American timber frame systems up to 1900

Introduction: Timber Frame Systems

The timber framing system is a centuries-old method developed by medieval Europeans. Its fundamental precepts have remained in place since then, but the physical manifestations of these fundamentals have taken on a variety of shapes. In America, from 1600-1900, we can see this variety develop. I wrote this paper in Fall of 2010, at the start of my work on an MSc in historic preservation at UMass-Amherst. It explores major American framing systems in three sections and: 1) will provide an overview of the components and interrelations of a basic frame; 2) will examine how joining techniques (practice) is influenced by stylistic concerns (aesthetics) and 3) will compare a 19th century New England house to a 19th century Chesapeake house.

Basic Framing Techniques and Theory

The whole unit represented in a complete timber frame may be broken-down into three subsections in order to better understand their intra/inter-workings: 1) the floor frame, 2) the wall frame and 3) the roof/ceiling frame. The floor frame is a combination of “[…] posts, beams, sill plates, joists and subfloor” (Anderson, 2002, pg. 19). The components that comprise the floor frame are arranged in order to reduce the amount of shrinkage and settling of the wall and roof frames. Said movements are owed to internal and external factors: the moisture content of the wood combined with the stresses and strains inherent in a frame, and the external forces of nature and living to which a frame is exposed. Post and beam meet at a 90 degree angle at the ends of the structure providing a horizontal base and vertical extension. The beams are crossected by joists which provide lateral support and stiffness to the frame. The sub-floor does not provide structural support; it provides a skin for the interior flooring.

The floor frame provides a basis upon which a wall frame can be constructed. Anderson recommends the following wood-types for use in wall frames: Douglas-fir, hemlocks, southern pine, spruce and white fir. The reasons he gives for these specifications are “[…] good stiffness, freedom from warp, good nail-holding ability and ease of working” (ibid, pg. 31). The components of a wall-frame include the vertical studs and their horizontal counterparts. The former are divided into the following types: single-storey and two storey. The latter are comprised of bearers, girts, window headers/sills top plates and joists. Additionally, single-storey studs may be reinforced by diagonal braces; these braces relieve pressure between beam and post, while adding stability to the studs.

The basic form of the roof-frame in a timber frame structure, the gable roof, is composed of the following elements: rafters (extending on a diagonal axis from the top plate and terminating at the top of the frame), the ridge board (the horizontal piece which forms the top of the frame and to which the rafters are secured), the end stud (the roof version of the single/two-storey stud), collar beams (which provide lateral support between the rafters) and ceiling joists. Anderson mentions three types of gable roofs: 1) the simple and familiar triangular form described above, 2) the gable dormer—featuring a windowed-protruding form from the roof and 3) the hip—which features triangular forms in the front and back and trapezoidal forms on the sides.

Timber framing and Balloon Framing

The move away from timber framing toward balloon framing begun in the 19th century—while balloon framing is not the subject of the present paper, it does provide a helpful contrast for understanding the history, evolution and aesthetic of the timber frame. The Old-House Journal notes that “The basic difference[s] between timber and balloon framing [are] that in balloon framing every stud in the frame is a load-carrying element […] [the substitution] of mechanical fasteners (nails) for the elaborate woodwork joints (mortise and tenon, etc.)” (1980, pg. 197). Thus, the move from timber to balloon framing occurred due to economic considerations: the balloon frame used less material, took less time to construct and required a more standardized and teachable skill-set.

When the Puritans came to America and settled in what would become the 13 original colonies of the U.S. they brought with them framing techniques practiced in Europe for centuries. The tradition of European framing had been passed down through these centuries owing to the artisanal guild system, which, having been created in the middle ages, provided a transnational system of teaching and developing construction techniques. The guild system would remain in place until the Industrial Revolution (exactly the time that balloon framing overtook timber framing as the preferred method of house construction). The basic joining technique was comprised of a mortise and tenon system. The system was developed in order how to solve the fundamental problem of construction: how to join a post and beam at a 90 degree angle? The ancient Greeks had bypassed this problem with a post and lintel system; the Romans innovated with the arch; medieval Europeans developed a female/male adaptor system.

The mortar/tenon process is a manual labor-intensive process. The mortise-cavities and tenons are formed with adzes. Additionally, the means of connection vary according to the training and preference of the carpenter in question. Conversely, mechanical means of joining and producing uniform studs limited the ways in which frames could be joined. The Old House Journal notes that distinguishing between a timber and balloon frame is difficult to do from an outside perspective; however, “[…] on the inside, there are usually tell-tale signs. The posts and summer beams are so big the usually protrude from walls and ceilings […]” (ibid). The reason for the size differential is two-fold: 1) before builders had access to mechanical means of cutting wood, all of the timbers used in a frame had to be cut-down from a near-by forest then planed and measured by hand; and, 2) the weight of a timber frame structure is dispersed among the beams and posts—whereas, in a balloon frame structure the load is spread evenly among the studs, braces, etc.

Changes in Joinery Techniques

The exposed interior common to timber framed structures led early American constructors to innovate in their approaches to joining techniques. It seems clear that the exposed interior posts presented a problem because they gave houses an unfinished structure. Jan Leo Lewandoski catalogs eight types of joining methods: 1) exposed decorated, 2) cased, 3) cornered, 4) deep wall, 5) thin wall, 6) vertical plank, 7) skeleton plank and balloon (1995, pg. 42). Without covering all of the individual differences it may be helpful to point out how these different techniques ‘solve’ different ‘problems’ presented by the timber frame structure. The easiest way of dealing with the problem of the exposed frame was to hand decorate it. The exposed decorated technique did not change the method of fastening; it simply altered the appearance of the exposed beam by fashioning its edges with “[…] chamfers, ovolos, and beads […]” (ibid, pg. 43).

Another technique that did not change the joining method (but only hid the exposed post) was adding casing, or draping the post with a skin that matched the walls. The cornered method simply cut-out a section of the post so that it would be plumb with the wall and the deep wall method extended the depth of the wall so that it would correspond to the thickness of the post. What each of these methods point to was the fact that there was something fundamentally disturbing to early Americans about the exposed interior. Lewandoski traces this disturbance to a shift in aesthetic sensibility: “[Early Americans] admired Greek and Roman structures [which] were built of masonry and had sharp, straight interior lines [they] sought to summon up the appearance of the masonry public buildings of the classical world in the average wooden residences of the new world” (ibid, pg. 44). Interestingly, Lewandoski implies that trends in the development of timber framing were not simply practical—they also had their origin in how they conceived of the ideal living space. Said space would not be interrupted by protruding hand-hewn posts.

Willie Graham, performing further research in the same area, examines the way that pre-industrial framing systems developed in order to deal with practical and theoretical concerns. He defines the system of pre-balloon framing in America as an example of a “vernacular” style as opposed to an industrial style (2003, pg. 179). The former represents a particular response to a specific problem of carpentry. The response is determined by the carpenter’s experience and training. The carpenter’s experience and training is determined in part by the unique conditions of his environment. Graham notes that the unique environmental conditions of the Chesapeake area were an abundance of wood and a lack of skilled labor.

Stylistic Flexibility of Timber Framing: Analysis

The flexibility of the timber framing process may be understood in further detail by examining two historical examples of its exteriors: the Bryant Cushing house in Massachusetts and Chesapeake-style house—both from the 19th century (Library of Congress, 2010, web). The Cushing house is a two-storey, rectilinear affair. Its two symmetrical halves are bisected in the middle by the entrance. Lewandowski’s point about early New Englander’s desire to emulate Greek and Roman architecture is well-taken in this example: the entrance-way is done in the Doric Greek style with a column, architrave, frieze and cornice. Additionally, the Cushing house is a fine example of a building method that stresses proportionality, regularity and simplicity. The Chesapeake house is different. It is two storeys—but, its second story is contained within a gabled and dormered roof. Its doorway and windows do not imitate any style—they seem to be simply and practically openings. The horizontally-oriented planks which cover the first-storey are irregular. If Graham’s point about the lack of carpentry skills available to Marylanders is correct, it is especially so when considering this example.

Conclusion

The structure and style of American timber framing systems up to 1900 is owed first to practical considerations and historical determinates and second to aesthetic sensibilities. Additionally, the environment in which carpenters work influenced them more 200 years ago than it does today. This is owed to factors such as standardized education, mechanization of building processes and the ability to transport materials across long distances. Despite the fact that the timber framing method was eventually overtaken by the more economical balloon framing method, it is still interesting and beneficial to examine the differences within the timber framing method. These differences speak at once to the diversity and similarity of the American building heritage.

References

Anderson, L.O. (2002) Wood – frame house construction. Washington: Books for Business.

Graham, Willie. (2003) “Preindustrial framing in the Chesapeake.” Perspectives in Vernacular Architecture, 9, 179-196.

Lewandoski, Jan Leo. (1995) ”Transitional timber framing in Vermont.” APT Bulletin, 26, 2/3, 42-50.

“Timber-frame houses in the historic American buildings survey.” (2010) The Library of Congress. Retrieved 5 December 2010, from http://www.loc.gov/rr/print/list/100_tim3.html

“Traditional house framing.” (Dec., 1980) Old House Journal, 8, 12, 197-200.

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