Posts by James R Kirby

James R. Kirby, GAF Roof Views Blog Contributor

James R. Kirby, AIA, is a GAF building and roofing science architect. Jim has a Masters of Architectural Structures and is a licensed architect. He has over 25 years of experience in the roofing industry covering low-slope roof systems, steep-slope roof systems, metal panel roof systems, spray polyurethane foam roof systems, vegetative roof coverings, and rooftop photovoltaics. He understands the effects of heat, air, and moisture movement through a roof system. Jim presents building and roofing science information to architects, consultants and building owners, and writes articles and blogs for building owners and facility managers, and the roofing industry. Kirby is a member of AIA, ASTM, ICC, MRCA, NRCA, RCI, and the USGBC.

Edge Metal Design Wall Zones 4 and 5
Keeping water out of a building is undoubtedly the primary function of a roof system. But one could argue that ensuring a building's roof stays in place during high-wind events is equally important. Let's face it, without a roof, it's hard to keep water out! This blog takes a look at one of the subsets of wind design of roof systems: Wall Zones 4 and 5 and their relationship with roof perimeters.
February 17, 2022
IBC and FM—What's the Difference When it Comes to Wind Design?
Introduction Wind design of roof systems can be confusing from an engineering perspective. Wind design can also be confusing because the International Building Code (IBC) provides specific requirements, but so does Factory Mutual (FM). If FM is specified, do the IBC requirements need to be followed? What is the wind-design strategy for FM-insured and non-FM-insured buildings? This blog will discuss the following:
July 16, 2021
Coatings and Liquid-applied Membranes— what's in a name?
Liquid-applied roof membranes (LAM) and roof coatings (aka, maintenance coatings) are not only here to stay, their use is on the rise. This blog takes a look at how the building code and the roofing industry generally differentiate between liquid-applied roof membranes and roof coatings. There is confusion because the intended use of each is different, yet many of the materials are the same for both applications. Here's what you need to know to help understand and differentiate between the two.
May 19, 2021
How will ASCE 7-16 affect the low-slope roofing industry? A Tale of Two Buildings
A common question being asked in the roofing industry is whether or not the 2016 version of ASCE 7 is going to increase the design wind pressures acting on a building. The answer is "yes" in many cases. So, the follow up question is "by how much?" And, that leads to the next question, "how much more capacity will roof systems be required to have when wind design follows ASCE 7-16?"
February 15, 2021
Ventilation of Steep-Slope Roof Systems and Transitions
Ventilation for steep-slope roof assemblies is often misunderstood. One must not only understand the code requirements, but be able to translate them into real-world installations. Building codes have requirements for ventilation of steep-slope attics and enclosed rafter spaces.Balanced ventilation — nearly equal amounts of intake and exhaust — typcially provides efficient ventilation.Transitions between low-slope and steep-slope roof areas require more distinct intake and exhaust details than traditional eaves/soffits and ridges.
October 13, 2020
Retrofit Single Ply Roof Systems: Physical Testing
In part 1, Retrofit Single Ply Roof Systems: An Assessment of Wind Resistance, we provided information about the following: Four (4) methods to re-cover a metal panel roofThe many options for attaching a single-ply system to a metal panel roofAn example calculation for wind uplift design pressures and appropriate fastener patterns that provide the necessary resistance capacityIndustry concerns about wind uplift when not attaching the retrofit single-ply system into every purlin
August 03, 2020
Value Engineering Part 2: Retaining Performance
In the first Value Engineering post about the attributes of high performing roof designs, value engineering is defined as "a concept that states there are less expensive ways to get equivalent performance," and the post described the performance attributes that make for a long-lasting, high-performing roof system. These performance attributes include: images
June 08, 2020
Value Engineering — Optimizing Performance or Reducing Costs?
Value engineering. We're familiar with the term, and many of our roof designs have been 'value engineered' during our careers. I'd argue that in today's construction world, real value engineering, i.e. optimizing functional value, isn't being performed, but rather value engineering (VE) is more commonly the term placed on the act of reducing installation costs.
December 05, 2019
Fresh Thinking About Cold Storage Roofs
A "cold storage building" is a building or a portion of a building or structure designed to promote the extended shelf life of perishable products or commodities. There are varying levels of cold storage, such as coolers, chill coolers, holding freezers, and blast freezers. Coolers range from approximately 32 to 55 degrees F (0 to 13 degrees C), while blast freezers can have interior temperatures from -20 to -50 degrees F (-29 to -46 degrees C)1. The biggest difference from a roofing perspective is the amount of insulation for the varying levels of cold storage.
April 19, 2019
Air Barriers and Vapor Retarders: The Current Conundrum in the Roofing Industry
The roofing industry continues to discuss vapor retarders but should be discussing air barriers. One of the primary purposes of a building envelope is to keep moisture out of a building. What makes this difficult is that water comes in many forms and can take many paths into a building. Therefore, building designers need to account for bulk water, capillary water, air-transported moisture, and water vapor, and deal with each of these with different forms of defense.
September 10, 2018
Condensation, Dew Point, and Roofing
Prepared with Co-authors Thomas J. Taylor, PhD, and James Willits Except in extremely arid climates, there is always some amount of water vapor in the air around us. When that air comes into contact with a cold surface, that water vapor condenses as a liquid onto the surface. A good example of this is the water droplets on the side of the glass of ice water. Those droplets are commonly known as "condensation" and are what results when the air gets too cold to hold the water vapor that is in it. Even when a cold surface is not available, if the air temperature suddenly drops, water vapor condenses out as mist or fog. Air can only hold so much water – more at higher temperatures and less at colder temperatures.
March 22, 2018
Condensation, Dew Point, and Roofing
Prepared with Co-authors Thomas J. Taylor, PhD, and James Willits Except in extremely arid climates, there is always some amount of water vapor in the air around us. When that air comes into contact with a cold surface, that water vapor condenses as a liquid onto the surface. A good example of this is the water droplets on the side of the glass of ice water. Those droplets are commonly known as "condensation" and are what results when the air gets too cold to hold the water vapor that is in it. Even when a cold surface is not available, if the air temperature suddenly drops, water vapor condenses out as mist or fog. Air can only hold so much water — more at higher temperatures and less at colder temperatures.
March 20, 0018

Posts by James R Kirby

My Documents