Solar Kiln

A Soggy Start Spring of 2008 was unusually wet, and I was trying to get a solar kiln built. Once the weather finally broke in May, we began ground preparation and dug the foundation footers. Soon after, the concrete slab was poured for a 28×24 storage building and an attached 12×12 solar kiln.

Building Alone I originally had someone lined up to help with construction, but he backed out right after the concrete was finished. I couldn’t stand to see the slab sitting empty, so I decided to start the build myself. I had already drawn the entire structure in AutoCAD, so I knew exactly what materials I needed. I ordered the lumber, framed the walls, and got them erected on my own.

Help Arrives Around that time, I learned my neighbor was a contractor — and he had time to help. He ordered the trusses, metal roofing, and siding. Since the project was practically in his backyard, it worked out well for both of us. They did excellent work, and together we got the exterior completed.

Interior Work Inside, I used a thin layer of spray foam to seal air gaps, followed by batt insulation. I did the same in the kiln. After researching proper kiln coatings, I used an aluminum‑based primer followed by Kiln Seal, a thick rubberized coating that has held up extremely well even at 140°F.

The kiln needed to reach at least 120°F for 6 hours to kill powder‑post beetles, so durability and heat retention were critical.

Automation & Controls I wanted more than just a passive kiln — I wanted control. I added:

A PLC to manage fan and vent operation based on temperature and humidity

An Arduino with temp/humidity sensors

Help from a robotics‑group mentor to handle the Arduino coding

A Raspberry Pi interface so I could monitor conditions from my computer

A 3‑phase fan motor with a variable‑frequency drive for adjustable airflow

The kiln design itself was based loosely on Wood Magazine Issue #70, but heavily modified to support automation and higher performance.

Result The finished structure is solid, efficient, and fully functional. The kiln reaches the temperatures needed for both drying lumber and killing pests, and the automated controls make it easy to manage. It remains one of the most technically involved and rewarding projects I’ve built.