Baby Roman Brick 
2 x 4 x 8 inch brick 

Back 
Gypsum wallboard side that come into contact with the framing. 

Back Arch 
Structural support for an interior or veneer wall that is arch shaped. Exterior support is provided by a lintel. 

Back Band
Molding which primarily is utilized as a door casing or around the outer edge of a rectangular window. 

Back Blocking 
Reinforcing a joint between framing members by laminating a piece of gypsum wallboard to the back of two gypsum panels with adhesive or joint compound. 

Back Clips 
In installations where wallboard is meant to be removable, clips are fastened to the back of the wallboard to fit into the framing and hold the wallboard in place. 

Back Cut 
Panel or board cut in the back to make it lie flat. 

Back Filling
Brickwork used between structural members or covering the outside curved surface of an arch. 

Back Gouging 
Removal of a substance from the back side of a weld. 

Back Hearth 
Floor portion of a fireplace combustion chamber. 

Back Pressure 
Pressure that resists the flow of fluid in a piping system. 

Back Rake 
Measurement of the angle at the top cutting edge of a lathe tool bit from the horizontal axis of the tool. 

Back Siphonage 
The negative pressure that permits fluids to flow to into the system of a potable water system. 

Back Surface 
Part of a panel that will be next to the framing members of a structure. 

Back Taxes 
Taxes owed from a prior year. 

Back Title Letter
Letter given by the title company to an attorney (with former title ins. information) to aid in his examination of the title for new title insurance purposes. 

Back Vent 
Plumbing fixture's separate vent in a building drainage system. 

Back Weld 
Also called a backing weld it is applied to the back side of a joint. 

Back-end Fees 
Commission received by a syndicator when real estate is sold and are typically paid after the investors receive their initial investment plus return. 

Back-end Ratio 
Lender calculations by which debt (principal, interest, property taxes and insurance + other monthly bills) is compared with gross monthly income. 

Back-Mop 
Installation of a built-up roof by applying asphalt to back side of roofing felt. 

Back-to-Back 
Two or more items that are placed in mirror image to one another. When used with plumbing fixtures, where a common wall is shared, back-to-back installation saves both space and money. Since the water supply and the waste drain and pipe venting are shared, repeat installation is unnecessary. 

Back-to-Back Escrow 
Arrangements necessary when a person plans the sale of one property and the purchase of another, simultaneously. 

Backbrush 
Process of initially applying pain or stain with a roller or spray and then rubbed into the surface with a brush. Exterior stains are among those products that are best forced into the pores of the wood with a brush. 

Backer Rod Foam 
Also referred to as backup, it's used in strips to partially fill any gaps before caulk is applied. Foam rope needs only a thin topping of caulk; Mortite, a semi-solid caulking strip and Oakum, a heavy, chemically saturated rope may also be used. These products are necessary since caulk cannot be applied thickly enough to fill deep gaps. 

Backerboard 
Rigid board used beneath tile, as the base layer for acoustical ceiling tile or as the first layer in a multiple-layer wall system. Base ply wall panels are used by keeping the long edges parallel to the wall studs, unless the wall height is more than 97 inches or you are using decorated wall panels. Face ply, second layer and base ply panels can't fall in the same place, which would weaken the joint, so they are staggered. Base ceiling panels are fastened with the long edges perpendicular to the to the ceiling joints or framing. Face ply is installed over this with the long edges parallel to the ceiling joist and are fastened though the base ply panels into the joists. 

Backfill 
Soil, stone or other material moved up against a foundation to solidify and support the foundation structure of a newly built house or replacing the excavated earth around and against the foundation. Compacted earth retains its shape so that water will flow away from the foundation wall. For that reason, backfill should be a blend of earth and stone and without materials that would deteriorate easily. 

Backflow 
Water reversing its flow to return back to the supply system rather than flowing to the intended point. 

Backflow Preventer 
Plumbing device which prevents the backflow of water (reversing its flow and returning to the supply system) by using a check valve, which permits flow in only one direction by using a hinged flapper or guided poppet that opens when the flow is going in one direction but will close if the direction reverses. An air gap, which is a vertical distance between the outlet of the supply and the overflow rim of the fixture into which the water flows. Water, under pressure, can pass over an air gap but cannot return to the supply. Plumbing codes usually require that backflow preventers are installed between the water main and the branch connections to individual service. 

Backhand Welding 
Form of welding with the torch facing the weld and being moved backward as the weld bead moves forward. 

Backhoe 
Piece of heavy equipment, used in construction, which has a bucket suspended on a movable boom. 

Backing 
1. Substance used behind a facing to add strength, stiffness or structural support. 
2. Block wall serving as a base for brick wall by using an occasional header brick to tie the brick wall to the backing. 
3. Supporting of the weld metal during welding by adding material to the back side of the root. 

Backnailing 
Nailing piles of built-up roof to substrate to supplement back mopping. 

Backplastering 
After the plaster or mortar on one side of a plaster wall has hardened, the application of a coat of plaster to the opposite side. 

Backpriming
The application of paint or stain to the backs of siding to ensure the stability of the wood because it keeps moisture from entering through the back sides of the siding. 

Backset 
The distance from the middle of the handle or knob to the edge of the door - 2-3/8" backset installed in a 2 ½ " hole is the most common size. 

Backsplash
Material installed above or behind a kitchen countertop, which prevents splashing or spilling of water, or other substances down the wall. Tile, Corian, granite, and Formica are common materials used. 

Backstamp 
Stamp on plywood panels showing approval by the American Plywood Association. Also known as an edgemark, all unsanded or touch-sanded panels or panels with A or B faces on one side only have the APA trademark on the panel back. 

Backup 
1. A substitute or standby. 
2. Structural portion behind a façade. 
3. Overflowing of a plumbing fixture due to stoppage. 
4. Sturdy, stationary object against which material can be pushed by a piece of earth-moving equipment. 

Backup Contract 
Second written agreement to purchase real estate in the event the first contract is not executed. 

Backup Offer 
An additional bid for a property that can be accepted if the initial offer falls through. 

Backward Inclined Fan 
The blades of the fan are inclined opposite to the air flow. 

Backwater Valve
Sewer line valve that prevents sewage from flowing back into house. 

Bad Faith 
Intent to deceive from the beginning of a deal or contract. 

Baffle 
Obstruction used to control flowing of gas, liquid, light or sound or used to control the splashing of liquid in a container. A heat shield used to deflect the byproducts of combustion.