Dry lumber kiln -- buying your first
by Eugene M. Wengert
Lumber drying is a very attractive valued-added processing operation. Almost every week, I am approached by someone that wants to look at the opportunities for “getting into lumber drying.” In this paper, I will cover a few of the considerations when purchasing a kiln for the first time. Additional information is contained in “Opportunities for Dehumidification Drying” from the Virginia Forest products Association (Sandston, VA), “Drying Oak Lumber” from the Forestry Department at the University of Wisconsin-Madison, and “Drying Southern Pine” from the Southeastern Lumber Manufacturers Assoc. Equipment manufacturers also have additional information. To talk to others who have recently gotten into the drying business, check the Sawing and Drying forum at WOODWEB. In short, I think that there is plenty of opportunity for well run, small- and medium-sized drying operations today.
By far the most important issue is the cost of drying-we dry lumber not to remove moisture but to make money!! Do not forget this. Lumber drying is a money making operation. The way you make money is to produce the highest possible, quality lumber. Drying time, energy usage, labor, and other expenses are small compared to the cost of quality loss. THINK QUALITY! There are many people drying lumber-it can be a jungle out there! But remember, in the jungle, the tiger starves last! Produce quality and you will survive easily.
The First Step
Incidentally, regarding financing, ALWAYS borrow as much money as possible, saving your cash to cover inventory costs, slow time periods, and so on. Cash flow can be a problem due to the cyclic nature of the wood business, so you need as much cash as you have available. Use a loan for the hardware. If you do indeed make a lot of money, then pay off the loan quickly, but ALWAYS maintain adequate cash reserves.
Your business plan would include the species and volumes of wood you plan to dry. It includes whether you will have title to the lumber or if your customers will have ownership. If you have title, then you must consider inventory expenses. Your plan would also indicate if you anticipate doing small custom drying. If you do, then your kilns, or at least one or two, should be very small to accommodate these small, yet very profitable, loads.
Contact your local Small Business Administration. Often your state university will have technical assistance, perhaps through the extension office. Many times the electric power companies will have business and technical assistance available too.
In brief, a few minutes spent planning can save you many headaches later on.
Certainly, the most popular small scale (under 2 million BF per year) dry kiln is the dehumidification dryer, powered by electricity. You are letting the power company do the energy generation for you (at a cost). There are other small scale kilns using hot water and hot air.
Talk to other kiln operators in your area or on WOODWEB to find out what success they have had. It is helpful when starting a business to have others around you that have the same or similar equipment. You will have access to others who can provide technical assistance. Should you have to hire a kiln operator as you increase in size, it is helpful to have more or less standard drying equipment.
Kiln Size. I think that one of the best kiln sizes is 25 MBF. It takes approximately 3 green truckloads to provide the green lumber and then, once dried, you have two truckloads of KD lumber. You also should consider a smaller kiln, maybe 2 or 3 MBF, to handle small custom jobs-no sense tying up your main kilns with a few feet of specialty products. Larger kilns often take too long to unload and load, for a small or medium sized business-kilns do not make money unless they are running!
I cannot recall anyone who wished that they had put in a larger kiln. But I know plenty of people who wished that they had smaller kilns! Smaller kilns offer more flexibility in what you can do. And for a small business, flexibility is often one more key to success-you can do what the “big guys” cannot do.
A very important concept is that almost everyone I have helped get into the drying business ends up adding more kilns within a year or two. So, in your initial planning, always give some thought to where you will put additional kilns.
Kiln Construction. I cannot think of any recent smaller kilns that used tracks for loading. Almost everyone uses fork-lift loaded kilns, often called package kilns. For very small kilns, manual loading may be used.
With the present cost of energy in North America, it is hard to financially justify saving much energy. Therefore, most kilns will have 4 inches of insulation maximum. However, some dehumidifier kilns will benefit from having 8 inches or more of insulation, because with electrical heat, we can afford to save energy. Because the fans are stirring up the air in the kiln, there is no need to increase the roof insulation much over the insulation level of the walls. However, a cold floor can be a source of tremendous heat loss as well as affect drying quality when high RHs are required. Therefore, always insulate the floor. This is most effectively done by keeping the soil under the concrete dry (which makes the soil a good insulator) and also insulating the perimeter of the foundation (usually using a piece of Styrofoam inserted vertically around the entire foundation.) Insulate the building in warm and cold climates.
The kiln building itself will usually have a concrete floor, which is sealed to prevent deterioration from acids and water. River rock is better than limestone.
The walls are either wood framed (typically with 2x8s) or are aluminum prefab kiln panels. The interior of the wood wall must be well sealed to prevent moisture from getting into the insulation. Use stainless nails. Many DH kiln manufacturers will have building plans. The aluminum kiln has two major advantages-long life and portability (that is, it can be moved in 20 years). Very seldom do kilns catch fire, so the fire hazard in a wooden kiln is not a large consideration.
In my experience, a commercial kiln door is better than any homemade door. Safety and durability are two advantages of the standard kiln door.
Kiln Controls. Absolutely, positively--get the best control system available. The control of kiln conditions is how you control quality. I prefer a computer controlled system. Remember that you are dealing with a valuable commodity in each kiln load. Perhaps you have $250,000 to protect in each kiln every year. Shouldn’t you spend a few dollars to assure that this value is well protected? Of course, even the perfect control system is not any good if the operator doesn’t use it according to the instructions, and according to established procedures for drying. The “tried and true” methods of drying have successfully dried billions of board feet of lumber annually for over 50 years; don’t ignore this proven track record.
Kiln Manufacturer. When choosing a kiln manufacturer, I suggest you zero in on one that you feel good about. Then take the specs from this company to any other potential suppliers and challenge them to meet or beat your first choice. Beware of false claims-check with previous customers. Make sure that anyone you contact is drying the same species, the same MC levels, and the same markets.
Kiln Operation. There are many 3 to 5 day kiln operators training schools, often sponsored by local universities (such as Oregon State here in the West). In addition, there are dry kiln operators educational associations throughout the U.S. and Canada that hold several meetings per year (for example, West Coast Dry Kiln Association). The Forest Products Society also has many texts on drying, including the “Drying Sourcebook: 40 Years of Experience.”
The drying operation also needs scales, an oven, an office to maintain records, a control room for the kiln controls, moisture meters, and other maintenance tools.
The typical drying operation will need some rolling stock for loading and unloading.
Once dried, the lumber will have to be taken off of sticks and stored in a dry location. Lumber storage in a closed shed will suffice for 2 to 4 weeks, depending on the exterior climate and the MC requirements of the customer.
Gene Wengert, Professor of Wood Processing, Emeritus, Univ of Wisconsin-Madison and President, The WoodDoctor's Rx, LLC, 2872 Charleston Drive, Madison, WI 53711-6502; 608-271-4441; Preferred e-mail: email@example.com
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