Glossary

Abutment Joints
Abutment joints occur where dissimilar materials touch without interweaving and allow for movement between the two materials (e.g. old foundations to new foundations, old brick to new brick).

Adjustable Fit
Because it is impossible to maintain perfect dimensional accuracy during construction, building components that must be positioned accurately should be detailed so that it's position can be adjusted during and after assembly.

Air Barrier Surfaces
The airtight surface that a building is wrapped in to reduce leakage through small openings e.g. asphalt-saturated felt (building paper), house wrap, Tyvek, portland cement parge, asphaltic mastic.

Airtight, Heavy, Limp Partitions
Airtight, heavy, limp partitions reduce the transfer of sound by not allowing sound waves to travel through them in the air, absorbing sound waves with their mass and diffusing sound waves by being soft (e.g. resilient channels, sound attenuation blankets, offset studs).

Building Separation Joints
Buildings that are large and horizontal are often broken into smaller, separate structural entities which can react independently to settlement, etc. The joints where the various pieces of the building butt together are building separation joints.

Butt Joint
Butt joints are the joints between two materials simply aligned together (not interlocking). They should be 90 degree joints if possible, and are often augmented with a reveal separating the two materials.

Capillary Break
A crack (opening) in a building assembly that is enlarged internally (1/4" min.) to prevent a drop of water from bridging it, thus preventing "capillary action".

Chemical Change Movement
Chemical change movement takes place as certain materials age and chemical processes occur within the material (e.g. gypsum plaster expands from a slurry to a solid, rebar that corrodes expands, many sealants shrink).

Clean Edge
Edges of materials that are detailed neatly and decisively to protect the material from damage and facilitate simple installation (e.g. chamfered edges, rounded edges, gypsum board corner beads).

Cold Roof
The outside surface of roofs in snowy climates must kept cold in winter to prevent snow from melting and creating ice dams which can damage flashings, shingles, etc. This is achieved by venting the underside of the roof with outdoor air. Common sources of venting are vented eaves & ridges with vent spacers.

Condensate Drainage
The application of channels and weep holes that allow gravity to remove moisture without damage to the building.

Contributive Details
Contributive details are those that add to the formal and spatial theme of the building (e.g. doric columns in a neo-classical buildings instead of HSS steel columns).

Control Joints
Control joints are intentional lines of weakness placed on the surfaces of brittle materials that tend to shrink, and control where the cracking occurs to keep the overall material stable (e.g. sidewalk control joints, around columns and to separate bays in poured concrete floors).

Cushioned Floors
Cushioned floors, which should also be airtight heavy and limp impede the transfer of sound by absorbing / diffusing sound waves and absorbing impact noise such as mechanical equipment. Floating floors, with a sub-floor separated from the finished floor by absorptive material (usually rubber) are another alternative, although usually of commercial application.

Dimensional Tolerance
The maximum amount by which a dimension can be expected to vary from the intended measurement because of inaccuracies in manufacture and installation. Details must be planned to allow for slight variance in size between drawings and site (e.g. shop-fabricated millwork made to fit in a nook).

Drain & Weep
The practice of providing methods for collecting and conducting away any water that leaks through the outer layer of a building assembly e.g. weep holes and flashing in masonry veneer walls.

Equalizing Cross Grain
Wood shrinks and swells across it's grain as it's moisture content changes, but very little along it's grain. To ensure balance, detail with equal amounts of cross grain wood on both sides of the building, and allow for movement in cross grain wood.

Expansion Joints
The joints that divide large surfaces of materials that expand after installation into smaller surfaces to prevent damage (e.g. joints in brick walls, joints at corners, openings, changes in height and pilaster in concrete walls).

Forgiving Surface
Surfaces that facilitate easy construction by concealing or camouflaging minor inaccuracies and blemishes (stippled ceilings, textured concrete, brick dimensional & colour variation).

Formal Transitions
Transitions between portions of a building that help to unify the composition of the building elements and create an improved aesthetic (e.g. buttresses, columns under vertical transitions).

Foundations Below Frost Line
Foundations must be placed below the frost line (deepest portion of soil to freeze during winter) to prevent frost heaving (lifting action caused by expansion of frozen water in soil).

Foundation Drainage
The process of removing water from the soil around a basement to prevent leaking e.g. sloping grade for surface drainage, foundation drainage (weeping tile & gravel)).

Foundation Settlement
Foundation settlement is the movement that occurs when a building's weight causes it to deflect or move. All buildings settle, and minor uniform settlement is acceptable, but differential settlement (portions of the same building settling different amounts) must be avoided or detailed for.

Intensification and Ornamentation
The process of embellishing details to improve the aesthetic of a building - simpler is not always better (e.g. patterns and textures in stonework, railing and baluster profiles).

Labyrinth
The construction of joints in building assemblies with a jog in them to prevent momentum allowing rain or snow to penetrate in a straight line e.g. labyrinth joint, baffle, astragal.

Laminated Glass
Clear plastic polyvinyl butyral sheet is sandwiched under heat and pressure between sheets of glass. When shattered, particles adhere to the plastic film and the break size is minimized.

Moisture Movement
The movement caused by change in moisture content in porous materials that causes them to shrink or swell (e.g. wood, plaster, concrete).

Multiple Glazing
The installation of two or more layers of glass with a space in between (often filled with inert gas) to improve the thermal efficiency of the windows.

Outside-Insulated Thermal Masses
Massive materials such as concrete, masonry and earth can be used to store large quantities of heat which is then harnessed to regulate building temperature.

Overhang & Drip
The process of preventing water from penetrating a building assembly through an opening by creating an overhang (drip edge) or continuous groove on the underside of the opening to cause the water to drip e.g. window sills.

Overlap
The practice of extending a higher surface over a lower surface to prevent the movement of water through the assembly by gravity (used on sloping or vertical assemblies) e.g. asphalt shingles, wood siding, flashing at door head, reglets above horizontal surfaces.

Phase Change Movement
The movement that occurs as a material changes phase (e.g. water expands as it changes phase from liquid to solid).

Progressive Finish
The process of detailing so that each stage of construction use a material that is more "finished", delaying the installation of final finished materials until the end of construction.

Quiet Attachments
Quiet attachments are connections that do not easily transfer noise. They can do so by eliminating movement, as in the case of screwed & glued sub-flooring, or by absorbing and diffusing noise when movement occurs, such as plastic or rubber hanging brackets for plumbing that is likely to vibrate.

Rainscreen Assembly
A building assembly that prevents water from penetrating by blocking air currents that push water through the assembly. Rainscreen assemblies are made of a rainscreen (outer wall surface), air barrier (interior) and pressure equalization chamber (P.E.C.) large enough to act as a capillary break in the middle.

Reflective Glazing
Windows that are reflective can turn away most solar heat before it enters a building, increasing the thermal efficiency of the building.

Reflective Surface and Airspaces
Reflective surfaces and airspaces such as a metal sheet or foil can be used to reflect away radiant heat energy. When used within a building envelope, these surfaces must face a clear airspace 1/2" thick minimum.

Relieved Back
Wood tends to cup (warp across grain) as it dries, damaging materials such as wood flooring, plastic laminated counters, door frames, etc. To reduce this, grooves or shapes are cut longitudinally into the back profile of wood, the back is paint primed, or back facing is adhered to the back profile of laminated wood.

Reveal
Reveals are recesses or offsets between two materials that relieve the contractor of having to exactly align the materials (e.g. reveal on railing cap). They also cast shadows that can underscore the joint for aesthetics and cover minor defects (e.g. reveal between drywall and frame of flush-framed doorway). Lastly, reveals prevent materials from bleeding their finish onto each other (e.g. joint between solid wood countertop and veneered vertical surface below of contrasting colour).

Sealant Joints and Gaskets
Elastic material placed in a joint to prevent the passage of air and/or water while allowing the two sides of the joint to move independently from each other. Gaskets are usually strips of synthetic rubber compressed into the joint which function by pressing outward against the two sides of the joint. Sealants are usually mastic materials injected into the joint that cure to a rubber state and function by adhering to the sides of the joint.

Seasoning and Curing
Refers to the fact that many porous construction materials should be seasoned or cured for a period of time before installation to allow their moisture content and size to stabilize (e.g. wood).

Sliding Fit
Sliding fit details allow one component of a building to overlap another, creating a very forgiving joint (e.g. baseboard with quarter round).

Sliding Joints
Sliding joints allow components of an assembly to slide past each other as they expand and contract with changing moisture content (e.g. horizontal wood siding).

Sound Absorbing Surfaces
Sound absorbing surfaces are soft, porous, thick materials that absorb most sound (e.g. carpet, laid in acoustic ceiling tiles, "eggcrate" walls in music / television studios). The porosity of the material breaks up sound waves, while the thickness and softness absorb the sound intensity and eliminate it's transfer to the other side of the material.

Structural Creep
The characteristic of materials such as wood and concrete whereby they sag in the first several years of the building's life, and then become dimensionally stabile.

Structural Deflection
The bending movement that building components such as beams, slabs, trusses and arches undergo as the load on them changes.

Structure / Enclosure Joints
The joints between the structural frame and infill components of a building, allowing them to move independently (e.g. joint between foundation wall and basement concrete slab).

Temperature Movement
The expansion and contraction that occurs within a building component due to rising and falling temperatures.

Tempered Glass
Tempered glass is produced by reheating and rapidly cooling annealed glass, which results in glass that is both stronger and more resistant to thermal stress. However, it's size cannot be altered after fabrication, so the manufacturer must provide the glass in the exact size and shape.

Thermal Breaks
Thermal breaks are strips of insulating material inserted into a building assembly to prevent rapid heat conduction through dense, highly conductive materials such as metal and masonry (e.g. rigid insulation over studs).

Thermal Insulation
Thermal insulation is low density material with many small pockets that trap and hold air. It is installed in building envelopes to reduce energy consumption and to maintain comfortable interior surface temperature.

Upstand
A dam constructed to prevent the passage of water forced by gravity or air through a horizontal joint e.g. sliding glass door sill.

Vapour Ventilation
Water vapour must be given an easy escape route from the cold side of any vapour retarder to reduce the chance that small amounts of moisture will be trapped and cause damage.

Vertical-grain Lumber
Lumber that has been sawn from the log in such a way that the growth ring of the wood runs perpendicular to the surface of the board to retain it's flat finish.

Warm Interior Surfaces
Surfaces inside a building should be detailed to ensure that their surface temperature remains above the dew point temperature of the air (e.g. pipe and duct insulation, basement wall insulation).

Warm-side Vapour Retarders
Vapour retarders (e.g. 6mil. polyethylene, vapour retardant paint) should be installed on the warm side of insulating materials to ensure that warm moisture laden air cannot travel through an insulating system to the cool side and condense inside the insulation causing damage.

White and Bright Surfaces
White and bright surfaces can reflect radiant heat (sun) from the surface of a building, reducing cooling costs.

Wash
A sloped surface used to drain water away from vulnerable portions of the building assembly e.g. window sills.

Weatherstripped Crack
A crack (joint) around an operable opening (door or window) in a building assembly protected with weatherstripping to prevent air from blowing through.