The carpenters must have had a clear understanding of each building before numbering began as there is normally a logic to the numbering pattern employed. It is at this point that the reader should be reminded that the generalisations that follow are just that. There is a great variety in the pattern of numbering and each building should be studied to understand the sequencing if the marks are to be used for interpretive purposes.
The main posts will commonly be numbered down the building in one of the two ways shown in the illustration below. Strictly speaking it is the joints which are numbered and the most obvious sequence is found in the braces of the cross frame within a barn. Since these numbers relate to the cross frames they should be sought on the upper or inside face of the principal posts.
The smaller timbers are then numbered as illustrated opposite. The carpenter has started with the first floor worked down on this truss, but worked up from the ground floor on the facing truss, so there is no general rule.
Note that the marks are placed at the first joint to be made for each timber and will thus be found at the bottom of the studs or braces, and seldom at the top. The numbers on the tie beam relate to the truss over and are from a different sequence as explained in reading the numbers below.
It is normal for the roof trusses and windbraces to form a unique number sequence, as illustrated above, suggesting that the carpenter considered the erection of everything above the tie beam as a separate task, once all the walls had been raised. The numbering illustrated is slightly unusual as the principals are more commonly numbered the same way as the main posts. One 'frame' that can easily be forgotten is the collar purlin, crown post and associated longitudinal braces. I have illustrated one
particularly elaborate numbering system under flags and tags below.
Unfortunately the upper face of the outer walls is often heavily weathered so marks may not always remain legible making walls sheltered by additions a good place to search for them.
Some numbers are set within the joint so are invisible once the building has been erected inside the lap dovetail for the tie beam. One exceptional example of this is the beautifully preserved (and unweathered) Tunmore Cottage in East Clandon which was thoroughly studied while the dendro-cores were taken but not a single carpenters mark was found!