History of oak framing

The skills and techniques of the Master Carpenters have been passed down through generations, being honed and developed to meet changing circumstances. Oak frames were typically made in a “framing yard”, which was close to the area in which the trees were felled before being transported to their final destination. Because a large number of different pieces of timber were involved in a frame, each piece was identified with a “carpenters mark”, which is based on the Roman numeral system. These different members could then be easily recognised once carted to site, to make up the various trusses and frames within the building.

Oak framed buildings were always prefabricated before raising the complete frame. The buildings were split into bays being divided by the major cross frames and roof trusses. Each separate cross frame would be fabricated on the ground with its face side pointing upwards, once this was completed the other frames such as the wall and roof would then be fabricated to make up the whole building. In this way every joint is cut before the raising of the frame, making it easier to go together on site. The joints were typically variations of mortice and tenons, which were fixed together using oak pegs.

The timber most commonly used was green oak, ie. oak used within a couple of years of the tree being felled. This timber still has a high moisture content and therefore is not dry in the middle (the heartwood). There were two reasons for this; the first being the amount of time it takes to dry an oak beam which can vary from 5 to 10 years depending on the size of the beam and therefore it would have been uneconomical to use dried oak. The second reason for using green oak is because it is easier to work with, being that much softer than dried timber. English oak has primarily been used for framing because it is a very strong durable timber containing its own natural preservative to protect it against rot and insect attack. Given the right conditions it will outlive most kinds of stone in construction.