SEPTEMBER 2006 »  book review

Timber-Frame Tutorial

Oak-Framed Buildings
by Rupert Newman
Guild of Master Craftsman Publications, Ltd., Lewes, U.K.; 2005
192 pp.; softcover; 188 color photographs, 92 drawings; $24.95
ISBN 1-86108-379-3

Reviewed by Frederick Wilbur

Anyone vaguely familiar with architectural history knows that wood has been the primary building material for thousands of years, though, by virtue of their survival, stone temples and cathedrals seem more iconographic, standing as milestones among the innumerable vernacular structures that have influenced humankind more anonymously. Oak-Frame Buildings, by Rupert Newman, is a book about the contemporary use of wood as a building material, though in the specialized context of timber-frame construction. Gauging by the listings and advertisements in a variety of home-building periodicals, the popularity of this ancient technique is increasing.

Anyone even casually versed in construction techniques will admire the geometry of the timber frame: how the jowl posts rise from a sole plate; how the diagonal dragon beam interrupts the joists in order to support the jetty; how from tie beam the crown post upholds the rafters and purlins; how cruck and braces hold the structure true. A timber frame is geometry in its simplest form – squares and triangles with graceful curves interspersed among them like the trees from which they come. Timber-frame design involves the cabinetmaker’s skill of joint-making, the architect’s three-dimensional visualization and the engineer’s statistical analysis.

Wood and geometry came together in dramatic fashion in the 16th and 17th centuries in the "black and white" or "half-timber" Elizabethan manor house. Timber-frame construction is associated with houses surviving from the late Medieval and Renaissance period in Europe, though the use and techniques came into prominence during the reign of the Plantagenets (1154-1485). The use of timber-frame construction continued until the 19th century, which not so coincidently produced the first studies of the technique in books such as The Evolution of the English House by S.O. Addy (S. Sonnenschein & Co.; 1898), and The Development of English Building Construction by C.F. Innocent (Cambridge University Press; 1916). The early-20th century, in America at least, saw a revival in the varied phases of Colonial architecture – Tudor/Gothic, Jacobean, up through Georgian. Many towns across America have "half-timber" Tudor houses that were built between 1890 and 1940.

Even the open-minded reader expects a book with such a plainly spoken title as Oak-Frame Buildings to be presented in an equally terse way, but this book is a truly handsome one consistent with the Guild of Master Craftsman Publications’ well-deserved reputation. The content, which would seemingly have a narrow audience, has a wonderful promoter in its attractive presentation. The photographs are generally of superlative quality and are often given full pages or, in several cases, spread onto the adjacent page. Essential to this sort of book, the photographs and the copious diagrams are placed adjacent to the pertinent text, reducing confusion between illustration and word. The care in using various layout devices – including sidebars, background color and graphics, margins, captions in juxtaposition to drawings and varying font size – makes this a pleasing book to read, as well as to study. And, not to read too much into it, the book is a perfect square – as if to bolster the geometry underlying the whole of the framing process.

Occasionally there is a redundancy between the sidebars and the text and there is a layering of graphics that seems fragmentary, but this does not detract from the obvious overall expertise of the layout professionals.

It may be tempting to abandon it on the coffee table, but this is a "working" book. In his introduction, Newman states that the impetus for the book was to answer questions posed to him over the years by clients, architects, design professionals and construction contractors, as well as by fellow carpenters. Anyone interested in timber-frame building will obtain a wide view from this book, though Newman continues, "Oak-Framed Building is not intended to be a step-by-step manual, rather its purpose is to provide readers with some knowledge of the techniques involved so they may better understand the overall process." The author explains everything as though the reader was planning to build a timber-frame house, but it is obvious that the process requires skill, and a skill acquired by on-the-job experience. The complete and behind-the-scenes information is presented as though the reader was a potential client. Bringing the reader into the process is an effective writing technique and to educate one’s potential clients is a sound business strategy as well.

Newman’s parameters include no less than the entire building process. His is a linear approach: beginning with a brief historical overview and more immediate considerations; continuing with site procurement, planning and dealing with zoning and review officials; and concluding with the actual design of the frame configuration. He discusses material, layout and cutting joints, as well as fabrication and assembly strategies, and concludes by considering glazing and insulation. The attention to details is doubtlessly derived from personal experience. Newman mentions the possibility of insect attack, the known shrinkage of the material and the fire resistance of oak compared to structural steel. His writing exudes a confidence gained by working with massive and dangerous timbers.

As any practicing artist needs to comprehend the primary tenets and precedent of his craft, Newman begins his book with a brief history of timber-frame usage. Instead of an academic tome laced with references to structures long decayed, or comparing one example to another, the author presents a synopsis of the evolution of the generic timber-frame building, aided by the clarity of skeletal diagrams. This recapping of the historical record may reinforce nostalgia for the past, but the photographs of contemporary houses throughout the book draw history into the present.

In "Starting Off" Newman immediately states, "For many people building their own home is one of the greatest milestones in their life, ranking alongside getting married or having a baby." If you have, in fact, built a house (or read Tracy Kidder’s book, House [Houghton Mifflin Co.;1985]) you know that prodigious amounts of sweat-equity and emotional angst have been invested. Newman attempts to ease that perceived trepidation in the first-time house builder. The advice on budgeting, finding a site and dealing with officials seems obvious and warnings like "Beware! Any figures given to you by builders or architects may be optimistic" seem unnecessary for anyone beyond the rudest naiveté. He does explain the custom of calculating costs by the square meter, and outlines a number of variables that arise with this method.

No doubt there are some things even a moderately seasoned builder might overlook, such as taxes, lawyer’s fees, permit fees, building and site insurance, land clearance and landscaping costs. He emphasizes that among the professionals involved with the design and approval of the design, the timber-frame contractor should be included, which, it is interesting to note, is the desire of all artisans who contribute to the architectural fabric, whether mosaic artists, woodcarvers or stained-glass artists. He then advises the client how to approach the design aspects of site orientation, room location and how the timber-frame structure will influence the design, advocating an open-plan building – a departure from the modularized originals. It is clear that an architect and often a structural engineer are necessary to fully design the building.

Having established the timber frame in the context of the building plan, Newman addresses the design of the timber frame itself, which is naturally more interesting to the reader who wants to get to the heart of the subject. The module is termed a bay, which is determined by the practical consideration of the material itself. Oak, indeed any building material, has properties that limit the safe and/or practical span it can sustain; thus 10 to 13 ft. is most often the width of a bay. A sidebar on loads and stresses provides a valuable explanation of the complex art of sizing beams to carry specific loads and the various stresses of compression, tension, shear and deflection. Again, cautionary notes suggest that a structural engineer should be consulted for anything very complicated. Bay divisions, counted down the length of the building, are carried across the building by "cross frames," of which there are several types. Included in cross frames are the trusses that form the support for the roof, making the cross frames the shape of the typical child’s drawing of a house. There are several types of trusses. This all may sound confusing, but the computer-generated diagrams and bullet-by-bullet reiteration makes the subject just the opposite. Of course, it would take some study to confidently identify each type in the field. Much of the point of the book is to display the possibilities from which to harvest what is personally attractive to the potential home builder.

Though reference was made at the very outset of the book to green wood construction, the subject is pinned down in the fourth chapter. Most woodworkers will have a fairly good idea of the anatomy of oak, but the justification for using 60- to 100-year-old trees is not a common one. There is an underlying feeling of guilt among a significant percentage of woodworkers for deforesting the planet, but the author feels justified, stating, "Overall CO² emissions in the atmosphere can be reduced by replacing fossil fuels with carbon-neutral wood." The tree, having removed CO² from the air, fixes it within its fiber [being], so a long-term use such as timber-frame construction is proactive conservation. According to the author, the energy used in producing timber frames is less than that used in conventional construction methods.

Another interesting explanation involves the properties of early and late seasonal growth of hardwoods. Among most woodworkers, particularly furniture makers and carvers, there is the idea that slow-growth wood with tight or fine grain has preferable working properties and appearance. Newman makes the case that "fast grown oak… has wide rings containing extra latewood growth, which comprises more of the dense fibers and fewer of the light vessels." Newman’s concerns are, of course, primarily structural. Converting logs into beams by hewing and splitting is not explained in great detail, because those older methods are not economical. All the contemporary buildings shown in the illustrations are made from material sawn at a mill.

Chapter Five, "Making Frames," is decidedly the core of the process where design, material, tools and technique dovetail. Anyone who is challenged by interlocking puzzles will thoroughly delight at the contents of this chapter. As with the book as a whole, old and new are compared and contrasted; the patina of the wonderfully worn mallets and axe handles gives way to the brightly colored plastic of chain mortisers, power drills and circular saws.

As one can imagine, joining all the beams, braces and numerous secondary pieces together into a unit that lies in one plane, especially when cumbersomely heavy, twisted or curved, requires the establishment of reference points and straight lines (imaginary as they might be). Logically, the timbers are laid horizontally with various beams laid on top in order to locate and scribe the position of the joints. Primary beams are joined first and ancillary timbers such as braces are fitted next. There are different approaches but they all make use of individually scribed joints, allowing for variations in dimension, twist and splits. The joints described are just about all based on the mortise-and-tenon joint common to all purposes of woodwork. While strength of joint may be behind the use of a particular joint in furniture, it is definitely of concern in building a house! There are several ways to strengthen the cabinetmaker’s common mortise-and-tenon joint. The beveled-shoulder tenon creates a ledge in the vertical beam upon which the horizontal beam rests. The dovetailed tenon ensures that the horizontal beam doesn’t separate from the vertical post. After fabrication, each piece is marked so that re-assembly on the foundation goes smoothly.

It is in raising the frames that the planning, layout and joining are "proved." After briefly discussing foundations, the logistics of delivering the 20 tons of wood for a "reasonably sized house" are addressed; even the quality of the gravel used to support heavy trucks and cranes is mentioned. Several hand methods of raising the frames are explained; these are followed by notes on site safety. Of course, one works from the ground up, but so obvious a statement belies the required physical strength, ordered approach and patience when coaxing ornery joints into place.

The remainder of the book seems a quiet denouement. Though building timber frames requires some different tactics to enclose the structure than are required by usual or customary building practices, much of the methods are covered by the latter. With contemporary concern for insulated buildings, the timber frame is usually visible to the interior and covered up on the exterior. The skin is a stick-built wall allowing for a tightly insulated house. Much attention is given to proper insulation, mentioning sustainability issues such as energy use and energy trade-offs. Construction methods to ensure the insulation is properly installed are explained thoroughly. Even the insulation values of straw bales are mentioned, but it is doubtful whether they would be used in an expensive timber-frame house. In tandem with the discussion of insulation is a final chapter on windows and passive solar heating. The few notes on floors, with an emphasis on under-floor heating, in this section seem almost an afterthought.

Anyone of sensitivity has to admire the integrity implicit in a book written by a practicing trades person, even disregarding the photo of the author in tool belt and climbing gear. This is a book of facts gleaned from years of experience, as well as building trades and forest-service literature. Though the author puts forward some justifications for using timber-frame construction, some readers may not be convinced that cutting up venerable old trees is something they should be doing to provide shelter for their families. A more extensive case could have been made by quoting reliable sources as to the available wood harvest and efforts made to renew the depleted resource. Only passing mention is made of roof loads, which seems the primary justification; except, of course, facilitating the open-floor plan and appearance advocated by the author. Because the frame is enclosed within the outer skin, the exterior appearance does not differ uniquely from other styles of building.

All this aside, Oak-Framed Buildings contributes valuable information to the contemporary use of timber-frame construction and is certainly a must-read for anyone planning to build a timber-frame building. So many other books on the market are simply picture books without the depth and sincerity of this one. 

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