- Stretch-out
- The flat width of metal needed to form a profile, found by adding every face, bend, and return of the finished shape. It drives how many sheets a gutter or flashing run requires, which makes it central to both fabrication layout and material ordering.
- Ogee gutter
- A rain gutter whose face has a flowing S-shaped curve, common on older and residential buildings and sold by its nominal size. It is formed on a roll former or by hand and capped with end pieces fixed using a snap-lock punch. Nominal sizes such as five inches are common in exam problems.
- Leader
- The vertical pipe that carries roof water from a gutter down to grade or a drain, also called a downspout. Its size comes from the roof area it serves and local rainfall, and it may be aluminum, galvanized steel, or copper.
- Projected roof area
- The plan-view area of a roof plane, measured horizontally rather than along the slope. Gutter and leader tables are entered with this number, and a wall that drains onto the roof adds a share of its area.
- Cornice brake
- A bench machine with a long clamping bar and folding leaf that bends sheet metal into straight-sided shapes such as flashings, trim, and downspouts. It makes sharp, accurate folds along the full bar length, though it cannot make rolled shapes, and the candidate should know which seam types it suits.
- Lock seam
- A joint made by folding the edges of two metal pieces so they hook together and are then pressed flat. It is strong enough for a fabricated downspout and is chosen over a plain butt or lap joint where the seam must hold itself.
- Standing seam
- A raised, folded joint between metal roof panels that keeps fasteners out of the water path. It allows roofs of very low slope, and the panels are clipped so they can expand and contract without tearing.
- Pattern development
- Drawing the flat shape of a fitting, such as an elbow, transition, or cone, so it can be cut and rolled or folded into three dimensions. Careful development is what keeps a complex fitting from needing rework.
- Sheet gauge
- A numbering scheme for metal thickness in which a bigger number means thinner sheet, and the same number differs between steel, galvanized, and nonferrous metals. Code tables list required thickness in both inches and gauge.
- Galvanic corrosion
- Accelerated attack on one metal where it touches a different metal in the presence of water. Choosing compatible metals and fasteners, for instance for copper roofs or aluminum gutters, prevents early failure, which is why fastener material is specified to match the roofing.
- Cricket
- A small peaked piece of sheet metal built behind a chimney or wide roof penetration that sheds water around it. It prevents ponding on the high side, and wider penetrations call for one, covered in sheet metal with the joints properly flashed.
- Product-conveying duct class
- A grouping of exhaust ducts by what they carry, from light fumes and fine dust to heavy abrasive material. The class, along with negative pressure and reinforcement spacing, selects the minimum metal gauge.
- Type I hood
- A commercial kitchen hood over equipment that gives off grease and smoke. It must be built of heavy steel or stainless with liquid-tight seams, overhang the cooking surface, and exhaust a minimum airflow per foot set by the heaviest appliance below.
- Net exhaust airflow
- The air a hood actually removes from the room, equal to the total the hood pulls minus whatever replacement air is supplied from within the hood itself. The fan has to be sized for the net requirement plus internal makeup air.
- Liquid-tight weld
- A continuous external weld on every seam, joint, and collar of a grease duct or hood so no grease can leak out. Bolts, screws, and tack welds do not meet this standard, and the same welded construction applies to the duct-to-hood connection.
- Clearance to combustibles
- The air space between a hot duct and nearby wood or other burnable material. The distance depends on the material, and spaced noncombustible sheet metal or mineral wool can reduce it, provided the air gap and the thickness of the shield are kept as the code specifies.
- Dryer transition duct
- The short listed connector between the dryer and the fixed rigid exhaust duct. It is not a substitute for the rigid metal run, which must be smooth inside, free of screws that catch lint, and kept within a maximum length that shrinks when extra elbows are added.
- Point of operation
- The spot on a shear, press brake, or similar machine where the knives or dies work on the metal. Guards must keep hands out of that zone, with opening sizes that grow wider only as distance from it increases, and a guard that can be removed only with a tool.
- Safety distance
- The minimum spacing between a sensing or two-hand control device and a press brake's danger zone, calculated from how fast a hand moves and how long the machine takes to stop. As brakes wear, stopping time grows, so the required distance grows with it.
