Solar kiln #1: from design to construction

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Blog entry by Julian posted 10-27-2008 10:55 PM 14224 reads 11 times favorited 12 comments Add to Favorites Watch
no previous part Part 1 of Solar kiln series Part 2: loading the charge »

A few years ago, I had the idea of building a small solar kiln. Well, life happened, and I didn’t have the time or money to build one. Then two weeks ago, my neighbor had a red elm cut down that had been struck by lighning earlier in the spring. I figured that a beautiful elm tree would never just fall into my lap, so I had the tree removal service roll the 8’, 30”+ main trunk into my front yard. After having it milled, I realized that I couldn’t wait an entire year to work with such a beautiful wood, so now the solar kiln is finally becoming a reality.

Here’s a rough plan I designed in sketchup. It was actually the first thing I designed using sketchup, and I must say that the program is excellent! The kiln deck measures 4×10. The rear wall is 5’, and the front wall is 1’, making the roof 45 degrees angled to the south. It will be just large enough to fit 200-250 bf of lumber, which is perfect for my small scale needs.

I used 11 7/8 lvl’s and I joists for the deck, and 2×4’s for the walls. The whole thing was sheated with 3/8 plywood( on sale for only 8$ a sheet!), then insulated and plastic wrapped. The inside was caulked and so far has a coat of alumized roof coating. My plan is to have a double layer of plastic sheathing 3 1/2” apart for the top for now, and in the spring will use clear corrugated fiberglass. The top, which is not yet finished, will be on hinges in back, and lift up for access.

Hopefully, I will have this kiln completed and ready for a charge of red elm by the weekend.

-- Julian, Park Forest, IL

12 comments so far

View Scott Bryan's profile

Scott Bryan

27250 posts in 3998 days

#1 posted 10-27-2008 11:37 PM

This looks like an interesting project. Keep us posted on how the drying goes.

-- Challenges are what make life interesting; overcoming them is what makes life meaningful- Joshua Marine

View darryl's profile


1795 posts in 4502 days

#2 posted 10-27-2008 11:45 PM

that’s really cool. “one of these days” I would also like to make one of these.

View jerryw's profile


158 posts in 4092 days

#3 posted 10-28-2008 04:32 AM

i use one of our greenhouses to dry wood . in the spring [ june] when the bedding plant are gone i stick green or air dried hardwoods in the greenhouse. i just took some ash out to check it that was put in about mid june. my moisture meter said 8 %. this ash was air dried outside for a couple of months before going into the greenhouse.
you may need vents in the front of your solar kiln so the air flows thru the sticked lumber and out the top back. cover the top of the pile with something to keep the sun off the lumber. i use a sheet of foam insulation. lumber goes thru a lot of stress during drying and the sun directly on the top board makes the wood do baaaaaad things.
you may need a fan or two in the top back hurry things up.

-- jerryw-wva.

View Julian's profile


880 posts in 3701 days

#4 posted 10-28-2008 08:03 PM

I plan on setting up a baffle, with a fan in the middle of it. I have a sheet of plywood left over that will be used to cover the lumber.

-- Julian, Park Forest, IL

View Julian's profile


880 posts in 3701 days

#5 posted 10-29-2008 03:43 AM

The weather was just warm enough for the aluminized roof coat to cure today, so I went ahead and painted the interior flat black. If I don’t get home from work too late tomorrow, I’ll try and get the top finished, and get the weatherstrip on so I can get this thing close to air tight. With some more luck, I hope to have the baffle, and fan installed this week.

On another note, I have found somebody in a nearby town with 2-2’x11’ black walnut logs that have been air drying for a few years on some blocks. I just might be getting them both for $100. Thats only 50$ EACH!!

-- Julian, Park Forest, IL

View Karson's profile


35140 posts in 4576 days

#6 posted 11-06-2008 04:24 AM

Great looking kiln and great catch on the wood.

-- I've been blessed with a father who liked to tinker in wood, and a wife who lets me tinker in wood. Appomattox Virginia †

View douglbe's profile


369 posts in 4137 days

#7 posted 11-06-2008 05:32 AM

I’ve been gathering a few materials and hopefully I can start on a solar kiln one of these days, been thinking about one for over a year now. Mostly, it’s finding the time. Your kiln is exactly what would fit my bill. Keep the posts coming.

-- Doug, Reed City, Michigan

View Julian's profile


880 posts in 3701 days

#8 posted 11-06-2008 05:33 AM

I let this wood air dry for a few weeks. I am under the impression that the mild weather won’t cause the wood to dry too quickly, so I am not too worried about it. If the weather was warmer out, then I would have let it air dry for at least 30 days.

-- Julian, Park Forest, IL

View Arnold's profile


215 posts in 3738 days

#9 posted 11-15-2008 04:14 PM


View gbvinc's profile


628 posts in 4122 days

#10 posted 02-25-2009 06:02 PM

Now that you have pulled your first load from the kiln, are there any design changes you would suggest for the kiln, or do you like it as is?

View Tim Pletcher's profile

Tim Pletcher

90 posts in 3250 days

#11 posted 01-14-2010 05:51 PM

does it work well????


View Julian's profile


880 posts in 3701 days

#12 posted 01-17-2010 03:08 AM

Yes it works just fine and even works in the dead of winter.

-- Julian, Park Forest, IL

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