Mike Silvers, CPRC, Owner Silvers Systems Inc. and FRSA Director of Technical Services
Since we were children, we’ve been told “words matter”. Then we go to school and learn “sticks and stones may break my bones, but words will never hurt me.” So we were left to wonder which is it? Life very quickly teaches us that the former is definitely true and the latter is…not so much. Words offered with the right motives can lift us up and carry us forward, while negative sentiments from people we care for and respect can very definitely hurt. Words left unsaid may be the most unforgiving of all. You may be asking yourself what does this have to do with codes? Well, after almost 70 of these articles some of this can be chalked up to literary license, while also hoping you can indulge an old man who wants to share a few life observations along the way. I hope the connection to the code will become clearer when we are done.
When dealing with the building code, as with most things in life, words definitely matter. If the words in the building code are to be properly understood, the definitions must play a big part. Terms used in construction do not always perfectly align with those
used in our everyday language. Some are not seen in any other context and are specific to a given trade or discipline. We look to the definitions within the code to help us understand the code’s intent. Those definitions are found in several areas. Most are located in Chapter 2 of any given code or subcode. Some that are trade-specific will be contained in their respective chapter as is the case with roofing-specific terms that are included in the Florida Building Code (FBC), Building Chapter 15 Roof Assemblies and Rooftop Structures. Most of the code definitions that impact roofing are shown in the following sections of the code:
■ FBCB (Building) Chapter 2 Definitions and Chapter 15 Roof Assemblies and Rooftop Structures
■ FBCR (Residential) Chapter 2 Definitions
■ FBCEB (Existing Building) Chapter 2 Definitions
■ FBCEC (Energy Conservation) Chapter 2 Definitions
The High Velocity Hurricane Zone (HVHZ – Miami-
Dade and Broward Counties) has its own set of
definitions with some minor variations from those
shown here. They can be found in:
■ FBCB (Building) Chapter 15, Section 1513 – High-Velocity Hurricane Zone Definitions
The first group of definitions shown below are some of those that have been added or revised in the FBC 8th Edition (2023). There are others too, but these are the ones that are clearly roofing-related. After the list of those that have been revised or added, I also provide some definitions that didn’t change but will serve as examples of the types of things included in the code’s definitions sections. Understanding the building code requires an understanding of the definitions. A thorough review is advised. The entire FBC can be found free of charge at floridabuilding.org/c/ default.aspx. Note: Words underscored below are new to the 8th Edition FBC.
FBC 8th Edition (2023) Added or Revised (Partial List)
EMITTANCE. The ratio of radiant heat flux emitted by a specimen to that emitted by a blackbody at the same temperature and under the same conditions.
GYPSUM BOARD. The generic name for a family of sheet products consisting of a noncombustible core primarily of gypsum with paper surfacing.
GYPSUM PANEL PRODUCT. The general name for a family of sheet products consisting essentially of gypsum complying with the standards specified in Tables 2506.2 and 2507.2, and Chapter 35. Gypsum board and glass mat gypsum panels are examples of gypsum panel products.
GLASS MAT GYPSUM PANEL. A gypsum panel consisting of a noncombustible core primarily of gypsum, surfaced with glass mat partially or completely embedded in the core.
GYPSUM SHEATHING. Gypsum panel products specifically manufactured with enhanced water resistance. For use as a substrate for exterior surface materials.
GYPSUM WALLBOARD. A gypsum board used primarily as an interior surfacing for building structures.
INSULATING SHEATHING. An insulating board. A rigid panel or board insulation material having a thermal resistance of not less than R-2 of the core material with properties suitable for use on walls, floors, roofs, or foundations.
NAILABLE SUBSTRATE. A product or material such as framing, sheathing or furring, composed of wood, wood-based materials or other materials providing equivalent fastener withdrawal resistance.
POSITIVE ROOF DRAINAGE. The drainage condition in which consideration has been made for all loading deflections of the roof deck, and sufficient slope has been provided to ensure drainage of the roof within 48 hours of precipitation.
RISK CATEGORY. A categorization of buildings and other structures for determination of flood, wind, tornado, snow, ice and earthquake loads based on the risk associated with unacceptable performance.
ROOF ASSEMBLY. A system designed to provide weather protection and resistance to design loads. The system consists of a roof covering and roof deck or a single component service as both the roof covering and the roof deck. A roof assembly includes the roof covering, roof deck, and may include a vapor retarder, thermal barrier, insulation or similar substrate.
ROOF COVERING. The covering applied to the roof deck for weather resistance, fire classification or appearance.
ROOF SYSTEM. A roof system consists of a roof covering and other interacting roofing components and may include vapor retarder, thermal barrier, insulation or other similar substrate. The system does not include the roof deck unless it is part of a single component serving as the roof covering and the roof deck.
SPRAY-APPLIED FOAM PLASTIC. Single- and multi-component, spray-applied foam plastic insulation used in nonstructural applications which are installed at locations wherein the material is applied in a liquid or frothed state, permitted to free rise and cure in situ.
STEEP SLOPE. A roof slope two units vertical in 12 units horizontal (17-percent slope) or greater.
VAPOR DIFFUSION PORT. An assembly constructed or installed within a roof assembly at an opening in the roof deck to convey water vapor from an unvented attic to the outside atmosphere.
As you can see, there have been extensive changes dealing with gypsum board, panels and sheathing. This should help clarify the many types of gypsum products now offered in the market and how they should be described. For roofing, a few products that would fit the definition of a glass mat gypsum panel would be DensDeck, Securock or other similar products.
The change in the definition of positive drainage will be helpful by changing additional slope to sufficient slope. The term additional slope has been interpreted to require some type of additional slope be added during reroofing. The old language that stated additional slope has been provided was meant to confirm that the designer of a structure added slope to accommodate deflection of the roof deck to ensure drainage of the roof within 48 hours of precipitation.
The addition of tornados to the Risk Category definition would seem to be concerning, but when you use the ASCE Hazard Tool (asce7hazardtool.online), it will help you understand whether or not tornado loads apply to a particular structure (see page 16). It primarily applies to buildings that have a risk category and a large footprint. The risk category inclusion is understandable,
but the footprint portion requires some explanation. In principle, the larger the building the more likely it is to be hit by a tornado. Basically, a large building provides a bigger target for what is (compared to hurricanes) a fairly confined event. For most buildings in Florida, it will not apply.
A definition of roof system has been added, replacing the old definition of roof covering system which said: See roof assembly. The definition of roof assembly includes the deck, which is not typically part of a roof system and should not have been part of the previously named roof covering system. Roof assembly was tweaked to clarify that some components (vapor barriers, insulation, etc.) may or may not be present in an assembly or system. The diagrams below serve as examples to help clarify these terms.
FBC 8th Edition (2023) Definitions Which Remain Unchanged (Partial List)
ACCESSORY COMPONENTS. Components used in the installation of pedestals and pedestrian deck panels or pavers of the exterior elevated flooring system. Accessory components are made of either plastic, metal or other approved materials. Accessory components may be used to provide lateral bracing of the pedestals, to provide vertical support, for leveling the pedestal, to restrain the pedestrian deck panels or pavers to the top of the pedestal, or for other system requirements.
AGGREGATE. In roofing, crushed stone, crushed slag or water-worn gravel used for surfacing for roof coverings.
ARCHITECTURAL METAL PANEL. Water shedding (hydrokinetic) roof panel fastened to a roof deck.
BALLAST. In roofing, ballast comes in the form of large stones or paver systems or light-weight interlocking paver systems and is used to provide uplift resistance for roofing systems that are not adhered or mechanically attached to the roof deck.
BASE SHEET. The bottom or first ply of a roofing assembly over which subsequent roofing plies are applied. A base sheet may be designed for mechanical attachment, full or partial adhesion to the substrate.
BUILDING. Any structure used or intended for supporting or sheltering any use or occupancy.
BUILDING INTEGRATED PHOTOVOLTAIC ROOFING. A roofing product consisting of electricity generating photovoltaic component integrated into a roof covering.
BUILT-UP ROOF COVERING. Two or more layers of felt cemented together and surfaced with a cap sheet, mineral aggregate, smooth coating or similar surfacing material.
“CLASS A” ROOFING ASSEMBLY. A roofing assembly that, in combination with the roof slope, has been classified by an approved testing agency, with a listing and follow-up service, as “Class A” in compliance with ASTM E108 or UL790.
“CLASS B” ROOFING ASSEMBLY. A roofing assembly that, in combination with the roof slope, has been classified by an approved testing agency, with a listing and follow-up service, as “Class B” in compliance with ASTM E108 or UL790.
“CLASS C” ROOFING ASSEMBLY. A roofing assembly that, in combination with the roof slope, has been classified by an approved testing agency, with a listing and follow-up service, as “Class C” in compliance with ASTM E108 or UL790.
CONTINUOUS ROOFING SYSTEM. A roof covering, composed from a single or multiple layers, forming a homogenous membrane over the entire roof surface, applied to either a flat or pitched roof surface(s).
COUNTERFLASHING. Formed metal or elastomeric sheeting secured on or into a wall, curb, pipe, roof-top unit or other surface to cover and protect the upper edge of a base flashing and its associated fasteners.
DISCONTINUOUS ROOFING SYSTEM. A roofing system with unsealed overlapping components, where the combined roofing system has openings at the point of overlap, applied to a sloped surface with a pitch of 2:12, or greater. Discontinuous roofing systems include asphalt shingles; concrete, clay or metal tile; wood shingles or shakes; and cement fiber roofing systems.
DRY-IN. The process of applying the first layer of felt in a roofing system.
FASTENER WITHDRAWAL RESISTANCE TEST. A static pullout test of mechanical fasteners, which are used to anchor any roofing component, to determine the force required to withdraw a fastener from the substrate. Testing shall be in compliance with the test procedure detailed in TAS 105.
FIRE-RESISTANT ROOF COVERING. Any Class A, Class B or Class C roofing system applied to the appropriate deck type within the specified slope of the listed classification.
FLASHING. The roofing component used to seal roofing systems, where the system is interrupted or terminated.
FLAT ROOF TILE PROFILE. Those tiles with less than 1/2-inch (12.7 mm) rise.
EXISTING BUILDING. A building erected prior to the date of adoption of the appropriate code, or one for which a legal building permit has been issued.
EXTERIOR ELEVATED FLOORING SYSTEM. An assembly installed over a roof assembly or other exterior supporting structure consisting of a walking surface of pedestrian deck panels or pavers mounted on pedestals using other accessory components, mechanical fasteners or adhesives as required by the manufacturer’s installation instructions for attaching pedestrian deck panels or pavers to pedestals and other accessory components. Exterior elevated flooring systems may have pedestals attached to the roof or other supporting structure or pedestals installed independently of the roof or supporting structure with the restraint of the pavers at the perimeter and discontinuous edges. Exterior elevated flooring systems are not part of the roof assembly.
- Attached systems. Attached systems are those where pedestals are attached to the roof or other supporting structure by mechanical fasteners, adhesives or both.
- Independent systems. Independent systems are those where pedestals are not attached to the roof but rest on the roof or other supporting structure.
HIGH ROOF TILE PROFILE. Those tiles having a rise to-width ratio greater than 0.20.
HIGH VELOCITY HURRICANE ZONE. This zone consists
of Broward and Dade counties.
HURRICANE-PRONE REGIONS. Areas vulnerable to hurricanes defined as:
1. The U. S. Atlantic Ocean and Gulf of Mexico coasts where the ultimate design wind speed, Vult, for Risk Category II buildings is greater than 115 mph (51.4 m/s);
2. Hawaii, Puerto Rico, Guam, Virgin Islands and American Samoa.
LIVE LOAD, ROOF. A load on a roof produced:
1. During maintenance by workers, equipment and materials;
2. During the life of the structure by movable objects such as planters or other similar small decorative appurtenances that are not occupancy related; or
3. By the use and occupancy of the roof such as for roof gardens or assembly areas.
LOW ROOF TILE PROFILE. Those tiles having a rise-to width ratio less or equal than 0.20; except those tiles meeting the flat profile definition.
METAL PROFILE. Including but not limited to eave and gable drip, gravel stop, raised edge systems and fascia systems. All composite and nonmetallic flashing materials shall have a product approval.
METAL ROOF PANEL, METAL ROOF SHINGLE MANUFACTURER. The party responsible that forms raw material into metal roof panels and/or metal roof shingles used in building construction.
METAL ROOF SHINGLE. An interlocking metal sheet having an installed weather exposure less than 3 square feet (0.279 m2) per sheet.
MODIFIED BITUMEN ROOF COVERING. One or more layers of polymer-modified asphalt sheets. The sheet materials shall be fully adhered or mechanically attached to the substrate or held in place with an approved ballast layer.
PHOTOVOLTAIC SHINGLES. A roof covering resembling shingles that incorporates photovoltaic modules.
PREPARED ROOF COVERING. Any manufactured or processed roof covering designed for use as the top layer of a discontinuous roofing system applied to a sloped roof.
RAS. Roofing Application Standards.
RECOVERING. The process of covering an existing roofing assembly with a new roofing system or a prepared roofing system.
REPAIR. The work of corrective procedures by replacing or altering an existing roofing component or system to eliminate water intrusion.
REROOFING. The process of recovering or replacing an existing roofing system, either in its entirety or in existing sections.
RIDGE VENT. A ventilator located within 18 inches (457 mm) of the ridge that allows the escape of warm and/or moist air from the attic area or rafter cavity.
ROOF COVERING. An assembly of multiple field applied components or a single component designed to weatherproof a building’s top surface. A roof covering may be a roofing assembly or form a portion thereof.
RISK CATEGORY. A categorization of buildings and other structures for determination of flood, wind, snow, ice and earthquake loads based on the risk associated with unacceptable performance.
ROOF DECK. The flat or sloped surface constructed on top of the exterior walls of a building or other supports for the purpose of enclosing the story below, or sheltering an area, to protect it from the elements, not including its supporting members or vertical supports.
ROOF REPAIR. Reconstruction or renewal of any part of an existing roof for the purposes of its maintenance.
ROOF REPLACEMENT. The process of removing the existing roof covering, repairing any damaged substrate and installing a new roof covering.
ROOF SECTION. A separation or division of a roof area by existing expansion joints, parapet walls, flashing (excluding valleys), difference of elevation (excluding hips and ridges), roof type or legal description; not including the roof area required for a proper tie-off with an existing system.
ROOF VENTILATION. The natural or mechanical process of supplying conditioned or unconditioned air to, or removing such air from, attics, cathedral ceilings or other enclosed spaces over which a roof assembly is installed.
ROOFING ASSEMBLY. An assembly of interacting roofing components [includes the roof deck, vapor retarder (if present), insulation, and roof covering].
ROOFING COATINGS, ADHESIVES AND MASTICS. Any and all liquid materials applied to the roofing membrane layer to enhance ultraviolet light resistance; increase resistance to fire; increase reflectivity of the roofing assembly; or, in some way, enhance the performance of the roofing assembly. Roofing coatings, adhesives or mastics shall not contain asbestos materials.
ROOFING COMPONENT. A roofing product that is incorporated into various roofing assemblies.
ROOFING MAINTENANCE. The work of extending the longevity of a roofing system through preventative care, such as refilling pitch pans, applying coatings, regraveling, resurfacing and recaulking.
ROOFING SYSTEM. A system of interacting roofing components, generally consisting of membrane or primary roof covering and insulation (not including the roof deck) designed to weatherproof, and sometimes to improve, the building’s thermal resistance.
SCUPPER. An opening in a wall or parapet that allows water to drain from a roof.
SHINGLE FASHION. A method of installing roof or wall coverings, water-resistive barriers, flashing or other building components such that upper layers of material are placed overlapping lower layers of material to provide for drainage via gravity and moisture control.
SINGLE-PLY MEMBRANE. A roofing membrane that is field applied using one layer of membrane material (either homogeneous or composite) rather than multiple layers.
STRUCTURAL METAL PANEL. Roof covering intended to be self-supporting between structural members (see Sections 2003.8.2 and 2222.4).
TAS. Testing Application Standard.
SUBSTANTIAL IMPROVEMENT. Any repair, reconstruction, rehabilitation, alteration, addition or other improvement of a building or structure, the cost of which equals or exceeds 50 percent of the market value of the structure before the improvement or repair is started. If the structure has sustained substantial damage, any repairs are considered substantial improvement regardless of the actual repair work performed. The term does not, however, include either:
1. Any project for improvement of a building required to correct existing health, sanitary or safety code violations identified by the building www.floridaroof.com | FLORIDA ROOFING 23 official and that is the minimum necessary to assure safe living conditions.
2. Any alteration of a historic structure provided that the alteration will not preclude the structure’s continued designation as a historic structure.
UNDERLAYMENT. One or more water-shedding layers applied to a sloped roof prior to the application of a prepared roof covering. The primary purpose of an underlayment is defined as a water shedding layer to function in combination with a prepared roof covering.
VEGETATIVE ROOF. An assembly of interacting components designed to waterproof a building’s top surface that includes, by design, vegetation and related landscape elements.
VENTILATION. The natural or mechanical process of supplying conditioned or unconditioned air to, or removing such air from, any space.
WIND-BORNE DEBRIS REGION. Areas within hurricane-prone regions located:
1. Within 1 mile (1.61 km) of the coastal mean high water line where the ultimate design wind speed, Vult is 130 mph (58 m/s) or greater; or
2. In areas where the ultimate design wind speed, Vult, is 140 mph (63.6 m/s) or greater.
For Risk Category II buildings and other structures and Risk Category III buildings and other structures, except health care facilities, the wind-borne debris region shall be based on Figure 1609.3(1). For Risk Category III health care facilities, the wind-borne debris region shall be based on Figure 1609.3(2). For Risk Category IV buildings and other structures, the wind-borne debris region shall be based on Figure 1609.3(3).
WIND SPEED, Vult. Ultimate design wind speeds.
WIND SPEED, Vasd. Nominal design wind speeds.
WOOD SHAKES. Tapered or straight pieces of red cedar, or other wood types, of widths ranging from 3 inches to 14 inches (76 mm to 356 mm) ranging in lengths from 18 inches to 32 inches (457 mm to 813 mm) applied to a sloped roof, in conjunction with an approved underlayment, forming a discontinuous prepared roof system.
WOOD SHINGLES. Tapered pieces of red cedar, or other wood types, sawn on both faces, of widths ranging from 3 inches to 14 inches (76 mm to 356 mm) and lengths of 16 inches (406 mm), 18 inches (457 mm), and 24 inches (610 mm) applied to a sloped roof forming a discontinuous prepared roof system.
As you can see by this partial list of definitions, words – and their definitions – definitely matter when it comes to the building code. Words can definitely hurt you if you install something that’s not compliant based on a lack of knowledge regarding their presence or definitions. And words left unsaid like the word ROOF as well as others that are not defined in the building codes can be unforgiving if an important one is left unsaid. And for you of little faith…see I brought it back to codes in the end!
FRM
Mike Silvers, CPRC, is owner of Silvers Systems Inc. and is consulting with FRSA as Director of Technical Services. Mike is an FRSA Past President, Life Member and Campanella Award recipient and brings over 50 years of industry knowledge and experience to FRSA’s team.
