68 terms · Plain English
Home Repair Glossary
What contractors mean by flashing, SEER2, GFCI, drain tile and more. Each term is explained in a sentence or two, with a link to the guide where it matters.
Roofing
- Chimney crown
- The concrete slab on top of a masonry chimney that sheds water. Read more →
- Drip edge
- Metal strip along roof edges that directs water into the gutter and away from the fascia.
- Flashing
- Thin metal that seals the joints where the roof meets chimneys, walls, vents and skylights. Read more →
- Ice dam
- A ridge of ice at the roof edge that traps melting snow and forces water under shingles. Read more →
- Pipe boot
- The rubber collar that seals around a plumbing vent pipe on the roof. Read more →
- Roof deck (sheathing)
- The plywood or OSB boards the roofing is nailed to. Read more →
- Soffit and ridge vents
- Intake vents under the eaves and exhaust vents at the peak that let the attic breathe. Read more →
- Square
- Roofing unit equal to 100 square feet of roof area. Read more →
- Step flashing
- L-shaped pieces of flashing woven into each shingle course where a roof meets a wall. Read more →
- Underlayment
- A water-resistant layer under the shingles that is the roof's second line of defense.
- Valley
- The inside angle where two roof slopes meet and water collects. Read more →
Plumbing
- Anode rod
- A metal rod inside a tank water heater that corrodes so the tank does not. Read more →
- Cleanout
- A capped access point for clearing clogs in a drain or sewer line. Read more →
- Dip tube
- The tube that sends cold water to the bottom of a tank water heater. Read more →
- Expansion tank
- A small tank that absorbs pressure when heated water expands. Read more →
- Flapper
- The rubber seal at the bottom of a toilet tank that lets water into the bowl. Read more →
- Hydro jetting
- Cleaning pipes with a high-pressure water stream. Read more →
- Main shutoff valve
- The valve that turns off water to the whole house, usually where the line enters. Read more →
- P-trap
- The U-shaped pipe under a sink that holds water to block sewer gas. Read more →
- PEX
- Flexible plastic water pipe widely used for repiping. Read more →
- Polybutylene
- Gray plastic pipe used from the 1970s to 1990s that is prone to failure. Read more →
- Pressure reducing valve (PRV)
- A valve that lowers high street water pressure to a safe level for the house. Read more →
- Slab leak
- A leak in water pipes under a concrete floor slab. Read more →
- T&P valve
- Temperature and pressure relief valve that releases water if a water heater gets too hot or pressurized. Read more →
- Wax ring
- The seal between the toilet and the floor flange. Read more →
Heating & AC
- AFUE
- Annual fuel utilization efficiency: how much of a furnace's fuel becomes heat. Read more →
- BTU
- British thermal unit, a measure of heat used to size heating and cooling equipment.
- Capacitor
- A part that gives the AC compressor and fan motors their starting and running boost. Read more →
- Condensate line
- The drain line that carries water away from the indoor AC coil. Read more →
- Contactor
- An electrical switch in the outdoor unit that turns the compressor and fan on. Read more →
- Dual-fuel system
- A heat pump paired with a gas furnace backup. Read more →
- Evaporator coil
- The indoor coil that absorbs heat from the air; it can freeze or leak. Read more →
- Flame sensor
- A rod that confirms the furnace burner is lit; if dirty, the furnace shuts off. Read more →
- Heat exchanger
- The furnace part that transfers heat to the air; a crack can leak carbon monoxide. Read more →
- Manual J
- The standard load calculation used to size heating and cooling equipment correctly. Read more →
- Reversing valve
- The heat pump valve that switches between heating and cooling. Read more →
- SEER2
- The current efficiency rating for air conditioners and heat pumps; higher means more efficient. Read more →
- Short cycling
- When heating or cooling equipment turns on and off too often. Read more →
- Tonnage
- AC cooling capacity; one ton equals 12,000 BTU per hour. Read more →
Electrical
- AFCI
- Arc-fault circuit interrupter: a breaker that cuts power when it detects dangerous sparking. Read more →
- Amperage (amps)
- How much current a circuit or electrical service can carry; homes typically have 100 to 200 amp service. Read more →
- Dedicated circuit
- A circuit that serves one appliance only, such as a range or AC unit.
- GFCI
- Ground-fault circuit interrupter: an outlet or breaker that cuts power to prevent shocks in wet areas. Read more →
- Ground wire
- The bare or green wire that gives fault current a safe path.
- Knob and tube
- Early wiring method (about 1880s to 1940s) with no ground wire. Read more →
- Overload
- Too many devices drawing power on one circuit, which trips the breaker. Read more →
- Service panel
- The main breaker box that distributes power to the home's circuits. Read more →
- Short circuit
- When a hot wire touches neutral or ground, causing a sudden surge and trip. Read more →
- Whole-house surge protector
- A device at the panel that limits voltage spikes to protect electronics.
Basement & foundation
- Backwater valve
- A valve that stops sewage from flowing back into the house through floor drains. Read more →
- Drain tile
- A perforated pipe around or under the foundation that collects water. Read more →
- Efflorescence
- White, chalky mineral deposits left when water moves through concrete or brick. Read more →
- Encapsulation
- Sealing a crawl space with a heavy vapor barrier and controlling humidity. Read more →
- Float switch
- The switch that turns a sump pump on when water rises. Read more →
- French drain
- A gravel trench with a perforated pipe that redirects water. Read more →
- Grading
- The slope of the soil around a house; it should fall away from the foundation. Read more →
- Hydrostatic pressure
- The force of water in saturated soil pushing against foundation walls and floors. Read more →
- Pier (foundation)
- A steel or concrete support driven down to stable soil to lift or stabilize a foundation. Read more →
- Sump pump
- A pump in a basement pit that removes groundwater. Read more →
Contracts & pricing
- 50% rule
- If a repair costs half or more of a replacement, replacing is usually better value. Read more →
- Change order
- A written agreement to change the scope or price after a contract is signed.
- Contingency
- Money set aside for surprises such as hidden damage. Read more →
- Deposit
- Money paid upfront before work starts; some states cap it. Read more →
- Flat-rate pricing
- A fixed price for a job rather than an hourly charge. Read more →
- Lien waiver
- A document confirming a contractor or supplier has been paid and gives up the right to file a lien.
- Permit
- Official approval from your local building department for certain work.
- Trip fee
- A charge for a service visit, separate from the repair itself. Read more →
- Workmanship warranty
- The contractor's guarantee on their labor, separate from the manufacturer's warranty.
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