The exposure of a specimen to a specified test environment for a specified time with the intent of producing in a shorter time period, effects similar to actual weathering.
A material to facilitate independent movement between two units that would otherwise bond together.
The unintended movement of air from a location where it is intended to be contained to another location
The cracking of the surfacing bitumen on a bituminous roof or coating on a SPF roof, producing a pattern of cracks similar to an alligator’s hide; the cracks may not extend completely through the surfacing bitumen or coating.
A group of natural, fibrous, impure silicate materials.
Random, inconsequential amounts of residual water on a roof membrane.
A small bubble or blister in the flood coat of an aggregate-surfaced built-up roof membrane.
An enclosed pocket of air, which may be mixed with water or solvent vapor, trapped between impermeable layers of felt or membrane, or between the membrane and substrate.
An upward, elongated displacement of a roof membrane frequently occurring over insulation or deck joints. A buckle may be an indication of movement within the roof assembly.
The formation of a powdery surface condition from the disintegration of a binder or elastomer.
A surface showing a texture where nodules and valleys are approximately the same size and shape. This surface is acceptable for receiving a protective coating because of the roundness of the nodules and valleys.
Making a material or surface unclean or unsuited for its intended purpose, usually by the addition or attachment of undesirable foreign substances.
a nonlinear separation or fracture occurring in a material.
(1) the deformation of a structural member as a result of loads acting on it; (2) any displacement in a body from its static position, or from an established direction or plane, as a result of forces acting on the body.
Also known as Bowing or Sagging.
A deleterious change in the chemical structure, physical properties or appearance of a material from natural or artificial exposure (e.g., exposure to radiation, moisture, heat, freezing, wind, ozone, oxygen, etc.).
Separation of the laminated layers of a component or system.
An encrustation of soluble salts, commonly white, deposited on the surface of stone, brick, plaster, or mortar; usually caused by free alkalies leached from mortar or adjacent concrete as moisture moves through it.
The loss of flexibility or elasticity of a material.
Any lightening of initial color.
A term used to describe a deck surface condition. A sharp raised edge (generally in concrete) capable of damaging a roof membrane or vapor retarder.
(also referred to as an edge wrinkle) (1) a half-cylindrical or half-conical shaped opening or void in a lapped edge or seam, usually caused by wrinkling or shifting of ply sheets during installation; (2) in shingles, a halfconical opening formed at a cut edge.
In protective coatings, the detachment of small pieces of the coating film.
The function of flashings is to provide a watertight junction between roofing materials and roof projections or other parts of the structure, and between roof sections. Flashings should be designed to furnish service for at least as long as the materials used in the field of the roof. Flashings are the most vulnerable part of any roof. Their importance and the importance of maintaining them properly cannot be overemphasized.
Many early roof problems are actually flashing problems. Often, repairing the flashings or providing new flashings is all that is needed to make the roof watertight again. Most flashing problems result from inadequate flashing design or faulty construction. Many flashing problems can be reduced or eliminated by careful examination by competent inspectors during roof installation, and by regularly scheduled inspection and maintenance.
In many instances, leaks occur at flashings where there are no flashing defects. These leaks may be the result of open joints in a masonry wall or coping cap, which permits water to enter behind the flashings and into the building. This problem may be eliminated by “through-wall” flashings.
Hail forms when frozen water drops are lifted in turbulent wind regimes during thunderstorms. The frozen drops of water increase in size and eventually fall to earth as hail having been driven by a combination of gravity and wind forces. Hail stones vary in size from pea size (1/4 inch diameter, little roof damage), through marble size (3/4 inch in diameter, threshold damage to roof materials) to golf ball size (11/2 inch in diameter, typically severe damage to roofing materials). Hail size distributions tend to be localized with some roofs damaged, while others are not. Wind direction plays an important role, as well as roof pitch. A direct impact of hail on a shingle is more damaging than that of a glancing blow.
Assessing hail damage is often accomplished by a roof inspection, which usually occurs several days to several months after the hail event. Determination of whether hail actually fell at a site can be made through statements and weather reports. Inspection of thin, aluminum fixtures helps verify hail impact.
An area where a liquid-applied material is missing or absent.
Voids left in concrete resulting from failure of the mortar to effectively fill the spaces among coarse aggregate particles.
A weak layer of cement and aggregate fines on a concrete surface that is usually caused by an overwet mixture, overworking the mixture, improper or excessive finishing or combination thereof.
In SPF-based roofing, physical damage to a completed SPF-based roof system not caused by normal wear and tear.
A superficial growth produced on organic matter or living plants by fungi.
A meandering ridge in a roof membrane not associated with insulation or deck joints.
Surface cracking resembling a dried mud flat.
SPF that has excess isocyanate or resin. Off-ratio will not exhibit the full physical properties of normal SPF.
Undesirable depositions of airborne spray.
In SPF roofing, a condition of the foam in which the surface shows a linear coarse textured pattern and/or a pebbled surface. This surface is generally downwind of the sprayed polyurethane path and, if severe, unacceptable for proper coating coverage and protection.
A tiny hole in a coating, film, foil, membrane or laminate comparable in size to one made by a pin.
In some thermoplastic roofing membranes, the loss of plasticizer chemicals from the membrane, resulting in shrinkage and embrittlement of the membrane, typically PVC.
A surface which is incompletely drained.
The excessive accumulation of water at low-lying areas on a roof that remains after the 48 hours after the end rainfall under conditions conducive to drying.
In SPF roofing, the condition in which the foam surface shows a coarse texture where valleys form sharp angles. This surface is unacceptable for proper coating and protection.
Undesirable excessive flow in material after application to a surface.
An upward-curled felt side lap or end lap.
In waterproofing, a separation in a material, such as a concrete substrate, caused by the inability of the material to resist a reduction in size which occurs during its hardening or curing process or both.
A change in the softening point of bitumen during storage or application.
A membrane tear resulting from tensile stresses.
In SPF roofing, the surface condition of the foam which shows a coarse texture where valleys form sharp angles. This surface is unacceptable for proper coating and protection.
Invisible light radiation, adjacent to the violet end of the visible spectrum, with wavelengths from about 200 to 400 nm (nanometres).
The movement of water vapor from a region of high vapor pressure to a region of lower vapor pressure.
In SPF roofing, the verge of popcorn surface texture is the roughest texture suitable for receiving the protective coating on a sprayed polyurethane foam roof. The surface shows a texture where nodules are larger than valleys, with the valleys relatively cured. This surface is acceptable for receiving a protective coating only because of the relatively cured valleys. However, the surface is considered undesirable because of the additional amount of coating material required to protect the surface properly.
An open space or break in consistency.
All roofing materials deteriorate from exposure to the weather at rates determined largely by the kind of material and the conditions of exposure. In general, inorganic roofing materials tend to deteriorate less rapidly from exposure than organic roofing materials. All types of roofing materials may be damaged by hail. Exposure to air pollutants and industrial or salt-laden atmospheres may accelerate the deterioration process of some roofing materials.
Roofing materials are subject to damage from strong winds and flying debris. Generally, roofs are not designed to withstand winds of hurricane and tornado intensity. However, roofs may also be damaged by winds of moderate intensity, with gust that may reach 50 to 75 miles per hour. The primary cause of wind damage is from the partial vacuum created by wind blowing over the edge of the roof. Nature tries to neutralize the low-pressure area by bringing in air from a higher pressure area, usually from inside the building. This air pushes up on the bottom side of the roof assembly and, over time, loosens fasteners and breaks the adhesion making the roof susceptible to damage from the next moderate or strong wind. To counteract the effects of wind-uplift forces, the roofing and insulation should be adequately fastened to the roof deck, and a securely-fastened perimeter detail should be provided.
The force caused by the deflection of wind at roof edges, roof peaks or obstructions, causing a drop in air pressure immediately above the roof surface.