Timber framing is the method of creating framed structures of heavy timber jointed together with various joints, but most commonly originally via lap jointing, and then later pegged mortise and tenon joints. Lengthening scarf joints. Diagonal bracing is used to prevent “racking”, or movement of structural vertical beams or posts.[2]
Originally, German (and other) master carpenter would peg the joints with allowance of approximately an inch, enough room for the wood to move as it seasoned, then cut the pegs and drive the beam home fully into its socket.
To cope with variable sizes and shapes of hewn (via adze or axe) and sawn timbers, two main carpentry methods were employed: scribe carpentry and square rule carpentry.
Scribing was used throughout Europe, especially from the 12th century to the 19th century and subsequently imported to North America where it was common into the early 19th century. In a scribe frame, timber sockets are fashioned or “tailor-made” to fit its corresponding timber; thus each timber piece must be numbered (or “scribed”).
Square-rule carpentry was developed in New England in the 18th century. It used housed joints in main timbers to allow for interchangeable braces and girts. Today, standardised timber sizing mean that timber framing can be treated incorporated into mass-production methods as per the joinery industry, especially where timber is cut by precision CNC machinery.
To finish the walls, the spaces between the timbers (in German called Fächer) were often infilled with wattle and daub, loam, brick, or rubble. Plastered faces on the exterior and interior were often “ceiled” with wainscoting for insulation and warmth.
This juxtaposition of exposed timbered beams and infilled spaces created the distinctive “half-timbered”, or occasionally termed “Tudor” style.
[edit] Jetties
For more details on this topic, see Jettying.
A jetty is an upper floor which requires a structural cantilevered horizontal beam called a jetty bressummer to bear the weight of the new wall, projecting outward from the preceding floor or storey.
In an era where houses were taxed with respect to ground-floor area (square footage) extensive jettying was employed to create higher storeys of greater area. In the city of York in the UK, the famous street known as The Shambles exemplifies this, where jettied houses seem to almost touch above the street.
[edit] Timbers
Historically, the timbers would have been hewn square using a felling axe and then surface finished with a broad axe. If required, smaller timbers were ripsawn from the hewn baulks using pitsaws or frame saws. Today it is more common for timbers to be bandsawn, and the timbers may sometimes be machine planed on all four sides.
The vertical timbers include
* posts (main supports at corners and other major uprights),
* Wall studs (subsidiary upright limbs in framed walls), for example, close studding.
The horizontal timbers include
* sill-beams (also called ground-sills or sole-pieces, at the bottom of a wall into which posts and studs are fitted using tenons),
* noggin-pieces (the horizontal timbers forming the tops and bottoms of the frames of infill-panels),
* wall-plates (at the top of timber-framed walls that support the trusses and joists of the roof).
When jettying, horizontal elements can include:
* the jetty bressummer (or breastsummer): the main sill (horizontal piece) on which the projecting wall above rests and which stretches across the whole width of the jetty wall. The bressummer is itself cantilevered forward, beyond the wall below it.
* the dragon-beam which runs diagonally from one corner to another, and supports the corner posts above and supported by the corner posts below.
* the jetty beams or joists which conform floor dimensions above but are at right angles to the jetty-plates that conform to the shorter dimensions of “roof” of the floor below. Jetty beams are morticed at 45° into the sides of the dragon beams. They are the main constituents of the cantilever system and determine how far the jetty projects
* the jetty-plates, designed to carry the jetty beams. The jetty plates themselves are supported by the corner posts of the recessed floor below.
The sloping timbers include
* trusses (the slanting timbers forming the triangular framework at gables and roof),
* braces (slanting beams giving extra support between horizontal or vertical members of the timber frame),
* herringbone bracing (a decorative and supporting style of frame, usually at 45 ° to the upright and horizontal directions of the frame).
[edit] Modern features
Porch of a modern timber-framed house
Interior of a modern hand-hewn post and beam home.