Flagging 
Flagstone pavement. 

Flakeboard 
Wood flakes bonded with a binder material to be used as sheeting veneer under cabinets or as sheathing, under the finish, for walls and roofs. 

Flame 
The burning gas or vapors of a fire; a flickering light of various colors. 

Flame-cut 
Metal cut with a torch. 

Flame-proof 
Something not easily damaged by fire or which does not catch on fire. Non-combustible. 

Flame Spread Rating 
Tests, done in accordance with ASTM Standard E84, for establishment of fire-resistant values of building materials by measuring how fast and far flames will spread over certain surfaces. 

Flammable 
Easily set on fire. Easily ignited.

Flange 
1. Projecting rim or collar on a wheel or pipe which holds it in place, gives it strength or allows it to attach to another object. Often there are bolt holes circled around the outer edge of the rim, with bolts with nuts holding the two flanges together against a gasket that separates them. 
2. The rim that goes around the metal enclosure that holds the electrical circuits, at the point where it passes into the electrical equipment enclosure. 
3. Side sections on an I-beam. 

Flank
1. The left or right side of something. 
2. To place at or to protect the side of something. 

Flanking Paths 
Sound transmission paths that are left in a structure that is built to stop or reduce sound transmission. The gaps, called flanking paths, that are left in the walls, allow sound to pass around the wall, destroying the soundproofing. Without gaps, sound would be resisted or eliminated. 

Flap Wheel 
A wheel which has short flaps covered with abrasive, attached to a handle held in the jaws of a drill motor, which turns causing the flaps to spin, sanding irregular, hard to reach surfaces. 

Flapper Ball 
Rubber valve covering the flush valve in a toilet tank. 

Flash Point 
Temperature at which a material will ignite, which differs depending on the type of material. Acetone has a zero degree flash point, making it very flammable. 

Flash Set 
The quick hardening or curing of mortar. 

Flashing 
Metal strips, used to prevent water seepage, and installed around chimney, vents, windows, doors, and skylights, along seams in the roof and beneath shingles. The purpose of flashing is to prevent the penetration of water as well as to provide a drainage passageway between joints, most commonly the joint between a roof and a wall. 

Flare 
1. A sudden bright light blazing unevenly. 
2. To curve or spread outward as in the bell of a trumpet or at the end of a cone.

Flare Bevel-groove Weld 
Curved piece welded together with a flat piece. 

Flare Fitting 
Flared tube end, which is joined with a male cone-shaped tube and then sealed with a coupling. 

Flare Header 
Exposed header, which is painted noticeably darker than the others. 

Flare V-groove Weld 
Two curved pieces welded together. 

Flaring Tool 
Tool used to create a cone-shaped enlargement at the end of a piece of tubing. This tool has a female die holding the end of the tubing and a clamp secured to the die. There is a cone-shaped mandrel on he threaded stem of the clamp, which screws down through the clamp. When the cone-shaped mandrel is forced into the end of the tubing, which is held by the chamfered female die, the tubing end flares out to match the chamfer in the die. 

Flash 
1. Sudden brief spurts of bright light. 
2. To apply a colored film of glass on other glass. 
3. Unevenly colored painted wall. 

Flash Point 
Lowest ignitable temperature for fuel or gas vapors. 

Flash Set 
Concrete that has set too quickly due to too much heat. 

Flash Welding 
Process where the entire closely connected parts are welded together simultaneously by resistance heating with electrical current and then having pressure applied to the welded joint. 

Flashing 
Installation of waterproof sheets of plastic or corrosion-resistant metal, along with exterior finishing materials for the prevention of water leakage in such paces as the intersection of a wall and roof or the valley of a roof. 

Flashing Cap Molding 
Metal flashing that is used as a drip cap over a door or window. 

Flashing Cement 
Also referred to as asphaltic plastic cement, this asphalt-based roofing cement remains pliable at colder temperatures. 

Flashover 
Electrical discharge, which appears on the surface of an insulating material that is not able to contain a very high voltage.

Flat 
1. An apartment, within a multi-family house, usually on one floor. 
2. Smooth and level with little or no depression or elevation. 
3. Paint without gloss or shine. 

Flat Arch 
This arch, also called a jack arch, straight arch, minor arch, segmented arch, or multicentered arch, has a horizontal top surface, with a span of up to 6 feet, can support loads up to 1,000 pounds per square foot, with a rise to span ratio of 0.15 or less. 

Flat Fee 
Set amount charged by a broker. 

Flat File 
Wood or metal, flat bar-shaped abrasive tool with rectangular cross-sections. 

Flat Grain 
Wood, which has been sawn across the growth, rings of a tree. 

Flat Lease 
Lease agreement having level payments during the contractual period and does not have an escalation clause, which would allow for increased costs due to increases in inflation, taxes or other related costs. 

Flat Paint 
Paint that has a high amount of pigment and dries without gloss. 

Flat Position Weld 
Weld, also called a downhand weld, made on the upper, horizontal surface of the work, which has been laid flat or almost flat. 

Flat Roof 
Roof with a level surface or less than a 10-degree slant. 

Flat Skylight 
Glass skylight that is flat rather than concave. 

Flat Slab Floor 
Concrete slabs, which are isolated from the foundation with rigid insulation and are reinforced in two directions or more. 

Flatting Agent 
Added paint pigment, which reduces gloss on a finished surface. 

Flaw 
Deficiency or defect. 

Fleche 
A slender spire, most commonly on the roof ridge of gothic style buildings. 

Fleet Angle 
Angle at which a hoisting rope diverges from being vertical. 

Flemish Bond 
Method of brick laying where the long and short sides of bricks are set alternately using one, than the other, and staggering the rows above and below, so that the short side is above the long side of the surrounding rows. 

Flex 
To bend or contract. The ability to move into a different position, temporarily. 

Flex Drive 
A wrench, which is on a flexible rod that is used to turn sockets at an angle. 

Flexible 
Able to bend. Not stiff or rigid. 

Flexible Base 
Base for a slab, driveway or path, made of compacted gravel or aggregate, so that it is able to change shape when the soil moves, preventing the slab from cracking. 

Flexible Hacksaw Blade 
Saw blade that is hardened only on the tooth portion so that the teeth remain sharp but the blade itself is flexible. 

Flexible Loan Insurance Program (FLIP) 
A graduated payment mortgage (GMP) developed to overcome the negative amortization aspects of the GMP. The buyer's own down payment is deposited in a pledged, interest-bearing account, where it is used as both cash collateral and a source of supplemental payments during the initial years of the loan. During this time, predetermined amounts are withdrawn, by the lender, from the savings account and added to the borrower's reduced payment, making a full mortgage payment. Decreasing every month, it disappears at the end of a predetermined period. Using this type of program is likely to make a borrower able to qualify for a larger loan than with a conventional fully-amortized mortgage. 

Flexible Metal Conduit 
Also called Greenfield conduit, this flexible, protective tubing is made from spiral-wound metal. 

Flexible Metal Conduit, Liquid Tight 
Flexible, protective tubing, which is covered with waterproof plastic coating. 

Flexible Payment Mortgage 
Loan allowing the borrower to pay only the interest for the first few years of the loan. 

Flexible Rate Mortgage (FRM) 
Mortgage with an interest rate that changes based on certain events, such as changes in the prime rate 

Flier 
One of the simpler styles of stair treads. 

Flight of Stairs 
Stairs that reach from one landing to another. 

Flint 
Fine grained, hard silica-based stone, which has sharp edges when broken and which produces sparks when hit with steel. 

Flip Switch 
Electrical switch, which is operated by pushing the control knob up or down. 

Flitch 
1. A lengthwise strip from the outer part of a tree trunk. 
2. A piece or bundle of wood veneer. 

Flitch Girder 
Double joists holding, between them, a metal plate at least ¼" thick, and fastened together with bolts. 

Flitch Plate 
The metal plate, which forms a girder by bolting together, two beams.