Many sawmills will tend to add on kilns to their operations to value add to their existing products. After a kiln, many sawmills will look to add even more value to their products by machining the lumber, be it S4S (surfaced 4 sides), adding tongue and grooves, shiplaps, or other profiles by using a molding machine. At Loxaco, we’ve already got the millwork shop set up and we process a few thousand board feet of lumber a week. As we grow, I’m looking to begin processing our own lumber.

How we’d use a kiln

Last year, I added a turbosawmill to our operation. It’s an awesome swing blade sawmill. I’ll go more in depth on the sawmill in future posts. More about our sawmill services can be found here.

However, now we’re making our own lumber. This was step one. To fully capitalize on this in the way I see it, we need to be able to kiln dry and heat treat our lumber. Kiln drying is simply drying the wet, green lumber in a controlled manor to minimize drying defects and to get the final moisture content down to be equal to the wood already inside your home. The heat treating aspect of this make sure any bugs, larvae, or eggs are killed. This makes sure that boring beetles, termites, and the likes are not introduced into the home.

Parts of a kiln

Wood drying kilns can be broken down into two parts – the insulated box and the controls. Last year, I was able to purchase the controls from another mill that was reducing their operations. The controller was a Nyle L200S dehumidification kiln that came with 8 fans. That’s enough fans for a 40 foot shipping container. Since then I’ve been trying to figure out whether I should build a kiln or buy a shipping container. I went back and forth on it. Here’s some of the pros and cons of each.

Used insulated reefer containers

If I were to buy an 40′ insulated shipping container, it would cost around $8,000 at a nearby port and would cost just under $1,000 to get it delivered to me. Once it’s here, I would have to buy or build a trolley system and carts for efficiently loading and unloading the kiln. I could purchase them on Nyle’s website for around $8,000, plus shipping. After that I’d have to wire it up and also build the fan wall, which would be the same for a homemade kiln. A 40′ high cube insulated reefer container would allow me to hold around 5,000 board feet of 4/4 lumber.

Designing the box

If I were to build the kiln box, it would be a front loading design, so the trolley and cart system would be unnecessary. That means I don’t need 80′ of space dedicated to the kiln (the trolley tracks extend 40′ outside of the kiln for loading/unloading). That’s a bunch of money saved right there. It would take my time to build, which is valuable. I figured on 2 weeks to build it. As part of the design constraints, I would want to be able to move it with a flatbed trailer. That means on a flatbed, it can’t be over 13′-6″ tall or over 12′ wide. Most flatbeds are around 3′ tall, so my max height can’t be over 10′-6″. For my purposes, I settled on a 9′ x 24′ footprint with a simple shed roof. It’ll wind up just over 9′ tall at the highest point, so moving it on a flatbed is no problem.

Getting estimates

After I came up with a design, I created lumber take offs and got some estimates on the lumber package. I considered cutting all my own lumber and then buying the panel products, but that would require even more of my limited time, so I opted to just purchase everything. The initial lumber quote came back at $4,500. That’s doable. I then called a few spray foam companies to get pricing on spray foam. Pricing came back around $4,500 also. I figure I’ll have a few hundred in hardware (door hinges), gasketing, and wiring for the fans. All in, I expect to be under $10k for the homemade kiln box. Based on this size box, I figure I can get around 2700bf of 4/4 lumber in the kiln.

Determining how much I can dry

Another big design component is: what will I be drying and how much of that lumber can the kiln controller handle per load? Simply put, different wood species dry faster and slower. Faster drying wood species put more moisture into the air as they’re drying than slower species, and at some point, there’s more moisture in the air than the dehumidifier can keep up with. This can lead to mold grown on the lumber. The specs on the Nyle L200S put the maximum board footages at 1,500bf of faster drying lumber or up to 4,000bf of slower drying species. At this point, the majority of what I plan to be cutting will be pine, which is a faster drying species. That means my max loads of green lumber should be 1,500bf.

Wasted space per load

The shipping container kiln can hold up to 5,000bf of lumber, but based on my dehumidifier unit, I could only load it with 1,500bf. Lots of empty space. In contrast, if I do the homemade kiln, it maxes out at 2,700bf, so not near as much wasted space on each load. Seems like the smaller homemade kiln will better suit our purposes.

Additional kilns in the future

One last item I considered was future use. My intention is to keep growing Loxaco. I expect that one kiln won’t be enough and that we’ll need to add a second kiln in the future. To add a second shipping container setup, I’d need another 80′ x 9′ area. Where I’m currently at, this would be very hard to come by. In contrast, I could add two more homemade kilns in the footprint of just one container kiln.

Homemade it is!

After considering all of that, which is a lot to consider, it seems pretty clear that the homemade kiln would be the way to go. I don’t really have the time to devote two weeks to the build, but at least with the holidays, we have a slight lull to where I can focus on the build without too many distractions. I guess it’s time to get some lumber ordered!