Essays on Barns


Two-Foot Scribe Marks

You never know what you might find in a two hundred year old barn. All kinds of things just might show their faces. One of the things of a seemingly inscrutable nature is the presence of the so-called – get ready for this – two-foot scribe marks. They are found most often on major sized beams in bents in many (not all) frame barns of the northeast that were built in the 1780 to 1820 time frame and sometimes outside this time.

What exactly are two-foot scribe marks and why did they mostly appear in that 40 year period – 1780 to 1820? Let it first be said that Eastern Barn Consultants does not pretend to have all the answers to this arcane topic that few people know about. It is a complex subject and to date EBC has never met anyone including any modern day timber framer who has even a good part of all the answers. This is an intriguing and challenging area for discussion of timber framing.

Where for heavens sake are two-foot scribe marks seen? The first thing to understand about these marks is that they are found on certain barns that were built in the scribe rule era of barn building traditions. There are two major building traditions – the earlier scribe rule era and the later square rule era.

Two Building Eras

Timbers in framed buildings no matter what the era were joined one to the other that used three methods. The first and earliest was the Scribe rule era – 1625 to about 1830 and rarely after that. The second was the Square rule era – 1810 to circa 1900 and perhaps even later. Thus there was a definite over-lap of perhaps about 25 years or so between the two eras of barn timber jointing in the first half of the nineteenth century. Both the scribe rule and the square eras employed the use of both hewn and milled timbers. However, as a good general rule hewn timbers were considerably more often seen in scribe rule era barns. The third method concerns the so-called mill rule era that will not be spoken about in this discussion other than the fact that this era was the last to appear. Milled wood beams were always used.

The Scribe rule era is the early system of uniting timbers in which, for example, corresponding members in a single bent or frame unit in a given barn are not interchangeable. That is, each particular tie beam because their tenons were cut in a specific manner, could only be received into two particular posts. They were “meant for each other.” They would not fit into or be joined to another set of joints in another timber frame. Framers in order to maintain close track of all structural members to prevent confusion when all of the barn timbers were assembled affixed “marriage marks” into corresponding bent parts. They are usually in the form of Roman numerals. Strict Scribe rule era barns were very labor intensive to make.

In the later Square rule era that was part of the burgeoning Industrial Revolution corresponding timbers in bents in a given barn were interchangeable (or mostly so). Because of this marriage marks were often not necessary and therefore not often seen. This new method of joining timbers in buildings greatly accelerated the production of barns.

It is good to know that certain barns actually employed the use of timbers that were joined by both the scribe rule method and the square rule method. In these barns usually larger timbers such as tie beams were joined with scribe rule methods while the smaller beams such as braces were joined with the square rule method.

Two-Foot Marks

Part of the manner in which certain scribe rule era barns were constructed was the use of two-foot scribe marks. These marks appear on a variety of timbers – vertical posts and horizontal beams such as anchor-beams and tie beams and even rafters. For purposes of illustration our discussion will focus on horizontal tie beams or anchor-beams (in Holland Dutch barns). The marks appear as vertical scribe lines on the lay-out faces (where anchor-beam, posts and end braces are all flush at one vertical face of the H-frame) on the anchor-beams set 24 inches from the lateral faces of the posts to which they are joined.

Sometimes the marks can not be easily seen when the timbers are viewed even when the viewer is quite close to the surfaces to be looked at. Dust and accumulations of old farm crops occasionally have to be cleared from the timber surfaces to render the proper view-ability of the marks. Probably at least 75 % of the time either full circles or half circles are associated with the scribe marks. When full circles are present the scribe marks in effect divide the circle in two equal halves. When half circles are seen they appear at the side of the mark toward the mid-point of the anchor-beam. Why this side was chosen by builders is not known.

Why Two-Foot Scribe Marks?

What was the reason for the inclusion of two-foot scribe marks in certain timber framed barns? No one seems to have any definitive answers. Nevertheless, it should first be realized that when a four-sided building is constructed all the side wall posts in all the bents need to be equidistant from each other in a transverse direction. That is all the posts at the one side wall need to be the same distance from each corresponding post in each bent from the other side wall. Further stated – if say for example the two posts in the first bent are – outer edge to outer edge – 25 feet the same distance or 25 feet between posts has to be maintained in all the other bents of the barn. Rectilinearity is thus established in this manner. Obvious is the fact that you can not have posts in one bent separated by 25 feet and the posts of the next bent 24 feet 8 inches apart. Similarly, posts in the next bent can not be 25 feet 3 inches apart. For simple reasons of solidity a uniform distance must be maintained between all the posts one side to the other in the various bents.

Same Distances between Posts

There is need for a further understanding before there is a total comprehension (at a certain level) for the reason why two-foot scribe marks were used. All the side wall posts made by the act of hewing did not result in the same cross-sectional dimensions. Dimensions (the widths of the posts) could vary by perhaps a half inch or more (up to 2 to 4 inches). Variations in widths of posts could potentially result in fully assembled bents of dissimilar widths – post to post. Since the dimensions in posts hardly ever were the exact same and since the distances between the posts among the bents had to be exactly maintained there had to be a way so that the same exact distances could be created. How was that done?

Maintaining the same distance between posts was done by the use of two-foot scribe marks. For purposes of illustration – let us call all the same corresponding ends of cross ties or anchor-beams in a given barn – A ends and the opposite ends – B ends. If a set of marks at all the A ends are made and a distance of say 25 feet is wanted between all corresponding A marks and B marks then a tool such as a traveler might have been used (circular like metal wheel with a mark with a wood handle tool to establish distances between points on wood or other object) to mark distances between the already established A marks and the opposite marks or B marks. Thus, all the A marks are separated by 25 feet from all the B marks in all the ties.

If a distance of 2 feet (24 inches) between the lateral edges of the posts and the scribe marks on the anchor-beams can be made at all the ends of the bents then a uniform distance can be established. Hence we can follow from the fore-going statements why there was a presence of two-foot scribe marks. The foregoing is only offered as a possible scenario in how two-foot scribe marks were generated in certain 1780 to 1820 timber framed barns.

Variety of Appearances of Two-Foot Marks

There are actually a number of different appearances or ways in which two-foot scribe marks were created on certain beams in certain early barns. Two-foot marks probably in a majority of cases were rendered such that the marks appeared for example from the top of the anchor-beam to the bottom of the same or they were what could be called full beam height marks. Occasionally the marks only appeared in the middle third of the beam – or the top half or (more rarely) the bottom half the beam. Not too un-frequently there were multiple concentric circles or half circles on a beam. One Dutch barn in Albany County, New York has an anchor-beam with eight concentric half circles at each end of the beam with each circle of course that has different diameters. The other interesting aspect of the half – circles was that they were located toward the tenon ends of the beam.

Sometimes there are no two-foot marks at all per se on a beam but there were – at the two-foot spot – certain marks of what ever nature such as angled marks that denoted the two-foot spot. Different timber framers had different ideas on how to incorporate marks in the various barns that they erected. Certainly a book length treatise could be written on two-foot marks that were included in the fine fabric of buildings that were built before the end of the first quarter of the nineteenth century.

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Barn owners often find that one of the most interesting aspects of a timber framed barn is the recognition and verification of the type of wood species that was used in its construction. This often conjures up images of the ancient trees and forests that were the sources of the timbers in these buildings. The original trees of the sizes that were attained in such lush primeval environments have long disappeared from almost all natural arboreal areas in North America. Such trees that yielded great timbers were cut and formed by builders such as posts, cross ties and barn length beams. Such beams up to one to one and a half feet across came from trees that were not indiscriminately chosen by builders but were most often chosen due to their ready availability in the forest and also their strength and durability and other traits.

In many areas of the northeast hardwood species such as maple, beech, ash, chestnut and very often oak were utilized in the construction of certain barns in various areas. Softwoods such as hemlock and more often pine were also used. Often in certain areas particular barns were constructed almost exclusively of either one or perhaps two species. Such an area for example was in southeast Pennsylvania where the great majority of barns their main construction timbers were of oak. Beams from oak timbers – genus – Quercus – were rather easily formed and possessed great strength and resistance to rot – especially the white oak variety. Long straight trees of oaks yielded great sized beams and to this day barns over 200 years retain great dimension oak timbers.

Other trees of other genus and species provided the necessary support in other areas and states. In many barns of certain areas of the Mahantango Valley northeast of Harrisburg, Pennsylvania and particularly in Holland Dutch style barns in the Schoharie and Mohawk River Valleys of New York State pine timbers achieved massive dimensions – often over 18 inches in diameter and sometimes up to a full two feet across. Great beams came from great sized trees.

The identification of wood species in a barn is most often not a difficult task. A small slice or piece of wood is taken from a beam and then examined either by the naked eye such as the case of oak (end grain) or by means of a hand held lens. The wood piece is then keyed out by a process of elimination and in 90% of cases the wood is categorized by species. Quite often one or perhaps two species of wood only are used in the great majority (above wagon floor) of timber framing elements in a given barn. Innumerable barns in southeast Pennsylvania consist of oak timbers.

It is quite remarkable how often historic building (house or barn) owners mistake species of wood used in a structure for another species. The assignment of chestnut –genus – Castanea – is notoriously made for the identification of so many species of woods seen in so many barns. Occasionally especially in certain local areas chestnut was used.