Dictionary of Construction Terminology

Dictionary of Construction Terminology

Search for glossary terms (regular expression allowed)
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Term Definition
R factor or value
A measure of a materials resistance to the passage of heat. New home walls are usually insulated with 6" of batt insulation with an R value of R-21, and a ceiling insulation of R-49.
R Value
- A measure of insulation. A measure of a materials resistance to the passage of heat. The higher the R value, the more insulating "power" it has. For example, typical new home's walls are usually insulated with 6" of batt insulation with an R value of R-21, and a ceiling insulation of R-49.
Rabbet-
A rectangular longitudinal groove cut in the corner edge of a board or plank.
Radiant heating
A method of heating, usually consisting of a forced hot water system with pipes placed in the floor, wall, or ceiling. Also electrically heated panels.
Radiation
Energy transmitted from a heat source to the air around it. Radiators actually depend more on convection than radiation.
Radon
A naturally-occurring, heavier than air, radioactive gas common in many parts of the country.  Radon gas exposure is associated with lung cancer. Mitigation measures may involve crawl space and basement venting and various forms of vapor barriers.
Radon system
A ventilation system beneath the floor of a basement and/or structural wood floor and designed to fan exhaust radon gas to the outside of the home
Rafter
- Lumber used to support the roof sheeting and roof loads. Generally, 2 X 10's and 2 X 12's are used. The rafters of a flat roof are sometimes called roof joists.
Rafter, hip
A rafter that forms the intersection of an external roof angle.
Rafter, valley
A rafter that forms the intersection of an internal roof angle. The valley rafter is normally made of double 2-inch-thick members.
Rail
Cross members of panel doors or of a sash. Also, a wall or open balustrade placed at the edge of a staircase, walkway bridge, or elevated surface to prevent people from falling off.  Any relatively lightweight horizontal element, especially those found in fences (split rail).
Railroad tie
- Black, tar and preservative impregnated, 6" X 8" and 6'-8' long wooden timber that was used to hold railroad track in place. Normally used as a member of a retaining wall.
Rake
- Slope or slanted.
Rake fascia
The vertical face of the sloping end of a roof eave.
Rake siding
- The practice of installing lap siding diagonally
Ranch
- A single story, one level home.
Ready mixed concrete
Concrete mixed at a plant or in trucks en route to a job and delivered ready for placement.
Rebar, reinforcing bar
Ribbed steel bars installed in foundation concrete walls, footers, and poured in place concrete structures designed to strengthen concrete. Comes in various thicknesses and strength grade.
Receptacle
An electrical outlet.  A typical household will have many 120 volt receptacles for plugging in lams and appliances and 240 volt receptacles for the range, clothes dryer, air conditioners, etc.
Recording fee
A charge for recording the transfer of a property, paid to a city, county, or other appropriate branch of government.
Redline, red lined prints
Blueprints that reflect changes and that are marked with red pencil.
Reducer
A fitting with different size openings at either end and used to go from a larger to a smaller pipe.
Reflective insulation
Sheet material with one or both faces covered with aluminum foil.
Refrigerant
A substance that remains a gas at low temperatures and pressure and can be used to transfer heat. Freon is an example and is used in air conditioning systems.
Register
A grill placed over a heating duct or cold air return.
Reglaze
- To replace a broken window.
Relief valve
A device designed to open if it detects excess temperature or pressure.
Remote-
Remote electrical, gas, or water meter digital readouts that are installed near the front of the home in order for utility companies to easily read the home owners usage of the service.
Retaining wall
A structure that holds back a slope and prevents erosion.
Retentions
Amounts withheld from progress billings until final and satisfactory project completion.
Ribbon (girt)
Normally a 1 X 4 board let into the studs horizontally to support the ceiling or second-floor joists.
Ridge
The horizontal line at the junction of the top edges of two sloping roof surfaces.
Ridge board
The board placed on the ridge of the roof onto which the upper ends of other rafters are fastened.
Ridge shingles
- Shingles used to cover the ridge board.
Rim joist
A joist that runs around the perimeter of the floor joists and home.
Rise
The vertical distance from the eaves line to the ridge. Also the vertical distance from stair tread to stair tread (and not to exceed 7 ½").
Riser
Each of the vertical boards closing the spaces between the treads of stairways.
Riser and panel
The exterior vertical pipe (riser) and metal electric box (panel) the electrician provides and installs at the "Rough Electric" stage.
Road base
- A aggregate mixture of sand and stone.
Rock 1, 2, 3
When referring to drywall, this means to install drywall to the walls and ceilings (with nails and screws), and before taping is performed.
Roll roofing
Asphalt roofing products manufactured in roll form. 36-inch wide rolls with and 108 square feet of material. Weights are generally 45 to 90 pounds per roll.
Roll, rolling
To install the floor joists or trusses in their correct place. (To "roll the floor" means to install the floor joists).
Romex
A name brand of nonmetallic sheathed electrical cable that is used for indoor wiring.
Romex
A name brand of nonmetallic sheathed electrical cable that is used for indoor wiring.
Roof jack
Sleeves that fit around the black plumbing waste vent pipes at, and are nailed to, the roof sheeting.
Roof joist
- The rafters of a flat roof. Lumber used to support the roof sheeting and roof loads. Generally, 2 X 10's and 2 X 12's are used.
Roof sheathing or sheeting
The wood panels or sheet material fastened to the roof rafters or trusses on which the shingle or other roof covering is laid.
Roof valley
The "V" created where two sloping roofs meet.
Rough opening
The horizontal and vertical measurement of a window or door opening before drywall or siding is installed.
Rough sill
The framing member at the bottom of a rough opening for a window. It is attached to the cripple studs below the rough opening.
Roughing-in
- The initial stage of a plumbing, electrical, heating, carpentry, and/or other project, when all components that won't be seen after the second finishing phase are assembled. See also Heat Rough, Plumbing Rough, and Electrical Rough.
Run, roof
The horizontal distance from the eaves to a point directly under the ridge. One half the span.
Run, stair
the horizontal distance of a stair tread from the nose to the riser.