Timber Frame 101

What is Timber Framing?

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.

What is a Timber Frame? from Carolina Timberworks on Vimeo.

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.

Joinery

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

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.

Timber Frame Truss curved arched lower chord

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.

Structural Insulated Panel and Timber Frame — SIPs being installed at Carolina Timberworks’ new shop

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.

Want to deepen your understanding of the timber frame elements showcased here? Visit our Timber Frame Glossary to explore the vocabulary of timber framing.

What Are Timber Frame Buildings?

We like the French word for brace/knee brace/struts a lot better: Jambes de force (translation: strong legs).

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.

Barn Home Conversion — Built Poetry designed by PLATT

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).

Benefits of Adaptive Reuse: Google Fiber Charlotte

Google Fiber’s timber framed offices in Charlotte

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:

Modern Contemporary Timber Frame — Contemporary timber frame homes often blend Natural materials like timber and stone with steel and glass.

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.

Conventional 2x construction — Conventional stick-built construction

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).

antique timber frame barn for sale — An antique timber frame barn during careful disassembly (note cow tags used to ID timbers)

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.

Old fashion barn raising — (Note to younger Carolina Timberworks employees: no, Eric Morley was not present at this raising.)

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.

Wetting Bush Tradition — A Wetting Bush pays homage to the trees that went into the frame and the hands that built it

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 in North Carolina where we’re located and beyond.

Remember Lao Tzu’s words: “A successful first step is always preceded by great questions“. Call us. We’re nice.

Timber Traditions: Our Industry Customs

Timber framing has been around, in some form or another, for over 2,000 years. So it stands to reason, some interesting timber framing traditions and customs have sprung up in connection with timber frame construction. We thought we’d share some of the more interesting ones…

Common Timber Frame Traditions

Topping Out Ceremony and the Wetting Bush

Timber framing traditions topping out ceremony

One of the more well-known timber traditions involves nailing a bough or small evergreen tree to the highest point of the timber frame. According to Fine Homebuilding Magazine,

The ritual serves two purposes. One pays homage to all the trees that went into the construction of the house, and to the many hands that built it. The other symbolizes the establishment of the house’s roots, which will nourish a long and prosperous life. The young tree is called a “wetting bush”, likely derived from the German tradition of watering it as a sign of the home’s first nourishment.

So, who gets to set the wetting bush? The youngest carpenter present.

The Barn Raising

Of course, this might refer to a home, an outbuilding, or even a post and beam shed, but Barn Raising evokes an image familiar to most of us–a community coming together to accomplish something big.

In the “olden days” the individual timbers for a house or barn would be cut and fitted by just a few men or a family. When all the individual walls were ready, the whole community would come together to raise the walls into position and set the rafters and ridge beam in place. This would be done using gin poles, ropes and pulleys, and of course, strong men. Although hard physical labor was required, “many hands make light work”, and the day ended with a celebration and party. The wives and children participated and a feast was held. There’s a real nostalgia in the thought of honest labor and participation in a feat that none of the individuals could have accomplished alone.

The Group Photo

This doesn’t happen when the sheetrock goes up…but once the last timber is raised and pegged, the moment is documented with a photograph. Why? Perhaps because timber framers often feel that the timber frame will never be more beautiful than at that moment (before it is covered by walls and a roof), perhaps because all present sense that this structure will outlast every one in the picture.

Feeding the Framers

Whether it’s a tradition, or simply good manners, timber framers always appreciate a hearty meal! So they perpetuate the superstition that feeding the crew will bring the building (and Owners) good luck…

Slaking the Framers’ Thirst

A French tradition, courtesy of Charpentiers Sans Frontières (Carpenters Without Borders), is to give the lady of the house the honor of pounding in the last peg. She is expected to owe the crew one drink for every blow of the mallet required to drive the peg home.

Using a Coin to Date the Building

Think of this as a very abbreviated time capsule! A coin minted the same year as the structure is built is placed under a post, where it (presumably) will not be found until the building is dismantled (and hopefully the timber frame reclaimed).

Carving the Date

The date of completion is carved into the frame. This may be done in a visible and conspicuous place, such as over a doorway, but it might also be done in a less obvious spot. For example, some timber frame companies carve the date in the location on the frame closest to where the home shop is located. In our case, the date would be carved on the side of the building closest to West Jefferson, North Carolina.

Signing the Frame

All the timber frame craftsmen (and craftswomen) who worked on the frame sign one of the timbers in a hidden place where it may lie undiscovered for a century or more.

Topping Out in Space

One of our clients worked for NASA and sent a photograph of Mission Specialist Joe Tanner topping out the International Space Station. The evergreen tree represents the highest point (top of the P-6 integrated truss structure) of the ISS.

Learn More: Our Timber Frame Glossary

Why Do Timbers Split and Crack?

Eric Morley on why timbers split and crack, how long it takes timber to dry, where to get dry timbers, and why gunshots in the night are nothing to be afraid of when you understand wood checking and splitting.

Wood checking and splitting, a natural phenomenon in timber, occurs as the wood dries and loses moisture. This process leads to splits and cracks, known as “checks.” While they do alter the appearance of the timber, checks also add unique character without affecting the wood’s structural integrity.

What Causes Wood to Crack?

Drying Does!

Splits and cracks (known as wood checks in the industry) occur when wood shrinks as it dries. Wood shrinks roughly twice as much along with the growth rings (radially) as it does across the rings (tangentially). It is this uneven shrinkage that causes checks to develop.

Is Wood Checking Bad?

Here at Carolina Timberworks, we think of them as wrinkles in a cotton shirt. It proves the timber is real. Checks are what make a solid timber look different from a boxed beam. Look at the reclaimed timber below. It is impossible to predict where a check will appear in timber. It is the check that gives this reclaimed white oak timber so much of its character and a big part of what makes it completely unique and different from any other beam in the world.

Ever Heard the Song of the Wood?

Have you ever taken a hot loaf of artisan bread out of the oven, and put your ear to it? If you do, you’ll hear the song of the bread–pops and crackles as the crust shrinks, cracks, and dries.

Walk into a timber framer’s shop one winter evening when everyone has gone home for the day. Throw another log into the woodstove, and listen carefully. If there are green (wet) timbers arrayed on sawhorses, within a few minutes, you’re likely to hear the song of the wood – a symphony of pops and cracks as wood checking occurs.

If one night, asleep in your new home, you’re awoken by a loud crack a little like a gunshot. Don’t worry. Roll over and go back to sleep. It’s just your timbers singing to you. That’s wood checking in action.

Why Does Wood Shrink?

It sometimes surprises people to learn that roughly half of a living tree’s weight is water. Let’s consider a 24’ long Douglas Fir log that measures 34” diameter at the large end and 14” at the small end as an example. This hypothetical green (wet) log would contain a little over 1 ton of water or about five 55-gallon drums of water.

Sometimes when we drive a chisel into green (wet) timber, water spurts out of the wood. Wood is hygroscopic – meaning it’s like a sponge in that it can absorb, hold and release water. When freshly cut, approximately half of a tree’s weight is water. The photograph below shows water in a freshly cut cypress timber–and how the timber is drying from the outside in.

How Long Does It Take a Timber to Dry?

It’s not exactly a fast process. It depends on the humidity of the environment in which the timber is located, but a rule of thumb is that timber air dries about one inch per year. Thus a 12” x 12” timber would take about six years to dry to the center.

How Dry Will the Timber Become?

A timber will eventually air dry to the Equilibrium Moisture Content (EMC) of its environment. The EMC is the point at which wood is neither losing nor absorbing water. A timber’s moisture content is determined by the atmospheric humidity of the timber’s environment.

That environment varies, of course. Is the timber located inside, or outside? What part of the country is it located in? What time of year is it? For example, in the dry mountain air of Denver, the outdoor EMC of wood exposed to the outdoor atmosphere in July is 9.4%, while New Orleans is 15.3% (Forest Products Laboratory: Equilibrium Moisture Content of Wood in Outdoor Locations in the United States and Worldwide, August 1988).

How Wet (or Dry) Are My Timbers?

Since we can’t see the water in the wood, moisture meters are used to measure moisture content. Inexpensive moisture meters measure the surface moisture content which works ok for 3/4” boards, but not 8” thick timbers. Professional moisture meters use electromagnetic scanning to read the moisture in the wood, not on the surface of the beam.

What is the Average Moisture Content in the U.S.?

The majority of the U.S. has an 8% average moisture content, the Southeast and California coastal areas have an 11% average moisture content, and the Southwest desert areas are closer to 6%.

Most Timber Frames Are Built From Green (Wet) Wood

It is impractical (it takes years) to air dry timber, and timber frame customers are nothing if not impatient, so for the last two thousand years, people have been building timber frames from green (wet) timber. Yes, green timber will shrink, check, and sometimes twist as it dries, but timber framers and engineers understand and account for the movement. Checks begin on the exterior surface of the timber and almost always stop at the heart (center) of the timber, and are almost never a structural concern.

By the way, if a crack were to develop all the way through a timber (splitting timber it into two separate pieces), it would be called a split and might be cause for concern.

Learn more about timber framing all the ways timber can be used here.

How Much Does Green (Wet) Timber Shrink as It Dries?

Shrinkage depends on the species, but more than you may think!

Since many timber frames are built from Douglas Fir, let’s start by looking at a 12×12 Douglas Fir (Coastal) timber. This particular green (wet) Douglas Fir timber, dried to a final moisture content of 8%, would be expected to shrink a little less than 9/16” on each face from 12” x 12” to a final size of 11-7/16” x 11-7/16”.

Western Red Cedar shrinks less: The same size timber in Western Red Cedar timber would shrink a bit less about 5/16” to 11-11/16” x 11-11/16”. Finally, how about a species with a high shrinkage rate, like White Oak? It would be expected to shrink a bit less than 3/4” to slightly larger than 11-1/4” x 11-1/4”.

6 Ways to Minimize Problems with a Green (Wet) Wood in a Timber Frame:

Specify Free-Of-Heart-Center (when available) instead of the lower Boxed Heart grade.
Apply a wax-based end sealer to the end grain to slow the drying process. We use Anchorseal, available at https://uccoatings.com/products/anchorseal/.
Utilize housed joinery wherever possible.
Drawbore pegged joints.
The slower the wood cracking when drying, and the more gradual the process, the better (i.e., the worst thing you can do is enclose the timber frame and immediately turn on the heat or air conditioning full blast.)
Do not apply a film-forming finish (i.e., polyurethane) to green (unseasoned) wood.
Sawing checking kerfs on an unseen timber face is a good practice and can help mitigate the visual checking.

I Don’t Want Wood Checking or Cracks in My Timbers. What Are My Options?

Don’t build with solid timber. Instead, ask us to price glulam beams for the timber frame, or to fabricate box beams from kiln-dried new or well-dried reclaimed lumber.

If you’re ok with some checks, but would prefer to avoid some of the characteristics of green lumber, consider purchasing your timber like you do your high-quality organic cotton t-shirts–pre-shrunk. There are two ways to buy dry beams: new timber that’s been dried in a kiln, or reclaimed wood that’s dried slowly and naturally for 50 or 100 years during its previous life as a timber frame barn or warehouse.

Where to Buy Kiln Dried Timbers?

We offer two types of kiln-dried timber: Conventionally kiln-dried (KD), and Radio Frequency Kiln Dried (RFKD). Conventional kiln drying dries about the outer 1” or so leaving most of the timber wet. The other method, RFKD, is similar to a giant microwave and dries timber to the core.

What you need to know about RFKD timber is that it currently works only on Douglas Fir, it is dry to the core, and it is more expensive. It is, however, not as dry as conventionally kiln-dried hardwood flooring or lumber (6-8% moisture content). For example the driest grade of RFKD timber measures 15% or less moisture content 3” in from the surface of the timber.

What About Using Reclaimed Wood in Timber Frame Construction?

Reclaimed wood beams that have naturally air-dried for 50-100 years during their previous life as a barn, factory, or warehouse are often completely dry to the core and the driest timbers available anywhere. It’s not easy to hand-scribe and connects irregular, twisted, and non-square reclaimed beams so the finished timber frame appears to have always been one frame.

We think a timber frame built from reclaimed wood is everything that today’s sleek, mass-produced, technology-saturated culture isn’t. It celebrates the cracks and character and dirt and all the other marks that time, weather, and use leave behind.

Interested in learning more about timber framing? Check out our timber frame blog.

The Benefits of Timber Framing

When you design a new home or modify your existing space, deciding on a building method is one of the first—and most important—choices you’ll have to make. If you’d rather avoid the standardized look of conventional construction, then the handcrafted aesthetic, the gorgeous exposed beams, and the open floor plans synonymous with timber framing may have caught your eye.

But is this method of building really the right choice for your home or family? What are the benefits of timber framing—and are there downsides you should know about?

At Carolina Timberworks, our team has collectively had more than 90 years to ponder these questions. Here’s what we think, based on our first-hand experience with building and customizing timber frame homes.

What Are the Benefits of Timber Framing?

We can think of quite a few:

It’s an Art

While watching Fine Homebuilding’s video of architect Caleb Johnson of Biddeford, Maine, discuss the winner of the 2015 Best New Home award, we were struck by his profound insights into the benefits of timber framing. His words beautifully capture why we’re drawn to and love timber framing: “Built poetry.“

“The materials go together in a fashion that you can tell he (architect Louis Kahn) cared deeply about the nature of those materials and the way they came together on a level that’s art–not just construction.“ It’s true: we’ve found that timber framing is much more than a building method. It’s an art.

It Gets Better With Age

As Caleb Johnson says, “If we use natural materials, as time goes on, these natural materials take on a character and patina that enhances the building. Whereas when you use manufactured materials, those materials will look best the day you put them in, and they will deteriorate from there, and there’s really nothing you can do to bring them back.“

Building a timber frame home requires heavy timber and wood joinery, which is about as natural as it gets. What does that mean for your family? You can expect your timber frame home’s aesthetic to continue to evolve and develop a character of its own over time. In other words, it gets better with age.

It’s Sustainable

From the new wood to the concrete and steel, stick-built homes are often the opposite of sustainable. Conventional construction generally uses highly embodied resources that produce extensive carbon emissions and younger trees that never get to realize their potential as a carbon sink.

In contrast, timber framing tends to be much more sustainable. What do we mean when we say timber framing is sustainable? This short comic says it all:

Carolina Timberworks - sustainability comic 1

Carolina Timberworks - sustainability comic 2

Carolina Timberworks - sustainability comic 3

Carolina Timberworks - sustainability comic 4

Carolina Timberworks - sustainability comic 5

It’s an Experience

A timber frame structure doesn’t typically require load-bearing walls. That means a timber frame home can often support (literally!) open floor plans that go beyond what conventional construction could create.

But that’s not all. As Caleb Johnson says, “I feel that the structure of a house can be the most expressive part of the architecture and I feel that when that structure is exposed, it’s most powerful when it’s authentic–like it’s actually bearing the load of gravity pulling the house down and the winds trying to push the house over.“ In other words, let’s just say living in a timber frame home is quite an experience.

Are There Disadvantages to Timber Framing?

Any timber frame company that tells you there are no downsides isn’t telling you the whole story. Most importantly, you should know that timber framing tends to cost more than conventional construction for a variety of reasons, including the engineering, the highly skilled labor, and the high-quality wood. Even if you opt for a timber frame home kit, you can expect it to be more expensive than a stick-built house—especially if you intend to modify the plans dramatically.

Can you cut the costs? Sure, there are a few ways to make timber framing less expensive. From careful planning to rethinking room size to repurposing space creatively, we have several suggestions for how to fit timber framing into your budget.

Need help understanding timber framing terms? Browse our Timber Frame Glossary for easy-to-understand explanations of the basics.

Should You Build a Timber Frame Home?

It may come as no surprise that at Carolina Timberworks, we think there’s nothing better than a timber frame structure. But a timber frame house certainly isn’t the right choice for everyone. So how can you decide? Take a look at our timber frame portfolio to see our work in action or contact us to talk about your project. We’re nice!

Special thanks to Shannon Richards of Caleb Johnson Architects for permitting us to reproduce Caleb’s words.

Differences Between Decorative and Structural Timber Framing

A homeowner building in the Outer Banks emailed a great question this week:

“I was wondering if people typically use your trusses as structural members or just as decorative members attached to the existing frame structure?” We build and install both decorative and structural timber framing.

What Is Decorative Timber Framing?

Non-structural, or decorative timber framing, is frequently timber frame trusses in a cathedral ceiling or beams on a flat ceiling. Our engineers call this timber framing non weight-bearingin other words, the timber isn’t holding up or supporting anything above it. As an example, suppose a great Room is designed with 2×10 ceiling rafters framing and holding up the roof. If you choose to install timber frame trusses under the 2×10 rafters, the timber frame trusses wouldn’t be structural because the 2×10 rafters are actually doing the work of supporting the roof.

Over the years, we’ve built a lot of non-structural timber framing. Our yardstick for this work is simple: to look right, it must look as if it is structural.

Back to our great room example. Structural trusses usually have between 6’ and 8’ spacing between trusses. So if a great room was 16’ wide and 24’ long, we’d design three trusses for the room — one at 6’, one at 12’, and one at 18’. Sometimes, we might include two more — one at each of the gable ends (at 0’ and 24’).

Often we make these end trusses half-thickness so as to appear partially embedded in the wall. In addition to truss spacing, in order to look right, the trusses must be built using appropriate timber sizes. A structural truss spanning a 16’ wide great room would probably need to be built from timber at least 6” wide – i.e. we might use 6” x 12” timber for the rafters and lower chords.

If the truss were built from smaller material, say 4” x 6”, it wouldn’t look structural, and that’s what would make it not look right. Conversely, to look structural, there shouldn’t be too many trusses, or built from timber sizes that are oversized–that doesn’t look right either.

Our yardstick for designing and installing non-structural timber framing involves a mental picture: at some point in the future, the homeowner has a guest visit the home. This guest may be an architect, an engineer, or perhaps another timber framer. We want that guest to look up, and stand there for many minutes trying to figure out if the timber is structural or non-structural, then turn to you and ask.

Pros of Decorative Timber Framing

A great place to use reclaimed beams. Reclaimed beams are normally not graded or grade-stamped, which is required by engineering for structural timber framing.
They can be (and often are) retrofit from below after the roof is in place. The benefit is that the timber is protected from the weather, and since it is installed later in the process, it is unlikely to be damaged by other trades. As you might imagine, this costs a bit more than setting heavy timber from above with a crane (picture each 400 lb. timber being unloaded and carried by hand into your great room).
Pre-finished. We frequently apply a finish to the timber because most builders agree that it’s less expensive for our crew to finish the timber framing in our shop while it’s on sawhorses than it is for a painting subcontractor to erect scaffolding and apply two coats of finish on site.
Great for remodeling. We can add or retrofit timber framing and beams to existing houses and have done so many times as a part of a remodeling project.

Cons of Decorative Timber Framing

Need to carefully consider spacing, timber sizes, and proportions so that it looks right (structural).
Added weight: timber is heavy. For example, a single 6” x 12” x 16’ Douglas fir timber weighs about 4 lbs. per board foot or 384 lbs. An engineer needs to be consulted to determine that your framing is designed to safely support the added weight of non-structural timbers.

What Is Structural Timber Framing?

Structural timber framing, as you might expect, is when the timber framing is weight-bearing, or doing the work of holding up part of the house above it. If we return to the great room example, your architect and builder might decide to support the roof using structural timber frame trusses. In that case, the timber frame trusses would be designed and engineered to support the weight of the decking (usually 2×6 tongue & groove) or sheetrock ceiling, the insulation, the roofing, and the wind and snow loads.

Pros of Structural Timber Framing

It looks right. The aesthetic concern of looking right is addressed automatically because the timber framing has been engineered to be structural.
It replaces some structural conventional 2x framing, which can help offset the cost.
Durability. If kept dry, timber framing can (and does) last for centuries.
Safety. We don’t like to think about it, but houses sometimes burn. Unlike steel or 2x4s, timber framing provides more time for the family to safely get out of a home in a fire (see the FOR ARCHITECTS section on our website for an article on the subject).

Cons of Structural Timber Framing

More expensive than conventional 2×4 framing.
Must be engineered; however, this isn’t a major cost in most projects.
Installed earlier in the building process — meaning it has to be planned in advance and protected during the balance of the construction process.

Learn More: Our Timber Frame Glossary