The secret to the strength of a timber frame structure is the brace. The brace is a diagonal member that stabilizes and squares a vertical post to a horizontal beam. The brace has a tenon at each end and fits snugly into the mortises in the post and beam at a 45 degree angle. This construction creates many right isosceles triangles within the frame. The triangle is the most rigid shape in structural design and prevents the building from racking or leaning from side to side.
A band saw was used to create a graceful arch in each brace, softening the final appearance. The heart of timber frame construction is the “bent” (a cross section of the structure), which is the truss at each gable end. Each bent is composed of posts, rafters, beams, collar ties, and braces all fitted and pegged together. In order to effectively assemble the numerous pieces, you need a large flat area to work upon. The deck foundation serves this purpose well.
During excavation of the foundation for our house, many variously shaped limestone rocks were uncovered. Because the stones were so irregular, they were stacked as a ruble wall, and eventually a raised landing area was created behind the wall. This staged feature cried out for some functional use, which spawned another great project: the pavilion. The plateau of this leveled-out area afforded a grand observational vantage of our many gardens, but the idea of a gazebo-type structure would offer an even loftier perch. However, a typical oriental gazebo would not be consistent with our timber home and other turn of the century accoutrements. Therefore, we embarked upon a traditional timber frame design (mortise and tenon with pegs) for our pavilion.
By vocation Gayle is a mechanical designer with a strong
background in CAD. We developed sketches of a modified
“hammer beam” truss with curved braces, and Gayle created
the three dimensional models on computer. The various
dimensions and curves could be easily altered to achieve the
look and feel we sought. In essence we built our pavilion twice:
first as a computerized model and finally as a real structure.
We initially designed the pavilion based on large timbers harvested from dead oaks here in our woods. Because most dead trees have hollow heartwood, we eventually abandoned the idea of using native timber and re-designed it using weather tolerant 6x6 treated posts and lumber. This decision will add many extra years of longevity to the structure. As with our house, this project began in the shop. Each timber had a variety of mortises (female square holes) and tenons (male square projections). These features are constructed using a large drill with auger bits, framing chisels, a slick, a mallet, and circular saw. Each timber is cut to specified lengths with all pockets and mating tenons precisely located within or terminated on that timber. The early American framers of old would have dearly coveted electricity and equipment that takes the drudgery out of the task.
The addition of furniture beckons visitors to enter and transforms this observation post into a hosta garden Shangri-La.
In a mature forest, many large oaks and hickories are reaching the end of their lifespan. Nature would normally re-cycle these trees back to the soil but instead, we harvest these dead logs and render them into boards on our one-man sawmill. These boards were air dried for a few years and once planed, were used as ceiling boards for the pavilion and then capped with 4x8 plywood sheets. Simulated slate shingles were then screwed into the roof for protection from the elements and to complement the natural beauty of the frame. During the construction phase electrical wiring was inconspicuously incorporated to provide a ceiling fan, sconce fixtures and spot lights to highlight the ceiling boards.