Abdomen. The region of an insect's body furthest from the head.
Adfreezing. Ground adjacent to the foundation attaching itself to the foundation during freezing, and then lifting the top portion of the foundation wall in the process of heaving.
AFCI. Acronym for Arc Fault Circuit Interrupter. A special kind of electrical outlet providing protection against arcing (unintended electricity jumping from one conductor to another over a gap or supposed insulator).
Air Gap. A space (of air) of at least one inch between a water supply faucet and the highest possible water level of its fixture.
Ampere. A measure of electrical flow directly proportional to voltage and inversely proportional to resistance.
Anchor Bolts. Bolts firmly anchored into the foundation wall that hold the sill down.
Anchorage. The securing of the roof structure to the rest of the building.
Antennae. A pair of sensory organs mounted on an insect's head above the mouth.
Anticipator. A small heater built into the thermostat designed to shut the furnace off a little before room temperature reaches the thermostat setting so that leftover heat after furnace shutoff does not make the house too warm.
Arch. A curved masonry structure used to span the top of a window or door opening.
Asbestos Cement. A kind of siding made up of light concrete reinforced with asbestos fibers and typically formed into shingles.
Asphalt Plastic Cement. An elastic cement used to secure nail heads in roll roofing and other applications.
Asphalt Shingles. Typically 36 inches by 12 inches by 1/8 inch thick. The exposure is usually 5 inches of the 12, with a head lap of 2 inches. Designed for slopes 4 in 12 and greater. Weight per square is 200-430 pounds and life expectancy is 12-25 years.
Automatic Vent Damper. An electronically controlled flap between furnace exhaust and chimney that closes (almost completely) when the furnace is not in use to prevent warm air from leaking out the chimney.
Awning Window. A type of window in which the upper portion is fixed and a bottom section hinged at the top opens out.
Backdraft. Exhaust gases and other combustion products from a furnace spilling out into the room instead of being drafted up through the chimney. Can be caused by inadequate Dilution Air, chimney obstruction, oversized chimney, or low inside pressure from exhaust fans or fireplaces.
Backfill. Earth (and potentially other material) used to fill in the space behind a foundation or retaining wall.
Backflow. A reverse in flow from that intended resulting from negative relative pressure.
Back Siphonage. A kind of backflow caused by atmospheric pressure exceeding that of the potable water supply. Requires a partial vacuum.
Baffle. A helical steel strip inside the flue of a fuel water heater designed to slow exhaust fumes and maximize heat transfer to the water.
Balloon Framing. Wall studs are continuous for the entire building height, passing through each floor system and resting on the sill plates or foundation. Contrast with Platform Framing.
Baluster. A vertical strip running from floor to guardrail. Also known as Spindle. Codes often require adjacent balusters to be no more than 4 inches apart.
Barometric Damper. A device mounted on the exhaust flue of an oil furnace to ensure adequate draft air. Analogous to a Draft Hood for a gas furnace.
Base Coat. See Scratch Coat.
Base Flashing. The flashing at roof/wall and roof/chimney junctures that is secured to the roof decking (in between shingles) and extends several inches up the vertical surface.
Basement. The full-height space between (bottom) floor and finished grade and surrounded by foundation walls.
Basement Walk-out. Exterior basement access via stairwell. If added after construction, frost may now be able to get lower than before and cause heaving.
Beam. A large horizontal member designed to transfer loads from floors, walls, and roofs to columns and foundation walls.
Bell Trap. A type of trap used primarily for floor drains consisting of a basin with a vertical exit pipe at its bottom and an inverted cup (or bell) positioned over the pipe just below the grate. Drain water is diverted into the basin by the bell and doesn't flow out until the water level exceeds the height of the pipe. It is not permitted for residential use because it is unreliable.
Bench Footings. Essentially curbs poured inside of and below the existing foundation as a technique for lowering basement floors.
Bevel. A horizontal wood siding using boards thicker at the bottom than at the top.
Bird Mouth. A notch in the end (toe) of a rafter to accommodate resting against the top plate. See Toe Bearing.
Board and Batten. A wood siding consisting of vertical planks with narrower strips (battens) over the joints between planks.
Bonding. A system for shunting voltage built up on unintended conductors (e.g., water pipes) directly to equipment ground to protect from electrical shock.
Borate. A chemical treatment for killing wood-feeding insects and fungi.
Bowing. Foundation bend with the arc of the bend horizontal.
Branch Vent. A pipe that joins individual vents to a stack.
Brown Coat. The second layer of stucco in a three-coat job, about 3/8 inch thick.
BTU. Acronym for British Thermal Unit. A measure of heat capacity equivalent to the heat needed to raise the temperature of one pound of water one degree Fahrenheit.
Buckling. A kind of column collapse caused by a too-slender column for its height and loading.
Building Drain. The lowest pipe in or under a home that carries sewage to the building sewer.
Building Paper. A thin breathable material put between sheathing and siding to deter or prevent water and/or wind penetration from the outside while allowing vapors on its inside to escape.
Building Sewer. The pipe that carries sewage from the building drain to the public sewer.
Built-up Beams. Nailed- or bolted-together dimensional lumber designed to be used in place of a single solid beam.
Built-Up Roofing. A type of flat roofing made up of layers (plies) of fibrous felts, each layer embedded in a full bed of hot asphalt. A top coat of gravel embedded in a flood coat of asphalt helps protect against deterioration from ultraviolet light.
Bulging. Foundation bend with the arc of the bend vertical.
Butterfly Roof. Like an upside down gable roof. Hence, it has a center valley instead of ridge.
Buttress. A large mass placed against a wall to resist movement.
B Vent. A double-wall metal chimney vent for gas or propane appliances, designed to operate up to 350° to 500°F.
Caissons. Foundation systems consisting of drilled-out holes refilled with concrete.
Cantilever. A joist extending past the last supporting beam, creating an unsupported end subject to deflection. Most codes limit the extension length to two feet or one-sixth the overall joist length.
Cap Flashing. Same as Counter Flashing.
Capillary Break. A discontinuity to break surface tension so that water doesn't flow back into the wall. Grooving the underside of window sills is a common way to achieve capillary break. Also known as Drip Edge.
Casement Window. A single-section window hinged on one side and opened (often with a crank) in or out. Some casement windows open out using pivots offset from the side instead of hinges.
Cavity Wall. A masonry wall of at least two wythes with air space between that provides a kind of moisture barrier and insulation. Metal ties usually join the inner and outer wythes.
Ceiling Joist. A horizontal board used with rafters and roof joists, often tying the bottoms of opposing rafters together.
Cellulose. Fibrous material used to form cell walls in plants.
Channel and Drop. Like shiplap but with boards having a wider notch end so that after overlap there is a visible channel. Can be horizontal or vertical.
Chimney Flashing. A combination of base flashing secured to the roof deck and cap flashing secured to the masonry. Typically made of galvanized steel, lead, or copper.
Chord. A top or bottom member of the main truss triangle or of an I-joist.
Cinder Block. Block made from slag. It is rougher, darker, weaker, and less moisture resistant than concrete block.
Circuit Breaker. An over-current protection device that breaks its circuit when amperage exceeds a certain level by physically tripping a switch.
Cladding. Material used for surfacing a frame building. Same as Siding.
Clapboard. See Bevel.
Clay Tile, curved Mission. A two-piece system with similarly shaped pans and covers. Typically 7 inches by 13 inches (or larger) by 1/4 to 1/2 inches thick. The exposure is more than 50%, with no head lap. Designed for slopes 4 in 12 and greater. Weight per square is 1000-1300 pounds and life expectancy is up to 350 years.
Clay Tile, curved Spanish. Each piece has a pan and cover with interlocking sides. Typically 7 inches by 13 inches (or larger) by 1/4 to 1/2 inches thick. The exposure is more than 50%, with no head lap. Designed for slopes 4 in 12 and greater. Weight per square is 850-1000 pounds and life expectancy is up to 350 years.
Clay Tile, flat interlocking. Essentially a single-layer system. Typically 7 inches by 13 inches (or larger) by 1/4 to 1/2 inches thick. The exposure is 80-90%, with no head lap. Designed for slopes 4 in 12 and greater. Weight per square is 800-1200 pounds and life expectancy is up to 350 years.
Clay Tile, flat shingle. Similar to slate ribbons. Typically 7 inches by 13 inches (or larger) by 1/4 to 1/2 inches thick. The exposure is less than 50%, with a head lap of 3 inches. Designed for slopes 4 in 12 and greater. Weight per square is up to 1700 pounds and life expectancy is up to 350 years.
Closed Valley. A roof valley whose valley flashing is covered by roofing material, typically asphalt shingles. The shingles may be half-woven (closed cut) or fully woven.
Cold Joint. A visible line, horizontal or nearly horizontal, between two portions of a foundation wall poured at separate times. It is often difficult to differentiate a cold joint from a crack.
Cold Pour. See Cold Joint.
Collar Tie. A method for reducing rafter span by tying opposing rafters at their midpoints with a horizontal on-edge board. Helps to prevent rafter sag (not rafter spread).
Column. A vertical pillar made of wood, steel, brick, or concrete designed to transfer loads from beams down through footings to soil.
Combustion Air. Air used to supply oxygen to the flame of a furnace or water heater. Small surrounding enclosures may have inadequate combustion air.
Complex Metamorphosis. A transformative process some insects undergo consisting of four stages: Egg, Larva, Pupa, and Adult.
Compressor. That portion of an air conditioning system that raises (gas) Refrigerant temperature much higher than outside air by compressing it.
Concentrated Loads. The funneling of weight from live and dead loads onto a single point or column.
Concrete Tile. Comes in curved, Spanish, flat interlocking, and flat shingle styles. Typically 14 inches by 10 inches by 1/2 to 3/4 inches thick. The exposure is less than 50% for flat shingles and more than 50% for the other styles. Flat shingles have a head lap of 2-4 inches; the other styles have no head lap. Designed for slopes 3 in 12 and greater. Weight per square is 900-2000 pounds and life expectancy is 50 years plus.
Condensate. Liquefied combustion exhaust produced by a Condensing Furnace, or moisture dripping off the Evaporator Coil in an air conditioner.
Condenser Coil. The outdoor coil of air conditioner piping where compressed Refrigerant is converted from gas to liquid (exploiting the Latent Heat of vaporization) as it cools.
Condensing Furnace. A furnace with an extra long Heat Exchanger (or two or three Heat Exchangers, all coiled within the combustion chamber) to maximize heat transfer and to exploit the latent heat of vaporization generated when the cooling exhaust gases condense. It requires stainless steel Heat Exchangers to protect them from the slightly acidic Condensate and a way to drain the Condensate. Efficiency percentage is roughly in the 90's.
Conducive Conditions. Conditions, usually moisture-related, that might enable or enhance an infestation of wood-destroying organisms.
Conduction. Transfer of heat through direct contact.
Conductor. Anything that allows electrical current to flow through it easily.
Control Joints. Vertically notched-out portions of concrete walls intentionally made weak so that shrinkage cracks will develop there and not elsewhere. The notches are pre-patched with caulking or sealant to prevent leaks.
Convection. Transfer of heat within a gas or liquid caused by masses of different temperature having different densities.
Corbelling. A masonry practice of staggering bricks so that higher bricks project out further than lower bricks.
Counter Flashing. The flashing at roof/wall and roof/chimney junctures that is secured to the vertical surface and overlaps the vertical extension of the base flashing.
Crawlspace. The less-than-full-height space between (bottom) floor and finished grade and surrounded by perimeter foundations or occupied by foundation piers.
Creosote. A tar-like byproduct of burning wood with incomplete combustion.
Cricket. A peaked structure (flashed with metal or shingles) placed behind the top of wide chimneys to deflect precipitation around the sides of the chimney.
Cripple Wall. A short stud wall between foundation and first floor that has little resistance to lateral forces. It can be converted into a shearwall by adding plywood or waferboard panels.
Cross Connection. A potential mixing of waste and supply plumbing resulting in the risk of potable water contamination. Typical examples are faucets below high water level (no air gap) and hose ends under water attached to bibbs without backflow prevention.
Crown up. Joists have a natural bend along their length, and the convex side is called the crown. Best practice is to install the joist crown up so that loading tends to straighten it out.
Crown-Vented Trap. A type of trap similar in appearance to the P trap except that the vent is attached directly to the weir instead of at the other end of the trap arm. It is not permitted for residential use because the vent can become obstructed and result in siphoning.
Cut and Fill Lots. Building a house on a sloping lot by cutting into the hill to form a pad for the uphill portion and depositing the removed material to form an extension of the pad on the downhill side. Because the uphill portion is built on undisturbed soil and the downhill part is on fill, the house is prone to differential settlement.
Cutting The Points. The practice of clipping the upper corners of shingles where they join with a valley to facilitate water flow down the valley.
Dead Load. The weight of the building materials and the soil surrounding the foundation.
Delamination. Separation of built-up lumber such as plywood into layers.
Dew Point Temperature. The temperature at which a mass of air with less than 100% relative humidity will reach saturation and condensation will begin to occur.
Differential Settlement. Two or more parts of a building settling at different rates, causing cracks to develop.
Dilution Air. Ambient air required to help maintain chimney draft and to dilute combustion products from a furnace.
Dip Tube. A pipe inside the water heater that carries cold water from its intake at the top of the tank down through the tank and discharges it at the bottom of the tank, close to the flame. (Hot water is drawn from the top of the tank.)
Discharge Tube. A pipe attached to a TPR valve for carrying released water down to a safe location (roughly 6 inches above floor level).
Dormer. An opening in roof framing to accommodate living space jutting out beyond the roof.
Double-hung Window. A type of two-section vertically moving window in which both the top and bottom sashes are operable.
Double Tap. Tying two separate circuits to the same breaker or fuse. Considered improper.
Double Trap. A bad practice consisting of the trap arm from one fixture connected directly to the drain of a second fixture. Flow velocity coming into the second trap is reduced, tending to cause clogging.
Downspout. A vertical pipe for channeling water from gutters down to the peripheral storm drainage system.
Draft Air. See Dilution Air.
Draft Hood. A diverter at the top of a furnace or other gas appliance used to funnel Dilution Air into the chimney.
Drain Pipe. Carries liquids and solids, or, in some areas, liquids only.
Drain, Waste, and Vent (DWV) Piping. Materials may be copper, galvanized steel, lead, PVC, ABS, cast iron, brass, clay.
Drip Cap. A kind of flashing installed over windows and doors that project out beyond wood siding. It is designed to keep water from collecting on the top of the window or door and working its way into the wall.
Drip Edge. See Capillary Break.
Drip Leg. A section of (capped) vertical pipe on a gas supply line below an appliance valve designed to collect sediment before it can clog the valve or burner.
Drip Loop. A bend in the wires from a Service Drop designed to allow water to drip off.
Drip Screed. A metal stop at the bottom of stucco walls whose purpose is to provide a finished edge, to allow drainage, and to prevent water from wicking up into the wall.
Drum Trap. A type of trap consisting of a drum in which drain liquid enters near the bottom and flows out near the top. It is not permitted for residential use because it is not self-scouring.
Dwarf Wall. See Knee Wall.
Eaves. That portion of the roof extending past the wall to form an overhang.
Eccentric Load. A load applied to a column off its center, resulting in a lateral force that tends to make the column buckle, bend, or hinge.
Efflorescence. The appearance of crystallized salts on the surface of brickwork, stone, or concrete resulting from moisture dissolving the salt as it seeps through the substance and then evaporating.
EIFS. Acronym for Exterior Insulation and Finish System. A kind of synthetic stucco wall system comprising a sheathing made of gypsym, OSB, or plywood; expanded polystyrene plastic foam insulation boards adhered or fastened to the sheathing; a base coat reinforced with an embedded glass fiber mesh; and a finish coat.
End Bearing. The size or length of full-width support under the end of a beam or joist. End bearing for beams must be 3.5 inches and for joists must be 1.5 inches.
Engineered Wood. Composite board made by binding derivative wood products (strands, particles, veneers, or fibers) with adhesives.
EPDM. Acronym for Ethylene Propylene Diene Monomer. EPDM is a form of synthetic rubber flat roofing that comes in sheets up to 50 feet wide and 30-60 mils thick.
Escutcheon Plate. A decorative (usually circular) plate with a central hole. Its purpose is to fit over a pipe and fit snug against the floor or wall to hide the hole through which the pipe passes.
Evaporator Coil. The indoor coil of air conditioner piping where Refrigerant is converted from liquid to gas (exploiting the Latent Heat of vaporization), thus drawing heat from the room.
Expansion Device. That portion of an air conditioning system that restricts the flow of Refrigerant in order to reduce its pressure and temperature.
Expansive Soils. Soils that are normally dry but expand perhaps by ten percent of their volume when saturated.
Fan-Assisted Water Heater. A water heater with an alternative venting mechanism in situations where use of a chimney for venting is unavailable or impractical. The fan draws a great deal of room air to dilute the exhaust and cool it to an acceptable temperature. It is typically vented through the sidewall.
Fascia. A vertical board at the end of rafters, often used for mounting gutters.
Feather-Edge. See Bevel.
Fiberboard. A kind of engineered wood product composed of wood fibers that are formed into panels using high temperature and pressure. Low-density fiberboard is called Particle Board and high-density fiberboard is known as Hardboard.
Fiber-Cement. A kind of siding made up of Portland cement, ground sand, cellulose fiber, additives, and water. It comes in panels or planks.
Fiber Cement Shingles. Typically 16 by 8, 22 by 5, 48 by 12, or 18 by 9 inches by 1/4 to 5/32 inches thick. The exposure is 7-8 inches, with a head lap of at least 2 inches. Designed for slopes 3 in 12 or 4 in 12 and greater. Weight per square is 350-600 pounds and life expectancy is 30-50 years.
Finish Coat. The final and decorative layer of stucco, at least 1/8 inch thick. It may be colored and/or textured.
Fire-cut Joist. This term applies only to joists embedded in solid masonry walls. The joist end is cut on a taper so that its bottom is longer than its top. This helps prevent the joist from acting as a lever to push out the masonry wall in case of fire.
Fixed Window. A window type that doesn't open. May be paned or blocks.
Flat Roof. Any single-sectioned roof with a slope less than 2 in 12.
Forced Air. A common method for distributing heat throughout a house by means of ducts and registers.
Forced-Draft. A type of burner for a furnace or water heater that forces air and/or gas through a piping system by means of a fan at its input.
Foundation Irrigation. A preventative technique of keeping expansive clay-based soils wet lest their shrinkage from drying out causes foundation movement.
Frass. Larval insect excrement similar in appearance and feel to granular or fine sawdust. The term is also used for byproducts of insect feeding or tunneling activity in wood or insulation.
Frost Heave. The frost line getting below footings (for various reasons), resulting in expanding soil applying upward pressure on them and causing cracks.
Fuse. An over-current protection device that breaks its circuit when amperage exceeds a certain level by burning up a thin filament.
Gable Roof. A long, symmetric, sloped roof with a single ridge in the center and its cross-section resembling an upside-down "V." Both end walls extend up to the roof peak.
Gable Vent. An opening in the top of a gable designed to facilitate attic ventilation.
Gallery. A tunnel or group of tunnels formed by wood-boring insects.
Gambrel Roof. A long, symmetric, sloped roof with a single center ridge and two side ridges parallel to the center, resulting in two central sections with a relatively shallow slope and two side sections with a rather steep slope. The cross-section resembles more of an upside-down "U" than the upside-down "V" of the gable roof.
GFCI. Acronym for Ground Fault Circuit Interrupter. A special kind of electrical receptacle with built-in Ground Fault protection.
Girder. See Beam.
Girt. A horizontal block between studs near their midpoint to resist buckling.
Glulam. Short for Glued Laminated timber. A kind of engineered wood product composed of several layers of board glued together.
Grade Beams. Concrete beams supported on footings, piles, or piers and situated at, slightly above, or slightly below grade.
Gravity Furnace. A furnace that relies on ?z, or gravity, for air circulation instead of fan.
Ground Fault. A kind of short circuit in which electricity takes an unintended alternative path from hot to ground instead of through the intended hot-to-neutral circuit.
Grounding. A system for shunting voltage surges from lightning and other sources directly to utility ground to protect the house's electrical equipment.
Guardrail. A barrier at the edge of a landing, deck, or balcony to prevent people from falling off.
Gusset Plate. A metal or plywood connector joining truss chords and webs.
Gutter. A near-horizontal trough positioned at the eaves to channel away water draining off the roof.
Handrail. A support for holding while going up or down stairs.
Hardboard. See Fiberboard.
H-clip. A piece of hardware the provides edge support for panel-type roof sheathing.
Header. A brick turned into the wall and spanning two wythes.
Head Lap. The amount of a shingle width directly above the shingle two rows below. Typically it is 2 inches (12 inches minus two times 5-inch offsets).
Heat Exchanger. A metal air channel or duct with relatively large surface area encased in a furnace combustion chamber. Heat in the chamber is transferred to the house air being circulated through the channel.
Heat Pump. Essentially an air conditioner used as a heater by reversing Refrigerant flow direction. May require an auxiliary back-up heating system if the differential temperature between indoors and outdoors is too great.
Heel Bearing. Rafter support accomplished by notching its bottom (heel) and resting the notch on the outside of the top plate. Considered proper practice.
Helical Anchors. Screws turned into soil with plates attached to the foundation, either as a form of underpinning or as a lateral tie-back.
High-efficiency Furnace. See Condensing Furnace.
High-efficiency Water Heater. A water heater that achieves 85%-95% efficiency (vs. the conventional water heater's 55%-60%) by means of an elaborate heat exchanger in the tank, better insulation, and a forced-draft burner. Combustion air is often directly vented from outside and exhaust temperatures range from 100°F to 150°F (vs. conventional heater's 300°F to 500°F). Produces condensate and may have the dual purpose of heating space.
Hip Rafter. A rafter accommodating change in direction and forming the frame of a sloped corner ridge of a hip roof.
Hip Roof. Differs from a gable roof only at the ends. In a hip roof, the end walls are no higher than the side walls and triangular roof sections at each end slope up to join the center peak. A hip roof has a center ridge and four sloped corner ridges.
Honeycombing. Large bubbling or voids in poured concrete walls appearing as aggregate surrounded by air or concrete missing its cement. It is typically caused by insufficient consolidation prior to pouring, and it is a sign of weakness both in terms of support and potential moisture penetration.
Hopper Window. A type of window in which the upper portion is fixed and a bottom section hinged at the bottom, may open in or out.
Horizontal Crack. Foundation crack that signifies a serious structural failing (bowing, bulging, and/or leaning) caused by lateral thrust.
Horizontal Slider. A type of two-section horizontally moving window in which one or both sections slide open.
Housewrap. A spun polyolefin fabric placed between sheathing and siding with the same purpose as Building Paper.
Hydrostatic Pressure. Increased lateral or upwards pressure on foundations due to soil saturation.
Ice Dam. A formation of ice caused by escaped heat from the house into the attic melting snow on the upper reaches of a roof and the melt re-freezing as it reaches the colder eaves (where no heat loss occurs). Ice dams are a common cause of leakage.
I-Joist. An engineered wood member comprising a top and bottom chord usually made of solid wood or LVL and a web connecting them made of plywood, waferboard, OSB, or metal.
Induced-Draft. A type of burner for a furnace or water heater that forces air and/or exhaust through a piping system by means of a suction fan at its output.
Insulation. A material that slows the rate of heat flow.
Insulator. Anything through which electrical current does not flow easily. The opposite of Conductor.
Jack Rafter. A shortened rafter connecting a hip or valley rafter either to the roof ridge or the top plate.
Jack Stud. A less-than-full-height stud for supporting a lintel. It is adjacent to the full-height stud defining the doorway.
Jalousie Window. A window that consists of a series of louvers, each louver hinged at the top and opening outward. The louvers are typically operated as a unit.
J Molding. A termination strip for metal or vinyl siding where it junctures with the tops and sides of windows.
Joist. Essentially a small beam designed to transfer live and dead floor loads to beams, walls, headers, sills, and foundation walls.
Joist Hanger. A metal bracket used to provide end bearing support for joists that are butted up against a ledger board.
Knee Wall. A method for reducing rafter span and preventing rafter sag by building a short stud-wall between the ceiling joists and rafter midpoints. It is vertical or up to 45° off vertical. Also called Dwarf Wall, Strut, or Strongback.
Knob and Tube. A system of branch circuit wiring used before 1945.
Laminated Strand Lumber (PSL). Similar to LVL but using smaller veneers.
Landing. A widened out area at the top or base of stairs, usually at least 3 feet by 3 feet. When positioned at an entrance, the landing should allow a person to stand on it without being hit by an outward swinging door.
Larva. The second stage of Complex Metamorphosis.
Latent Heat. The energy needed to change state, either from solid to liquid (latent heat of fusion) or from liquid to gas (latent heat of vaporization).
Lateral Support. Structural members providing resistance against lateral thrust.
Lateral Thrust. Pressure against the foundation wall from the surrounding soil.
Ledger Board. A board placed horizontally, with its wide side against the house, as a support for joists. Often used to construct decks.
Lime-Cement Stucco. A mixture of cement, aggregate, lime, and water whose volume is more than 50% lime.
Lintel. A horizontal support of wood, brick, stone, concrete, or steel across the top of a door or window.
Liquid Line. The relatively narrow uninsulated copper pipe (housing hot, high-pressure liquid Refrigerant) running from the Condenser Coil to the Expansion Device in an air conditioning system.
Live Load. The weight of people, furniture, precipitation, wind force, and wet or frozen soil surrounding the foundation.
Load-Bearing Wall. A wall that carries roof or floor loads from above.
L Vent. A double-wall metal (steel) chimney vent for oil furnaces, designed to operate up to 1000°F.
LVL. Acronym for Laminated Veneer Lumber. A kind of engineered wood product composed of multiple layers of thin wood (veneer) assembled with adhesives.
Main Disconnect. The means of shutting off electrical power to the entire residence.
Mansard Roof. Essentially a hip roof with a flat top instead of a center ridge. A mansard roof has four horizontal perimeter ridges and four sloped corner ridges.
Mast. A vertical pole mounted on the roof designed to keep Service Drop wires and the Drip Loop off the roof.
Mastic. See Asphalt Plastic Cement.
Mat Foundation. A type of floating foundation used to float over weaker soils. It is constructed of strongly reinforced concrete and shaped like a mat.
Metal Shingles. Typically made of steel or aluminum. Typically 24 by 12, 12 by 9, 60 by 10, 120 by 12, or 45 by 16 inches by 0.016-0.021 inches thick. The exposure is essentially 100%. Designed for slopes 2.5 in 12 to 6 in 12 (depending on manufacturer) and greater. Weight per square is 35-255 pounds and life expectancy is 25-50 years plus.
Mid-efficiency Furnace. A furnace that increases efficiency by using an Automatic Vent Damper, a Forced-Draft burner, an Induced-Draft burner, a direct venting system, or a combination of these. Efficiency percentage is roughly in the 80's.
Modified Bitumen (Mod Bit). A type of flat roofing that can also be used on steep roofs. It is an asphalt-based product that comes in sheets and is also known as rubberized asphalt. Ultraviolet protection can take the form of granular, foil, or latex surfacing.
Mud Jacking. Pumping concrete slurry (grout) below footings in unstable soil to provide support down to sound soil.
Mud Sill. A wooden beam laid directly on soil in place of any kind of foundation and upon which are built floors and wall systems. Susceptible to rot and frost heaves.
Mullion. A post that separates two adjacent windows within the same Window Frame.
Muntin. A of a set of dividers within a Window Sash that separate the glass into individual panes.
Non-shrink Grout. Used as a means to avert differential settlement in underpinning applications where new footings are poured below original footings
Notch and Hole Rules. There should be no notches or holes in beams. Codes typically allow notching and hole drilling in joists, subject to certain constraints.
Nymph. The second stage of Simple Metamorphosis.
Open Valley. A roof valley whose valley flashing is exposed to the elements. The flashing material is usually metal or roll roofing.
OSB. Acronym for Oriented Strand Board. A kind of engineered wood product composed of cross-oriented wood flakes compressed and bonded with wax and resin adhesives.
Pad Footing. A load-spreading foundation pad supporting a column or pier.
Parallel Strand Lumber (PSL). Similar to LVL but using veneers with more defects and more randomly patterned.
Parapet Wall. A wall that extends up above a flat roof.
Parge(t). To cover a masonry, stone, or concrete wall with mortar or plaster so that an ornamental pattern or damp-proof coating may be applied to it.
Particle Board. See Fiberboard.
Partition Wall. A non-load-bearing wall.
Petiole. The part of the anatomy of some insects that connects the Thorax to the Abdomen.
Piers. Load-bearing columns or posts, with or without separate footings, that are completely or partially concealed in soil. Piers are made of concrete, concrete block, wood, brick, or stone.A
Pilaster. A thickening of a foundation wall to stiffen it or to receive a concentrated load.
Piles. Used for foundations instead of footings in poor-quality soil. Piles may be drilled into bedrock or deep enough to attain sufficient soil friction. Piles are made of concrete, steel, or wood.
Pipe Flashing. A flat rectangular flange (acting as base flashing) with a tapered collar that fits over a pipe (stack or vent) penetrating the roof.
Platform Framing. Wall studs are story height and rest on the subfloor at each level. Contrast with Balloon Framing.
Plywood. A structured wood panel made by gluing together an odd number of layers of thin wood veneer (plies) such that grain is oriented 90° to adjacent layers.
Portland Cement Stucco. A mixture of cement, aggregate, lime, and water whose volume is more than 50% Portland cement.
Post-tensioned Slabs. A foundation system of slabs and/or grade beams consisting of steel cables or tendons encased in poured concrete. The cables are tightened after pouring to strengthen the assembly. Used over expansive soils that make traditional foundations risky.
Power-Vented Water Heater. Same as Fan-Assisted Water Heater.
Premature Backfilling. Backfilling against the foundation before the concrete has fully cured and/or full lateral support is constructed. This can lead to cracks and/or excess lateral thrust.
Preserved Wood Foundation. A foundation constructed from treated wood plates and studs, the interiors of which are often finished as living space. Due to susceptibility of rot and insect damage, preserved wood foundations are typically more successful in dry soils than in wet.
P Trap. The only type of trap permitted for residential use. It is shaped like a capital P on its side, with flow going from the fixture through the crook (trap dip) and out the trap arm before reaching the vent.
Public Sewer. The municipal sewage system.
Pupa. The third stage of Complex Metamorphosis.
Purlin. A method for reducing rafter span and preventing rafter sag by running a board (like a small beam) perpendicular to the rafters at their midpoints. The purlins must be supported by posts or struts.
Pyrolysis. A lowering of the auto-ignition temperature of wood (from 500° to as low as 200°) resulting from overheating wood repeatedly over time (such as might occur next to a chimney).
Racking. A nominally rectangular (un-braced) wall frame changing into a parallelogram in response to a lateral force such as wind.
Radiation. Transfer of heat by means of light waves traveling through a medium.
Rafter. A structural board for a sloped roof running from the roof peak down to the eaves. The rafters support the sheathing and carry the live and dead loads above them.
Raft Foundation. A type of floating foundation used to float over weaker soils. It is constructed of strongly reinforced concrete and shaped like a raft (i.e., relatively thick).
Recovery Rate. A measure of the time it takes for a water heater to raise the temperature of its entire tank 90°F.
Refrigerant. The fluid used in the piping of an air conditioner.
Reinforced Masonry Wall. A double-wythe masonry wall with steel reinforcement embedded in the grout between wythes.
Relative Humidity (RH). The amount of moisture in air at a given temperature relative to the amount of moisture that air could hold if saturated, given as a percentage.
Return Duct. What carries room-temperature air in the house back to the furnace.
Ribbon Board. A small wooden strip running parallel to a beam and nailed to the underside of joists where they cross the beam as a means of lateral bracing.
Ridge Beam. A piece of lumber spanning the roof ridge and supported directly with vertical posts. Typically required for roof slopes less than 4 in 12.
Ridge Board. A piece of lumber spanning the roof ridge and used as a convenience to help build the roof. Used for roof slopes 4 in 12 or greater and may even be omitted where rafter pairs directly oppose each other. Because there is no direct ridge support, rafter bottoms must be tied with ceiling joists.
Ridge Vent. An opening all along a roof ridge to facilitate attic ventilation.
Rim Joist. A joist that runs around the perimeter of the house, toe-nailed into the sill and end-nailed into the joists. Also called header joist or band joist.
Rise. The difference in height between adjacent steps. Usually no more than 8 inches.
Rising Damp. Moisture drawn up from wet soil into mortar, masonry, or wood through capillary action.
Roll Roofing. Typically comes in 36-inch wide rolls and cut to 12-18 inch lengths. Thickness is typically 1/8 inch. The exposure is either 50% or all but 2-4 inches along one edge, with no head lap. Designed for slopes 1 in 12 (i.e., flat) and greater. Weight per square is 90-150 pounds and life expectancy is 5-10 years.
Roof Dishing. The plane of the roof taking on a concave shape.
Roof Joist. Identical in function to a rafter, but for flat roofs.
Roof Sag. A dip or sag in the ridge system.
Roof Spreading. The rafters flattening and pushing outwards.
Roof Vent. An opening through the roof (somewhat below the ridge) to facilitate attic ventilation.
Rot. Wood deterioration that occurs when and only when (a) the wood is surrounded by air (which always contains fungal spores), (b) the wood moisture content is at least twenty percent, and (c) the wood temperature is roughly between 40° and 115°.
Rubberized Asphalt. See Modified Bitumen.
Run. The horizontal distance between the faces of adjacent steps. Usually at least 9-11 inches.
Sacrificial Anode. A rod inside the water heater, typically made of aluminum or magnesium, designed to react with corrosive chemicals in the water as a deterrent to chemical reactions with the tank itself.
Saddle. Same as Cricket.
Sail Switch. A flap placed in the air path across the heating elements of an electric furnace that disables the furnace if there is no airflow (i.e., if the fan is off).
Scaling. A pitting of concrete surface.
Scratch Coat. The first layer of stucco, about 3/8 inch thick. Also called Base Coat.
Scupper. A penetration in a parapet wall for water drainage off a flat roof.
Self-Scouring. A term used to describe traps designed to keep the waste that flows through them moving and not clogging.
Selvage Roofing. See Roll Roofing.
Sensible Heat. A change of temperature without change in state.
Sequencer. A timing device for an electric heater that activates successive heating elements at 30-90 second intervals to avoid a demand surge that might occur if they were activated all at once.
Service Box. The main control center of the house's electrical system, acting as termination for the Service Entrance and containing the Main Disconnect.
Service Drop. The collection of overhead wires bringing electrical power from the utility to a house.
Service Entrance. The wires running from the Service Drop or Service Lateral to the service box and/or electrical meter.
Service Lateral. The collection of underground wires bringing electrical power from the utility to a house.
Service Panel. The switchboard used to distribute electricity throughout the house. Each circuit on the service panel governs all the outlets for a separate room, a set of rooms, or an appliance. Often the service panel is integrated with the Service Box.
Shake. A piece of wood (usually cedar, redwood, or cypress) resembling a large chip or shim and used for sidings and roofs. Typical shake lengths are 18 or 24 inches and shake thickness is between 1/2 and 1 inch.
Shearwall. A stud wall strengthened for its entire height with plywood or waferboard panels to resist racking caused by earthquake- or hurricane-generated lateral forces.
Sheathing. A covering placed on the outside of wall studs. Its three functions are (a) to stiffen the wood frame, (b) to support exterior siding, and (c) to help prevent wind and water penetration.
Shed Roof. A sloped roof that is high at one end and low at the other, similar in appearance to a lean-to.
Shingle. A piece of wood (usually cedar, redwood, or cypress) resembling a large chip or shim and used for sidings and roofs. Typical shingle lengths are 16, 18, or 24 inches and shingle thickness is between 3/8 and 1/2 inch.
Shiplap. A wood siding using boards essentially reamed down to half thickness on both sides but asymmetrically (i.e., a notch end and an overlap end) so that adjacent boards nest and overlap. Can be horizontal or vertical.
Short Circuit. A circuit having virtually no resistance, causing tremendous amperage, which in turn should trip a circuit breaker or blow a fuse.
Short Cycling. A furnace or other thermostat-controlled appliance going on and off in quick succession (i.e., every minute or two). Can be caused by a faulty thermostat, a defective or improperly set fan limit switch, or rapid firing of the high temperature limit switch for a variety of reasons. Air conditioner Compressors are also susceptible to short cycling.
Shrinkage Cracks. Cracking that forms in concrete during natural curing. These are rarely a structural problem.
Siding. Material used for surfacing a frame building. Same as Cladding.
Sill. A wooden board connecting the top of the foundation to the wood floor and/or wall systems.
Sill Gasket. A compressible material between foundation wall and sill designed to stop air leakage and physically separate the sill from the concrete.
Simple Metamorphosis. A transformative process some insects undergo consisting of three stages: Egg, Nymph, and Adult.
Single-hung Window. A type of two-section vertically moving window in which only the bottom sash is operable.
Sister Joist. A second joist of the same size attached to a sagging or weakened joist to give it more strength.
Sister Wall. A separate wall constructed against the foundation to strengthen it against lateral thrust.
Slab-on-grade. A kind of foundation consisting of a concrete floor slab poured at grade level. The slab may be floating, supported, or monolithic.
Slate Ribbons. Typically 10-24 inches by 6-14 inches by 3/16 or 1/4 inches thick. The exposure is 3.5-10.5 inches, with a head lap of 3 or 4 inches. Designed for slopes 4 in 12 and greater. Weight per square is 650-8000 pounds and life expectancy is 50-250 years.
Sleeper Floor. A floor mounted on edge-up 2 X 4's or similar boards set directly on a slab or the ground.
Soffit. A covering of the rafters under the eaves.
Soffit Vent. An opening in the soffit to facilitate attic ventilation.
Soil Pipe. Carries both liquid and solid waste, such as from a toilet.
Soil Stack. A vertical pipe that carries solids, liquids, or air through one or more stories.
Soil Types. In order from strong to weak: bedrock, gravel, coarse sand, fine sand, clay, silt, organic material.
Sole Plate. The base or bottom board of a conventional wood-frame wall, resting flat on the floor.
Solid Masonry Wall. A single-, double-, or triple-wythe masonry wall with no space between.
Spalling. Chipping or crumbling of concrete or masonry, usually caused by moisture penetration through the wall or poor-quality materials.
Spillage. See Backdraft.
Spindle. See Baluster.
Splash Block. Something non-erosive placed under a downspout to direct exiting water away from the house.
Spread Footing. Wide perimeter pads that support foundation walls.
Square. A section of roofing material 100 square feet in area installed with its intended exposure.
Stack Effect. The tendency for cold air to be drawn into a house (through cracks and openings) at ground level and warm air to be pushed out of the house near the roof, caused by temperature differences in those locations and their corresponding pressure differences relative to outside pressure.
Stack Flashing. See Pipe Flashing.
Stack Vent. The extension of the soil or waste stack above plumbing fixtures.
Staged Furnace. A "variable speed" electric furnace that activates only the number of heating elements sufficient to meet demand. It requires a special thermostat that can detect whether or not room temperature has begun to rise.
Standpipe. A pipe assembly for receiving clothes washer waste, consisting of a vertical pipe 18" to 30" in length connected to a trap between 6" and 18" above the floor connected to a trap arm that attaches to a vented stack.
Starter Strip. A row of shingles placed along the lower edge of the roof underneath the bottom row of shingles to achieve double coverage for the bottom row.
Step Flashing. Base flashing along sloped junctures of chimneys and walls.
Step Footings. Footings installed on sloped lots that form steps to accommodate the contour.
Stop and Waste Valve. A shutoff valve that provides a mechanism for bleeding or draining fluid from the lines on its downstream side.
S Trap. A type of trap shaped like a capital S on its side. It is not permitted for residential use because it siphons, defeating the purpose of the trap in the first place.
Stretcher. A horizontal brick turned parallel with the wall course.
Stringer. The jagged framework (sides) of a flight of stairs.
Strip Footing. See Spread Footing.
Strongback. See Knee Wall.
Strut. See Knee Wall.
Stucco. See Lime-Cement Stucco and Portland Cement Stucco.
Subfloor. Typically wood planking, plywood, or waferboard forming a horizontal surface over joists. The subfloor transfers live loads to the joists.
Suction Line. The (relatively) large insulated copper pipe (housing cool, low-pressure Refrigerant) running from the Evaporator Coil to the Compressor in an air conditioning system.
Supply Duct. What carries heat from the furnace to room in the house.
Supported Slab. A concrete floor slab supported on granular fill or soil.
Suspended Slab. A concrete floor slab engineered to suspend over living space.
Tankless Coil. A device for generating hot water by means of submersing a copper tubing coil inside the boiler used to heat the house.
Temperature/Pressure Relief (TPR) Valve. A device attached to a water heater designed to open when the water temperature exceeds 210°F and/or the pressure exceeds 150 psi. The release prevents the water heater from exploding.
Tempering Valve. A device used in hot water systems (not thermostat-controlled water heater) that keep the water at 180°F. The valve mixes cooler water with the hot before delivering to faucets to avoid scalding.
The 1/3 Rule. A rule of thumb for determining pier stability. If the pier is out of plumb by more than one-third its thickness, it is considered unstable.
Thermal Bridge. A place where insulation is interrupted, such as at joists or plates, allowing heat conduction through the ceiling or wall and potentially concomitant condensation.
Thermal Resistance (R). A measure of insulation effectiveness equivalent to the inverse of a material's thermal conductivity.
Thermocouple. A sensor that prevents the intake gas valve from opening if there is no pilot light.
Thorax. The middle region of an insect's body (between head and Abdomen), which bears the legs and wings.
Toe Bearing. Rafter support accomplished by notching its end (toe) and butting the notch against the inside of the top plate. Considered improper practice and tends to cause rafter splitting.
Tongue and Groove. A wood siding using boards shaped into a tab (tongue) on one side and a slot (groove) on the other such that adjacent boards nest. Can be horizontal or vertical.
Top Plate. The top double-board of a conventional wood-frame wall.
Tracing Wire. An insulated metal wire wrapped around submerged plastic piping as a means of locating the pipe from aboveground with a metal detector.
Trap. A plumbing fitting that provides a water seal in a drain pipe to prevent sewer gases from entering the home.
Trap Arm. The pipe connecting the trap to the vent.
Trap Dip. The inside of the lowest part of the trap.
Trap Primer. A device that periodically drips water into a floor drain (that gets little use) to replace evaporated water in the trap so that the water seal is maintained.
Trap Seal. The vertical distance between the trap dip and the trap weir.
Trap Weir. The inside bottom of the highest part of the trap outlet.
Tread Width. The horizontal span of a step. It is typically 1 inch greater than the run due to nosing (overhang).
Truss. A manufactured support system commonly used for roof structures instead of rafters and ceiling joists.
Truss Uplift. A phenomenon occurring in winter only. The bottom chord of a truss tends to shrink because, being next to the ceiling, it is relatively dry and warm, whereas the other chords tend to expand, being colder and wetter. The result is an arching up of the bottom chord, creating a gap between the top of interior partitions near the house center and the ceiling.
Underlayment. A thin layer placed between sheathing and shingles on roofs or between subfloors and floors. Roofing underlayment is made of felt or synthetic material, while flooring underlayments are made of foam, cork, plastic, or rubber.
Underpinning. Effectively widening or deepening a footing in unstable soil. There are various methods and various applications.
Uniform Settlement. All parts of a house settling together. Unless settlement is so severe to strain utility lines, there is no internal stress and no cracking.
Upstand. An inverted "V" along the length of metal valley flashing designed to keep water that is driving down one side of the roof from flowing up under the shingles on the opposite side of the valley.
Valley Flashing. Material used to shed water from where two different roof slopes come together to form a trough or valley. The valley is vulnerable to leakage because (a) it carries a large volume of water, (b) snow and ice can accumulate to cause ice dams, (c) the flashing is subject to stretching and buckling forces, and (d) the valley slope is less than that of either neighboring roof.
Valley Rafter. A rafter accommodating change in direction where two perpendicular gable roofs join.
Vapor Barrier. A material designed to retard vapor penetration not from vapor diffusion but from air movement.
Vapor Diffusion. Movement of (water) vapor without accompanying movement of air.
Veneer Wall. Stone or brick used as siding on the outside of a wood-frame wall.
Vented Rain Screen. A technique for preventing moisture damage to a wood-frame wall behind a masonry veneer wall. The veneer is built one inch away from the frame and weep holes at the bottom of the veneer allow for equalization of air pressure between the outside and the cavity. The lack or near lack of pressure differential reduces wind-driven moisture penetration, plus any water that does get through escapes out through the weep holes.
Vent Pipe. Carries air only (no liquids or solids).
Vent Stack. A vertical pipe used only as a vent and carries no liquids or solids.
Vertical Shear. One part of a building dropping relative to another.
Volt. A measure of electromotive force. Household electrical systems typically receive 240 volts from the utility and split it into two 120-volt branches.
Waferboard. A kind of engineered wood product composed of randomly oriented wood flakes compressed and bonded with wax and resin adhesives.
Waste Pipe. Same as Drain Pipe.
Waste Stack. A vertical pipe that carries liquids or air (not solids) through one or more stories.
Water Pressure Regulator. A device for stepping down high municipal water pressure to below 80 psi so as not to strain appliances.
Water Service Piping. The piping leading from the water main to the house. Materials may be copper, brass, cast iron, asbestos cement, galvanized steel (gray-silver in color, used before 1950), lead (dull gray, used before 1940), PVC (blue or white, used after 1968), CPVC (cream, used after 1968), polybutylene or PB (blue, used after 1978), polyethylene or PEX (black, used after 1965).
Water Supply Piping. The piping leading from the service piping to points of use within the house. Materials may be copper, galvanized steel, CPVC, polybutylene (recalled), polyethylene.
Watt. A measure of the rate of electrical energy consumption.
Web. An internal truss or I-joist component, typically running from top chord to bottom chord.
Weep Holes. Openings at the bottom of masonry veneer walls, whose two functions are (a) air pressure equalization on both sides of the veneer and (b) water drainage. See Vented Rain Screen.
Wet Vent. A vent for one fixture also acting as a drain for another fixture.
Window Frame. The fixed perimeter structure of a window.
Window Sash. The potentially movable set of structural members holding the glass.
Wood Shakes. Typically 18 or 24 inches by 8-12 inches by 0.5-1.25 inches thick. The exposure is 7.5 or 10 inches, with a head lap of 3 or 4 inches. Designed for slopes 4 in 12 and greater. Weight per square is 220-450 pounds and life expectancy is 20-40 years.
Wood Shingles. Typically 16, 18, or 24 inches by 8-12 inches by 0.4-0.5 inches thick. The exposure is 5, 5.5, or 7.5 inches, with a head lap of 6, 7, or 9 inches. Designed for slopes 4 in 12 and greater. Weight per square is 150-200 pounds and life expectancy is 20-40 years.
Wythe. A measurement of masonry wall thickness corresponding to the width (i.e., middle dimension) of one brick.