coach screw: meaning, definition, pronunciation and examples
C1Technical / Trade
Quick answer
What does “coach screw” mean?
A large, heavy-duty wood screw with a hexagonal or square head, designed to be driven with a wrench or spanner, typically used in heavy timber construction.
Audio
Pronunciation
Definition
Meaning and Definition
A large, heavy-duty wood screw with a hexagonal or square head, designed to be driven with a wrench or spanner, typically used in heavy timber construction.
In broader usage, any large, heavy screw with a bolt-like head used for joining heavy materials, especially timber to timber or timber to metal. The term can sometimes be used interchangeably with 'lag screw' or 'lag bolt', though technical distinctions exist.
Dialectal Variation
British vs American Usage
Differences
The term 'coach screw' is more common in British, Australian, and New Zealand English. In American English, 'lag screw' or 'lag bolt' is the predominant equivalent term.
Connotations
In British contexts, it strongly connotes timber framing, decking, and heavy DIY. In American contexts, the same object is more readily called a 'lag bolt', which may carry a slightly more generic hardware-store connotation.
Frequency
'Coach screw' is low-frequency in general American English but understood in trade contexts. 'Lag bolt' is the high-frequency American term.
Grammar
How to Use “coach screw” in a Sentence
[fasten/secure/attach] + [object] + with + coach screws[drive/screw] + a coach screw + into + [material][use/require] + coach screws + for + [purpose]Vocabulary
Collocations
Examples
Examples of “coach screw” in a Sentence
verb
British English
- We need to coach-screw the ledger beam directly into the brickwork.
- He's out there coach-screwing the new fence posts.
American English
- We need to lag-bolt the ledger board to the rim joist.
- He's out there lag-screwing the new deck frame.
adverb
British English
- [Not standard]
American English
- [Not standard]
adjective
British English
- The coach-screw fixings must be stainless steel for outdoor use.
- Use a coach-screw driver attachment for your impact wrench.
American English
- The lag-screw connections failed under load.
- Use a lag-screw bit in your drill.
Usage
Meaning in Context
Business
Used in procurement for construction or timber trade.
Academic
Rare; might appear in engineering or materials science papers on timber connections.
Everyday
Used in DIY contexts, e.g., building a deck, shed, or pergola.
Technical
Precise term in carpentry, joinery, and structural timber framing specifications.
Watch out
Common Mistakes When Using “coach screw”
- Confusing it with a 'carriage bolt' (which has a smooth, domed head and a square section under the head).
- Using it without a pre-drilled pilot hole, causing the timber to split.
- Pronouncing 'coach' as in 'sports coach' with excessive emphasis.
FAQ
Frequently Asked Questions
In practical terms, they are often used interchangeably, especially in general DIY. Technically, 'lag bolt' is the more common American term, while 'coach screw' is British. Some purists argue a 'bolt' requires a nut, whereas a 'screw' creates its own thread, making 'coach screw' more accurate.
You need a wrench, spanner, or a socket drive (often with a hex or square socket) to turn the head. An impact driver with the correct bit is commonly used for driving them efficiently.
It is not recommended. For most hardwoods and to prevent splitting, a pilot hole (a hole slightly smaller than the screw's core diameter) should be drilled first.
Primarily for joining heavy timber (e.g., in decking, framing, fencing) or for fixing timber to metal or masonry (often using a wall plug in masonry).
A large, heavy-duty wood screw with a hexagonal or square head, designed to be driven with a wrench or spanner, typically used in heavy timber construction.
Coach screw is usually technical / trade in register.
Coach screw: in British English it is pronounced /ˈkəʊtʃ ˌskruː/, and in American English it is pronounced /ˈkoʊtʃ ˌskruː/. Tap the audio buttons above to hear it.
Phrases
Idioms & Phrases
- “[None specific to this term]”
Learning
Memory Aids
Mnemonic
Think of an old-fashioned COACH being built with strong wooden frames, held together by massive SCREWS. A COACH SCREW is the screw strong enough to build a coach.
Conceptual Metaphor
STRENGTH IS MASSIVE THREADING (The robust connection is conceptualised through the deep, coarse threads of the screw).
Practice
Quiz
What is the primary defining feature of a coach screw?