressed, the smaller the scope and cost of repairs. Cleaning out leaves and debris from gutters as often as necessary is essential for durability and proper performance.

Careful inspection by a competent roofer is critical to the longevity and success of the system. He or she will look for defects, such as localized damage caused by fallen limbs or other debris, cracks from expansion and contraction at joints or folds, or pinholes from corrosion. Roofing tar and other bituminous compounds should never be used to patch, repair or coat gutter linings. It makes the condition of the gutter indeterminable, corrodes metal linings, will crack and fail quickly, and cannot be removed without destroying the lining. Ice damming is not uncommon in the winter but should not be removed with sharp tools for obvious reasons.

When tin or terne-coated steel gutter linings fail, water intrusion will occur and cause wood rot. Eventually, architectural details will be lost and replacement will be necessary.

When tin or terne-coated steel gutter linings fail, water intrusion will occur and cause wood rot. Eventually, architectural details will be lost and replacement will be necessary.

RESTORATION

Restoration of long-neglected built-in gutter systems that leak and have caused decay in the cornice and roof structure is often complicated and can be costly. But once the work is completed, a regularly maintained, well-detailed system can last 60 to 100 years or more, depending on the life of the metal lining. A preservation architect or consultant should inspect the building, propose treatment options, develop working drawings and specifications, and supervise bidding and construction. Temporary protection and permanent repairs should be performed by a roofer experienced in this specialty on historic buildings.

“We encourage restoration of historic built-in gutter systems,” says Michael Devonshire, a building conservator and principal at Jan Hird Pokorny Associates, New York. “The use of modern building materials as an adjunct to traditional materials boosts longevity.” Devonshire states the typical steps involved with a built-in gutter restoration involve:

  • Removing the gutter lining and 2 feet of the roof covering above the curbing of the gutter.
  • Repairs to rotted or otherwise deteriorated frame work. Where rafter ends or lookouts are rotted, install sisters (new rafter ends adjacent to old ones) or scarf in new wood and sisters.
  • Replacing the old wooden gutter bottom with a sustainable wood material, such as cedar or kilndried- after-treatment (KDAT) plywood. KDAT is treated for resistance to decay, minimal expansion and contraction, and increased longevity.
  • Installing the gutter lining: an elastomeric ice-and-water shield on the bottom (not always required); building felt; a slip-sheet of rosin paper; and copper on top (16 or 20 ounce, depending on the dimensions of the gutter).
  • Installing the roof covering on the roof deck above the gutter. This includes 2 feet of elastomeric ice-and-water shield (or copper flashing) beneath.
  • Repairing or replacing cornice mouldings, brackets and other architectural woodwork.

PHOTOS: WARD HAMILTON

Pages: 1 2

Deft Planning and Skillful Moves Play Out on the Reroof of the World’s Largest Water Filtration Plant

Reroofing the 10.3-acre surface of Chicago’s highly sensitive James W. Jardine Water Filtration Plant posed logistical challenges on par with the building’s magnitude. Phasing to ensure the plant continued to supply fresh water to its 5 million customers in the city of Chicago and its suburbs, the need for complete containment areas, roof-load restrictions, unique stainless-steel expansion joints and the Department of Homeland Security’s onsite presence all made for intricate operations. But John Cronin, president of Chicago-based Trinity Roofing Service, says Mother Nature was his toughest challenge.

The James W. Jardine Water Filtration Plant arguably was the largest and most complex roofing project in Chicago during the past decade.

The James W. Jardine Water
Filtration Plant arguably was the largest and most complex roofing project in Chicago during the past
decade.

“Conducting construction on the Lake Michigan waterfront during Chicago’s harshest winter in 30 years [2013-14] was by far the hardest part of this job. Driving rain, wind, black ice and snow—it was unmerciful,” asserts Cronin. “Constant communication had to be our priority, because we could go to the site in the morning and discover that weather made impossible the sequence of work we had planned. Senior Project Manager J.J. Matthews, Job Superintendent Rob Reno and I had to be incredibly flexible to keep the job moving.”

Water Protection

The water-treatment plant’s 50-year-old coal-tar roof and concrete roof deck had been leaking, which created potential health concerns. The plant supplies approximately 1 billion gallons of clean water a day, which meant many concrete filter beds had to remain operational and free of contamination during construction. Filter beds beneath the phased work area were drained. To protect the drained beds, Trinity cut a hole in the roof and erected a specialized watertight “shoe box” work zone, extending 6-feet down. These shoebox areas consisted of a plywood scaffolding platform blanketed by a 60-mil membrane. Inside the box, existing structural steel had to be sand blasted free of lead paint, inspected and replaced in some spots. At any given time, the team had two 56,000-square-foot scaffolding platforms in place.

Winter winds blew snow across the flat roof and down into these protection zones carrying multiple forms of contamination. Rooftop bird droppings were one source. Asbestos from the original 1960s roof was another. The team had to bring in heat torpedoes (portable forced-air or convection heaters) to melt the snow and divert it through custom-made gutters into cisterns to be hauled offsite so workers could access the steel.

Protecting materials from the elements was also paramount. More than 1,000 rolls of fleece-backed membrane had to remain completely dry. In addition, cellular glass roof insulation (specified from Belgium for its proven 50-year track record on the facility) had an eight-week timeframe for production and overseas delivery, making critical that each square of insulation stayed in pristine condition. Chicago rain can fall in isolated pockets, so every load had to be fully secured with tarp, even on seemingly sunny days.

The harsh Chicago winter of 2013- 14 didn’t stop Trinity Roofing Service from completing the twoyear project on schedule. Seven miles of backer rod are being laid between seams of concrete roof channels despite snow and ice.

The harsh Chicago winter of 2013-14 didn’t stop Trinity Roofing Service from completing the two-year project on schedule. Seven miles of backer rod are being laid
between seams of concrete roof channels despite snow and ice.

“It was an ongoing job to impress the importance of covering all the materials that came to the site, especially at the slightest hint of rain,” Cronin says. “It worked, though. We fully inspected every material load that came to the job site. Out of more than 712,000 board feet of new insulation, none of it was rejected thanks to our strictly enforced quality-control program.”

Despite the snow and ice accumulation on staging areas, no salt was allowed on the property for fear of water contamination, which meant Trinity also dealt with slippery walking and driving surfaces.

Pages: 1 2 3