Rabbet
A notch or groove cut into a piece of material to allow two sections to be combined with a flush joint.

Rabbet Plane
A woodcutting tool used to cut an L-shaped groove into a piece of material. see also Rabbet.

Race
A strong current in a stream or river.

Raceway
1. An enclosed metal channel, usually fire-resistant, installed in a building to hold electrical wiring.
2. A chute that directs the flow of a material to a specific location in a device.

Raceway, One Piece
A channel holding electrical wiring that is designed to look like a piece of decorative trim or molding.

Raceway, Overfloor
A channel holding electrical wiring designed to be installed on a floor. The unit has a low profile and sloping edges to facilitate walking over it.

Racial Steering
The illegal practice of directing certain races away from some neighborhoods and into others.

Rack
1. A storage unit designed to hold various objects.
2. To cause a structure to shift so that it is out of plumb.

Racking
1. A force that causes a structure to shift so that it is out of plumb.
2. Installation of bricks or other masonry units so that each course is stepped back from the previous one.

Radial
Straight-line outward movement from a circle's center.

Radial-arm Saw
A power saw with a circular blade that is mounted on a moveable arm. The arm is lowered or raised to move the cutting blade to or away from the material to be cut.

Radial Drill
A drill press with a moveable arm that can be swung to various positions on the work table.

Radial Ducting
An HVAC system with ductwork running outward from a central heating and/or cooling unit.

Radial Surface
The surface of a log cut down the center.

Radiant Floor Heating
Heating system where electrical or hot-water heating elements are installed in a concrete slab floor.

Radiant Heat
see Radiant heating.

Radiant Heating
Use of radiation to generate heat such as with baseboard heating where the circulating hot water is radiated through conduction by thin metal fins at the bottom of the wall. The room is warmed by air circulating around the heating unit using convention.

Radiator
Heating unit that is exposed and which transfers heat generated by hot eater or steam through conduction. When the air circulates around the radiator using convention, the room is heated.

Radius
The distance from the center of a circle to the circumference. One-half of the diameter of a circle.

Radius Gauge
A tool used for checking the radii of convex and concave surfaces.

Radon
Radioactive gas that seeps into some homes, from the ground, through sump pumps, cracks in the foundation, etc., it is considered a health hazard.

Rafter
Any of the beams that slope from the ridge of a roof to the eaves to serve as support for the roof.

Rafter Anchor
A metal fastener attached to the top plate of a wall to hold a rafter.

Rafter, Fly
A rafter parallel to the gable end that projects out to form an overhang.

Rafter Overhang
The end of a rafter extending beyond the line of a building's walls.

Rafter Pattern
A guide used when cutting rafters.

Rafter Plate
The top plate of a building's walls. The rafters rest on the rafter plate.

Rafter Plumb Cut
The vertical cut made into a rafter so it will rest on the wall plate. see also Rafter Seat Cut.

Rafter Seat Cut
The horizontal cut made into a rafter so it will rest on the wall plate. see also Rafter Plumb Cut.

Rafter Shortening
Cutting a section off of the end of a rafter equal to one-half of the thickness of the ridge board (the rafter on the other side of the ridge board receives a similar cut).

Rafter Tables
Tables, often printed on a framing square, containing the data required to calculate angles and lengths of rafters for various roof types.

Rafter Tail
see Rafter Overhang.

Railing
A horizontal structure used as a handhold or to block off a drop or other unsafe area.

Rails
1. Continuous metal bars on which wheeled vehicles travel (i.e. railroads).
2. The horizontal sections of a panel door.
3. The top and bottom sections of a window sash.

Rain Caps
Waterproof cap, also called weatherheads, mast heads or entrance caps, which is placed at the upper part of an electrical mast at the point where the wires are run to the inside electrical meter. Wires hang from the pole to the entrance cap so that the entrance cap is not the low point in the downhill run from the pole because water will run to the low point before dripping to the ground. Wires enter the entrance cap at an upward angle through a tight insulator. Water is further stopped from getting through the entrance cap because of this entrance angle.

Raised Grain
Wood where the fibers have swelled, usually because of becoming wet. Wood is often sanded with the grain raised to achieve an extremely smooth finished surface.

Rake
1. A fork-like tool used for gathering materials (i.e. leaves) or smoothing an area of soil.
2. A roof overhang on a building's gable end.
3. An angle between objects.

Raked Joint
A masonry joint where a portion of mortar has been removed, creating a groove between masonry units. A raked joint if often used in brickwork.

RAM (Reverse Annuity Mortgage)
Mortgage, most commonly used by the elderly who have substantial equity in their homes. A periodic payment is made to the borrower from the lender thus, increasing the loan balance, causing negative amortization.

Ram
A hydraulically powered piston used for driving a weight.

Ramp
A sloping surface used to move from one elevation to another.