Air Barrier (System) – Materials and components that together provide a barrier to air through an assembly and thus limit the potential for heat loss and condensation due to air movement.

Addendum – A change to the bid package (usually a modification of the drawings and specifications) issued during the bid period and before execution of the contract.

Assembly – The collective layers of components and materials, which together comprise the complete cross section of the wall or roof.

Balcony – A horizontal surface exposed to outdoors, and intended for pedestrian use, but projected from the building so that it is not located over a living space or acting as a roof.

Base Flashing – The part of the roofing that is turned up at the intersection of a roof with a wall or another roof penetration. It may be made of the same material as the main roofing membrane or of a compatible material.

BEP – Building Envelope Professional.  The Building Envelope Professional reviews the building envelope design and reports to the project architect or co-coordinating registered professional with respect to environmental separation and the performance of materials, components, and assemblies of the building envelope.

Blackberry (sometimes referred to as Blueberry or Tar-Boil): a small bubble or blister in the flood coating of an aggregate-surfaced built-up roof membrane.

Building Envelope – Those parts of the building which separate inside conditioned space from unconditioned or outside space, and includes windows, doors, walls, roofs, and foundations.

Cap Flashing – Sheds water from the tops of walls.  Cap flashing must be sloped toward the roof to prevent staining of the exterior cladding.  It is difficult to make metal cap flashing waterproof at joints and intersections, and it therefore requires a secondary, continuous, and waterproof membrane below it.

Capital Cost Reserve Fund Study – See Reserve Fund Study

Cladding – A material or component of the wall assembly which forms the outer surface of the wall and is exposed to the full force of the environment.

Control Joint – An assembly or part of an assembly installed to control movements and cracking by expanding and contracting.  Often found in stucco cladding and concrete slabs.

Cross Cavity Flashing – Intercepts and directs any water flowing down the cavity of a wall assembly to the exterior.

Deck – A Horizontal surface exposed to outdoors, located over a living space, and intended for pedestrian use in addition to performing the function of a roof.

Deflection – A water management principle that utilizes features of the building and assembly geometry to limit the exposure of the assemblies to rain.

Depreciation Report – See Reserve Fund Study

Drainage – A water management principle that utilizes surfaces of the assemblies to drain water away from the assembly.

Drip Flashing – Directs water flowing down the face of vertical elements, such as walls or windows, away from the surface so that it does not continue to run down the surface below the element.

Drying – A water management principle that incorporates features and materials that speed diffusion and evaporation of moisture from materials that get wet.

Durability – The ability of a material, components, assembly or building to perform its required functions in its service environment over a period of time without unforeseen maintenance, repair or renewal.

Efflorescence – A white, chalky or sometimes hard stain which is formed on concrete and masonry when water dispersible materials such as salts come to the surface and dry.

Elevation – A term used to describe a wall or side of a building.  The direction preceding the word “elevation”, as in “north elevation” is the direction that the wall is facing and the direction you would be looking if you were in the building looking straight outside.

Face Seal – A strategy for rain penetration control that relies on the elimination of holes through the cladding.

Fascia – A board installed across the ends of the rafters at the eaves or between the top of the siding and the bottom of a soffit.

Field Applied Preservatives – Wood preservatives commonly applied at the job site using brush, spray, roller or other non-pressure method for protection against wood decay.

Fire Wall – A type of noncombustible fire separation which subdivides a building or separates adjoining buildings to resist the spread of fire.

Flashing – Materials used to deflect water and make waterproof connections at interfaces and joints within and between wall and roof assemblies.

Frieze Board – A horizontal exterior trim member positioned between the siding of a structure and its soffit.

Guards – A protective barrier used to prevent falls from one level to another.  Often referred to as guard rails but that is technically just one part.

Kiln Dried (KD) – Designation added by lumber manufacturers to indicate that the wood was dried in a kiln, a process that involves the rapid removal of moisture by the use of high temperatures.  Kiln-dried wood has a moisture content of 19 per cent or less, usually between 15 and 19 per cent.

Living Space – The interior of a dwelling or building that is separated from the exterior by the building envelope.

Maintenance – A regular process of inspection, minor repairs and replacement of components of the building envelope to maintain a desired level of performance for the intended service life without unforeseen renewal activities.

Mansard Roof – A roof style with a steeper lower part, originally used in France.  The term is also used for a sloped roof overhang at the perimeter of a building that drops down to a flat roof over the rest of the building.  The drop is a mansard wall.  The framing cross section is often a triangle.

Moisture Barrier – The moisture barrier is the surface farthest from the exterior which can accommodate moisture without incurring damage to the assembly.

Moisture Content (MC) – The amount of water in a material such as wood, expressed as a percentage of the oven-dry weight of the material.

Parapet Wall – A low wall on the edge of a balcony or roof.

Partition Wall – An interior wall that is not typically load bearing.  Usually this refers to walls between rooms inside of a suite.

Party Wall – A wall jointly used by two suites.

Patio – An outdoor area used by the occupants of the adjacent suite and situated over the parkade or on soil.  The floor is usually finished with concrete or pavers.

Penetration – An intentional opening through an assembly in which ducts, electrical wires, pipes, and fasteners are run from inside to outside.

Pressure-treated Wood – Wood that has been treated with chemical preservatives, injected at high pressure, for protection against wood decay and termite attack.

Privacy Wall – A wall that provides a visual barrier, such as the wall between two adjacent balconies.

Rainscreen – A strategy for rain penetration control that relies on deflection of the majority of water at the cladding but also incorporates a cavity that provides a drainage path for water that penetrates beyond the cladding.

Rehabilitate – A program of comprehensive, overall improvements to building envelope assemblies and details so the building can fulfil its originally intended functions.

Renewals – Activities associated with the expected replacement of worn out components or materials of a building envelope and are typically for items with life cycles in excess of one year.

Repair – Replacement or reconstruction of envelope assemblies, components, or materials at specific localized areas of the building envelope so that it can fulfill its originally intended functions.

Reserve Fund Study – Also known as a Depreciation Report.  A study of the expected maintenance and renewal costs of a building over an extended time period, including, but not limited to, annual and lump sum contribution scenarios.

Roof Deck – A flat open area over living space, such as a terrace or a sundeck.

Saddle – The junction or transition of a horizontal surface, such as a balcony floor or the top of a parapet wall, with a vertical surface, such as the exterior wall of the building.

Scupper – An outlet through the side of a building or wall that is used to drain water.  They are commonly a metal box shape or a round pipe.  Scupper drains are the primary drain for water while overflow scuppers only flow when the primary drain is plugged.

Sheathing – A material (generally oriented strand board (OSB) or plywood) used to provide structural stiffness to the wall framing and to provide structural backing for the cladding and sheathing paper.

Sheathing Membrane – A material in an exterior wall assembly whose purpose is to retard penetration of water further into the structure once past the cladding. Waterproof type sheathing membranes can also perform the function of the air barrier and the vapour barrier. These materials include both breather type sheathing membranes such as building paper, house wraps (like Tyvek or Typar), and waterproof sheathing membranes.

Slab Band A thickening in a suspended slab where a concentration of reinforcing steel also exists.  These are located where concentrated loads such as building walls exist above.  Slab bands span between columns.

Soffit – The underside of a structure such as a balcony or roof overhang.

Spalling – a fragment of concrete that becomes loose or falls, usually due to corroded reinforcing steel in the structure.

Strapping – Vertically oriented lumber (usually pressure treated 1 x 2s or strips of pressure-treated plywood) that form the cavity between the cladding and the sheathing paper in a strapped cavity rainscreen wall assembly.

Strata Corporation – Similar to a condominium corporation.  The Strata Property Act replaced the Condominium Act of B.C. in 1999.  The strata corporation has a legal obligation to repair and maintain the common property, common facilities and assets of the strata corporation.

Strata Council – A group of owners elected to carry out the duties of the strata corporation.

Suspended Slab A structural element comprising of concrete and reinforcing steel that usually acts as a floor or roof.  The “ceilings” above parking garages are suspended slabs.

System – Describes a combination of materials and components that perform a particular function such as an air barrier system, or moisture barrier system.

Tar Boil – Small bubble found in the flood coat of an aggregate-surfaced built-up roof; usually the result of trapped moisture vapor encased in a thin film of bitumen. Tar Boils are also known as blueberries or blackberries.  A term sometimes used to describe weather blisters. These are small surface blisters, which can be seen in large numbers over the entire roof area, more predominant during warm weather where roofs are exposed directly to the sun, and which are a result of natural weathering of the surface bitumen. Volatiles and water vapor in the bitumen tend to be driven off by heat, and when the gases are trapped they form small blisters. This type of blistering usually does not cause any failure during the normal life of the roof. Also called pimpling, pin blistering and bitumen bubbling.

Thermal Break – A building element that has low thermal conductivity and reduces the flow of thermal energy (hot or cold) through the assembly.  In a window, the thermal break is intended to keep the inside of the frame warm and prevent condensation on the inside face of the window.

Through-wall Flashing – A water proof membrane or metal flashing placed under segmented precast concrete, stone masonry or brick units known as copings close to the tops of masonry walls to prevent water from entering the wall at joints in the coping. Through-wall flashing is also used to prevent capillary transfer of moisture through porous materials such as concrete or masonry if they extend from high moisture locations such as below grade.

Vapour Barrier (also vapour diffusion retarder) – A material with low vapour permeability that is located within the assembly to control the flow of water vapour and limit the potential for condensation due to diffusion.

Warranty – An agreement that provides assurance by a warranty provider (insurance program or contractor) to the owner that the warrantor will assume stipulated responsibilities for correction of defects and failure to meet specific performance criteria within a stated period.

Water Ingress – The act of water leakage or penetration into a building or other object.

© 2011. These definitions were reproduced, in part, from CMHC documentation and with their permission.


What People Are Saying

"I found Touwslager Engineering a highly technically qualified firm, really dedicated and 100% reliable throughout the lengthy and complicated process..."


Connect With Us

Touwslager Engineering Ltd.
829 East 14th Avenue
Vancouver, B.C.
Canada V5T 2N5

Telephone (604) 618-4367