The junction of a roof surface with a wall, or any other structural feature, which arises above it.
The process in which materials are exposed to a controlled environment where various exposures such as heat, water, condensation, or light are altered to magnify their effects, thereby accelerating the weathering process. The material’s physical properties are measured after this process and compared to the original properties of the unexposed material, or to the properties of the material that has been exposed to natural weathering.
Maximum strength per unit surface area, which can be measured by shear or tensile testing. It is measured following EN 1348:1997, EN 1324 or EN 12003:1997 depending on the type of adhesive.
A polymeric material which is capable of holding two materials together by surface attachment.
Rock, stone, crushed stone, crushed slag, water-worn gravel or marble chips used for surfacing and/or ballasting a roof system.
The cracking of the surfacing bitumen on a built-up roof, producing a pattern of cracks similar to an alligator’s hide; the cracks may or may not extend through the surfacing bitumen.
The quantity (mass, volume, or thickness) of material applied per unit area.
A bituminous waterproofing agent applied to roofing materials during manufacturing.
British Board of Agrément.
Fibres aligned and woven in two directions to provide a fine mesh sheet of fibres.
Bubbles that may appear on the surface of asphalt roofing after installation.
The removal of structurally damaged or chemically effected concrete prior to repair.
Defects left in the surface of hardened concrete as water evaporates during the hardening process.
The process where carbonic acid, created by the combination of carbon dioxide and water present within the atmosphere, neutralises the alkaline environment of the concrete, from the surface inwards. Whilst the carbonation process has minimal effect on the structural characteristics of the concrete, it does reduce the pH, and can if allowed to reach the steel reinforcement lead to the loss of passivation the alkaline environment provides, and active corrosion of the steel can commence.
A material whose primary binder is cement.
The capability of a material to resist chemical agents. It is measured according to EN 1208-1.
The highest fire-resistance rating for roofing as per ASTM E108. Indicates roofing is able to withstand severe exposure to fire originating from sources outside the building.
Treatment to produce a continuous layer on the surface of concrete. The thickness is typically 0.1mm to 5.0mm. Particular applications may require a thickness greater than 5.0mm.
The ability a rigid material has to resist force in tension before an internal fracture occurs.
The change of water from vapour to liquid when warm, moisture-laden air comes in contact with a cold surface.
The process of making a material or surface unclean or unsuited for its intended purpose, usually by the addition or attachment of undesirable foreign substances.
The time required to effect curing. The time required for a material to reach its desirable long-term physical characteristics.
A value that a manufacturer is confident in achieving, bearing in mind the precision of test and variability of process, and testing in laboratory environment.
The failure of a system at one of the layers building up the construction, often at the interface between them.
Temperature at which water vapour condenses.
A metal flashing, or other overhanging component, with an outward projecting lower edge, intended to control the direction of dripping water and help protect underlying building components. A drip edge also can be used to break the continuity of contact between the roof perimeter and wall components to help prevent capillary action.
Dry film thickness (DFT)
The thickness of a surface applied coating after it has fully dried. Usually measured in microns.
The formation of a white powder on the surface due to the drying of a crystalline hydrate.
Properties of a material that will permit it to return to its original shape after being stretched
Elastic or plastic extension of a structural member under tension, expressed as % strain of the member.
A structural separation between two building elements that allows free movement between the elements without damage to the roofing or waterproofing system.
A vertical or steeply sloped roof or trim located at the perimeter of a building. Typically, it is a border for the low-slope roof system that waterproofs the interior portions of the building.
Where the thickness of a material tapers down to a thin layer at its edge. Due to the grading of repair materials this can be difficult to achieve and can leave a weak edge to the material.
An inert ingredient added to roofing materials in order to alter their physical characteristics
The last coat, decorative or not, or a multi-coat rendering or plastering system.
The maximum value of a grout prism failure determined by exerting a force in flexure at three points. It is measured according to BS 4551-1.
A substrate or fixing surface that is soft and can be easily scraped away with a knife.
A triangular portion of the endwall of a building directly under the sloping roof and above the eave line.
A fibre spun from an inorganic product of fusion which has cooled to a rigid condition without crystallising.
The propulsion of an abrasive material against a surface under high pressure to roughen a smooth surface or remove surface contamination.
The use of a hammer to survey a concrete structure to identify all loose and delaminated concrete, by tapping the surface and listening to the audible response.
Used to define a material which has a smooth variation of properties with no discontinuities or jumps.
The tension which occurs in circular structural components, where the load is carried wholly by ring tension, normally seen in liquid retaining structures or highly loaded columns.
Many plastics hydrolyze (degrade in water and steam). However, Triflex systems resist hydrolysis and perform well in water environments. This makes them excellent choices for waterproofing due to their ability to withstand repeated exposure to water.
The ability of a roofing material to resist damage (e.g., puncturing) from falling objects, application equipment, foot traffic, etc. The impact resistance of the roofing assembly is a function of all of its components, not just the membrane itself.
Insurance-backed guarantee (IBG)
An independent insurance policy that underwrites the installer's guarantee. If the contractor ceases to trade the insurers will take the place of the guarantee for the remaining term of cover.
Any of the parallel horizontal beams set from wall to wall to support the boards of a floor, ceiling or roof of a building.
Sheet metal trim that fits over a panel rib after it has been cut and bent.
Occurs where overlapping materials are seamed, sealed, or otherwise bonded.
A defect that remains undiscovered at the time of practical completion but which results in actual physical damage later. It could be the result of a failure either in materials used or in the application of those materials.
The penetration of fluid through structural defects within concrete, normally cracks or joints, causing potential long term issues and undesirable long term issues especially if salts are present. Can be penetration of fluid into an existing structure such as ground water or loss of fluid from a fluid retaining structure. A verity of remedial actions are available depending on the exact situation.
A thin layer render to repair minor defects and used to provide a smooth pore free surface prior to the application of decorative protective coatings. View our levelling mortars
Physical damage to concrete commonly caused by vehicular of industrial plant impact, but can include abrasion, often leading to structural damage, reduction in cover to reinforcement, and reduced aesthetic appearance. On precast elements damage can be caused during the erection process. Any repair strategy should also include protection from subsequent damage.
Migrating corrosion inhibitor (MCI)
A liquid applied to the surface of hardened concrete that penetrates via the pores and capillaries within the concrete and provides a protective monomolecular layer on the surface of the steel reinforcement, either delaying the onset of corrosion or reducing the subsequent rate of corrosion.
Night seal (or night tie-off)
A material and/or method used to temporarily seal a membrane edge during construction to protect the roofing assembly in place from water penetration. Usually removed when roofing application is resumed.
A valley where both sides of the roof are trimmed back from the centerline to expose the valley flashing material beneath.
Any object that pierces the surface of the roof.
A small hole in a coating, foil, membrane, or other roofing material.
A flanged piece of flashing material placed around irregularly shaped roof penetrations and filled with grout and a pourable sealer to seal around the penetration in order to seal it from against moisture entry. Pitch pockets are a good source of leaks and should be avoided if possible.
Material incorporated into rubber and plastic in order to increase their flexibility and workability.
The combining of monomers to produce polymers.
The accumulation of water at low-lying areas on a roof.
The period of time during which a material with multiple ingredients can be applied or administered after being mixed together.
A roofing or waterproofing membrane that has been strengthened by the addition or incorporation of one or more reinforcing materials, including woven or nonwoven glass fibres, polyester mats or scrims, nylon, or polyethylene sheeting.
Liquid or meltable solid synthetic resins with reactive epoxy end groups. In combination with hardeners, they cross-link by polyaddition and therefore belong to the family of thermosets. Properties: high bond strength on an extremely wide range of substrates, high viscosity, low shrinkage, high water and chemical resistance.
A rough coating scratched into the surface to ensure adhesion and levelling to the next coat.
Bringing the surface of concrete to the final, desired look and finish by removing any excess or unwanted material.
The continuous longitudinal overlap of neighboring like materials.
The enclosed underside of any exterior overhanging section of a roof eave.
The surface upon which the waterproofing or surfacing membrane is applied.
The amount of longitudinal pulling stress that a material can withstand before being pulled apart The amount of longitudinal pulling stress that a material can withstand before being pulled apart.
A bar, usually metal or vinyl, used to seal and anchor the free edges of a roof membrane.
Urban heat island effect
An urban heat island, or UHI, is a metropolitan area that's a lot warmer than the rural areas surrounding it. Heat is created by energy from all the people, cars, buses, and trains in big cities like New York, Paris, and London. Urban heat islands are created in areas like these: places that have lots of activity and lots of people.
The overall coefficient of heat transfer of an assembly measured in BTUs per square foot, per degrees Fahrenheit difference in temperature per hour.
The natural movement of water vapour from regions of higher vapour pressure to regions of lower vapour pressure.
Wet on wet
Application of a resin onto the surface of a similar material which has set but not hardened.
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. This force is then transmitted to the roof surface. Uplift may also occur because of the introduction of air pressure underneath the membrane and roof edges, where it can cause the membrane to balloon and pull away from the deck.