Man has used fire to escape winter's chill since primitive times. Today, technology allows you to use a solar kiln when weather, moisture or dry-rot inhibit your wood's ability to light. Solar kilns efficiently dry firewood and protect your cache from the elements. The kiln, a wooden structure the size of a shed, traps and insulates sunlight as solar powered fans ventilate the accumulated humidity. Construct a solar kiln using inexpensive materials and operate it without electricity.
Lay the pressure-treated 50-by-150-mm (2-by-6-inch) boards on the ground to frame a floor. Center the 50-by-150-mm (2-by-6-inch) every 40 cm (16 inches) to the floor joist. Secure the frame with two nails in each stud.
Place 9-mm (3/8-inch) exterior-grade plywood over the floor frame and secure with nails to create the floor of the kiln.
Frame the east and west walls centring 50-by-100-mm (2-by-4-inch) studs every 40 cm (16 inches) to the wall joists. The roof joists of these walls will taper at a 45-degree angle so it is essential to construct the frame lying on the ground. Secure each stud with two nails.
Frame the shorter north and south walls, centring 50-by-100-mm (2-by-4-inch) studs every 40 cm (16 inches) to the wall joists, to fit inside the frame of the east and west walls. The north wall should be equal in height to the south wall, built to accommodate the glazing. The north wall is the cripple for the loading door.
Frame a fifth wall to fit under the north facing cripple, onto the floor, and into the east and west walls. Center 50-by-100-mm (2-by-4-inch) studs every 40 cm (16 inches). This will serve as the loading door. Secure the loading door to the frame of the east and west walls with screws, hinges, and a latch.
Cut and nail 9-mm (3/8-inch) exterior-grade plywood to the outside of the frame to create the outer walls.
Roll batt insulation inside the frame of the kiln and cover with .06 millimetre thick plastic sheeting to seal moisture.
Create the inside wall by nailing 9 mm (3/8-inch) exterior-grade plywood to the frame, covering the plastic and batt insulation.
Paint the inside of the roofless kiln with two coats of black rubber-based concrete sealer to lock out moisture and effectively capture light. Let dry.
Secure the glazing with a light frame built for the roof, which is set at a 45-degree angle.
Cut four vents into the cripple of the north wall and hang three plastic solar-powered electric fans 45 cm (18 inches) from the vents using a baffle. The air flow of the fans will face the glazing.
Seal the outside of the kiln with wood stain to protect the kiln and firewood from the elements.
Check the weather. Letting the sealant and the stain dry is essential. The glazing should face south for the most effective orientation to the sun. Crack the loading door a bit when not operating. Temperatures can reach excess and melt the plastic fans.
Things you need
- Pressure-treated 50-by-150-mm (2-by-6-inch) studs
- 50-by-100-mm (2-by-4-inch) studs
- 9-mm (3/8-inch) exterior-grade plywood
- Glazing, greenhouse rated corrugated polycarbonate
- Framing nails
- Door latch designed for a shed
- Batt insulation
- .06mm plastic film
- Rubber based concrete sealer
- Outdoor wood stain
- 3 plastic solar-powered fans
- Carpenter's pencil
- Tape measure
- Framing square