Glulam, or glue-laminate, is engineered wood that is twice the strength of #1 grade timber and is sometimes used as a beam. It is composed of several layers of dimensioned timber bonded together with durable, moisture-resistant structural adhesives.
Glulam is frequently used in large scale projects like airports and manufacturing facilities in order to achieve a large open span. As an industrial component, it looks good, but for a residential application, we use Glulam in a different way.
First, to soften the laminated look, it’s best if the glue in the lamination is clear. Then, we wire-brush the surface in order to blend the glue lines in. Finally, we use a dark stain color.
Glulam can be an affordable alternative to big timbers. At any size bigger than 8 in. x 14 ft., or longer than 24 ft., the cost of kiln dried timber rises to exceed that of engineered wood . . . and then the point is reached where natural timber at that size does not exist. For this project, an industrial feel is part of the design concept, so Glulam is the material of choice.
Wood offers lots of options. One of the most important to homeowners—because it concerns the entire timber surface that you see (and live with) in the finished house—is the finish. If you want a rustic feel to your timber but don’t like fuzzy fibers that catch dust and provide an easy path for spiders, a comb finish may be the answer for you. In most cases, vertical grain is the favored grain look, but in a comb finish, flat grain is also pleasing to look at it.
To achieve a comb finish, we scrub a nylon brush along the grain that digs into, and compresses, the softer fibers. This makes the tight-grained winter growth stand out in relief. Running your hand over it feels good—you get to feel the grain, not just see it.
A comb finish also stands out more when stained.
It’s more work for us, which means a bit more cost, but the result is stunning. Most people who see it (and feel it) really love it.
For more, see our article, “Wood Texture,” on our website’s Downloads page.
We work on many projects, so we receive lots of connection specs from many engineers. It seems like the post anchor connection is still a grey zone in terms of best practices.
This year, we’ve used epoxy anchor connections for almost all of our frames. Why? I think it’s because epoxy anchors lived up to all we thought they would be in their reasonable cost, ease of use, and reliability.
In most steel plate connections, the plates need to be embedded. Plates designed to be attached after the raising still need to be specially fabricated. We often get a phone call after the contractor has installed the frame: “Can you send me detailed information on the connections?” Strangely, we expect to get this information from the contractor! Clearly, there is clearly no generally-accepted standard connection for post anchors, so we have decided to provide a solution for it.
To see this YouTube video of the epoxy connection being assembled, click the image or this link—epoxy video.
When we see the new-building details for post anchors specified with expensive knife plates, we know it means lots of work to set them in place and prepare the timber slot for the plate, which in turn means much greater cost and lots of communication. If we knew who designed this, we could send them information in advance about what we’ve found works better. The epoxy system we favor is much easier to handle.
I explain it to engineers like this. “The epoxy connection is just like a threaded rod cured with epoxy in concrete and wood, except the engineer doesn’t need to worry about whether epoxy will fill properly, because our preferred system is designed to do that.”
Epoxy is injected into threaded rods.
The cavity fills from the middle.
I instruct the job supervisor as follows: “On the concrete that will support the post, find the spot that will be the center of each post, and drill a 6-in.-deep hole there, making sure no rebar is placed in that area. We will provide the rods. Please make sure to insert them with the injection nose accessible for filling the epoxy in once the frame is built.
“Regular concrete epoxy starts to cure in about 5 minutes, so each post needs to be stabilized in its final position for this time. With our system, you don’t need to hold each post in a definite position for 5 minutes. It allows the entire frame to be raised first. You can adjust the post locations, plumb them, and then inject the epoxy, which will set in place.
“The threaded rod is hollow; the injection nozzle plugs into it halfway down its length. The epoxy will flow out from the end of the rod, so when we see any excess from the injection hole, we know the entire space is filled.”
Setup for injecting the epoxy. Note the small hole at the bottom of the timber.
The epoxy is injected into the hole. When epoxy oozes out, the cavity is full.
To summarize, here are the advantages of this system.
It requires no steel fabrication.
It does not require any preparation in the concrete, except to make sure the center of the post location is rebar-free.
The epoxy doesn’t need to be filled while building is happening; you inject the epoxy once all adjustments are complete and you’re ready to secure the post.
There is no distributor in North America for this epoxy system, so we carry the stock. For further details, please email us.
We see two different types of timber frame. One is a frame covered with Structural Insulated Panels (SIP) for high energy efficiency: a highly insulated, air-tight house system.
The other has an infill wall system where the frame is visible both inside and outside. In the infill wall frame, we use full-size tenons so the air cannot penetrate, but we also started using a gasket that is slotted into the joinery and then fills at the frame raising. The HannoWerk seal from Germany is a closed cell seal that expands to block any air or water that might run into the space.
Since we use a seal, the tenon does not need to be full size. We couldn’t achieve this effect with a bead of caulking because timber can shrink and, if a gap occurs, the caulk doesn’t have the ability to expand. Here you can see a groove just to the left of the tenon, where the seal will sit.
The seal in its groove. The groove is necessary so that the seal is seated and is not crushed as it expands.
The groove, with seal, is outside of the joinery. Most likely, the seal will be hidden by a framed infill wall.
Seal arrives to us compressed in a roll that will expand to almost 10 times its original size, to ensure that the gap is sealed.
Why stain early?
The right finish protects timber, making it both more useful and more beautiful. The most important types of protection are from sun, from moisture, and from fungus. Also, applying an oil or other coating system will allow timber to cure very slowly. Curing slowly means fewer twists or checks: it means the timber stays stable.
It’s best to apply the coating to all timber surfaces including butt ends and “inside” (hidden) joinery such as tenons and mortises. The only chance to do this is when the individual, unassembled timbers are in our shop. We apply multiple coats of the wood finishes we use.
Wood colour and orientation (straight-grain or cross-grain) affect finished colour. End-grain surfaces, where the stain penetrates more into the fibre are darker. And flat grain timber shows a lighter colour than vertical grain because flat grain shows more of the summer growth ring (less dense than the winter grow ring). Surface texture also makes a difference: rough surfaces hold more stain and are darker than smooth surfaces.
Our choices: LandArk and BoMol
LandArk, formulated and produced in the United States, is the most natural system available to protect the wood fibre. It’s an oil finish that soaks deep into the wood.
We also use BoMol Woodcare Products, made by Bohme, a Swiss company. Besides being environmentally friendly (no volatile organic compounds), they are water-based and provide effective UV radiation protection and moisture damage protection.
We use 7 different colours in the BoMol system, ranging from transparent clear to very dark brown. Of course, final colour depends on grain orientation, denseness, and surface texture, as well as type of wood. Here’s a subset of our finishes:
LandArk Oil Finish
The most natural system available, it soaks deeply into the wood. It brings out the richness of the wood grain, a real advantage to enhance the quality of high-grade timber. BoMol Clear
This transparent colour really is clear—it almost feels bare. It’s popular for those who want to keep the fresh look of the timber in its unadulterated beauty. It still contains the UV and fungus protection, though.
BoMol Natural
Our most common finish colour, a bit darker than Pine with more orange.
BoMol Cedar
A decidedly red colour.
Bomol Walnut
The darkest colour we use. It’s really a chocolate, but the wood grain is still visible. Stunning.
The other colours we carry are BoMol Pine, Chestnut, and Butternut. To see the full set plus more in-depth information about the staining process at Daizen, see the Downloads page on our website.
Timber is tricky, and to achieve predictable, consistent results, Daizen specializes in controlling it. Many people don’t understand how wood can be so varied in its behavior: wood is wood, right? Well, in fact, there are many, many variables. Wood fiber is a natural product. No two trees, even of the same species, are exactly the same; timbers behave differently in different drying processes (air or kiln dry, for example).
Part of our timber drying test.
To clarify how we evaluate information, we conducted a test of kiln drying behavior, comparing two species of Douglas fir (coastal and interior) that we use very frequently. We compared wood from two locations on each tree (boxed heart: BH; free of heart center: FOHC) and, for the interior D. fir, we also compared two stages of dryness:green—live when cut—and standing dead (SD). (Coastal D. fir is not subject to as many fires, since it’s much wetter.)
Timbers are planed square, to exact size, in order to monitor the changes after drying.
The coast’s mild, rainy climate causes trees to grow larger and faster. In the interior’s climate, colder winters and hotter summers make for slow growth and very tight winter growth rings, which in turn means the fiber is denser than the coastal version.
We took samples by drilling to the core and placing the chips into sealed containers so as not to lose moisture.
We prepared six timber samples (coastal D. fir: BH and FOHC; interior D. fir: BH green and SD; FOHC green and SD) and planed them to the exact same size (7½ x 11½ in.) to measure the dimension loss—shown in this PDF chart in the “After drying” row. This chart is a comprehensive report of all our test results.
A normal moisture meter gives only an indication of moisture, not a precise reading. Moisture varies even in different spots in one timber; accuracy requires taking several readings to arrive at an average read. The most accurate measure comes from several readings plus measuring the weight difference after drying.
This moisture meter measures the weight difference before and after drying in its built-in oven. It also calculates for moisture content. This can also be done with an accurate scale and a microwave at home.
Since BH timber often splits lengthwise, kiln drying it may result in dryer timber since more surface area is open to moisture escaping. So we tested both BH and FOHC timber, for further comparison.
Our conclusions: if kiln drying, coastal Doug fir gives better results, but interior Doug fir may perform better in air drying. We have several test sets in air drying now; the full cycle will take two to three years, and we are measuring every couple of months.
Samples resting on their timbers after kiln drying.
We started using Sherpa fasteners in 2008, experimenting to determine their viability. Now, Sherpa is a must-have fastener in Daizen’s timber framing.
Many connections work with wood joinery, and we do not push ourselves to use Sherpa, but when we see a challenging situation (like a long spanned beam to receive a floor joist normally in a dovetail or simply a housing), we use Sherpa so as not to take any wood out of the main beam, thus keeping it at maximum strength. Dai asked Maik Gehlof, Sherpa’s manager of technical support, to explain the Sherpa to us.
Q. Maik, can you give a brief history of Sherpa and describe how they are used in today’s market in Europe? I use it not only structurally, but also for stairs and railings.
A. Hi Dai, Sherpa was born from the need for a connector that is easily installed and assembled.
In 2005, the Austrian company Harrer needed a connector solution that just wasn’t available, so they came up with their own: the first Sherpa. Made of steel, it worked just as well as their successors today made of cold-rolled aluminum. Steel had some drawbacks; it’s not only heavy, making the connector harder to handle, but it also rusts and is much harder to machine than aluminum. Optimizing the Sherpa connector started right at its birth and will continue on with every new generation.
Today’s European market is a very competitive one. Structures get larger, wackier, and more dependent on their connections, while having very tight budgets and timelines. The Sherpa connector is tailor-made for this.
Sherpa is a standardized system with a known set of parameters, so it’s easy and fast to design with them. As you mentioned, Dai, you are able to keep main beams at their full cross-section, so they can be smaller, saving resources and money. Since Sherpa connectors are pre-installed in the shop’s controlled environment and even the screws are labeled for easy verification, pre-manufacturing is fast and efficient, which Europeans are very keen on as it controls both cost and quality. Onsite, crane time is minimized, as there is no need to line up bolts or maneuver very heavy beams into place.
All told, you have a product that allows you to save money at several stages, but foremost it gives you a way to budget and schedule a project accurately. That is what the European competitive market is asking for and what the Sherpa connector is able to deliver.
The shape of the connector resembles the traditional dovetail, offering numerous advantages that Sherpa connectors borrow and improve on since there is no short grain to fail. This image shows the cuts along the long grain.
You are absolutely right, Dai, on the multitude of uses for the Sherpa connector. We have a dedicated series of connectors—the assembly series—designed for projects like stairs. And, of course, a Sherpa connector in the hands of a creative person can result in very interesting structures.
—Maik Gehloff
Below, an unusual use for Sherpa–table and benches.
A closer look at the connections and their curious symmetry.
Here’s how Sherpa connectors go together (YouTube).
Even if two houses had the same floor plan, there are ways we could deliver a different feel to each frame. These include joinery design, of course, but also the finish surface of timbers. Finishing timbers seems such a, well, surface task. But when someone comes into a house and feels the wood of a post (and many people do this instinctively), the touch of the surface evokes one of their deepest responses.
Stain color has a lot to do with the timber surface, but the final texture is also key in delivering the result to match what you are
looking for. Daizen has five different timber surface finishes to respond to the variety in demand. From smooth to rough, they change the feel, literally, of the total frame. Standard
The most common finish. Our timber is normally dressed in our four-sided planer to be exactly square and dimensional, but for the stain to penetrate into the fibre, the timber surface will require further treatment. Super fine
Depending on how fine a finish is desired, it may be applied along with a finer-grid sanding, or we may use a hand planer to achieve the surface. This is our standard for “high-touch” applications like stairs or for anyone looking for finest surface quality. Comb finish
We raise the grain, for a patina effect to this finish. This is a great finish for those who want a bit of rustic feel yet desire a clean finish as well. Rough sawn finish
Sawmill surface, for a true rustic feel. Rough sawn timbers are the only ones we can’t put in the planer, so the surface planes may not be totally square (common in traditional timber framing). This adds to the rustic feel. Joinery may be somewhat less tight in this finish, although structural integrity is never compromised. Adze finish
The classic traditional finish, evoking a time before electric tools. We raise the grain, to give depth. A great finish for those who want a bit of rustic feel yet desire a clean finish as well. The faceted texture gives a warm, handmade feel.
A never-ending challenge at Daizen is to help both homeowners and associated building professionals understand the multi-layered, interdependent options in choosing timber for a building project. As they say, it’s not trivial.
Dai recently made a concerted effort to explore and demystify the several choices everyone faces when clarifying their vision of the ideal
dwelling (or other construction). The resulting eight-page article, Understanding the Timber, is now available for download from the Daizen website.
It’s worth your while to peruse this document. If you do, you’ll understand much better why there is no one answer to what seems to an outsider like such a simple question. In fact, wood is a profound personal choice.
Epoxy is a very reliable substance that bonds wood, steel, and stone. The epoxy itself must be precisely formulated for the specific materials it will bond. In our continued testing, we have found some epoxies that pass the test of a bond between wood and steel, and some that fail.
Here, at a Wood Works! BC conference in December, 2010, the steel rod broke (at 12) before the epoxy or the wood did.
Our testing apparatus.
Recently, we’ve been testing and using an epoxy fastening system from Japan that bonds wood, steel, and stone together. The other benefit of this system is its epoxy delivery method: it allows us to place all structural members and inject the epoxy afterwards. It injects from the middle of the rod, flows out from the end, and fills out from all the injection holes so we know the entire space is filled with epoxy, ensuring that the connection is properly done.
Above, square hole in the very bottom of the post, with the injection gun in place. The nose is within the wood, not visible.
Once the epoxy is applied, the only visible sign is a small square hole in the post bottom. We can leave as is or we can plug it with wood.
The Japanese diagram below explains how the epoxy is filled inside the timber by using red colored epoxy and two different types of rod. The rod comes in various lengths, and application is not limited just to a post connection.
