Starting a lumber drying kiln
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Lumber drying is an attractive valued-added business with plenty of opportunities for well run, small- and medium-sized drying operations.

The most important issue is the cost of drying we dry lumber to make money! The way to do that is to produce the highest quality lumber possible. Drying time, energy usage, labor, and other expenses are small compared to the cost of quality loss. Think quality!

1. Form a business plan

Planning now can save you headaches later and is critical if you need financing. It allows you to shape the future in a more logical and prudent manner. A plan should include your dreams, goals and realistic objectives.

If writing business plans is new to you, get a free copy of " A Planning Guide for Small and Medium Size Wood Products Companies: The Keys to Success " by Jeff Howe and Steve Bratkovich (Report NA-TP-09-95; US Forest Service, State & Private Forestry, U of MN, St. Paul, MN).

2. Set up financing

Always borrow as much money as possible, saving cash to cover inventory costs, slow periods, etc. Cash flow can be a problem due to the cyclic nature of the wood business, so you need as much cash as possible. Use a loan for the hardware. If you make a lot of money, then pay off the loan quickly, but always maintain adequate cash reserves.

3.  Decide on a power source

The biggest decision is how you will power your kilns. Will you go with a wood burning installation, which is rarely practical when drying less than 2 million BF per year? Will you use natural gas? Will you use electricity? Will you have go with steam heat or hot air?

The most popular small scale (less than 2 million BF per year) dry kiln is the dehumidification dryer, powered by electricity. There are other small-scale kilns using hot water and hot air.

It is helpful to have others around you that have the same or similar equipment. You'll need 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.

4.  Choose a kiln size

Figure out the best kiln size for your operation. It is seldom reasonable to mix species in the same kiln. This means that you need several small kilns rather than one big one, and the smallest suggested size is 10 or 12 MBF. Besides this main kiln, you might also consider a smaller kiln, maybe 2 or 3 MBF, to handle small custom jobs. Kilns larger than 25 MBF often take too long to unload and load for a small- or medium-sized business.

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.

Almost everyone I have helped get into the drying business ends up adding more kilns within a year or two. So, always give some thought to where you will put additional kilns.

5.  Construction

Almost everyone uses fork-lift loaded kilns, often called package kilns. For very small kilns, manual loading may be used.

Most kilns will have four inches of insulation maximum. Some dehumidifier kilns will benefit from having eight 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.

A cold floor can be a source of tremendous heat loss as well as affect drying quality when high RHs are required. Always insulate the floor. Keep the soil under the concrete dry (which makes the soil a good insulator) and insulate the perimeter of the foundation (usually using a piece of Styrofoam inserted vertically around the entire foundation.) Do this in all climates. The kiln building will usually have a concrete floor sealed to prevent deterioration from acids and water. River rock is better than limestone.

The walls are either wood-framed or 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. Very seldom do kilns catch fire, so the fire hazard is not a large consideration.

In my experience, a commercial kiln door is better than a homemade door. Safety and durability are two advantages of the standard kiln door.

6.  Control system

Get the best control system because that is how you control quality. I prefer a computer-controlled system. 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?

Even the perfect control system is not any good if the operator doesn't use it according to the instructions and established procedures for drying. The "tried and true" methods of drying have successfully dried billions of board feet of lumber annually for more than 50 years.

7.  Choosing a manufacturer

When choosing a kiln manufacturer, zero in on one that you feel good about. Take the specs from this company to 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, MC levels and markets.

8. Training

There are many three to five day kiln operator training schools, often sponsored by local universities. Dry kiln operators' educational associations throughout the United States and Canada hold several meetings per year. The Forest Products Society has texts on drying, including the "Drying Sourcebook: 40 Years of Experience."

9.  Other equipment

Drying requires facilities for stacking promptly. Green lumber left tightly piled will begin to lose color and develop stain within days at times. End checks are also more common after storage. Prompt handling is essential.

Once stacked, the lumber must be protected from excessive wind, sun and rain. Put green lumber in an open-sided shed to allow substantial reduction of moisture content without much risk of quality loss. Air drying has too much risk of loss.

The drying operation also needs scales, an oven, an office for records, a control room for controls, moisture meters and other maintenance tools. A typical operation needs 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 two to four weeks, depending on the exterior climate and the MC requirements of the customer.

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About the author
Gene Wengert

Gene Wengert, “The Wood Doctor” has been training people in efficient use of wood for 45 years. He is extension specialist emeritus at the University of Wisconsin-Madison.