Protect Roofs with an Easy-to-install Pathway

FlashCo’s Tuff Trac Walkway

FlashCo’s Tuff Trac Walkway

Building owners face the problem of expensive single-ply roofing membrane being prematurely damaged from dropped tools and heavy foot traffic around rooftop equipment. FlashCo’s Tuff Trac Walkway adds an extra layer of protection against foot traffic while increasing slip resistance for workers. The Tuff Trac Walkway is available in TPO and PVC in white, gray and tan with multiple traction designs, and with or without yellow borders. Installed in three simple steps, standard roll sizes are 0.156 inch by 30 inches by 50 feet.

Waterproof and Maintenance-free Roof Penetrations

The fewer people with access to the roof, the better chance the roof has at meeting the basic expectation of keeping the elements out of the building.

Pitch pockets are flanged, open-bottomed metal containers, placed around roof penetrations.

Pitch pockets are flanged, open-bottomed metal containers, placed around roof penetrations.

Because they make their living on the roof, commercial roofing installers know how to complete a watertight system, one that does not allow damaging moisture into the building. Unfortunately, when the roofing installer finishes the job, more work, perhaps by other trades, most notably HVAC contractors, may be done with possible impacts on the roofing membrane.

Someone has to get on the roof to install that equipment and at that point it’s going to be an equipment installer, not a roofing installer. It’s important to be aware of who is doing what on the roof!

Attaching equipment to the building structure, through the roof, is the most efficient method of attachment, but often such work is done without consideration of waterproofing concerns. Any attachment penetration must not compromise the integrity of the roofing system.

This is why RoofScreen Manufacturing got into the business: to discover and develop a better method for leak-proof attachment for all types of roofing and building structures.

the caulk and band method, commonly used on round penetrations, which employs a single-ply or soft lead pipe flashing around the penetration.

The caulk and band method is commonly used on round penetrations and employs a single-ply or soft lead pipe flashing around the penetration.

The equipment installer has options. A traditional penetration waterproofing system is what is known as the pitch pocket. Pitch pockets are flanged, open-bottomed metal containers, placed around roof penetrations. They are filled with coal tar pitch, hot asphalt, grout or other chemical sealants. They are effective around odd-shaped penetrations but require maintenance, which means slapping on more sealant when it leaks.

Another method is the caulk and band method, commonly used on round penetrations, which employs a single-ply or soft lead pipe flashing around the penetration. Near the top of the flashing is an adjustable draw-band that clamps the flashing to the penetration. Caulking is applied around the top of the flashing to make the final seal.

Both practices are accepted by the National Roofing Contractors Association. The problem is both require annual or semi-annual maintenance to check if the sealant has cracked or separated from the penetration and addition of sealant as necessary.

RoofScreen offers a patented engineered and leak-proof roof attachment system to ensure the integrity of the roofing system. It starts with a 6- by 6-inch steel base support, available in a variety of lengths to accommodate any insulation thickness. The support is attached with bolts or lag screws to the roof structure through the interior of the base support. Specially fitted flashing boots are then installed and roofed in by a qualified roofing contractor. After roofing is completed, a self-adhesive EPDM gasket strip is applied around the top of the flashing, which provides added protection from snow, ice and splashing water. The final step is to install the Base Cap Assembly, which counterflashes 2.4 inches over the flashing and creates a seal by compressing the gasket. This watertight structural mounting point is ideal for mechanical equipment screens, equipment platforms and solar panel racking systems.

This watertight structural mounting point is ideal for mechanical equipment screens, equipment platforms and solar panel racking systems.

A watertight structural mounting point is ideal for mechanical equipment screens, equipment platforms and solar panel racking systems.

Many roofing manufacturers require penetration flashings to extend a minimum of 8 inches above the roof surface. RoofScreen has performed successful independent lab testing on its roof attachment system with only a 3-inch flashing height and had no leaks. Ultimately, it’s up to the roofing contractor and the roofing manufacturer to determine the flashing height in relation to the roof. Consult with both, especially if there is a roofing warranty involved.

If a base support needs to be raised to meet a required flashing height, RoofScreen offers 5-, 9- and 12-inch versions of the base support, plus 3- and 4-inch extensions. A taller base support should, in most cases, provide enough clearance for the amount of insulation being used. It should be noted the height of base supports impacts the overall design of the frame. RoofScreen provides fully engineered solutions incorporating all equipment screen variables.

In addition to installing a patented engineered leak-proof roof attachment system, RoofScreen eliminates the need for periodic maintenance. There will never be a need to add temporary caulking. With no need for maintenance, there’s one less reason for anyone being up on the roof to compromise the roofing system. That’s a good thing.

Wind Loading on Rooftop Equipment

I recently attended a continuing-education conference for civil/structural engineers that discussed changes in the 2012 International Building Code (IBC) and the referenced ASCE 7-10 “Minimum Design Loads for Buildings and Other Structures”. During the seminar, the question was asked: “Who is responsible for the design of wind loading to rooftop equipment as defined in the IBC and Chapter 29 of ASCE 7-10?” The most accepted response was to add a section in the structural general notes that wind design on rooftop equipment is to be designed “by others”.

A structural engineer designed the metal support system and load transfer from the new HVAC unit down through the structure.

A structural engineer designed the metal support system and load transfer from the new
HVAC unit down through the structure.

The design requirements for wind loading on rooftop equipment have been included in previous editions of the IBC and ASCE 7, but significant changes have been included in ASCE 7-10. The increased attention is in part because of more severe wind events in recent years. While it is not the primary responsibility of the roofing consultant or contractor to evaluate the systems being placed on the roof, it is good to understand the code’s requirements for loading to rooftop equipment, how the load is determined and applied, and how the load is transferred to the building structure.

CODE REQUIREMENTS

The primary focus of the roofing professional in the IBC is concentrated on Chapter 15 (Roof Assemblies). While there are requirements in Chapter 15 addressing rooftop structures, these requirements, particularly in relation to wind loading, extend beyond Chapter 15. It is therefore imperative to be familiar with other sections of the code.

For instance, Section 1504 (Performance Requirements) refers the user multiple times to Chapter 16 (Structural Design) for wind-loading-design requirements. While roof manufacturers typically prequalify their systems based on various industry standards (ASTM, FM, ANSI, etc.), rooftop equipment supports are not typically prequalified because of the variability of placement and conditions. Similarly, new to this code cycle, Section 1509.7.1 includes the requirement for wind resistance for rooftop-mounted photovoltaic systems per Chapter 16 of the IBC. Other industries or trades have similar requirements. Section 301.15 of the 2012 International Mechanical Code and Section 301.10 of the 2012 Fuel and Gas Code require “equipment and supports that are exposed to wind shall be designed to resist the wind pressures in accordance with the IBC”.

Section 1609 of Chapter 16 (Wind Loads) applies to wind loading on every building or structure. Section 1609.1.1 provides two design options. The designer can use chapters 26 to 30 of ASCE 7-10 or Section 1609.6 of the IBC. Note however that Section 1609.6 is based on the design procedures used in Chapter 27 of ASCE 7-10, which does not address wind loading on rooftop equipment and thus is not applicable. Chapter 29 of ASCE 7-10 (Wind Loading on Other Structure and Building Appurtenances) contains the procedures used to determine wind loading on rooftop structures and equipment.

DETERMINING AND APPLYING WIND LOADING ON ROOFTOP EQUIPMENT

Properly specified ballasting blocks are designed and formed to better address the freeze/thaw cycle.

Properly specified ballasting blocks are designed and formed to better address the freeze/thaw cycle.


To determine wind loading on rooftop equipment, the first step is to identify the building Risk Category (formerly the Occupancy Category) and the building location. The Risk Category is determined from Section 1604.5 and Table 1604.5 of the IBC or Table 1.5-1 of ASCE 7-10. There are slight variations in the two codes but typically each will produce the same Risk Category.

The Risk Category and the location are then used to determine the design wind speed based on published wind-speed maps, available in Section 1609.3, figures 1609 A to C of the IBC, or Section 26.5.1, figures 26.5-1 A to C of ASCE 7-10. It can be difficult to read these maps to select the appropriate wind contour line, specifically along the East Coast. The Redwood City, Calif.-based Applied Technology Council (ATC), a non-profit that advances engineering applications for hazard mitigation, has digitized the maps providing a valuable resource for determining design wind speeds by GPS coordinates or the building’s address. Visit ATC’s wind-speed website. Note however that it is always advisable to cross check this design wind speed with the maps in the adopted code or with the local building authority.

PHOTOS: MIRO INDUSTRIES INC.

Pages: 1 2