You’ve heard a bit about timber framing, you might even be interested in incorporating it into your project. But how does it work and what does it look like? And more importantly, is it right for you? From the key timber frame components to the biggest benefits of this building method, we’ll walk you through the timber framing basics.
The Timber Frame: A Definition of Beauty and Grace
Traditional timber framing is the art of connecting two or more pieces of timber using wood-to-wood joinery. Before metalworking, this is how timber posts and beams were attached to frame the homes, barns, and businesses our ancestors lived and worked in. Held together without nails, bolts, or metal connectors, the timber frames of old tended to withstand the test of time—lasting centuries instead of decades.
Although there are many joinery variations, the mortise and tenon joint has been used to connect pieces of wood for well over 1,000 years. The basic joint comprises two components: the mortise hole and the tenon tongue, locked together by one or more wooden pegs. You’re probably already familiar with mortise and tenon joinery, as you’ll see it in finely made furniture.
Trusses are timber frameworks that support a roof (or bridge). Their primary function is structural (to span distances impractical for solid members), but today are often designed to be aesthetically striking as well. They can also be decorative, and there are many types of timber frame trusses from which to choose.
Structural Insulated Panels (SIPs)
Structural insulated panels, or SIPs, are a popular way to insulate a timber frame structure. A SIP looks a bit like an ice cream sandwich: two structural OSB (oriented strand board) sheets “sandwich” a thick layer of foam in the center.
In timber frame structures, SIPs are used on the outside of the timber frame—wrapping the whole frame in a high-performance insulating blanket. This leaves the gorgeous timber frame fully exposed on the inside of the building.
Like any construction method, there are pros and cons:
- Here are the main benefits of SIPs buildings: The panels insulate the structure with a higher R-value than you’d get from a standard stick-built structure with stud walls. Comparing 2x stick building to SIPs isn’t an apples-to-apples comparison because a SIP building is a high performance energy-sipping structure which will reduce energy bills for decades. Because the panels arrive from the factory pre-cut and pre-labeled, and because SIPs work as framing, insulation, and exterior sheathing, the building can be erected and in the dry more quickly–thereby reducing the overall time to build, financing costs, mold, and jobsite waste. Incidentally, SIPs do a pretty good job of soundproofing.
- Naturally SIPs aren’t perfect: They are more expensive (at least initially) than 2x stick building. Although not difficult to install, most construction personnel have not been trained in SIP installation, and this is not something you want your timber frame builder to learn on your job. Moisture control is important: SIPs are typically made with oriented strand board (OSB) which doesn’t like getting wet. Because wiring (but not plumbing) gets hidden inside exterior walls, holes must be created in the foam for wiring. This is done at the SIP factory and isn’t a big deal except that you need to have your electric plan figured out (where outlets and light switches will go). Finally, foam insulation has a relatively high embodied carbon content compared to other insulation options, and therefore some do not consider foam insulation to be a sustainable building method. So… what did we do? We built our new timber frame shop using SIPs. Why? We wanted to get our new building up as quickly as possible, and we rationalized that the energy the super insulated building envelope will save over the coming years will outweigh the higher initial cost and the carbon used in making foam.
What Are Timber Frame Buildings?
Timber frame buildings come in all shapes and sizes. From the outside, sometimes it’s impossible to tell that it’s a timber frame (they can be brick or wood-sided just like any other building). Sometimes architects incorporate some timber framing on the exterior (perhaps a timber framed entry) to suggest what’s hidden inside.
Timber Frame Homes
We believe the primary interest in timber framing is the aesthetics and the experience of living in the structures. When thoughtful design and craft work together, these buildings can be built poetry.
You might be surprised to learn that a timber frame home doesn’t have to use this building method exclusively. Many of the timber frame homes we’ve been a part of over the years are hybrid timber frames, which seamlessly combine timber with conventional 2x framing.
Non-Residential Timber Frames
Not only are timber frames wonderful places to come home to, but commercial timber frames (or non-residential as engineers prefer us to call them) are also inspiring and pleasant places to work (and shop).
Timber Frame Kits
Let’s be clear: we believe in custom design because we’ve repeatedly seen the process and end result improve people’s lives. A pre-designed plan or kit is a bit like cultured stone–good from afar, but far from good. Like an off the rack suit, it won’t fit particularly well (you or the land). We came up with our kits as an idea to keep our people working during COVID-19 (if our building was shut down, they could load up their truck with timber and cut a kit at home). We’ve since discontinued our timber frame kits and are happy to discuss custom timber frame projects with you.
Want even more ideas? Here you can find our concept drawings for timber frame structures including a solar panel carport, an RV garage, outdoor pavilions, a boat house, a farmers market, and more.
Timber Frame Construction vs. Post and Beam Construction vs. Conventional Construction
Traditional timber frame techniques rely on beautiful (and sometimes exquisite) wood-to-wood joinery to connect heavy timbers. Traditional timber framing doesn’t use much metal–and what metal is required by engineering, is typically hidden.
Post and beam construction also uses heavy timber, making it similar to timber framing. But the main difference between post and beam construction and timber frame construction is the way the pieces of timber are connected. Post and beam structures rely on metal fasteners like steel plates and bolts.
As an aside, we’re not traditional timber frame purists. We happen to think that steel and timber can be striking:
Conventional construction and stick-built 2×4 and 2×6 structures don’t use heavy timber. They use smaller pieces of lumber connected by nails and metal fasteners, and load-bearing walls provide additional support.
What Are the Benefits of Timber Framing?
We’re glad you asked. We think there are quite a few advantages of timber framing.
Timber framing is sustainable. About ten years ago we wrote an article (here) about what makes timber framing sustainable, and it’s still widely quoted.
Learn more about the benefits of timber framing with our take on it.
Finally, we’d add that we find timber framing to be a satisfyingly tactile antidote to the virtual world.
A Thousand Years of Craftsmanship
Timber framing has quite a rich history. Centuries ago, builders used timber framing to construct temples in Japan, cathedrals in Europe, and manors in England–many of which still stand today in silent testimony to the durability of timber framing. Go anywhere in New England, peel back a couple of hundred years of remodeling from the original homes and churches, and you’ll discover that they also were timber framed (as were their barns, which often were the first structure a farmer would build).
Timber framing’s popularity declined in the early 1800s for practical reasons. Water-powered sawmills made smaller and easier-to-handle dimensional lumber cheaply. Railroads permitted sawmills to ship the new lumber wherever it was needed (as opposed to utilizing the trees that grew on the building site). A new framing system (balloon framing) using standard 2×4 lumber nailed together to form a light framework didn’t require the skilled craftsmen that timber framing demands. Then, in about 1880, the proverbial nail in the coffin: we invented machines to make wire nails (nails used to be so valuable that after a fire people would sift through the ashes to recover the wrought iron nails).
In the 1970s, builders rediscovered the allure of timber framing while taking down old houses and barns. Ever since, a small but enthusiastic group of craftspeople worldwide—including our team at Carolina Timberworks—have continued to dedicate themselves to this building method.
Timber Framing Traditions
Building a timber frame structure is a fascinating process that involves a long list of traditions. The most important? The raising of course. On raising day, you get to see your dreams and hard work realized.
Not too long ago, raising involved ropes and pulleys and feeding a whole team of very hungry people. As the structure was raised, the community could see the building come to life and celebrate all the hard work with a feast.
Today, we have machinery and safety meetings to make the job a little bit easier. But we still honor the traditions. After all, why not celebrate your new timber frame home or building in style?
Some other timber traditions include:
- Carving the date into the frame once it’s complete and signing the timber in a hidden place.
- Placing a coin minted in the same year as the structure under a post.
- There’s a superstition that feeding a timber framer will give you and your building good luck. What can we say? Timber framers always appreciate a good meal.
- Everyone loves to see how their hard work turned out. After that timber frame is raised, it’s a tradition to take a group photo.
- The lady of the house has the honor of driving the last peg. For every blow it takes to drive the peg home, she owes the crew one drink.
- When building a new structure, timber framers have historically attached a wetting bush to the highest point to symbolize its roots.
Timber Framing Terms to Know
As you design a timber frame home or go through our timber frame process, you’ll learn a lot of new timber framing words. Here are some common timber frame terms you’ll encounter:
- Bay: An aisle perpendicular to the ridge that is bounded by two bents.
- Beam: Horizontal framing member.
- Bent: The cross frame; a section of a framed building put together on the ground and raised at one time.
- Brace: A timber that resists distortion.
- Chamfer: A decorative bevel cut continuously along the length of timber, or stopped a prescribed distance before the end of the timber or any intersecting timber.
- Check: A crack in a timber that does not go all the way through–but typically stops at the heart (center) of the timber. Want to know why timbers split and crack?
- Girt: Horizontal timber which joins wall posts. A wall girt runs parallel to the ridge, a bent girt runs perpendicular to the ridge.
- Green Wood: Freshly cut wood that has not been seasoned by air or kiln drying.
- Housing: A shallow reduction or mortise to receive the full section of a timber end for load-bearing.
- Hybrid: A structure that combines timber framing and 2x conventional building methods.
- Joint: The connection between two or more pieces of timber.
- King Post: The vertical central member in a king post truss that extends upward from the horizontal tie beam (or lower chord) to receive the upper ends of two rafters (upper chords).
- Knee brace: Small, short, and placed between two members at right angles to stiffen the connection.
- Mortise and Tenon: The end of one timber is reduced in section to form the tenon which is inserted into a corresponding cavity, the mortise, and typically pinned with a wooden dowel or peg.
- Peg: A wooden pin usually 3/4″ or larger of oak or other hardwood.
- Post: A vertical supporting timber.
- Post and Beam: A structural system of primarily vertical and horizontal timber simply butted together and fastened with metal hardware.
- Purlin: A lengthwise timber connecting or supporting rafters.
- Rafter: An inclined timber in a roof spanning from the eave to the ridge.
- Roof Pitch: The inclination of a roof is described in inches of rise per foot of run.
- Scarf Joint: Used to join two equally sized timbers in their length so as to make a longer beam.
- Sill plate: A horizontal timber fastened to, and resting upon, the foundation.
- Span: The unsupported distance from support to support.
- Spline Joinery: Also known as a “free tenon.” Typically a 4′ or longer hardwood board the thickness of a tenon is used to join beams to posts especially when the mortises for three-way or four-way connections would weaken the post.
- Structural Insulated Panel (SIP): An insulating panel applied to the outside of a timber frame, typically made of two pieces of OSB (oriented strand board) sandwiching a foam core.
- Timber: Large (typically 6″ or bigger) square or rectangular piece of wood.
- Timber Frame: Frame of large timbers connected primarily by wood-to-wood joinery.
- Truss: A framework of timbers that form a rigid assembly capable of spanning longer distances or supporting heavier loads.
We Build Cool Timber Frame Projects
For almost 20 years, Carolina Timberworks has collaborated with some of the country’s most talented architects and builders to craft timber frame homes and businesses, timber frame barns (including the largest horse barn in the United States), porches, porte-cochères, tree houses, entryways, natatoriums, pavilions, and even the world’s best mailbox post. We’ve worked for billionaires and non-millionaires alike. From New York to Nebraska to Washington State. Take a look at the cool stuff we’ve built.
Remember Lao Tzu’s words: “A successful first step is always preceded by great questions“. Call us. We’re nice.