The Homeowner
Lexicon

A type of circuit breaker that detects the electrical signature of an arc fault — an unintended spark that can ignite insulation or wood. Required by code in all bedrooms since 2002, and extended to most living areas in recent code cycles. An AFCI looks like a standard breaker but has a TEST button. If yours trips repeatedly without explanation, it may be detecting damaged wiring — have an electrician investigate before simply resetting it.

A rotating tool used to clear drain clogs. A hand auger (drain snake) is a coiled cable inside a housing — you feed the cable into the drain and crank to break up or retrieve the blockage. A toilet auger has a protective sleeve that prevents scratching porcelain. For main-line blockages, a power auger (or hydro-jetter) is needed. Never use a toilet auger in a sink; the cable diameter is wrong.

A J-shaped or L-shaped bolt embedded in concrete that connects wood framing (the sill plate) to a foundation. Required by code at specific intervals. During inspections, an inspector will check that anchor bolts are present and properly torqued. If you're doing a foundation repair or sill plate replacement, anchor bolts must be added using a hammer drill and epoxy-set anchor system.

The system of intake vents (typically in soffits) and exhaust vents (ridge or gable) that allow air to flow through an attic. Proper ventilation is critical: in summer it expels heat that would otherwise raise cooling bills; in winter it prevents warm moist air from condensing on the roof deck, which causes rot and mold. The standard ratio is 1 sq ft of net free vent area per 150 sq ft of attic floor, split 50/50 between intake and exhaust.

The vertical spindles that fill the space between a handrail and stair treads or a deck floor. Not just decorative — balusters must be spaced no more than 4 inches apart to prevent a child's head from becoming trapped (most codes). Balusters attach to a bottom rail (or directly to the tread) and the handrail above. When replacing, measure center-to-center spacing carefully and check local code for spacing requirements.

A wall that carries structural load from floors or roof above it down to the foundation. You cannot remove a load-bearing wall without adding a properly sized beam to transfer the load. Interior walls that run perpendicular to floor joists and sit above a beam in the basement are usually bearing walls. Always consult a structural engineer before modifying any wall you suspect is load-bearing.

A rigid, water-resistant substrate made of cement or foam that goes behind tile in wet areas (showers, tub surrounds, bathroom floors). Standard drywall will deteriorate when wet even if tiled over. Common brands: HardieBacker, Durock, Kerdi board. Fasten with corrosion-resistant screws and tape joints with mesh tape and thin-set, not standard drywall compound.

Minimum standards set by local, state, or national authorities for construction, electrical, plumbing, and mechanical work. In the US, most jurisdictions adopt the International Building Code (IBC) or International Residential Code (IRC) with local amendments. Permits trigger inspections that enforce code compliance. Unpermitted work can cause issues at resale and may need to be torn out if discovered.

A flexible, waterproof sealant applied to joints and gaps to prevent water infiltration and air leakage. Key types: Silicone caulk — most waterproof, ideal for tubs and sinks, can't be painted; Latex/Acrylic caulk — paintable, for interior trim gaps and windows; Polyurethane caulk — best for exterior gaps and horizontal surfaces. Proper caulk application = wet surface cleaned, old caulk removed, surface dry, 45° nozzle angle, pushed (not pulled) bead, smooth with a damp finger within 5 minutes.

A resettable switch inside your electrical panel that automatically trips (opens) when too much current flows through a circuit. Each breaker is rated in amps (typically 15A or 20A for household circuits; 30A–50A for large appliances). A tripped breaker sits midway between ON and OFF — push it fully to OFF before resetting to ON. Breakers that trip repeatedly indicate either an overloaded circuit or a fault — do not simply replace with a higher-rated breaker.

A visible line or plane of weakness in concrete where a pour stopped and a new pour was added after the first had partially set. Cold joints are a structural weakness and a potential water entry point. During foundation inspections, look for horizontal cracks or discoloration lines — these may indicate cold joints from original construction or signs of settling.

A shallow, unfinished space beneath a house that provides access to plumbing, electrical, and HVAC without a full basement. Typically 18"–48" high. Moisture control is critical — most problems in crawl spaces come from ground moisture migrating up. A vapor barrier (6-mil poly sheeting on the ground) is the minimum; an encapsulated crawl space with sealed walls and a dehumidifier is the gold standard.

The three-part plumbing system that removes used water and sewage from a home. Drain pipes carry wastewater by gravity to the main sewer line. Waste pipes are typically the larger collectors (3"–4"). Vent pipes extend through the roof to allow air into the drain system, preventing siphoning of traps (which would let sewer gas into the home). A gurgling toilet often indicates a venting problem.

Interior wall and ceiling sheathing made of gypsum plaster pressed between two layers of paper. Standard: ½" for walls, ⅝" (Type X) for fire-rated assemblies. Moisture-resistant drywall (green or purple board) is used in bathrooms but is not a tile substrate. Fastener heads are driven slightly dimpled (not through the paper) and covered with joint compound ("mud"). Seams are taped and coated with three coats of compound, each feathered wider than the last.

A paste-like sealant used to seal joints in HVAC ductwork. More durable and effective than foil tape for long-term duct sealing. Applied with a brush to all joints and seams before insulating. Do not use standard duct tape (the silver-colored fabric tape) — it fails within a few years. Use UL 181-rated foil tape or mastic for any permanent duct repair.

White, powdery or crystalline deposits that appear on the surface of concrete, brick, or mortar. Caused by water carrying soluble salts to the surface as it evaporates. Efflorescence itself is cosmetic, but its presence indicates moisture is moving through the masonry — which is the problem to solve. Brush off with a stiff brush; use a mild acid wash for stubborn deposits. Then identify and stop the moisture source before waterproofing or painting the surface.

Thin-walled steel conduit used to protect and route electrical wiring. Common in garages, basements, and exposed runs where wiring would otherwise be vulnerable. Easier to bend and work with than rigid conduit. Requires specific connectors and approved wire fill calculations (cannot fill conduit more than 40% for three or more conductors). All wiring in conduit must be individual THHN conductors, not Romex cable.

Thin sheets of metal (typically galvanized steel, aluminum, or copper) installed at roof transitions, valleys, chimneys, skylights, and wall-to-roof junctions to prevent water infiltration. The most common cause of roof leaks is failed or improperly installed flashing, not the shingles themselves. Step flashing goes between shingles and a vertical wall; counter flashing is embedded into mortar joints above step flashing. Never simply caulk over flashing — eventually caulk fails and the underlying leak worsens.

The maximum depth at which ground freezes in a given location in winter. Any foundation, footing, or outdoor plumbing that sits above the frost line is at risk of frost heave — the ground expansion that can shift or crack structures. The frost line in Miami is near zero; in Minneapolis it is around 42 inches. All footings for decks, fences, and additions must extend below local frost depth.

The fill mechanism inside a toilet tank that controls water level. When the tank empties after a flush, the float drops, opening the valve. As water fills, the float rises and shuts the valve at the preset level. If your toilet runs continuously, the float is typically set too high (causing overflow into the bowl through the overflow tube) or the valve itself is worn. Modern fill valves are tower-style and easy to replace in 15 minutes.

An outlet or breaker that monitors the balance of current between hot and neutral wires. If any current — even 4–6 milliamps — flows through an unintended path (like a human touching a live part), the GFCI trips in 1/40th of a second. Required by code within 6 feet of any water source (kitchens, bathrooms, garages, outdoors, crawl spaces). The TEST/RESET buttons on the outlet face identify a GFCI. One GFCI outlet can protect all downstream standard outlets on the same circuit.

A putty-like material used to seal the glass pane into a wood window frame. Older homes with single-pane windows have hardened, cracked glazing — a common source of drafts and moisture infiltration. Re-glazing: remove loose material, prime the bare wood, press in oil-based glazing compound at a 45° bevel, smooth with a wet putty knife, allow to skin for one week, then prime and paint. Linseed oil-based glazing compound is more flexible and longer-lasting than latex types.

The slope of the ground away from the foundation. The IRC requires a minimum of 6 inches of drop over the first 10 feet away from the foundation on all sides. Negative grade (ground sloping toward the house) is a leading cause of basement moisture problems. Correct by adding and compacting clean fill soil against the foundation, sloping it away, then establishing turf or mulch ground cover.

A horizontal framing member above a door or window opening that carries the load around the opening (since you've cut through a stud cavity). Typically made of doubled 2× lumber (often 2×10 or 2×12 for larger spans) with a ½" plywood spacer to reach 3½" total width. Header size is determined by the span and the loads above. An undersized header over a window can cause the wall above to sag, leading to sticking doors and visible cracks.

A synthetic membrane applied over wall sheathing before siding is installed. Blocks bulk water and wind while remaining vapor-permeable (allowing any interior moisture vapor to escape outward). Common brands: Tyvek, Typar, Zip System. Proper installation requires: lapping top over bottom (like shingles), taping all horizontal seams, and integrating with window flashing tape. Without house wrap, siding alone does not reliably keep water out.

A self-adhering waterproof membrane applied to the roof deck at eaves, valleys, and around penetrations before shingles are installed. It protects against water backing up under shingles due to ice dams. Required by code in most northern climates for the first 24" inside the exterior wall (or 36" in very cold climates). The adhesive back seals around every nail penetration. Never omit it at valleys — that is where most leak-prone points exist.

A valve that stops water flow to a specific fixture or zone. Every toilet, sink, and appliance water line should have one. If yours don't — that's a weekend upgrade worth doing. Two types: gate valves (older, fail by corrosion); ball valves (quarter-turn, preferred, rarely fail). Know where your main shut-off is before any plumbing emergency. It's typically near the water meter or where the main line enters the house.

Horizontal structural members that span between beams or walls and support a floor or ceiling. Typically 2×8, 2×10, or 2×12 dimensional lumber, or engineered I-joists. Spaced 12", 16", or 24" on-center. Never cut a joist without engineering review — even a notch in the wrong zone can reduce a joist's load capacity by more than half. Sagging floors are a sign of damaged, undersized, or over-spanned joists.

A metal or plastic enclosure where electrical wires are joined (spliced). All wire splices must be inside a covered junction box — never in open wall cavities or ceiling spaces. Code requires that junction boxes remain permanently accessible; they cannot be buried behind drywall. If you discover an inaccessible junction box during a renovation, it must be made accessible or the splice must be redone at an accessible location.

A full-height stud on either side of a door or window rough opening, running from bottom plate to top plate. The king stud supports the header above the opening and transfers the load to the floor framing below. King studs are paired with shorter jack studs (trimmer studs) that run from the bottom plate up to the underside of the header. Together they form the rough opening framing for all doors and windows.

A short wall, typically 3' to 5' tall, that supports rafters in an attic space converted to living area, or fills the sloped areas under stairs. Often a challenge to insulate because the wall cavity transitions to an unconditioned triangular attic behind it. The proper approach: insulate the knee wall itself and the sloped ceiling above it, and air-seal carefully at the top and bottom plates to prevent cold-air infiltration into the living space.

A horizontal support member — typically steel angle iron or precast concrete — that spans above a masonry opening (window, door, or fireplace) to carry the masonry weight above it. Lintels can rust and expand, causing masonry cracks above openings. Spalling brick or mortar cracks at window corners are common signs of lintel failure. Replacement is a masonry contractor job requiring temporary shoring.

Window glass with a microscopic metallic coating that reflects infrared (heat) radiation while allowing visible light to pass through. Low-E reduces heat transfer by up to 50% compared to standard clear glass. "Low-E2" or "Low-E3" refers to the number of coatings. In cold climates, windows with the coating on the inside face of the outer pane retain interior heat; in hot climates, the coating on the outer glass face blocks solar gain.

See Duct Mastic under D. A paste sealant for ductwork joints. Should not be confused with flooring mastic (a tile adhesive) or roofing mastic (a rubberized roof sealant) — these are different products despite sharing the name.

A material that slows or stops moisture vapor from passing through walls, floors, and ceilings. The location of the vapor retarder depends on climate: in cold climates it goes on the warm side (interior face of insulation); in hot-humid climates it goes on the exterior side; in mixed climates, omit a retarder and use vapor-permeable materials. Incorrect vapor retarder placement is a major cause of mold in walls.

Non-metallic sheathed cable — the most common wiring in residential construction. Contains two or three insulated conductors plus a bare ground, all wrapped in a plastic outer jacket. Identified by its wire gauge and conductor count: 14/2 NM = 14 AWG, 2 conductors + ground (for 15A circuits); 12/2 NM = 12 AWG (for 20A circuits). Cannot be run exposed in garages, basements, or anywhere it could be damaged — use conduit in those locations.

The stated size of dimensional lumber, which is larger than its actual (dressed) size. A "2×4" actually measures 1½" × 3½". A "2×6" is 1½" × 5½". This matters for everything from door rough opening calculations to insulation thickness. The discrepancy exists because lumber shrinks during kiln-drying after milling. When buying lumber, the nominal size is what's listed on the label and used in construction plans.

The measured distance from the center of one structural member to the center of the next. Standard stud spacing is 16" OC; some walls use 24" OC. Knowing OC spacing is essential for finding studs with a tape measure once you've located the first one, for knowing what size drywall sheets span properly, and for calculating how many framing members you need for a given wall length.

An engineered wood panel made from compressed wood strands arranged in layers oriented at angles to each other. Now more common than plywood for wall and roof sheathing, and subfloor. Slightly more moisture-sensitive than plywood at cut edges — keep edges sealed and covered during construction. OSB is stamped with its span rating and approved use (structural, sheathing, etc.). Don't use OSB rated for wall sheathing as subfloor; they have different loading specs.

The curved section of pipe below a sink or other fixture drain. It holds a small amount of water that creates a seal blocking sewer gases from entering the living space. P-traps must be present under every drain fixture. If a sink drain smells like sewer gas, the trap has dried out (run water to refill it), been improperly installed, or lost its seal. Double-check that the trap arm (going into the wall) is level to slightly downhill — never uphill, which allows siphoning.

Official authorization from the local jurisdiction to perform construction, electrical, plumbing, or mechanical work. Permits require inspections at specific stages, ensuring code compliance. Work typically requiring permits: new structures, additions, significant electrical work, plumbing changes, HVAC installation, structural alterations. Cosmetic work (painting, flooring, cabinet replacement) usually doesn't. Working without required permits can invalidate homeowner's insurance and create problems when selling.

The box or chamber directly attached to the air handler (furnace or air conditioner) from which supply ducts branch off (supply plenum), or where return ducts collect air to send back to the unit (return plenum). Also refers to the space between a suspended ceiling and the structural floor above, which some buildings use as an air return — requiring any wiring in that space to be plenum-rated (CMP), not standard cable.

A measure of thermal resistance — how well a material resists heat flow. Higher R-value = better insulation. R-value is additive: two layers of R-13 batts gives R-26. DOE recommendations for attic insulation range from R-30 (Zone 1–2, South) to R-60 (Zone 6–8, North). Common values: fiberglass batts R-3.2/inch, closed-cell spray foam R-6.5/inch, open-cell spray foam R-3.7/inch, rigid polyiso board R-6 to R-6.5/inch.

The horizontal member at the top of a roof to which rafters attach. A ridge board is a non-structural member — the rafters on each side push against each other and the board only provides alignment; the walls and ceiling joists provide resistance to the outward thrust. A ridge beam is structural, carries load, and requires posts or walls beneath it. Identifying which type you have matters enormously if working in an attic or adding a cathedral ceiling.

The framed opening in a wall into which a door or window unit is installed. Always larger than the window or door's nominal size — typically ½" to 1" wider and ½" to ¾" taller — to allow for shimming level and plumb. Every door and window comes with its manufacturer's required rough opening dimensions. Frame to those specs exactly, then use shims and expanding foam (low-expansion) to fill the remaining gap after installation.

The lowest piece of dimensional lumber in a wood-framed wall, bolted directly to the top of the concrete foundation. Because it sits on concrete (which can transmit moisture), the sill plate must be pressure-treated wood (not standard lumber, which would rot). A sill seal (foam gasket) goes between the concrete and the sill plate to reduce air infiltration. Termite damage and moisture rot of sill plates are among the most serious structural repairs a homeowner can face.

The underside of the roof overhang (eave). On the exterior, soffits are typically finished with vented panels that allow outside air to enter the attic for ventilation. On the interior, a soffit can also refer to a boxed-out ceiling area that conceals ductwork, beams, or plumbing. Blocking soffit vents with insulation is one of the most common attic mistakes — baffles (rafter baffles) must maintain a clear channel from soffit vent to attic regardless of insulation depth.

The structural panel layer nailed or screwed to the floor joists; the surface onto which the finished flooring (hardwood, tile, carpet) is installed. Typically ¾" tongue-and-groove OSB or plywood. Squeaks usually come from movement at subfloor fasteners or between T&G edges — fix from below with construction adhesive and screws when possible. Subfloor must be flat (not level — flat) to within ⅛" over 10 feet for tile installations.

A cement-based adhesive mortar used to bond tile to floors, walls, and backer board. Available as standard (gray or white), large-format tile (medium bed), or polymer-modified for better flexibility. Never use mastic adhesive in wet areas — it re-emulsifies when wet, causing tiles to detach. Mix to a "sticky peanut butter" consistency; use the correct notch trowel size for your tile size (larger tile = larger notch). Back-butter large tiles for full coverage, avoiding hollow spots.

A brand name (DuPont) for a high-density polyethylene house wrap that has become genericized for the product category. See House Wrap. Tyvek HomeWrap is the standard residential product; Tyvek CommercialWrap has higher perm rating for commercial use. Tyvek Stucco Wrap and Tyvek DrainWrap have textured surfaces designed to create a drainage plane behind cladding systems.

A measure of how readily a window, door, or skylight conducts heat — the inverse of R-value. Lower U-factor = better insulation. ENERGY STAR requires U-factors of 0.27 or lower for northern climates. U-factor includes all components — glass, frame, spacer, and edge effects. When comparing windows, U-factor is a more complete measure than just the glass specification (like "triple pane") because a well-made double-pane can outperform a poorly made triple-pane due to frame and spacer differences.

The V-shaped intersection where two roof planes meet. Valleys channel large volumes of water from both planes and are among the highest-risk leak areas on any roof. Two methods: open valleys (metal flashing is exposed) and closed valleys (shingles overlap the valley). Ice and water shield is mandatory in valleys. Metal valley flashing should be at least 24" wide and have a center crimp to prevent water from one plane flowing under shingles on the other.

See Moisture Barrier under M. Specifically, a material with a perm rating of 0.1 or less (Class I) — typically 6-mil polyethylene sheeting or glass-faced rigid insulation. Used on crawl space floors and, in some climates, inside wall assemblies. Contrasted with vapor retarders (Class II: 0.1–1.0 perms) and vapor-diffusion-open materials. The right choice depends entirely on climate zone and wall assembly type.

Decorative wood paneling applied to the lower portion of an interior wall, typically 32"–48" high, topped with a chair rail moulding. Traditional wainscoting is raised-panel wood; simpler versions use MDF board-and-batten or flat panels. Originally a practical feature to protect plaster walls from chair backs and moisture. When installing, locate studs carefully — panels attach to them, not just to drywall — and plan your panel width to avoid narrow slivers at corners.

Small openings at the base of masonry walls, above window lintels, and in retaining walls that allow trapped water to drain out. Never fill or caulk weep holes — even if they look messy. Blocking them traps water behind the masonry, which leads to efflorescence, spalling, and eventual structural damage. The standard spacing for masonry weeps is 24" on-center; for above window lintels, weeps are placed at every third mortar head joint.

A Z-shaped metal or vinyl flashing strip used at horizontal transitions in siding — most commonly where a band board meets the siding above a window or where siding changes material. The top leg tucks behind the upper siding; the bottom leg diverts water out over the top edge of the lower siding or window trim. Missing Z-flashing at horizontal siding joints is a frequent source of wall rot in wood-framed homes, especially above windows and at floor-line transitions.