View source for Cruck

{{short description|Curved timber used as roof support}}
[[File:Cruck framing.jpg|thumb|right|250px|Cruck framing, [[Leigh Court Barn]], [[Worcester, England|Worcester]], England]]
[[File:Morlanich Longhouse 2004.jpg|thumb|The [[Moirlanich Longhouse]], a byre dwelling with a cruck frame]]
A '''cruck''' or '''crook frame''' is a curved [[lumber|timber]], one of a pair, which support the [[roof]] of a [[building]], historically used in England and Wales. This type of [[timber framing]] consists of long, generally naturally curved, timber members that lean inwards and form the ridge of the roof. These posts are then generally secured by a horizontal beam which then forms an "A" shape. Several of these "crooks" are constructed on the ground and then lifted into position. They are then joined together by either solid walls or cross beams which aid in preventing 'racking' (the action of each individual frame going out of square with the rest of the frame, and thus risking collapse).

==Etymology==
The term ''crook'' or ''cruck'' comes from [[Middle English]] ''{{lang|enm|crok(e)}}'', from [[Old Norse]] ''{{lang|non|krāka}}'', meaning "hook". This is also the origin of the word "crooked", meaning bent, twisted or deformed, and also the crook used by [[shepherd]]s and [[crosier|symbolically by bishops]].

==Use==
[[File:Cruck cottage in Wick - geograph.org.uk - 742651.jpg|thumb|A half timbered house in [[Worcestershire]] framed with a full cruck]]
Crucks were chiefly used in the [[Middle Ages|medieval]] period for structures such as houses and large [[tithe barn]]s, which were entirely timber-framed. They were also often used for the roofs of stone-walled buildings such as churches. However, these bent timbers were comparatively rare, as they were also in high demand for the shipbuilding industry. 

Where naturally curved timbers were convenient and available, carpenters continued to use them at much later dates. For instance, base crucks are found in the roofs of the residential range of [[Staple Inn]] Buildings, Nos. 337 – 338, [[High Holborn]], London. This is dated by documented records to 1586, with significant alterations in 1886 (under [[Alfred Waterhouse]]) and further restorations in 1936, and 1954–55. Despite these changes Cecil Hewett, an authority on English Historic Carpentry, has stated that these 16th-century crucks are original.

The large main barn of the manor house [[Barlow Woodseats Hall]] features what is claimed to be the longest continuously roofed cruck barn in [[Derbyshire]], and possibly even in the United Kingdom.

An example of a [[Yorkshire]] cruck barn complete with a heather-[[thatched roof]] can be found in [[Appletreewick]].<ref>{{Cite web |url=http://www.craven-cruckbarn.co.uk/cruck%20barn.htm |title=Craven Cruck Barn |access-date=2013-01-06 |archive-url=https://web.archive.org/web/20130215021328/http://www.craven-cruckbarn.co.uk/cruck%20barn.htm |archive-date=2013-02-15 |url-status=dead }}</ref> The crucks or cruck "blades" are a single oak tree riven (split) in two to form an equally shaped A frame.

Rare examples of cruck framing are found on continental Europe such as in Belgium,<ref>{{cite web|first=Nat|last=Alcock |title=The Significance of the Cruck Construction at Néchin, Belgium |work=L'architecture vernaculaire|volume=tome 34-35 (2010-2011) |url=http://www.pierreseche.com/AV_2010_alcock.htm |date=June 5, 2011}}</ref> Flanders, Northern France and the [[Corrèze]] region of France.<ref>{{cite web|url=http://lacorreze.com/documents/charpente_a_cruck.htm|title=La charpente à cruck|language=fr}}</ref> No cruck frames are known to have been built in North America though there are rare examples of what may be an upper cruck or knee rafters.

==History==

The oldest surviving crucks with dates confirmed by [[Dendrochronology|tree ring analysis]] date from around the middle of the 13th century.<ref name=Roberts20>{{cite book |last1=Roberts |first1=Edward|chapter=True Crucks and Related Frames |date=2003 |title=Hampshire Houses 1250-1700: Their Dating and Development|publisher=Hampshire County Council |page=20|isbn=1859756336}}</ref> They may have declined due to providing an inconveniently shaped space in cases where an upper floor was used.<ref name=Roberts21>{{cite book |last1=Roberts |first1=Edward|chapter=True Crucks and Related Frames |date=2003 |title=Hampshire Houses 1250-1700: Their Dating and Development|publisher=Hampshire County Council |page=21|isbn=1859756336}}</ref>

===Revival===
During the current revival of green-oak framing for new building work, which has occurred mainly since approximately 1980 in the UK, genuine cruck frames have quite often been included in traditionally carpentered structures.<ref>{{cite book
 | last1 = Ross | first1 = P.
 | first2 = C. | last2 = Mettem
 | first3 = A. | last3 = Holloway
 | title = Green Oak in Construction
 | location = High Wycombe
 | publisher = TRADA Technology
 | year= 2007
 | pages = 8–9, 14, 57, 112–3 
 | isbn = 978-1-900510-45-5 }}
</ref> 

There are also some fine, historically authentic reconstructions. For instance, [[Tithe Barn, Pilton]], [[Glastonbury]], whose original roof was destroyed by lightning, has been carefully rebuilt in 2005 from curved oaks. The necessary trees were sought out, using special templates, in English woodlands.

==Types==
[[File:St. Michael's Church Baddiley - geograph.org.uk - 272728.jpg|thumb|A jointed cruck]]
# True cruck or full cruck: The blades, straight or curved, extend from a foundation near the ground to the ridge. A full cruck does not need a tie beam and may be called a "full cruck - open" or with a tie beam a "full cruck - closed".<ref name="Brown66-67">{{cite book|last=Brown|first=R. J.|title=Timber-framed buildings of England|location=London|publisher=R. Hale|year=1997|orig-year=1986|pages=66–67|isbn=0709060920}}</ref>
# Base cruck: The tops of the blades are truncated by the first transverse member such as by a tie beam.<ref name="Brown66-67"/>
# Raised cruck: The blades land on masonry wall and extend to ridge.<ref name="Brown66-67"/>
# Middle cruck: The blades land on masonry wall and are truncated by collar beam.<ref name="Brown66-67"/>
# Upper cruck: The blades land on tie beam, very similar to knee rafters.<ref name="Brown66-67"/> 
# Jointed cruck: The blades made from two pieces joined near eaves. They can be joined in at least five ways.<ref name="Brown68">{{cite book|last=Brown|first=R. J.|title=Timber-framed buildings of England|location=London|publisher=R. Hale|year=1997|orig-year=1986|pages=68|isbn=0709060920}}</ref>

The apex of a cruck frame also helps to define the style and region of the cruck.  Different types include the butt apex, halved, housed, yoke, and crossed forms.<ref name="Brown68"/>

== See also ==
* [[Hammerbeam roof]]
* [[Vernacular architecture]]

== References ==
{{Reflist}}

==Further reading==
* Hewett, Cecil A. (1980), ''English Historic Carpentry'', Philimore, pp 231–233. {{ISBN|0-85033-354-7}}
* Harris, Richard (1978), ''Discovering Timber-Framed Buildings'', Shire Publications Ltd. Princes Risborough, Buckinghamshire. {{ISBN|0852634277}}
* Alcock, N. W., Barley, M. W. ''et al'' (1996), ''Recording timber-framed buildings - An illustrated glossary'', Council for British Archaeology, York. {{ISBN|1872414729}}

==External links==
* [http://archaeologydataservice.ac.uk/archives/view/vag_cruck/ Cruck database]
* [http://www.blackandwhitehouses.co.uk Black and White Timber Framed houses]
{{Woodworking}}

[[Category:Woodworking]]
[[Category:Vernacular architecture]]
[[Category:Timber framing]]
[[Category:Structural system]]