Appendix A. Terminology
Anodic treatment
Surface treatment of metal (especially aluminium) to render it more corrosion resistant.
APP
Atactic polypropylene is a plastic-based interface modifier used to improve the properties of bituminous felt.
Fireproof membrane
Fibre-glass membrane used for fire-proofing thatched roofs.
Buildability
The practicality of working safely with a minimum of complications.
Foamed glass
Insulation material based on foamed glass.
Diffusion
Transport of moisture as vapour through materials.
Duo-roofs
A type of warm roof where the roofing membrane lies inside the insulation layer – with insulation both below and above the roofing membrane.
Net coverage
Effective width of a roof covering (i.e., how much of the underlying structure is protected by it).
Equalise
To make uniform in terms of thickness.
EPDM
Roofing membrane based on ethylene propylene diene monomer, a collective term for ethylene propylene and various diene monomer compounds.
Geotextile fabric
Vapour-permeable material typically a so-called ’non-woven’ textile.
Flat roofs
Roofs with a slope below 10 °.
Dormer cheek
A side of a dormer.
Unsupported joint
Roofing boards (these may be used with unsupported joints if they are tongue-and-groove at the ends).
Cleat edge flashing
Flashing at the eave level ensuring the discharge of rainwater into a gutter. Roofing underlayment is usually finished with a cleat edge flashing.
Joint sealant strip
A strip laid in joints between corrugated fibre-cement sheets to improve or ensure watertightness (for fibre-cement products).
Bird grating
A synthetic material fitted in the vent opening below corrugated or tiled roof coverings to prevent the ingress of birds and insects.
Moisture-adaptive
A term used to denote special vapour barriers which change their properties (adapt) depending on ambient relative humidity.
Hip
An outward angle joining two roof surfaces.
Burr
A prolonged rough edge or ridge on a surface (e.g., in casting joints).
Hip vent strip
See Ridge vent strip.
Insect mesh
A synthetic fibre used to prevent ingress of insects and birds. Insect meshes are typically placed in vent openings between roofing underlayment and insulation or on the top side of soffit boards.
Box gutter
A delimited channel in the roof which collects water from the roof surface and drains it off to a roof outlet.
Ridge
The top edge of a roof.
Cold roofs
Roofs where parts of the supporting structure are not insulated externally.
Convection
Air current in structures due to pressure differences (e.g., wind pressure or the stack effect).
Ridge cross poles
Split pieces of oakwood placed across the ridge in thatched roofs to keep it in place.
Depression
A depression in a surface. On roofs, these typically in places with ponding (i.e., where the water is not drained towards a roof outlet).
Batten spacing
The distance between roof battens, measured from centre-to-centre.
Inverted roofs
A type of warm roof where the roofing the membrane lies below the insulation. Thus the roofing membrane also functions as a vapour barrier.
PIB
A roofing membrane based on polyisobutylene.
PVC
A roofing membrane based on polyvinyl chloride. It is also used as surface treatment agent.
PVF2
A surface coating based on polyvinylidene difluoride.
Pitched roof
A roof with a slope bigger than or equal to 10 °.
Ridge vent strip
A strip laid across the ridge board in tiled roofs to prevent ingress of insects and birds and to ensure that there is ventilation between roof covering and roofing underlayment.
SBS
Styrene-buradiene-styrene is a rubber-based modifier used to improve the properties of bituminous felt.
Dormer downspout
A box-shaped gutter to drain water from the sides of dormers.
Apex
The top part of a collar roof (above the tie beam).
Tilting fillet/arris rail
A tilting fillet is a tapered piece of wood placed at the eaves to change the direction of the fall relative to the rest of the roof.
Valley
An inward angle formed by two intersecting planes (of a roof), including those between two roof surfaces and between roof surfaces and dormer cheeks.
Crawl space
The space enclosed by sloping walls, flooring, and a vertical wall (primarily in collar roof assemblies).
Snow guard pipe
See insect mesh.
Level difference
A level difference between two neighbouring surfaces (e.g., between two roofing slabs).
Fascia
The finish at the rafter foot level.
Fascia board
A board fitted to rafter feet.
Structured matting
Structured matting used for metal roofs (especially of zinc) to ensure oxygen access to the reverse side of the roof covering and allowing the discharge of condensate.
Sloping roof
See pitched roof.
Eaves
The lower part of a pitched roof, typically facing the gutter.
Roofing membrane
The term for products used as roof covering for flat roofs. The products are typically roll material and normally based on either bitumen (bituminous felt) or synthetic materials such as plastic or rubber (roofing foil).
Coatwork (thatched roof)
The coatwork denotes the total thickness of straws or reeds (i.e., the levelling course and underlying straw or reeds).
Conventional roof
A flat warm roof where the membrane lies above the insulation (as opposed to inverted roofs and duo-roofs).
Tent effect
This refers to the phenomenon where materials in contact with one another can cause water to penetrate (as in old-fashioned tents).
Terrain class
The impact of wind load on buildings is determined in relation to their location relative to the roughness of the immediate terrain (e.g., the wind load is relative to whether the surroundings are smooth or open (great wind load) or sheltered (less wind load)).
TPO fin.
A roofing membrane based on thermoplastic polyolefin.
Airtightness enclosure
The imaginary surface preventing convection or airflow through the climate envelope. The airtight enclosure typically consists of a vapour barrier, back walls, windows, doors, etc. Ideally, the airtight enclosure must be continuous inside the house.
Hip roof
A sloping ‘cut-off’ at gable ends. This may extend as far as the eaves (hip roof) or end halfway down (half-hip roof).
Warm roof
A roof where the supporting structure lies immediately below the insulation.
Vent space
A gap through which vent air flows once it has entered the vent opening. Actual gaps exist in couple roofs and in sloping roofs in attic-trussed assemblies.
Vent tile
Roof tile used to vent the reverse side of the tiles.
Roof vent
An opening in the roofing underlayment designed as a prefabricated vent fitted to the underlayment.
Vent opening
An opening from a vented structure into the open (e.g., at the eaves, ridge, or roof vents in the roofing underlayment).
Barge board
Roof-cover flashing by eaves at gable ends.
Barge board cap-over
Metal flashing covering barge board.
Purlin
A strong horizontal plank, bracing the roof longitudinally and supporting the roof covering.