R

R-Value

A measurement used to describe the resistance to temperature changes in insulation.

Rabbet

A groove cut along the edge of a board producing an L shaped strip. Used as trim and in joint work in cabinet construction.

Radiant Heating

A method of heating, usually consisting of a forced hot water system with pipes placed in the floor, wall, or ceiling; or with electrically heated panels.

Radiation

The flow of heat from a warm source through space in waves of infrared or visible light energy.

Rafter

One of a series of structural members of a roof designed to support roof loads. The rafters of a flat roof are sometimes called roof joists.

Rail

The horizontal framing pieces of a panel door.

Rake

Refers to the slope of the roof at the end of a gable, where the outside part of the overhang forms an upside down V.

Random Rubble

Stonework having irregular shaped units and no indication of systematic course work.

Rebar

Ribbed steel bars installed in foundation concrete walls, footers, and poured in place concrete structures designed to strengthen concrete. Comes in various thickness' and strength grade.

Red Cedar

A reddish to dull brown softwood. The premier wood for shingles used in the United States because of its durability, ease of working, and lightweight. Also used for interior and exterior trim, sash, doors, and siding.

Red Oak

Hard and tough hardwood used for flooring, interior trim, stair treads, and railings. Popular as a face veneer plywood for paneling and cabinetwork. A rich light to medium brown in color. White oak has similar characteristics and applications.

Redwood

Light to deep reddish brown softwood. Mill products include sash, doors, blinds, siding, and trim. Extensively used for garden furniture and exterior decking.

Register

The open end of a duct for warm or cool air; usually covered with screening.

Reinforced Concrete

Concrete with steel bars or webbing embedded for strength.

Retaining Wall

A wall that holds back an earth embankment.

Reveal

The side of an opening for a window or door, between the frame and the outer surface of the wall.

Rheostat

An instrument used for regulating electric current.

Ridge

The top edge of the roof where two slopes meet.

Ridge Board

The board placed on edge at the ridge of the roof into which the upper ends of the rafters are fastened.

Ridge Vent

A vent mounted along the entire ridge line of the roof to allow the passage of air through the attic or cathedral ceiling.

Riprap

A wall or foundation of random stone to prevent erosion on an embankment.

Rise

In stairs, the vertical height of a step or flight of stairs.

Riser

Each of the vertical boards closing the spaces between the treads of stairways.

Riser Wall

A short wall.

Roof Sheathing

The boards or sheet material fastened to the roof rafters on which the shingles or other roof covering is laid.

Roof Vent

A louver or small dome mounted near the ridge of the roof to allow the passage of air through the attic.

Rough In

The installation of all parts of the plumbing system that can be completed prior to the installation of fixtures, including drainage, water supply, vent piping, and the necessary fixture supports.

Rough Opening

A framed opening in a structure into which doors, windows, and other finished trim are set.

Run

In stairs, the net width of a step or the horizontal distance covered by a flight of stairs.