Plank (wood)

{{Short description|Timber in the shape of long rectangular prisms}}

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File:US Navy 090513-N-1060K-122 Ship restorers Chris Hanlon, bottom, and Paul Chiasson line up a new plank of white oak along USS Constitution's starboard side.jpg

A plank is timber that is flat, elongated, and rectangular with parallel faces that are higher and longer than wide.{{cite web |title=Definition of PLANK |url=https://www.merriam-webster.com/dictionary/plank |website=www.merriam-webster.com |access-date=28 June 2024 |language=en |date=18 June 2024}} Used primarily in carpentry, planks are critical in the construction of ships, houses, bridges, and many other structures.{{cite book|author=Karen Bush Gibson|title=Plank Houses|url=https://books.google.com/books?id=igmgVMTGKwEC&pg=PA5|access-date=28 January 2011|date=1 January 2005|publisher=Capstone Press|isbn=978-0-7368-3725-5|pages=5–}} Planks also serve as supports to form shelves and tables.

File:Sandakan Sabah Sawmill-20.jpg]]

Usually made from timber, sawed so that the grain runs along the length, planks are usually more than {{convert|1+1/2|in|mm|abbr=on}} thick, and are generally wider than {{convert|2+1/2|in|mm|abbr=on}}. Planks are often used as a work surface on elevated scaffolding, and need to be thick enough to provide strength without breaking when walked on. In the United States, planks can be any length and are generally a minimum of 2×8 ({{cvt|1+1/2|x|7+1/4|in|mm|disp=or}}), but planks that are 2×10 ({{cvt|1+1/2|x|9+1/4|in|mm|disp=or}}) and 2×12 ({{cvt|1+1/2|x|11+1/4|in|mm|disp=or}}) are more commonly stocked by lumber retailers. Timber is categorized as a board if its width is less than {{convert|2+1/2|in|mm|abbr=on}}, and its thickness is less than {{convert|1+1/2|in|mm|abbr=on}}. In Germany, the national norm (DIN 68252) stipulates that the thickness of a plank (termed Bohle) must be 40 mm minimum.{{Cite web |title=DIN 68252-1 - 1978-01 - DIN Media |url=https://www.dinmedia.de/de/norm/din-68252-1/779026 |access-date=2025-04-23 |website=www.dinmedia.de}}

A plank used in a building as a horizontal supporting member that runs between foundations, walls, or beams to support a ceiling or floor is called a joist.

The plank was the basis of maritime transport: wood (except some dense hardwoods) floats on water, and abundant forests meant wooden logs could be easily obtained and processed, making planks the primary material in ship building. However, since the 20th century, wood has largely been supplanted in ship construction by iron and steel, to decrease cost and improve durability.{{cite web|title=Iron and steel in ships|url=http://www.environment.nsw.gov.au/MaritimeHeritage/researchcentre/ironsteel.htm|publisher=New South Wales Office of Environment and Heritage|access-date=24 November 2013}}