OBSERVATIONS
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Among the aids to determining the chronology of a building are nails. Because the technology and chronology of nail manufacturing are generally known, the different types of nails encountered in an old building can offer valuable clues to the age of the components they connect. Wrought nails were universally used from the earliest settlements until the early nineteenth century. This oldest type of nail was hand-wrought by beating a thin iron bar of square cross-section to taper it uniformly to a point. The head was beaten onto the opposite end of the nail. The manufacture of wrought nails was labor-intensive, and the nails were costly.
Cut nails, as their name implies, were sheared, or cut, from thin plates of metal. The first patents for nail-making machines were issued soon after 1780, and by 1800 cut nails were rapidly supplanting wrought nails for most purposes, primarily because of their cost. Mechanical nail-making was much more economical; twenty-five cut nails could be bought for the price of one wrought nail.
Initially cut nails were made of wrought iron, although steel eventually came into use. Cut nails are distinguished from wrought nails by their shape: Since they are sheared from a plate, two sides of the shaft taper and two sides do not. The heads of some early cut nails were made by hand, and look just like the heads of wrought nails, but machines were quickly developed to shape the heads as well as to cut the nails. Cut nails were used throughout the nineteenth century, and into the twentieth (Some carpenters still prefer cut nails for some applications). Later in the nineteenth century a process was developed for making nails from wire. The first wire nails were small brads, but by the end of the century technology had been developed to allow making large building nails. Wire nails were less expensive than cut nails, but the innate conservatism of carpenters, who believed their holding power to be inferior to that of cut nails, tended to restrict their use to finish applications well into this century.
Wire nails are made by nipping a pyramidal point on one end of a short piece of wire, and stamping a head at the other. Their shaft is untapered. The characteristic grooves around the top of a wire nail's shaft are artifacts of the clamp that holds the wire during manufacture. Although most wire nails have a round cross-section, some are square. Since we wrote this piece, further information has surfaced concerning how late wrought nails were made and used. Go to More nails in Observations 22. Recommended for further reading: Lee H. Nelson: Nail Chronology as an aid to dating old buildings, Technical Leaflet 48. Nashville: American Association for State and Local History, 1968, and Maureen K. Phillips: Mechanic Geniuses and Duckies, A Revision of New England's Cut Nail Chronology Before 1820, APT Bulletin Vol. XXV No. 3-4, and Mechanic Geniuses and Duckies Redux: Nail Makers and Their Machines, APT Bulletin XXVII No. 1-2. Back
to the top Getting a good, reasonably long-lasting wood shingled roof has become increasingly difficult of late, with leak-producing failures--cracks, rot, and other deterioration--occurring shockingly soon after installation. The problem is largely the result of a decline in the quality of the wood from which shingles are made, exacerbated by measures taken to reduce the consequences of premature failure (such as an asphalt felt ["tarpaper"] or ice and water shield ["Bituthene"] layer beneath the shingles). John Leeke, a preservation consultant based in Maine, some time ago recommended a defensive approach that can increase the life of a wood roof. We've added some thoughts of our own to his original idea: First, use only the best quality red cedar shingles ("No. 1 Blue Label"). If you can't afford them, you probably shouldn't consider a wood roof. Before using the shingles, sort them into ideals that can be used as is, reworks that can be modified into ideals, and culls that are not suitable for roofs.
This process takes time; the associated labor and discarded material can be expected to add a third or more to the material cost. It can also be expected result in a roof that will last significantly longer before starting to fail. Back to the top BUILDING CODES AND HISTORIC BUILDINGS Building codes contain requirements that are difficult or impossible for old and historic buildings to meet. Most model codes recognize this difficulty, and contain provisions for easing their requirements when historic buildings are concerned. The BOCA National Building Code is widely used in New England. It provides an exception for historic buildings, which it defines as "existing buildings or structures identified and classified by the state or local government authority as historic buildings," exempting them from its requirements, subject to some clearly spelled-out and reasonable provisions. Dealing with an historic building then becomes a matter for negotiation between its owner and the local building official. The Massachusetts State Building Code --which incorporates most of the BOCA code--deals more extensively with historic buildings, which it defines primarily as buildings listed individually in the National Register of Historic Places or eligible for listing, or as contributing buildings in State or National Register historic districts. For qualified buildings, code provisions relating to continuing use, alteration, energy conservation, and post-fire reconstruction are modified. The most interesting part of the Massachusetts Code is not its treatment of historic buildings in general, however, but a special category, the Totally Preserved Building. The Code defines this as an historic building or structure whose principal use is "an exhibit of itself [and] which is open to the public not less than twelve days per year..." For these buildings, once some simple requirements with regard to fire protection, occupancy, floor load, and inspection are met, code stipulations are greatly relaxed. Totally Preserved Buildings are listed by name and location in the Building Code. Not all buildings that seem to be eligible for designation appear in that list; if you think your Massachusetts historic property might be such a structure, I will be happy to review it with you by phone or email, and suggest appropriate action. In addition to general building codes, regulations governing access for the disabled, including the sweeping recently-passed Americans with Disabilities Act (which is not a code at all, but a civil rights act) also affect historic buildings. They are entirely separate (and separately administered) from building codes. Back to the top WHAT DO YOU THINK YOU'RE DOING? In developing the goals for working on a building, I find it useful to ask this question: What do you need/ want/ hope to do for/ with/ to your building? Your answers will help order your priorities from two viewpoints--the program, and its effect on the building. To begin with, needs are critical, and usually take the highest priority. They have to be met, "or else..." Wants are not as critical to the project as needs, but are nevertheless important. Hopes are the icing on the cake, the "electives" that would be nice, if... Similarly, things to be done for the building are relatively benign--replacing an aging (but not original) roof comes to mind as an example. Doing something with the building implies a partnership, perhaps not as totally benign as replacing the roof, but still respectful of what is there. Doing something to the building, though, implies major change, and often, less respect for the building and a greater hazard to its integrity. Major interior layout changes often fall into this category; replacing serviceable windows with new units of different size almost always does. Responsible preservation work tries to maximize work done for and with the building while doing as little harm to the building as possible. All other things being equal, the parts of the work calling for doing things to the building should come in for extra-heavy scrutiny to confirm that they are really necessary, and that there is no way of accomplishing those goals with less stress on the structure |
