Dendrochronology

Dating Old Welsh Houses

North West Wales Dendrochronology Project

WHAT IT IS

Dendrochronology (obtaining the felling date of a tree by tree-ring dating) works by utilising the variation in width of the annual growth rings as influenced by climatic conditions common to a large area. It is these climate-induced variations in widths which allow calendar dates to be ascribed to undated timbers when compared with a firmly-dated sequence. If a tree-section is complete out to the bark edge then a precise date-of-felling can be determined. A narrow core is extracted from across the annual growth rings of the timber, with no detriment to its strength or stability.

WHY IT IS USED

House designs and plans were sometimes used over a long period. Architectural features are therefore only a very rough guide to the date of a house as it cannot be known whether a building was the first or last of that design, nor how quickly new design fashions spread within a region.

Someone intending to build a house would, however, cut down or purchase, and then collect on site, sufficient large timbers, usually of oak, for constructing the roof and other key elements. As seasoned timber was too hard to work and shape, unseasoned timber was used in houses built before c.1650. These early buildings would therefore usually have been erected very soon after the latest date of the felling of the main timbers. Obtaining the felling date for main roof timbers can thus give useful information about the date of erection of a building, and comparisons can then be made relating to the spread of that building or style of carpentry within a region, using houses which have survived without major alterations.

DENDROCHRONOLOGY