Post and Beam and Timber Framing -- Ancient Building Crafts
The old expression "Raise high the roof-beam" regains its meaning when the structure in question is a timber frame. As the crane lifts the oversized timbers and swings them into place, the crew taps the hand-cut mortise and tenon joints together with huge mallets called beetles or "persuaders" and then pounds in wooden pegs that are the only nails. When all the timbers have been fitted into place, the frame looks and acts like the skeleton of the house, defining its outline while holding all the structural weight.

Timber framing is the most sophisticated form of what is called post and beam construction. "Post and beam" is the oldest method of building, dating back at least to the early Greeks. It includes any structure built of vertical posts that hold up beams laid horizontally across them. The posts and beams may be of wood or stone, or even concrete, in modern times.

There is more than one kind of post and beam construction that uses over-sized wooden timbers. Some connect the timbers with large metal plates and bolts. Timber framing makes the connections, instead, by carving joinery into the wood the way a fine piece of furniture is made. Timber framing made possible the beautiful churches of the Middle Ages, with their hammer beam vaults. It remained the primary method of building wooden structures until the development of stick framing in the mid-eighteen hundreds.

Stick framing allowed uniform dimensional lumber to be shipped to the building site for quick and easy construction, speeding the settlement of the American West. Timber framing was largely forgotten. However, the Amish continued to use timber framing in the Mid-West to build their spacious barns, thus preventing the craft from being lost.

Timber framing began to enjoy a new vogue as the most popular type of post and beam construction for residences in the 1990's. The number of companies that produce timber frames has grown from a few pioneers to a large and diverse group spread out across the U.S. While some companies have turned to large computer-run machines, many continue in the age-old tradition of hand-chiseling the joinery into the timbers.

It is easy to understand the great popularity of post and beam homes when standing in a finished timber frame and looking up at the heavy-beamed cathedral ceiling filled with light from the huge expanses of glass. There is great satisfaction, as well, in knowing that your home is a secure haven that connects you to the traditions of the past and will stand strong well into the future.

Features of Post  and Beam

Preparation of Members
When off site preparation is done, drilling, cutting and milling can be done with only erection and fastening left to be done in the field. Although some site adjustments will usually be required, wood is a building product which is easily cut and shaped with hand and power tools quickly and easily.

The advance preparation of members for erection and the speed with which wood panels and particularily wood plank decking can be installed, means a building can quickly be covered from above to provide protection to ongoing work inside.

Appearance
Post and beam buildings, on the other hand, are most often constructed with the main structural members left exposed. The exposed wood colour and texture can result in dramatic and pleasing appearances in both the exterior and the interior.Because appearance is often of primary importance, appropriate care must be taken to avoid damage from impact and weather by protecting materials during storage, handling, erection, fitting and connecting.Once erection commences, building closure should follow as quickly as possible to avoid dimensional change from moisture absorption, discoloration from sun, moisture, or staining resulting from the oxidation of metal connectors.

Flexibility
However, post and beam methods can be combined with conventional framing load bearing walls where a partition is required and a column is not suitable. In such cases, the load bearing wall must be designed to accept concentrated beam loads.

Fire Safety
Post and beam construction qualifies as Heavy Timber construction for the purpose of fire safety when the members are of certain dimensions. This allows roof and floor members to remain exposed rather than be covered with a protective layer of gypsum wallboard.

Construction Joint
Construction joints are purposely placed in concrete to facilitate construction; to reduce initial shrinkage stresses and cracks; to allow time for the installation of embedded metalwork or to allow for the subsequent placing of other concrete. Bond is required at construction joints regardless of whether or not reinforcement is continuous across the joint. A construction joint allows a reasonable size concrete placement or a point to terminate a placement. The interface between two successive placings of concrete where bond, and not permanent separation, is intended.

Contemporary post and beam construction and timber frame differ in the following ways:
Post and Beam

  • Timber, glulam, parallel strand lumber (PSL) and laminated veneer lumber (LVL) are used for main members
  • Shop preparation of connections is possible
  • Metal fasteners are used for speed, economy, and strength

Timber Frame

  • Hardwood or softwood timber is used for main members - usually in a 'green' state, or of a high moisture content. Recycled or radio-frequency kiln dried timber is also available to reduce movement and checking in the timbers as they dry out. Both these options come with higher cost considerations. Glulam can also be incorporated into timber framing.
  • Precise shop preparation of joints is almost always required
  • Fastening is based on the interlocking of members by friction fit, by the use of hardwood pegs, and where employed, traditional joining techniques.