lag screw
C2Technical
Definition
Meaning
A heavy wood screw with a hexagonal head designed to be tightened with a wrench, used for fastening large structural timbers.
A type of fastener used primarily in heavy construction and timber framing to join large pieces of wood, often requiring a pilot hole; functionally similar to a bolt but threaded along its entire length.
Linguistics
Semantic Notes
"Lag screw" is a technical term primarily used in carpentry, construction, and engineering. It refers specifically to the fastener itself, not the action of installing it. The word "lag" in this context is historical, relating to its original use in securing barrel staves (lags).
Dialectal Variation
British vs American Usage
Differences
In British English, the term "coach screw" is more common and is a direct synonym. "Lag screw" is understood but is primarily an Americanism.
Connotations
Both terms are purely technical with no special connotations.
Frequency
"Lag screw" is high-frequency in US technical contexts; "coach screw" is the standard UK term.
Vocabulary
Collocations
Grammar
Valency Patterns
[use/install] + lag screw + [in/to/through] + [timber/beam][fasten/secure] + [object] + [with] + lag screwVocabulary
Synonyms
Neutral
Weak
Vocabulary
Antonyms
Usage
Context Usage
Business
Rare, except in procurement for construction projects.
Academic
Used in engineering, architecture, and wood technology papers.
Everyday
Virtually never used outside DIY or construction hobbies.
Technical
Core term in construction manuals, carpentry guides, and engineering specifications.
Examples
By Part of Speech
verb
British English
- The timber will need to be coach-screwed to the foundation.
American English
- We need to lag-screw the ledger board directly into the wall studs.
adjective
British English
- A coach-screw fixing is more secure than nails.
American English
- Use a lag-screw connection for the main support post.
Examples
By CEFR Level
- The shelf is held up with strong screws.
- For the deck frame, we used special heavy screws called lag screws.
- Structural integrity is ensured by fastening the beam with three 10mm galvanized lag screws, each driven into pre-drilled pilot holes.
Learning
Memory Aids
Mnemonic
Think: LAG = Large, Awesome Grip. A LAG screw GRIPS large pieces of wood.
Conceptual Metaphor
A METAL TOOTH biting deeply into wood to hold massive weight.
Watch out
Common Pitfalls
Translation Traps (for Russian speakers)
- Avoid direct translation like *'отстающий винт'*. The correct technical term is 'глухарь' (glukhar') or 'шпилька' (shpil'ka) depending on the exact type.
Common Mistakes
- Confusing it with a 'lag bolt' (which typically has a bolt-like shaft with a nut).
- Using it to refer to any large wood screw.
- Pronouncing 'lag' as in 'jet lag' instead of /læɡ/.
Practice
Quiz
In British English, what is the most common synonym for 'lag screw'?
FAQ
Frequently Asked Questions
In common US usage, they are often used interchangeably, but purists note a 'lag screw' is threaded all the way and turned into wood, while a 'lag bolt' might have an unthreaded shoulder and be used with a nut.
A lag screw is installed using a wrench (spanner) or socket driver on its hexagonal head, often after a pilot hole has been drilled.
Primarily in construction, timber framing, deck building, heavy-duty DIY projects, and engineering specifications for wooden structures.
The term originates from its early use in securing the staves of wooden barrels, which were called 'lags'.