As trendy as they are for green building and demonstrably beneficial for energy savings
through daylighting, skylights are sometimes viewed with a certain trepidation by roofing
contractors. After all, skylights are essentially holes in the roof with the potential to compromise roofing workers’ handiwork by providing unintended leakage paths.
Proper installation is essential to realizing designed-in leak-free performance and can vary by type of roofing involved and the type of skylight. It is recommended to always refer to and use the skylight manufacturer’s instructions that are specific to the roof system being installed. Of course, applicable code requirements supersede any instructions to the contrary.AAMA 1607-14, “Installation Guidelines for Unit Skylights”, which is an industry consensus guideline published by the Schaumburg, Ill.-based American Architectural Manufacturers Association, intended for use when manufacturer instructions are absent or incomplete, provides basic step- by-step installation instructions for 19 different ways to integrate various roofing materials, underlayment, flashing and skylight-mounting configurations to preserve the drainage plane. This must be the overriding intent of any installation protocols.
Note that some roofing contractors warrant their work against leakage, and skylight installation should not compromise or void such warranties. When in doubt, independent installers should confer with the roofing contractor.
Proper installation begins with selection and use of the proper supplies—notably sealants, fasteners and flashing.
If sealants are recommended by the manufacturer, follow the manufacturer’s specifications. When the manufacturer is silent about the use of sealants and the installation guidelines dictate their use, the following recommendations should be observed:
- Compatibility—The sealant must not adversely react with or weaken the material it contacts.
- Adhesion—The sealant must have good long-term adhesion. Surface preparation, cleaning procedures and, in some cases, primers are recommended by the sealant manufacturer.
- Service Temperature—If the installation location involves elevated ambient temperatures, the sealant should exhibit corresponding service temperature performance.
- Durability—The sealant must be capable of maintaining the required flexibility and integrity over time.
- Application—Proper bead size and other application details should be followed to ensure a well-performing joint. Improper use of sealants can dam water pathways, so an important rule of thumb is not to block any weep holes that may be in the skylight system.
Typically, sealant or roofing cement is applied around the perimeter of the rough opening (deck mount) or the flange of self-flashing units or the top edge of a mounting frame. However, some skylights are designed with integral flashing flanges to be installed without the need for sealants.
It is also possible to utilize rolled roofing membranes as a substitute for sealants or plastic roofing cement.
The Lucas #9500 is compatible with Lucas water-based acrylic coatings. It is suitable for repairing hail-damaged polyurethane foam roofs. It may also be used in conjunction with custom-manufactured Lucas PolyPans and metal pitch pockets.
The #9500 comes in white and black colors, guns easily in cold or hot weather, and comes packaged 12 per case.
Bonded Building Materials Inc. has partnered with Roofinox to distribute the company’s Tin-plated (Terne) roofing products throughout New York State and the surrounding area. Roofinox tin-plated (Terne) was designed to ensure long-term sustainability and corrosion-resistance for wall-cladding, flashing, rainware, interior design and virtually all forms of roofing applications.
“As a supplier of window, roofing and building materials in New York, we are always on the outlook for products that meet our contracting customer’s best needs,” says Gary Curcio, Jr., general manager, Bonded Building Materials. “The products are durable and can be expected to turn a matte grey over time. It’s perfect for our architectural projects and our many institutional clients. With our sister company, Architectural Sheetmetal Products Inc., we can even roll form or create custom details to fit any client needs.”
“We are constantly looking to increase our national reach through partnerships with suppliers like Bonded Building Materials,” adds Dave Rowe, vice president at Roofinox America. “They’ve been serving the marketplace for nearly 40 years and understand the best interests of their customers. This is a relationship that will benefit both of our companies and contractors based throughout the State of New York.”
The Roofinox product line consists of Roofinox Classic brush-rolled stainless steel, Roofinox Pearl bead-blasted stainless steel, Roofinox Plus ribbed stainless steel, Roofinox Chroma mirror-rolled stainless steel and Roofinox Tin-plated (Terne), a tin-plated stainless steel product specifically developed and manufactured for roll forming and fabricating.
Originally developed to withstand the climatic conditions found in Central Europe, the Roofinox stainless steel product line is ideal for applications ranging from rural, urban and light industrial areas to historic and commercial sites and extreme coastal environments. Available in coil or sheet, materials can be ordered by themselves so customers can do their own forming or prefabricated by distributors.
Based in Scotia, New York, Bonded Building Materials is a family-owned and operated business supporting contractors across the entire state of New York since 1980. The company can be contacted through the website or by phone (518)346-2395.
For more information on Roofinox, Roofinox Tin-plated (Terne), Roofinox Classic, Roofinox Pearl, Roofinox Plus or Roofinox Chroma please call (732)440-8069, email email@example.com or visit the website.
“What a genius! His spatial conception is magnificent, even after 100 years.”
“But all his buildings leak!”
I used to give a talk to University of Illinois architecture students in which I told them the quickest way to go out of business is to be sued. The quickest way to be sued is to have a building allow moisture intrusion. If he were alive today, Frank Lloyd Wright—God rest his soul—would be in jail (and a few current architects may be well on their way). Owners are not very kind when their “babies” leak.
Many roof termination interfaces are never even thought about by designers and are left to the roofing contractor to work out. This is not a recommended practice. One such condition—that every architect should be able to detail—is how the roof base flashing terminates at a masonry wall that has through-wall flashing and weeps at the base of the wall above the roof. I believe so fervently that architects should be proficient in detailing these conditions that I believe it should be required to procure their license.
WHY THE IMPORTANCE
The interface of roof base flashing and masonry through-wall systems occurs on a majority of commercial construction projects. If this transition is not performed correctly, moisture intrusion behind the roof base flashing to the interior will occur (see Photo 2). When this occurs, besides angering owners, it befuddles the architect. Photo 1 (left) shows a nice through-wall flashing drip extended out from the wall, weeps and roofing terminated with a termination bar and sealant. What could be wrong?
The exposed brick above the termination bar and below the stain- less-steel drip of the through-wall flashing is susceptible to water flowing down the surface of the brick. Water passing through the brick above is supposed to be weeped out; however, at the exposed brick above the termination bar, the water moves into the wall and has nowhere to go but inward.
The cost to repair these conditions can be, depending on the conditions, expensive. Repairs often require brick removal and through-wall flashing mitigation. In this particular case, be- cause there is a stainless-steel drip, my team recommended a stainless-steel counterflashing be pop-riveted to the drip and extended over the termination bar.
Why is the interface of roof base flashing and masonry through-wall systems so difficult for architects and roof consultants to detail? I believe it is because they have no clue it needs to be detailed as an interface, especially because detailing of appropriate through-wall systems is so sporadic. I endeavor in this article to change at least the knowledge part.
The detailing of this condition not only requires the ability to interface two building systems, but also requires considerable time to ensure specification of wall sectional details and roofing details are appropriately placed where the responsible trades will see them.
New construction provides us a clean slate to “do it right the first time”. The first order of business is to determine the height of the base flashing. This can be tricky with tapered insulation and slope structures with saddles. Let’s consider the following examples (see Detail 4, page 3):
We are dealing with a flat roof, tapered insulation, cover board and bead-foam insulation in ASHRAE Climate Zone 5, which has an R-30 minimum.
- The roof drain is 32-feet away from the wall. Code requires 5.2 inches of insulation at 4 feet from the drain, so let’s assume 5 inches at the drain.
- 1/4-inch tapered starts at 1/2 inch at 32 feet. That’s 8 inches, plus the starting thickness of 1/2 inch, which equals 8 1/2 inches.
- Cover-board thickness is 1/2 inch.
- Bead foam thickness is 3/16 inch for each layer. Let’s assume five layers, so 1 foot of bead foam.
Thus, the surface of the roof at the wall will be 15 inches above the roof deck.
Because you would like to work at the masonry coursing level and given that concrete masonry units (CMU) are nominal 8 inches, you are looking at placing the through-wall flashing 24 inches above the roof deck.
This 24-inch dimension of where to place the through-wall flashing needs to be placed on the building section and/or wall section because the mason, which will be onsite prior to the roofing contractor, will need to know this information.
This 24-inch height begs another termination question: What occurs at the roof edge with this height? Hold that thought for now. Terminations at intersections will be discussed in future articles.
Code-mandated Thermal Insulation Thicknesses Require Raising Roof Access Door and Clerestory Sill Details
I’m a bit taken aback by this concern; I have been dealing with roof access doors and clerestory sills for the past 30 years and, for the most part, have had no problems. My first thought is that roof system designers are now being forced to take these conditions seriously. This is a big deal! They just have no clue.
In the next few pages, I’ll review several possible solutions to these dilemmas, provide some detailing suggestions and give you, the designer, some confidence to make these design and detailing solutions. For the purpose of this article, I will assume reroofing scenarios where the challenge is the greatest because the conditions requiring modification are existing.
THE ACCESS DOOR
For many and perhaps most contractors who sell and, dare I say, design roofs, it is the perceived “large” expense of modifying existing conditions that is most daunting. Often, these conditions are not recognized until the door sill is several inches below the new roof sur- face. Not a good predicament. Planning for and incorporating such details into the roof system design will go a long way to minimizing costs, easing coordination and bringing less tension to a project.
Door access to the roof is the easiest method to access a roof. These doors are typically off a stair tower or mechanical penthouse and most often less than 12 inches above the existing roof as foresight was not often provided (see photos 1, 2 and 6 through 9). With tapered insulation thickness easily exceeding 12 inches, one can see that door sills can be issues with new roof systems and need to be considered.
Designers should first assess the condition of the door and frame, typically hollow metal. Doors and frames that are heavily rusted should not be modified and reused, but discarded, and new ones should be specified. The hardware too needs to be assessed: Are the hinges free of corrosion and distortion? Is the closure still in use or detached and hanging off the door frame? The condition of door sweeps, knobs, lockset and weather stripping should also be determined. Ninety-nine percent of the time it is prudent to replace these parts.
As the roof system design develops, the designer should start to get a feel for the thickness of insulation at the door. It is very important the designer also consider the thicknesses that vapor retarders, bead and spray-foam adhesives, cover and board and protective pavers will add. These can easily be an additional 4 inches.Once the sill height is determined, the design of the sill, door and frame can commence. If the sill height to be raised is small—1 1/2 to 3 inches—it can often be raised with wood blocking cut to fit the hollow metal frame, flashed with the roofing membrane, metal sill flashing and a new door threshold installed, and the door and frame painted. This will, of course, require the removal of the existing threshold and door which will need to be cut down to fit and then bottom-sealed with a new metal closure (see details A and B, page 3).
When the door sill needs to be raised above 3 inches, the design and door considerations increase. Let’s consider that the door and frame is set into a masonry wall of face brick with CMU backup. Although most hollow metal doors are 7 feet 2 inches to match masonry coursing, after the modification the door may be shorter. For example, if a door is 7 feet 2 inches and you must raise the sill 5 inches, the new door and frame will need to be 6 foot 9 inches.
PHOTOS & ILLUSTRATIONS: Hutchinson Design Group Ltd.
ATAS International Inc. has expanded its three-year partnership with Roofinox America with the addition of the company’s stainless steel roofing products to the 2016 ATAS complete product line catalog.
The Roofinox product line consists of Roofinox Classic brush-rolled stainless steel, Roofinox Pearl bead-blasted stainless steel, Roofinox Plus ribbed stainless steel, Roofinox Chroma mirror-rolled stainless steel and Roofinox Tin-plated (Terne), the only tin-plated stainless steel roofing product specifically developed and manufactured for roll forming and fabricating. Designed to offer long-term sustainability and corrosion-resistance for wall-cladding, flashing, rainware, interior design and virtually all forms of roofing applications, each Roofinox product is also easy to seam, while offering superior aesthetics and reducing machine and tool wear.
“We are always looking to support our customers ranging from builders to appliance and toy manufacturers with the highest quality products available in the marketplace today,” says Gary Miller, ATAS’ OEM manager. “Roofinox supports this goal in two distinct areas. Their Tin-plated (Terne) is not only ideal for roll forming and fabricating, its popularity has grown with architects that enjoy the grey patina look these products achieve over time. We have found Roofinox stainless steel products to be more ductile and offer less spring back than similar products, in addition to providing excellent corrosion protection.”
“ATAS is a great partner,” says Dave Rowe, vice president at Roofinox America. “They know the market well and are striving to expand their customer base with products for architects and contractors. We are thrilled to be featured in the latest ATAS product line catalog and made available to their growing list of national clients.”
Originally developed to withstand the harsh climatic conditions found in Central Europe, the complete Roofinox stainless steel product line is ideal for applications ranging from rural, urban and light industrial areas to historic and commercial sites and extreme coastal environments. Available in coil or sheet, materials can be ordered by themselves so customers can do their own forming or products can be prefabricated by distributors like ATAS.