By Everett Pollard
This article appeared in the Fall issue of Design Lines magazine, a publication of the American Institute of Building Design.
The traditional joinery of timber framing has a timeless, elegant beauty that my wife Robin and I had long been drawn to when we set out to design our own timber frame home in New Hampshire ten years ago. In some ways, it was an ambitious undertaking. Even though I had been a residential designer for 24 years and had built several post-and-beam homes by then, I had never designed or built a true timber frame, one held together with mortise-and-tenon joints and wood pegs instead of mechanical fasteners and steel plate connectors.
Because timber frame homes have a sturdy, self-supporting structure comprised entirely of interlocking wood parts, I assumed that a critical component of the design would require getting that intricate, hidden geometry exactly right. As it turned out, I was only half correct, but like so much to do with timber framing, I had a lot to learn and not much time to do it. After selling our previous house—a modest Cape Cod—faster than we intended, Robin and I had squeezed ourselves, two cats and a dog into a 700-square-foot cottage, and when the one-year lease expired, we needed someplace to move into. My crash course in timber framing took less than three months, but what I learned about designing these houses will last a lifetime.
Hitting the Books
Fortunately, I couldn’t have picked a better place to learn about timber frames than my own home state. New Hampshire is for timber framers what Montana is for log builders—a Mecca for devotees and practitioners of this Old World craftsmanship. Even the real estate agent who sold our home had more than a passing knowledge of timber frames having been the sales manager for a nationally known timber frame company before switching careers. When I asked him which timber frame company was the best, he surprised me by naming, not the large company he had once worked for, but a small Canadian business instead, Pine Ridge Timber Frame Homes in London, Ontario.
Two weeks later, Robin and I headed to Ontario to meet Mike Mader, the owner of Pine Ridge. We knew we had found the timber frame company for our home when we toured Mader’s plant, where all the beams were initially cut and milled. His shop crew hand-finished the joints, chamfered the edges and sealed the beams with Danish oil. We even visited several timber frame homes, including Mader’s. In fact, Mader would become both friend and tutor in my efforts to learn more about timber frame design.
The teetering stacks of timber frame magazines lying around my house were another educational resource. Written primarily for consumers, these magazines offer a wealth of information about design and construction as well as the process of working with a timber frame company. Books on timber framing also helped, particularly The Timber-Frame Home by Tedd Benson, the owner of a New Hampshire timber frame company who is credited with reviving this style of home. His book has great details on how to design a timber frame with structural insulated panels that enclose the exterior of the frame, which still remains exposed indoors.
Putting the Pieces Together
One important discovery I made right away: I did not need to know how to design timber frame joinery; Pine Ridge would do that for me. But I did need to understand the building blocks of timber frames, including their primary structural component: the bent, a network of timbers that form one cross-sectional piece of the frame. Bents are made up of principal rafters, tie beams and posts and are connected to each other with some combination of girts, plates, joists, purlins or ridge plates to form a bay.
There are a variety of bents, any of which can be modified to construct sections of the house and give it a distinct shape. I designed my own home with five bents, placed roughly every 14 to 16 feet. Rafters or horizontal purlins make up a timber frame’s roof structure, but its artistry lies with the trusses. A designer can complement the main frame using different styles of trusses such as king post, scissor or my favorite, the hammer beam, which I included in my own home.
As luck would have it, Mader had a frame to erect in Maine, and on his way there, he stopped and stayed with us for two days to teach me more about timber frames. I was especially surprised to learn that only two opposing knee braces were needed for each wall, no matter its length. For decorative purposes, more braces could be added to frame a window or passageway. Mader also advised using a conventionally framed floor system over the joist beams to provide space not only for sound-attenuating insulation but also for recessed lights, plumbing, heating and wiring—anything, in fact, that needs to be completely hidden. That’s a challenge with timber frames because they offer few places to hide a home’s infrastructure. For simplicity, I designed my home so that all the plumbing and wiring runs through interior rather than exterior walls, where the framing is exposed.
Although I relied heavily on Pine Ridge’s expertise for the structure, I still needed to learn the many sizes and spans of beams to design the home’s spaces accurately. For example, my design needed to account for where a beam or post would be to ensure that a door had enough room to open completely. Because the timber frame’s structure is inside the building shell, I also needed to allow enough depth for headroom, especially over doors, and I quickly discovered that the home looks more attractive if interior walls are placed to intersect with the beams and posts, just not in mid-span.
SIPs were another component of the design that Mader shared with me. These panels encase the frame’s exterior in the most insulating, energy-efficient envelope possible. They also help support the structure because timber frames have no load-bearing walls; the posts carry the structure’s entire load instead. As a result, every post must be part of the floor system with solid blocking beneath it so that the weight can be transferred directly to the foundation.
Because a timber frame is built from the inside out, its construction is a carefully choreographed sequence of delivery and installation. Each bent is assembled first on the ground, then raised and connected together in a process much like an old-fashioned barn raising, except that today’s timber frames make prodigious use of cranes and forklifts. (The building site needs to be generous to accommodate the crane, the home’s footprint and a place to assemble the frame.) Once the frame is up, the pine paneling on the roof comes next, serving as the finished ceiling. At that time, any wiring for chandeliers or ceiling fans is installed. Then the drywall is screwed to the frame’s exterior sidewalls, with SIPs placed last around the structure’s perimeter and over the roof. When my own home was built, Mader and one of his project managers were on site to supervise raising the frame and installing the panels.
One nice construction feature: Timber frames go up quickly. Our 4,000-square-foot home had its timber frame assembled, raised and enclosed with SIPs in just nine days. The entire experience was so thrilling that in the ensuing years I’ve designed and built over a dozen timber frames for clients with Pine Ridge’s help. In fact, we have one under construction right now and another in design. Meanwhile, Robin and I continue to enjoy our home’s warm, natural beauty, and if we should ever move, we are certain of one thing: It will be to another timber frame.
Everett Pollard is president and senior designer of Northcape Design Build in Sunapee, N.H. To view pictures of his timber frame home, visit www.northcapedesign.com, click on “portfolio” and under “new homes,” select “Harbor Haven.”