How to Build a Kiln Dryer Box for Lumber

Wood that comes direct from a lumber yard for projects such as a deck or porch is often still green, or wet. If you build with green lumber you run the risk of it warping and cracking as it dries. Meanwhile, you will be unable to paint or stain it for several months, which means it might be exposed to the weather for a period. Building a quick PVC-pipe box to use as a kiln dryer allows you to avoid both problems as the dryer box will dry the wood in a week instead of leaving it alone for several months to dry naturally. When you are finished you can dismantle the box and either keep it for another time or recycle the components into other projects.

12 1/2-inch-diameter PVC pipes, 10 feet long
8 1/2-inch-diameter PVC 3-way connectors
Reciprocating saw
5 plastic or canvas tarps to match the sides of the dryer box
Ceramic electric space heater
Rotating pedestal fan
Extension cord with multiple outlets
Tent stakes and tent cord
Mallet
Large cup hook
4 concrete blocks

Instructions

- 1
  Stack the lumber where you can keep it out of the way for at least a week. To ensure that your box will fit the wood, you will build the dryer box around the stack -- so how big the dryer box will be is based upon the lumber dimensions. For example, if you are drying 8-foot lengths of 2-by-4 inch studs or standard 4-by-8 foot sheets of plywood, your box will have to be at least 10 feet long.
- 2
  Lay four PVC tubes on the ground around the lumber stack to make a rectangle. The margin should be at least 6 inches of space between the PVC and the lumber on three sides and 24 inches on the side you designate as the front. Don't worry about it being too long or wide, a few inches or even a few feet won't make a difference as long as there is adequate space around the edges.
- 3
  Slide the ends of each tube into one of the connectors, making a solid base. The connectors must have their third opening pointing upward. Drive tent stakes along each side and wrap the PVC tubes with 24 inches of cord tied to the stakes to keep the box from blowing away in the wind.
- 4
  Cut four PVC pipes so that, when they are set into each corner connector, the height of the pipes will be about 12 inches higher than the high point of the lumber stack.
- 5
  Cut four PVC pipes to match the base if necessary and connect them to the four corner pieces, making a complete cube.
- 6
  Tie a tarp to the top and three sides of the box, leaving the front open. Depending upon the size of the box and your tarps you may need multiple tarps. Do not worry about small gaps between the tarp and the box frame; they are necessary for ventilation. Do try to avoid having any gaps pointing directly upward so that rain does not get in any more than necessary.
- 7
  Set the four concrete blocks on the grass to provide a base for the fan and heater. Place the heater so that the fan blows the output from the heater over the lumber.
- 8
  Twist the cup hook into one of the corner posts about 3 feet high until it is secure. Hang the extension cord onto the cup hook so that the outlets are at least 2 feet off the ground. Plug in the fan and heater and turn them on. Test to make sure the heat is blowing directly toward the lumber.
- 9
  Tie a tarp to the front of the box, leaving one side loose enough so that you can access the inside of the drying box to check on the lumber and the appliances.

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