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.
The Short Answer: Wood Checking
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 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 timber frame 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 hydroscopic – 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 one 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 we humans are an impatient species, 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 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 instead of the less expensive 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 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 the greenwood.
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 well-dried new or 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 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 videos and see what makes Carolina Timberworks the best in the nation.
Champagne timber framing on a (craft) beer budget
After receiving the latest Carolina Timberworks newsletter, a potential client emailed a great question: “Can you show a recent home for a customer on a 300k budget, else this stuff is non-realistic to normal non-millionaire folks“.
My Emailed Reply
With respect to non-millionaire projects, we do a lot of them. One way to fit timber framing into the budget is to consider hybrid timber framing — i.e. timber frame only certain parts of the house as opposed to building a timber frame house. You might consider identifying an area or two within your plan that you might like to timber frame (for example the front entry and great room) and establish a budget. Then, give us a call and we’ll do our best to come up with something great that fits your budget.By the way, if the timber framing is structural (versus decorative) there is some cost offset savings to be realized (since the timber framing is replacing 2x conventional construction).
Admittedly, timber framing is more expensive than conventional construction, but it’s also for us non-millionaire folks. I have a timber framed heavy duty mailbox post, one curved timber bracket at my front entry, and a timber framed garage/guesthouse.
Finally, you can design, cut, and raise the timber frame yourself. It’s a heavy lift (pun intended), but your ancestors probably did it, and people today find it highly rewarding. By the way, there are wonderful schools that teach introductory timber framing (Heartwood in MA, and Yestermorrow in VT).
A More Considered Reply
Most of the timber frames Carolina Timberworks builds are for architect-designed homes — so to be clear, we do not design homes. My personal design philosophy has been shaped by the architect-designed timber frames we’ve been involved with, as well as two books:
Sarah Susanka’s design philosophy might be summarized as follows: Keep your budget as is, but design a smaller home with less square footage. Spend the cost savings on great design, quality materials, and craftsmanship.
Suppose you want to budget for some timber framing in your home, have a smaller home design in hand, and have already chosen which areas of your home to timber frame. Here are some factors under your control that will determine how much your timber frame costs:
- The timber frame design itself. The simpler the timber frame design, the less expensive it will be.
- Your timber choices are varied, and certain timber species are less expensive than others.
- Within a given timber species, sometimes a lower grade is available that will produce a serviceable yet still beautiful (and less expensive) timber frame.
- Reducing timber sizes. If structurally feasible (here’s where quality timber frame engineering pays for itself), these savings can add up fast. For example, an 8×8 post has 36% less wood than a 10×10 post.
- The Golden Triangle applies to timber framing, just as it does to other purchases. Pick any two sides. You can have fast and cheap (but mediocre), good and cheap (but slow), or fast and good (but not cheap). You can’t have all three.
Need Some Ideas About Designing a Smaller Home So You Can Fit Timber Framing Into the Budget?
Since we don’t design homes, it was timely that Brice Cochran of Timber Frame HQ recently sent me some good advice on the topic.
Planning Is the First Step
Whether you’re buying your first starter home, downsizing after the kids have flown the coop, or are financially limited to a smaller timber frame home, planning the most practical way to use your space can make that house seem more spacious.
It’s great when you can have a room for each of your family’s activities, but it usually isn’t feasible. By thinking ahead, planning your space, and getting creative, you can come up with a solution that gives everyone in the family the space they need for various hobbies and activities.
Consider the Things You Want to Do
Of course, you could make a laundry list of dozens of things you’d like to do in your home, and those may be good for your bucket list. However, think seriously about your family’s lifestyle options. What hobbies do your family get involved with and what responsibilities do family members have that require special space?
Be realistic about your needs, now and in the future. Make contingency plans and put future expansion and remodeling ideas into your design. If you envision a future addition, make sure you have the space on your property for it. Make sure there is easy access to add electrical, HVAC, and plumbing to the room when the time comes.
Rethink the Size of Rooms
It’s become very popular to have huge master bedroom suites and oversized spa bathrooms. It sounds cool to think of having a private getaway in your bedroom with plenty of space for a desk, a comfortable chair, or even an exercise machine. In addition, that spa bathroom that’s big enough for the whole family to use at once might seem glamorous, but when you’re planning a modest home, these two rooms may need some rethinking. The extra square footage you gain when you scale down those oversized rooms can go a long way to giving other smaller rooms the space they need to become roomy multi-purpose rooms the entire family can enjoy.
Hallways are a big waste of space. Plan your home to have the smallest square footage of the hallway as possible and use the extra space to enlarge other rooms.
If you never use your formal dining room and have ample space in your kitchen or family room, repurpose it as an office, hobby room, or exercise room. You don’t need a huge laundry room. In designing your home, consider using a closet for your washer and dryer.
Consider creating a centralized all-in-one space that includes your HVAC, plumbing system, storage, and laundry area. This compact use of space frees up valuable real estate for expanding smaller rooms.
Choose Furniture That Does Double Duty
Think further than a hide-a-bed when you’re considering furniture that can multitask. Of course, a convertible sofa is a good answer for a guest room that doubles as an office or study. There are lots of furniture options that make changing the role of your room easy and look great.
Certainly not cheap, but a great space saver for a guest room is a Murphy bed. These units have been around for years and today’s models are sleek and stylish. An adjustable height coffee table that rises to become a worktable or eating space is a perfect space-saving option for a desk or craft table in a study.
If you don’t have room for a desk, there are fold-down wall-mounted units that hide beneath an art print or mirror surface when it’s stowed away.
A long counter with base cabinets can be used as a desk or work area with plenty of storage space. This area can double as an entertainment area in a family room.
There’s a wide variety of furniture that incorporates storage into the base. Benches, footstools, low chests all are available with built-in storage space. Under-bed storage options vary from off-season clothing storage to a child’s toy storage and play surface to a pull-out trundle bed. Expandable tables are popular for feeding a crown or as a roomy work table.
Make Use of Lost Space
You may have some wasted space that can be converted to useful living space. The area beneath the stairs can serve a number of purposes. Open up space and create a compact workspace with a built-in desk and shelves. Another option is to create a storage space with a closet or a wall filled with drawers. Depending on its location, it could become a cozy reading nook, wet bar, or a diminutive powder room.
Space under the eaves can be fitted out with drawers for built-in storage, or if there’s enough headroom, lay down sturdy flooring and use it for long-term storage.
The most overlooked and underused space in most homes is the vertical wall space. Shelving can be installed around doors, above and adjacent to windows, in a wide hallway, and can reach to the ceiling. With all the added storage that doesn’t take up floor space, you can minimize bulky furniture like dressers and cabinets. You’ve opened up the room to accommodate the things you need for your multi-purpose plans.
Spend time planning how you’ll realistically use your home and develop a strategy to make the most of your home’s square footage. You may be surprised at how much you can do with the space you have.
Finally, you might enjoy this article about the low cost of quality: https://www.carolinatimberworks.com/a-return-to-quality/
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 and why we are drawn to, and love timber framing:
“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.”
“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.”
“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.”
Special thanks to Shannon Richards of Caleb Johnson Architects for permitting us to reproduce Caleb’s words.
To look at their work, visit http://www.cjab.me
Search for “problems with tree houses” and Google will serve up 37,100,000 results: it’s impossible not to harm the trees, trees grow over time, trees die, there aren’t the right trees where you’d really like to have a tree house…
Our take on the tree house solves these problems. Carolina Timberworks’ two and a half story Timber Frame Tree House Tower is an engineered and architecturally designed kit that doesn’t rely on trees for support. This allows you to site your tree house on the best spot on your property instead of being limited to where the right trees are. No trees? No problem. Ever wanted to spend an afternoon hanging out in a fire tower gazing out over the forest and valleys? Got an amazing view if only you were 25’ higher? Brilliant, right?
Want to learn more? Here’s a link to our timber frame tower kit.
Whether it’s the cathedral-like atmosphere or the honesty of the structure, barns seem to resonate with people.
Bittersweet Farms Party Barn
“Buy it”. I asked Jim Becher to repeat what he’d just told me. Then I had to admit we didn’t have enough money in our checking account to buy the antique timber frame barn in Pennsylvania I’d been telling him about. “You’ll have a check by Fed-Ex tomorrow morning”. He told me he was looking forward to working with us and hung up.
My next call was to the architect (Jim Meyer of Meyer Greesen Paullin Benson) to ask if he thought Mr. Becher was serious. After Jim Meyer assured me I didn’t need to worry about Jim Becher’s word, my third call was to my Mennonite friend in Pennsylvania, who that morning, had emailed me photos of a spectacular antique hand hewn Oak timber frame barn he was reclaiming. I told him we had a client who wanted to purchase the timber frame barn and build a party barn on his farm.
So began our involvement with Jim and Betty Becher’s fast track project to covert their existing cattle barn into a Party Barn. Betty and Jim’s inspiration to build a Party Barn came from a visit to Blackberry Farm in Tennessee and the fast track part of the project came from Betty’s approaching birthday party deadline.
The first thing we needed to do was to get the 200 year old Pennsylvania barn to our shop in Boone. The reason? We needed to know if it contained enough timber, in the right sizes and lengths, to build what the architect had designed for the space. It turned out that there wasn’t enough long timber in the first centuries old timber antique barn, so we acquired a second post and beam barn–this one a few miles outside Gettysburg, PA. Here’s what the first barn looked like during dismantling:
To fully appreciate this project, it helps to know that it was completed from start to finish in 4-1/2 months. Here are the ‘before’ pictures:
Jim Becher’s emailed comments after we finished?
Your crew to the man was fantastic in every respect. Eric is a gentleman in every respect, and what a talent and fine representative of Carolina Timberworks. Thanks for a great job and experience. JB
Located on over 700 acres in the rolling mountains of Alleghany County in western North Carolina, Bittersweet Farms is home to over 300 head of black Angus and black Belted Galloway cattle.
New Jersey Party Barn
Don’t have an existing working cattle barn on your property to renovate? Build a new Party Barn–either using a relocated antique post and beam barn or use new timbers and build a party barn like this one. Michael Brandes (Brandes Maselli Architects) selected Carolina Timberworks to fabricate and erect the timber frame for a new Party Barn located on a golf course in Bedminster, NJ.
In order to keep costs down, new rough sawn Douglas Fir was chosen for the timber frame. It’s not easy to replicate the patina of time and weather-worn barn timber. At first glance, a piece of antique timber looks gray. A closer inspection will reveal subtle shades of brown, black and silver. We’ve seen new timber faux finished in an attempt to duplicate the look of aged timber, but it often falls short of the mark. However, the finish that Michael’s people applied to these new timbers is, in our opinion, quite authentic.
Three years later, it was decided that the Party Barn needed a silo. We built the timber framed domed silo roof from Douglas Fir reclaimed from the San Diego & Arizona Eastern Railway, better known as “The Impossible Railroad”. Built from 1907 – 1919, the construction of this 146 mile long railroad from San Diego to El Centro to the east overcame a series of catastrophes and misfortunes–including, but not limited to, the Mexican Revolution, a prolonged legal battle, floods, World War I, labor shortages, tunnel collapses, and a pandemic thrown in for good measure.
North Carolina Mountains Party Barn
A friend of mine, upon seeing the photographs of these party barns, exclaimed “Everybody should have a Party Barn!”
Timber frame and post and beam homes are wonderful spaces.
So, is timber framing sustainable?
Buildings that are loved get maintained, and well-maintained buildings last far longer. Timber framing may be one of the best ways to conserve our resources because post and beam homes are special places that people love, and because they are loved, they are maintained over the years, and because of that care, post and beam homes last for centuries rather than decades.
Wood is one of our only renewable resources. Think about this sometimes overlooked and obvious fact.
Timber is a natural product. It is recyclable, biodegradable, and renewable. It does not off-gas toxins because there are none.
Timber, unlike 2×4 and 2×6 lumber, upon the end of the useful life of the timber frame or post and beam home, will be carefully dismantled and reused. Used 2x4s may one day be reused, but today are going into landfills, rotting, and releasing their stored carbon into the atmosphere.
Wood is a carbon sink. If kept dry, wood lasts indefinitely. If you leave a tree in the forest to die a natural death, it will rot and release its stored carbon. If you cut down a tree at the end of its natural life, it has spent years storing carbon and producing oxygen. If you then fabricate it into a timber frame, and keep it dry for centuries, the post and beam home is acting as a long-term carbon storage unit.
The figure we’ve heard is around 30% less. There are some caveats here, and it may seem counter-intuitive at first, but take a look at the photo (at left) from Stewart Elliot of Riverbend Timber framing.
Timber frame homes use big timbers which come from big trees. Here’s another counter-intuitive one. Big timbers come from big trees–sometimes old-growth trees. Big trees have spent many, many years storing carbon and producing oxygen. Today’s 2x4s are manufactured from young, small trees–trees that have not lived long enough to store much carbon or to have produced much oxygen. What we’re doing to make 2x4s cheaply is to grow genetically-engineered super fast-growing trees, cutting them down in 10 years, and then replanting. By the way, when we replant these crop trees, we’re not doing it by hand. We’re burning diesel fuel. Is it a cheaper way to produce a 2×4? Undoubtedly. Is it greener wood? We’re not so sure.
Timber frames or post and beam homes are the best use of old trees. Related to (7) above: in our view, it is far greener to cut down a majestic old-growth Douglas Fir tree at the end of its life, and fabricate it into a functional and gorgeous timber frame that will be treasured and maintained for centuries, than to cut it down and saw it into 2x4s that will eventually go into a landfill and rot, or produce window sashes which will rot, or make paper. Better to revere these fantastic trees by turning them into an architectural solution to a structural problem that is so stunning and useful that generations of people will benefit from, and take care of the building.
Some post and beam homes are built without cutting down a single tree by using reclaimed wood and beams from old buildings and factories.
Nearby is a photograph of one of our timber homes that utilized reclaimed wood. We love putting old wood back to work, and the timber in this project is structural and is holding up the roof.
Timber framing is a darker shade of green. Having spent a week in a photovoltaic solar class, we’d note that no building material or technology is without consequences to the environment–not even solar panels. We contend that timber frame and post and beam homes, while not an environmentally perfect building solution, are demonstrably and quantifiably greener than most other conventional building methods.
Is there progress to be made? Sure! Yet, even so, timber framing, teamed with structural insulated panels and solar photovoltaic panels, is the most beautiful, green, and energy-efficient method of building we know of.
Want to know where Carolina Timberworks is heading? Carolina Timberworks 2.0