They’re everywhere and they are not, and perhaps that is part of the problem. With Carpenter’s Marks being somehow so ingrained in our collective subconscious, most everyone (even those without interest in historic carpentry and its methods) holds for them some blip of understanding, some seemingly just short of intuitive sense of their necessity and purpose. Perhaps this is why so much assumption is intertwined in much of the written description found on what and why they are.
Much of the supposition as to purpose is wound around how Timber Framed structures were often scribed, cut, and partially assembled in Carpenters’ Yards miles or more from where they were ultimately erected. While this is happenstantially true, it is only tangentially a driver in why the marks are necessary, and over-complicates the case. The real driving need for their use is far simpler than that.
Most Timberframe constructions have multiple copies of the same piece, arranged in assemblages of which there are also multiple copies, be they walls or bents or roof planes, or in the case of bridges, a pair of like trusses and the braced Tie and Floor Beam systems which connect them – Much to keep track of.
Carpenters’ Marks are a simple system to identify place for each individual piece to properly maintain its relationship with adjacent pieces – In the most common form in which such marks are found, that means assigning the low number roman numeral to the reference end / reference corner of the frame, this most often chosen as the Southeast corner – The entirety of the first Bent is assigned Roman Numeral I – Differentiation as to East & West corners (and any pieces found between these) is achieved by incising that Roman Numeral with chisels graduating in size. To these numerals there are often slight variations added to delineate and describe placement as to such things as first & second floor…
Scribe type layout is also a driver in the need for this system, with each individual piece, no matter how much it looks like a carbon copy of its opposite other, only fitting in the one place into which it was scribed.
The system however survived the transition to Square rule layout, (See Dec ’12 archival entry – Overnight Turn on a Paradigm) simply as a proven aid in efficient assembly on raising day.
I still use traditional Carpenters’ Marks on both Scribed and Square Ruled frames. I find it both simpler and more interesting than a grid described with Sharpie markers & ABC / 123 – I’ve also found it holds appeal for clientele. This driven home some years ago in a newly raised house, with the owner beginning a friends introduction to the frame, not with a view of some interesting detail in the timber-work, but in pointing out the Carpenters’ Marks in the Great-Room. (These typ incised on reference faces in the area of the Brace joinery on both the Posts & Braces – ie: A standing height field of view) In watching his description of their purpose play out, his genuine enthusiasm for what he was working to describe suggested to me that he felt his choosing to build a Timberframed home was in some way including he and his family, through their home, in some nameless and timeless continuum – Something I feel part of each and every day.