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Dutch Barn Preservation Society Dedicated
to the Study and Preservation NEWSLETTER, Spring 1990, Volume 3, Issue 1 The Tree Nail in Timber Framing of the Past By John Fitchen Instead of using metal nails or spikes to secure the joints in
timber framing, the carpenters of the past relied on the time-honored,
long established tradition of tree-nails: that is, all wood connections.
Trenails (or treenails) were hardwood pins or pegs whose use involved
profound consequences. For example, unlike metal nails, the trenails
had to be individually prepared and shaped, one by one, and the
holes for their insertion, in turn, had to be bored separately,
one by one. Moreover - and this was the most inexorable requirement
- joining the members had to be done by mortice and tenon (or some
analagous device) which meant that they could not be butted together.
Rather, a tenon had to be fashioned at the end of a member, for
insertion into a matching mortice. The Greater Wemp Barn, formerly located at Schoharie Crossing, NY, exhibits the ends of hickory pegs (trenails) which secure braces to post and anchorbeam. Rare chamfering is exhibited on braces. Also rare is the shaping of the anchorbeam where the brace enters. The barn has been removed from its site, but will be re-erected in Albany County, NY. Photo by Clarke Blair. In consequence of this additional length in the member, the sequence of assemblage was irrevocably determined. A horizontal strut, for example, between two studs, could never be framed after both studs were in place, and this absolute, categorical situation came about because the length of the strut was greater than the distance between the studs due to the presence of the tenons at either end of it. These modifications - shaping the tenons and voiding the mortices - obviously required skilled work, and considerable time, to execute. But they also influenced the order and sequence of the framing process in an inescapable way. For whereas a nailed strut can be inserted at any time between two stationary studs, the all-wood scheme of timber framing imposed a sequence of operations at the start. Thus, with only one stud in place, a tenon of the strut had to be inserted in that stud's mortice before the other stud could be maneuvered into place so as to engage the tenon at the strut's other end. Consequently, compared to the rapidity and off-hand ease of nailed attachment, pegged joints required both time and precision in executing them. The holes had to be laboriously bored by hand, using such tools as augurs or wimbrels. And since the purpose of the pegs was that of achieving a secure, permanent attachment of the two members, there had to be some means by which the peg would not work out of the hole, either due to shrinkage or to any movement due to vibration or other stress in the joint. Where any such action was not expected to be a problem, smoothly shaped pins were carefully hewn to fit snugly into the hole. But wherever such action was anticipated, a different procedure was adopted. Obviously, the holes bored to receive the pins (the trenails) were necessarily and inevitably cylindrical, but the pins themselves were not. They were never turned out on a lathe (as some wheel spokes and slender balusters might have been, and modern dowels invariably are). Instead, they were painstakingly shaped by hand, usually employing the tool called a drawknife. The shaping operation that resulted from the use of this tool quite naturally caused the pin to be octagonal instead of circular in cross section. The longitudinal edges - the arrises - made the pin oversized with respect to the hole; consequently, it could not be slipped in and out but had to be forced into the hole. This feature was intentional and welcome, for the arrises bit into the sides of the hole, preventing the pin from becoming loose and indeed resisting any attempts to withdraw it subsequently. The joint, so fashioned, was made permanently secure, thanks to the circle of longitudinal "teeth" biting into the sides of the hole. An extreme case of this gripping function of the arrises of octagonally hewn tree-nails is to be found in the thick planking of the floor of the Deertz Barn. The jarring, pounding and bouncing effect of horse's hooves, and of the heavily-laden hay wagons in season, had to be positively guarded against at all costs. So here, astonishingly, square pegs were driven into round holes. Obviously, this could be done only by a heavy maul in the hands of a strong and particularly adept worker. For, once driven home, or even perhaps split or smashed in the process, there was no way in which the pin could be drawn out; the hole would have had to be bored anew. The pegs, bluntly tapered just enough at the entering end for them to be firmly positioned upright in the hole, were square in section, with sides the same dimension as the diameter of the hole. Since both peg and flooring were of oak, it obviously took considerable force to drive the pegs all the way in, but, once in, they were there for the duration. It should be recognized that, even where the craftsmanship was of the highest quality, there were instances of the use of smoothly cylindrical pins, or at least ones having long tapered points without arrises. Such pegs were commonly used, temporarily, in the procedure of test-assembling a timber framework before its final, permanent consolidation. This requirement was an essential concomitant in barn building, for example, where the columns had to conform to both longitudinal and transverse linkages in the ensemble. Here, in the double test-assemblage operations, the pins had to be quickly and easily withdrawable, and hence without any gripping arrises. In these two test assemblages-when first one and then the other of the longitudinal and transverse test assemblages were involved - the provisional pins were usually tapered, and they were invariably made longer than the combined thickness of the two timbers they penetrated. This extra length of the provisional pins meant that, when driven into their holes, their smaller ends projected well beyond the far side of the hole that accommodated them. This was done in order that the pins might easily and quickly be removed by tapping them out from their pointed ends. Another and much less frequent instance in which smoothly contoured pins were sometimes installed - permanently, this time - was in situations where they were used to assure a very tight fit against gapping at the joint, such as where the drawing apart or opening up of the joint due to shrinkage had to be permanently and strongly guarded against. Here, instead of boring the hole for the trenail straight through both members of the connection at once (which was the customary procedure), the hole, was bored through both sides of the mortice, then separately and slightly off-set, through the tenon. In this situation, when the two timbers were brought together-when their mortice and tenon were linked - the hole through them was unaligned. Hence, driving the tapered pin into and through its hole caused it to exert great and continuous pressure in squeezing the two timbers together at their joint. The gripping function of the wooden pins' arrises is similar to what happens in the case of metal nails which, in being driven into the wood, force its fibers apart and thereby unite wood and metal in a tenacious, permanent grip. The degree to which precision was required in shaping the trenails was augmented by a comparable handicrafted individualism existing in the very tools of the carpenters in former times. Although the bits of augur or wimbrel might be nominally of the same diameter, these tools were not manufactured in a factory in innumerable replicas but were forged individually. Consequently, in a sizeable undertaking such as constructing a massive barn, the team of men assembled to construct the project might include a number of carpenters, each with his own kit of tools. The fact that their individual augurs might vary even slightly in diameter meant that those assigned to prepare the pegs had to be meticulously precise in shaping them-particularly the smooth ones - in order that they might fit snugly into the holes bored for them. No wonder that today" one occasionally comes upon a smoothly contoured pin that is loose in its hole. The foregoing comments go far to account for the universality of the trenail as the essential unit in timber framing throughout the past. It was essentially a handicrafted feature in which the quality of performance was explicitly controlled at every step of the procedure. When metal nailing eventually became universal, the latter's rapidity of execution made the trenail and its not inconsiderable advantages obsolete. But we can be deeply impressed with the quality and integrity of the heritage of its surviving achievements. John Fitchen, architect and formerly Professor of Fine Arts at Colgate University, authored the book The New World Dutch Barn: A Study of its Characteristics, Its Structural System, and Its Probable Erectional Procedures (Syracuse University Press, 1968). If A Barn Could Talk By Everett Rau My wood shingles have long since decayed. Some kind owner put some black tar paper on my roof to keep it from leaking; this also aged and before many years needed repair. Seems farmers don't always have ready cash, but finally, in the year 1929, Ev Rau's brother Raymond, working for General Electric, had the money to put galvanized steel roofing over that tarpaper on my roof. In those years of the 1920's and 1930's, when Ev Rau was a boy, laughing men filled me with loose hay in June and July. In November, the traveling baler came, and then the cash crop was sold. But farm prices over the years did not keep up with industry's wages; no longer did I hear laughter in summer and fall and seldom did any person come near. Yet I remember that in 1932 or 1933, men jacked up my main posts, the supports for my big anchor beams. They put some flat stones back under my sills, already half decayed. But my owners forgot to keep watching for the frost action on my foundation. Every year, my stone supports slipped away. Maybe Ev Rau cared for me, but he was raising a family and working away from home. He did not see the slow settling of one anchor beam post (rotting was going on down below) or see my purl in plate bend sharply, dropping down 10 or 11 inches. Nor did he notice my sills were gone. Years passed. Finally, Ev Rau retired and was back on the farm. One day Mark Hesler asked him to join the Dutch Barn Preservation Society. Ev had not thought about the historic value of his Dutch barn until he took a Dutch barn tour and listened to visitors talking about how once there were many old barns but how now they were rapidly disappearing. Ev met Vince, Jack, Chris, Shirley and the others. These people were concerned about saving Dutch barns. That did it. The very next day, "Doctor" Ev started looking at me to see what needed fixing. Well, the good thing was that over the years I managed to keep fairly dry because of my metal roof. But, even so, my purlin was bent and cracked, my sills were gone, except for the section under the granary, and I was eight inches out of level. My roof was sagging due to my bent purlin plate. My doors were off or rotten on the bottom. My flooring had been two inches thick, but it was rotten four feet in from the doors. My floor supports were broken from heavy tractor loads. My south siding was weathered by the sun until it looked like a screen. Soon Ev was digging under my anchor beam support posts with a shovel and bar and a come-along. Some old stones were removed. They were big, and they had been tipped sideways by settling. Ev dug around them and poured concrete into the 40"deep hole he had made. Two weeks passed. I thought I was forgotten again, but one day I felt my bent purl in being gently raised by a hydraulic jack. The plan was to jack up 2" that day and 2" the next day, and so on until my purlin plate was straight. My east sill once was 42'-3" long. Now it was rotted out. To replace it, Ev cut one out that long, 9" by 10" thick, with a chain saw. There is more to come. The west sill will be sawed on our sawmill after Ev extends the carriage to support the 42' length. Now I have cement piers, four on each side. I'm not level yet, but I look better. My door frame had an old notch on top for a center pole for the two doors that used to swing there in the opening. Maybe Ev will make a new set of wooden hinges like I used to have. Maybe someday he will replace the hay barrack that stood beside me. He knows that farmers still used them when I was built. If I could speak, I would shout "Hurray!" for the people in the Dutch Barn Preservation Society. But for them, I would have to yield to the forces of nature - wind, rain, rot, ants, and, finally, gravity. Thanks to repair by Ev and the others, I can live on as a monument to early settlers who braved the wilderness and endured many hardships to start this farm. I knew those who fought to be free in the Revolutionary War and others who went to the Civil War. Those families, and the workers whose names are written on my timbers, "made it happen" for you today. I hear you people are coming to measure and study me. I'll be looking for you. Keep up the good work. The author, Everett Rau, resides on his family farm near Altamont, NY. |
