On this page I define a few terms and acronyms we use on the construction site. In the blog I’ve tried to give an explanation whenever I use a term for the first time, but I can’t expect you, dear reader, to sift through every post looking for the first mention of OSB. Instead you can refer here… and you may also find some goodies I don’t mention anywhere else.

14-2, etc.: Shorthand for a type of electrical cable. The first number is the gauge of each conductor (smaller gauge equals larger wire) and the second is the number of conductors in the cable.

2×4, etc.: Nominal dimensions for dimensional lumber. A 2×4 is actually 1 1/2 inches by 3 1/2 inches, and so on.

3-tab: A type of asphalt shingle. Used to make cap shingles for roof peaks and hips.

4-on-12, etc.: A roof pitch, where for every 4 inches of rise the roof has 12 inches of run. Always expressed as “X-on-12”.

“45 it”: Cut it at a 45-degree angle.

AU: Attention Unit. Colin’s expression for something he has to remember. It’s best to keep AUs to a minimum.

Beam: A long piece of material that spans between two points, creating an open space below while supporting loads from above. In construction, beams are usually made of wood or steel.

BCH: A very small measurement. Refers to the thickness of a Black Curly Hair (or something much ruder). See also RCH.

BFE: Base Flood Elevation. Defined by FEMA as the high-water level that has a 1-in-100 chance of being reached in any given year. It’s a good idea to keep buildings above BFE.

Cement: A powdery substance that reacts with water to create a quick-drying paste. Add sand and gravel to the mix and the result is concrete. If you want to really annoy a structural engineer, say “cement” repeatedly when you mean “concrete”.

Cleat: A piece of lumber that provides footing for a worker on a steep-pitch roof, or supports a beam in the process of being raised. Cleats are usually taken down once they’ve served their purpose.

Clincher: A nail pounded diagonally to connect two pieces of lumber. Stud walls are often built with two straight nails plus a clincher at each connection, providing extra shear strength.

Flashing: Nonporous material intended to keep water out. It’s usually aluminum sheets cut to size, and it’s most often used to cover weak spots like corners where a wall meets a roof.

GFCI: Ground Fault Circuit Interrupter. A safety feature on an electrical circuit that senses a short circuit and switches off power before it can cause damage. Sometimes informally shortened to just GFI.

Glulam: Glued Laminated Lumber. A bunch of thin strips of wood glued together to make a piece with useful dimensions and more consistent properties than dimensional lumber.

“Go to 11”: Spinal Tap reference, meaning better than the best. Used onsite as often as possible.

HVAC: Heating, Ventilation, and Air Conditioning.

ICF: Insulated Concrete Form. A block with two polystyrene faces and a void in between. You stack the blocks to build a wall, then fill the void with concrete.

Joist: A beam that supports a floor or ceiling. Joists are horizontally flat, as opposed to rafters, which support a roof and follow the roof pitch.

Ledger: A piece of lumber running along the outside of a building to support exterior beams, such as for a deck.

Luan: One-ply plywood, usually 1/4″ thick. Useful in remodeling to shim a floor level or a wall plumb.

LVL: Laminated Veneer Lumber. Similar to glulam but with even more layers. High bending strength makes it good for transfer beams.

Moisture content: The proportion of water in something, such as a concrete mix. Wet concrete with a low moisture content reaches full strength faster, but it’s less workable and may crack easily.

OSB: Oriented Strand Board. Looks like plywood, but the grains all run the same way. Stronger and typically more expensive.

Patty: The pattern piece used to trace all the other pieces. Often used for repetitive, complicated cutouts like rafters.

PCF: Pounds per cubic foot, a common unit of density. (Concrete for example has a density of 150 PCF… so if you know the volume of concrete, you know how much it weighs.) Similarly, PSF is pounds per square foot, a unit of pressure, and PLF is pounds per linear foot, a unit of distributed force.

PE: Professional Engineer.

RCH: A measurement even smaller than a BCH. Refers to the thickness of a Red Curly Hair (or a rude variation).

Ring shanks: Nails with a ribbed shaft that secures them better in plywood. Also called “sheathing nails”; often come in clips for a nail gun.

Romex: A brand of electrical cable, often used as shorthand for any cable. Also used in phrases like “Romex connector” for the round plastic or metal inserts that cables slide through only one way.

Shim: A thin piece of something used to make up any discrepancy in distance or length. Wedge-shaped wood shims are very useful for making base cabinets level.

Sluggo: The sledgehammer.

Stickers: Thin pieces of wood used to separate rows of lumber in a stack, keeping the lumber dry and off the ground.

Strapping: Lumber running over the top of a room to support a drywall ceiling.

Tack nail: To fasten something in only one or two locations, holding it weakly in place while you confirm your measurements. If the placement is wrong, it’s easy to remove the tack nails and start over. Once it’s correct, fasten as many more nails as you need for a strong connection.

Woody: The wood ladder. Aluminum ladders are generally called by their color and sometimes their size, i.e. “greenie” or “big silver”.

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