First, kudos to Dr. Brian Bond, students, and staff at Virginia Tech (VT) Department of Wood Science and Forest Products for developing a solar kiln and providing the well-written plans at:
I, of course, modified the VT plans. The solar kiln is basically a box with a greenhouse roof that generates hot air with a internal solar collector. The hot air is blown through the wood with two (2) fans. A load of wood should take approximately one (1) month to dry.
Revision for correct air circulation: I had initially installed the fans on the outside of the kiln, blowing cool, outside air into the kiln. After visiting the sawmill which had two (2) solar kilns and rereading the VT plans, I realized that the fans should be installed inside the kiln to recirculate the heated air within the kiln. Blowing in cool air would lower the kiln temperature too much and reduce the drying effectiveness. I constructed and installed an interior baffle with the fans mounted on the baffle and cut holes in the solar collector to allow for recirculation. It would have been easier to construct the baffle prior to installing the greenhouse roof but live and learn. Refer to Step 9 for baffle installation.
The kiln is also made completely solar with the addition of a photovoltaic solar panel shown in Step 10.
The wood is being dried to build an 18 foot Grand Banks dory which will used to haul picnic supplies and picnic princesses to islands offf the coast of Maine. Google the Maine Island Trail Association to get a sense of the place. Building a kiln before building the boat in order to haul picnic supplies is my typical, over-zealous approach.
Thanks to all who voted for my Instructable in the Green Contest.
List of materials:
Enough wood to build structure - I used a combination of new and salvaged materials so don't have a list; the longer pieces and treated lumber were store bought
plywood - 3/4 inch thick, exterior grade, 2 sheets
Polygal and brackets - 10 ft x 6 ft piece; cut in half
flashing - aluminum
styrofoam insulation - 2 in thick, 2 sheets
Reflectix bubble wrap insulation
DC fans - 2, 16 inch with ring frame
GRK screws - exterior grade; various lengths
paint - green for solar collector
photovoltaic solar panel - 65 watts
Step 1: Building the Base or Floor
The first question when building anything is where are you going to position it. A solar structure needs as much direct sun as possible and your neighbor may not be so keen on you cutting down their trees, even for a "green" project. I also positioned it uphill and adjacent to our workshop/garage to allow future duct work from the kiln to heat the workshop when not drying wood or other items. The position is a compromise between these functions.
The "foundation" is limestone blocks on the uphill side and a treated 4 inch by 6 inch posts on the downhill side. I set the floor level so that future duct work would intersect the adjacent workshop without hitting any wall supports.
Also my relatives on Fogo Island off the north coast of Newfoundland, had a sport of moving houses. Refer to the excellent book titled "Tilting - house launching, slide hauling, potato trenching, and other tales from a Newfoundland fishing village" by Robert Mellin for more information on this "sport. " I constructed the kiln so that it could be moved, if needed.
The next question is size. The VT plans use a base with dimensions of 160 inch by 78 inch but I reduced the dimensions to 144inches by 48 inches or 12 feet by 4 feet. I choose these dimensions to reduce building costs and the roof panels have a combined width of 12 feet and a plywood sheet is 4 feet wide.
The base is constructed of 4 inch by 6 inch treated lumber cut to a length of 11 feet 9 inches. All wood near the ground is treated lumber due to termite issues in our area. I used 2 inch by 6 inch by 4 feet long treated boards and screwed them the ends of the 11 feet 9 inches timbers to create a 12 foot by 4 foot box. Measure twice and cut once is the old carpentry policy.
Within this box, I installed cross-members. The 2 inch by 6 inch boards are connected with Simpson Strong-Tie connectors using Simpson nails (http://www.strongtie.com/). It won't be to building code without the Simpson nails. (A neighbor's contractor had to remove and replace all the wrong nails on a project of theirs; the weight of the structure is borne by these nails.) I also used leftover 4 inch by 6 inch material and attached with galvanized lag screws. I counter-sunk the lag screws so that siding could be placed over the screws.